forked from Minki/linux
2505a98111
604 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Filipe Manana
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f6df27dd27 |
btrfs: do not commit delayed inode when logging a file in full sync mode
When logging a regular file in full sync mode, we are currently committing its delayed inode item. This is to ensure that we never miss copying the inode item, with its most up to date data, into the log tree. However that is not necessary since commit |
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Filipe Manana
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5328b2a7ff |
btrfs: avoid attempt to drop extents when logging inode for the first time
When logging an extent, in the fast fsync path, we always attempt do drop or trim any existing extents with a range that match or overlap the range of the extent we are about to log. We do that through a call to btrfs_drop_extents(). However this is not needed when we are logging the inode for the first time in the current transaction, since we have no inode items of the inode in the log tree. Calling btrfs_drop_extents() does a deletion search on the log tree, which is expensive when we have concurrent tasks accessing the log tree because a deletion search always acquires a write lock on the extent buffers at levels 2, 1 and 0, adding significant lock contention, specially taking into account the height of a log tree rarely (if ever) goes beyond 2 or 3, due to its short life. So skip the call to btrfs_drop_extents() when the inode was not previously logged in the current transaction. This patch is part of a patch set comprised of the following patches: btrfs: check if a log tree exists at inode_logged() btrfs: remove no longer needed checks for NULL log context btrfs: do not log new dentries when logging that a new name exists btrfs: always update the logged transaction when logging new names btrfs: avoid expensive search when dropping inode items from log btrfs: add helper to truncate inode items when logging inode btrfs: avoid expensive search when truncating inode items from the log btrfs: avoid search for logged i_size when logging inode if possible btrfs: avoid attempt to drop extents when logging inode for the first time btrfs: do not commit delayed inode when logging a file in full sync mode This is patch 9/10 and test results are listed in the change log of the last patch in the set. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
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a5c733a4b6 |
btrfs: avoid search for logged i_size when logging inode if possible
If we are logging that an inode exists and the inode was not logged before, we can avoid searching in the log tree for the inode item since we know it does not exists. That wastes time and adds more lock contention on the extent buffers of the log tree when there are other tasks that are logging other inodes. This patch is part of a patch set comprised of the following patches: btrfs: check if a log tree exists at inode_logged() btrfs: remove no longer needed checks for NULL log context btrfs: do not log new dentries when logging that a new name exists btrfs: always update the logged transaction when logging new names btrfs: avoid expensive search when dropping inode items from log btrfs: add helper to truncate inode items when logging inode btrfs: avoid expensive search when truncating inode items from the log btrfs: avoid search for logged i_size when logging inode if possible btrfs: avoid attempt to drop extents when logging inode for the first time btrfs: do not commit delayed inode when logging a file in full sync mode This is patch 8/10 and test results are listed in the change log of the last patch in the set. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
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4934a81502 |
btrfs: avoid expensive search when truncating inode items from the log
Whenever we are logging a file inode in full sync mode we call btrfs_truncate_inode_items() to delete items of the inode we may have previously logged. That results in doing a btree search for deletion, which is expensive because it always acquires write locks for extent buffers at levels 2, 1 and 0, and it balances any node that is less than half full. Acquiring the write locks can block the task if the extent buffers are already locked by another task or block other tasks attempting to lock them, which is specially bad in case of log trees since they are small due to their short life, with a root node at a level typically not greater than level 2. If we know that we are logging the inode for the first time in the current transaction, we can skip the call to btrfs_truncate_inode_items(), avoiding the deletion search. This change does that. This patch is part of a patch set comprised of the following patches: btrfs: check if a log tree exists at inode_logged() btrfs: remove no longer needed checks for NULL log context btrfs: do not log new dentries when logging that a new name exists btrfs: always update the logged transaction when logging new names btrfs: avoid expensive search when dropping inode items from log btrfs: add helper to truncate inode items when logging inode btrfs: avoid expensive search when truncating inode items from the log btrfs: avoid search for logged i_size when logging inode if possible btrfs: avoid attempt to drop extents when logging inode for the first time btrfs: do not commit delayed inode when logging a file in full sync mode This is patch 7/10 and test results are listed in the change log of the last patch in the set. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
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8a2b3da191 |
btrfs: add helper to truncate inode items when logging inode
Move the call to btrfs_truncate_inode_items(), and the surrounding retry loop, into a local helper function. This avoids some repetition and avoids making the next change a bit awkward due to a bit of too much indentation. This patch is part of a patch set comprised of the following patches: btrfs: check if a log tree exists at inode_logged() btrfs: remove no longer needed checks for NULL log context btrfs: do not log new dentries when logging that a new name exists btrfs: always update the logged transaction when logging new names btrfs: avoid expensive search when dropping inode items from log btrfs: add helper to truncate inode items when logging inode btrfs: avoid expensive search when truncating inode items from the log btrfs: avoid search for logged i_size when logging inode if possible btrfs: avoid attempt to drop extents when logging inode for the first time btrfs: do not commit delayed inode when logging a file in full sync mode This is patch 6/10 and test results are listed in the change log of the last patch in the set. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
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88e221cdac |
btrfs: avoid expensive search when dropping inode items from log
Whenever we are logging a directory inode, logging that an inode exists or logging an inode that has changes in its references or xattrs, we attempt to delete items of this inode we may have previously logged (through calls to drop_objectid_items()). That attempt does a btree search for deletion, which is expensive because it always acquires write locks for extent buffers at levels 2, 1 and 0, and it balances any node that is less than half full. Acquiring the write locks can block the task if the extent buffers are already locked or block other tasks attempting to lock them, which is specially bad in case of log trees since they are small due to their short life, with a root node at a level typically not greater than level 2. If we know that we are logging the inode for the first time in the current transaction, we can skip the search. This change does that. This patch is part of a patch set comprised of the following patches: btrfs: check if a log tree exists at inode_logged() btrfs: remove no longer needed checks for NULL log context btrfs: do not log new dentries when logging that a new name exists btrfs: always update the logged transaction when logging new names btrfs: avoid expensive search when dropping inode items from log btrfs: add helper to truncate inode items when logging inode btrfs: avoid expensive search when truncating inode items from the log btrfs: avoid search for logged i_size when logging inode if possible btrfs: avoid attempt to drop extents when logging inode for the first time btrfs: do not commit delayed inode when logging a file in full sync mode This is patch 5/10 and test results are listed in the change log of the last patch in the set. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
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130341be7f |
btrfs: always update the logged transaction when logging new names
When we are logging a new name for an inode, due to a link or rename
operation, if the inode has ancestor inodes that are new, created in the
current transaction, we need to log that these inodes exist. To ensure
that a subsequent explicit fsync on one of these ancestor inodes does
sync the log, we don't set the logged_trans field of these inodes.
This was done in commit
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Filipe Manana
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c48792c6ee |
btrfs: do not log new dentries when logging that a new name exists
When logging a new name for an inode, due to a link or rename operation, we don't need to log all new dentries of the parent directories and their subdirectories. We only want to log the names of the inode and that any new parent directories exist. So in this case don't trigger logging of the new dentries, that is only need when doing an explicit fsync on a directory or on a file which requires logging its parent directories. This avoids unnecessary work and reduces contention on the extent buffers of a log tree. This patch is part of a patch set comprised of the following patches: btrfs: check if a log tree exists at inode_logged() btrfs: remove no longer needed checks for NULL log context btrfs: do not log new dentries when logging that a new name exists btrfs: always update the logged transaction when logging new names btrfs: avoid expensive search when dropping inode items from log btrfs: add helper to truncate inode items when logging inode btrfs: avoid expensive search when truncating inode items from the log btrfs: avoid search for logged i_size when logging inode if possible btrfs: avoid attempt to drop extents when logging inode for the first time btrfs: do not commit delayed inode when logging a file in full sync mode This is patch 3/10 and test results are listed in the change log of the last patch in the set. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
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289cffcb03 |
btrfs: remove no longer needed checks for NULL log context
Since commit
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Filipe Manana
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1e0860f3b3 |
btrfs: check if a log tree exists at inode_logged()
In case an inode was never logged since it was loaded from disk and was modified in the current transaction (its ->last_trans matches the ID of the current transaction), inode_logged() returns true even if there's no existing log tree. In this case we can simply check if a log tree exists and return false if it does not. This avoids a caller of inode_logged() doing some unnecessary, but harmless, work. For btrfs_log_new_name() it avoids it logging an inode in case it was never logged since it was loaded from disk and there is currently no log tree for the inode's root. For the remaining callers of inode_logged(), btrfs_del_dir_entries_in_log() and btrfs_del_inode_ref_in_log(), it has no effect since they already check if a log tree exists through their calls to join_running_log_trans(). So just add a check to inode_logged() to verify if a log tree exists, and return false if it does not. This patch is part of a patch set comprised of the following patches: btrfs: check if a log tree exists at inode_logged() btrfs: remove no longer needed checks for NULL log context btrfs: do not log new dentries when logging that a new name exists btrfs: always update the logged transaction when logging new names btrfs: avoid expensive search when dropping inode items from log btrfs: add helper to truncate inode items when logging inode btrfs: avoid expensive search when truncating inode items from the log btrfs: avoid search for logged i_size when logging inode if possible btrfs: avoid attempt to drop extents when logging inode for the first time btrfs: do not commit delayed inode when logging a file in full sync mode This is patch 1/10 and test results are listed in the change log of the last patch in the set. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
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cfd312695b |
btrfs: check for error when looking up inode during dir entry replay
At replay_one_name(), we are treating any error from btrfs_lookup_inode() as if the inode does not exists. Fix this by checking for an error and returning it to the caller. CC: stable@vger.kernel.org # 4.14+ Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
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8dcbc26194 |
btrfs: unify lookup return value when dir entry is missing
btrfs_lookup_dir_index_item() and btrfs_lookup_dir_item() lookup for dir entries and both are used during log replay or when updating a log tree during an unlink. However when the dir item does not exists, btrfs_lookup_dir_item() returns NULL while btrfs_lookup_dir_index_item() returns PTR_ERR(-ENOENT), and if the dir item exists but there is no matching entry for a given name or index, both return NULL. This makes the call sites during log replay to be more verbose than necessary and it makes it easy to miss this slight difference. Since we don't need to distinguish between those two cases, make btrfs_lookup_dir_index_item() always return NULL when there is no matching directory entry - either because there isn't any dir entry or because there is one but it does not match the given name and index. Also rename the argument 'objectid' of btrfs_lookup_dir_index_item() to 'index' since it is supposed to match an index number, and the name 'objectid' is not very good because it can easily be confused with an inode number (like the inode number a dir entry points to). CC: stable@vger.kernel.org # 4.14+ Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
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52db77791f |
btrfs: deal with errors when adding inode reference during log replay
At __inode_add_ref(), we treating any error returned from btrfs_lookup_dir_item() or from btrfs_lookup_dir_index_item() as meaning that there is no existing directory entry in the fs/subvolume tree. This is not correct since we can get errors such as, for example, -EIO when reading extent buffers while searching the fs/subvolume's btree. So fix that and return the error to the caller when it is not -ENOENT. CC: stable@vger.kernel.org # 4.14+ Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
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e15ac64137 |
btrfs: deal with errors when replaying dir entry during log replay
At replay_one_one(), we are treating any error returned from btrfs_lookup_dir_item() or from btrfs_lookup_dir_index_item() as meaning that there is no existing directory entry in the fs/subvolume tree. This is not correct since we can get errors such as, for example, -EIO when reading extent buffers while searching the fs/subvolume's btree. So fix that and return the error to the caller when it is not -ENOENT. CC: stable@vger.kernel.org # 4.14+ Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
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77a5b9e3d1 |
btrfs: deal with errors when checking if a dir entry exists during log replay
Currently inode_in_dir() ignores errors returned from btrfs_lookup_dir_index_item() and from btrfs_lookup_dir_item(), treating any errors as if the directory entry does not exists in the fs/subvolume tree, which is obviously not correct, as we can get errors such as -EIO when reading extent buffers while searching the fs/subvolume's tree. Fix that by making inode_in_dir() return the errors and making its only caller, add_inode_ref(), deal with returned errors as well. Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Marcos Paulo de Souza
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3736127a3a |
btrfs: tree-log: check btrfs_lookup_data_extent return value
Function btrfs_lookup_data_extent calls btrfs_search_slot to verify if the EXTENT_ITEM exists in the extent tree. btrfs_search_slot can return values bellow zero if an error happened. Function replay_one_extent currently checks if the search found something (0 returned) and increments the reference, and if not, it seems to evaluate as 'not found'. Fix the condition by checking if the value was bellow zero and return early. Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
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8be2ba2e0e |
btrfs: avoid unnecessarily logging directories that had no changes
There are several cases where when logging an inode we need to log its parent directories or logging subdirectories when logging a directory. There are cases however where we end up logging a directory even if it was not changed in the current transaction, no dentries added or removed since the last transaction. While this is harmless from a functional point of view, it is a waste time as it brings no advantage. One example where this is triggered is the following: $ mkfs.btrfs -f /dev/sdc $ mount /dev/sdc /mnt $ mkdir /mnt/A $ mkdir /mnt/B $ mkdir /mnt/C $ touch /mnt/A/foo $ ln /mnt/A/foo /mnt/B/bar $ ln /mnt/A/foo /mnt/C/baz $ sync $ rm -f /mnt/A/foo $ xfs_io -c "fsync" /mnt/B/bar This last fsync ends up logging directories A, B and C, however we only need to log directory A, as B and C were not changed since the last transaction commit. So fix this by changing need_log_inode(), to return false in case the given inode is a directory and has a ->last_trans value smaller than the current transaction's ID. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
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1f29537302 |
btrfs: update comment at log_conflicting_inodes()
A comment at log_conflicting_inodes() mentions that we check the inode's
logged_trans field instead of using btrfs_inode_in_log() because the field
last_log_commit is not updated when we log that an inode exists and the
inode has the full sync flag (BTRFS_INODE_NEEDS_FULL_SYNC) set. The part
about the full sync flag is not true anymore since commit
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Filipe Manana
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d135a53396 |
btrfs: remove no longer needed full sync flag check at inode_logged()
Now that we are checking if the inode's logged_trans is 0 to detect the possibility of the inode having been evicted and reloaded, the test for the full sync flag (BTRFS_INODE_NEEDS_FULL_SYNC) is no longer needed at tree-log.c:inode_logged(). Its purpose was to detect the possibility of a previous eviction as well, since when an inode is loaded the full sync flag is always set on it (and only cleared after the inode is logged). So just remove the check and update the comment. The check for the inode's logged_trans being 0 was added recently by the patch with the subject "btrfs: eliminate some false positives when checking if inode was logged". Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Boris Burkov
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77eea05e78 |
btrfs: add ro compat flags to inodes
Currently, inode flags are fully backwards incompatible in btrfs. If we introduce a new inode flag, then tree-checker will detect it and fail. This can even cause us to fail to mount entirely. To make it possible to introduce new flags which can be read-only compatible, like VERITY, we add new ro flags to btrfs without treating them quite so harshly in tree-checker. A read-only file system can survive an unexpected flag, and can be mounted. As for the implementation, it unfortunately gets a little complicated. The on-disk representation of the inode, btrfs_inode_item, has an __le64 for flags but the in-memory representation, btrfs_inode, uses a u32. David Sterba had the nice idea that we could reclaim those wasted 32 bits on disk and use them for the new ro_compat flags. It turns out that the tree-checker code which checks for unknown flags is broken, and ignores the upper 32 bits we are hoping to use. The issue is that the flags use the literal 1 rather than 1ULL, so the flags are signed ints, and one of them is specifically (1 << 31). As a result, the mask which ORs the flags is a negative integer on machines where int is 32 bit twos complement. When tree-checker evaluates the expression: btrfs_inode_flags(leaf, iitem) & ~BTRFS_INODE_FLAG_MASK) The mask is something like 0x80000abc, which gets promoted to u64 with sign extension to 0xffffffff80000abc. Negating that 64 bit mask leaves all the upper bits zeroed, and we can't detect unexpected flags. This suggests that we can't use those bits after all. Luckily, we have good reason to believe that they are zero anyway. Inode flags are metadata, which is always checksummed, so any bit flips that would introduce 1s would cause a checksum failure anyway (excluding the improbable case of the checksum getting corrupted exactly badly). Further, unless the 1 << 31 flag is used, the cast to u64 of the 32 bit inode flag should preserve its value and not add leading zeroes (at least for twos complement). The only place that flag (BTRFS_INODE_ROOT_ITEM_INIT) is used is in a special inode embedded in the root item, and indeed for that inode we see 0xffffffff80000000 as the flags on disk. However, that inode is never seen by tree checker, nor is it used in a context where verity might be meaningful. Theoretically, a future ro flag might cause trouble on that inode, so we should proactively clean up that mess before it does. With the introduction of the new ro flags, keep two separate unsigned masks and check them against the appropriate u32. Since we no longer run afoul of sign extension, this also stops writing out 0xffffffff80000000 in root_item inodes going forward. Signed-off-by: Boris Burkov <boris@bur.io> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
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6e8e777deb |
btrfs: eliminate some false positives when checking if inode was logged
When checking if an inode was previously logged in the current transaction through the helper inode_logged(), we can return some false positives that can be easily eliminated. These correspond to the cases where an inode has a ->logged_trans value that is not zero and its value is smaller then the ID of the current transaction. This means we know exactly that the inode was never logged before in the current transaction, so we can return false and avoid the callers to do extra work: 1) Having btrfs_del_dir_entries_in_log() and btrfs_del_inode_ref_in_log() unnecessarily join a log transaction and do deletion searches in a log tree that will not find anything. This just adds unnecessary contention on extent buffer locks; 2) Having btrfs_log_new_name() unnecessarily log an inode when it is not needed. If the inode was not logged before, we don't need to log it in LOG_INODE_EXISTS mode. So just make sure that any false positive only happens when ->logged_trans has a value of 0. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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David Sterba
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214cc18432 |
btrfs: constify and cleanup variables in comparators
Comparators just read the data and thus get const parameters. This should be also preserved by the local variables, update all comparators passed to sort or bsearch. Cleanups: - unnecessary casts are dropped - btrfs_cmp_device_free_bytes is cleaned up to follow the common pattern and 'inline' is dropped as the function address is taken Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
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2ac691d8b3 |
btrfs: avoid unnecessary lock and leaf splits when updating inode in the log
During a fast fsync, if we have already fsynced the file before and in the
current transaction, we can make the inode item update more efficient and
avoid acquiring a write lock on the leaf's parent.
To update the inode item we are always using btrfs_insert_empty_item() to
get a path pointing to the inode item, which calls btrfs_search_slot()
with an "ins_len" argument of 'sizeof(struct btrfs_inode_item) +
sizeof(struct btrfs_item)', and that always results in the search taking
a write lock on the level 1 node that is the parent of the leaf that
contains the inode item. This adds unnecessary lock contention on log
trees when we have multiple fsyncs in parallel against inodes in the same
subvolume, which has a very significant impact due to the fact that log
trees are short lived and their height very rarely goes beyond level 2.
Also, by using btrfs_insert_empty_item() when we need to update the inode
item, we also end up splitting the leaf of the existing inode item when
the leaf has an amount of free space smaller than the size of an inode
item.
Improve this by using btrfs_seach_slot(), with a 0 "ins_len" argument,
when we know the inode item already exists in the log. This avoids these
two inefficiencies.
The following script, using fio, was used to perform the tests:
$ cat fio-test.sh
#!/bin/bash
DEV=/dev/nvme0n1
MNT=/mnt/nvme0n1
MOUNT_OPTIONS="-o ssd"
MKFS_OPTIONS="-d single -m single"
if [ $# -ne 4 ]; then
echo "Use $0 NUM_JOBS FILE_SIZE FSYNC_FREQ BLOCK_SIZE"
exit 1
fi
NUM_JOBS=$1
FILE_SIZE=$2
FSYNC_FREQ=$3
BLOCK_SIZE=$4
cat <<EOF > /tmp/fio-job.ini
[writers]
rw=randwrite
fsync=$FSYNC_FREQ
fallocate=none
group_reporting=1
direct=0
bs=$BLOCK_SIZE
ioengine=sync
size=$FILE_SIZE
directory=$MNT
numjobs=$NUM_JOBS
EOF
echo "performance" | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
echo
echo "Using config:"
echo
cat /tmp/fio-job.ini
echo
echo "mount options: $MOUNT_OPTIONS"
echo
umount $MNT &> /dev/null
mkfs.btrfs -f $MKFS_OPTIONS $DEV
mount $MOUNT_OPTIONS $DEV $MNT
fio /tmp/fio-job.ini
umount $MNT
The tests were done on a physical machine, with 12 cores, 64G of RAM,
using a NVMEe device and using a non-debug kernel config (the default one
from Debian). The summary line from fio is provided below for each test
run.
With 8 jobs, file size 256M, fsync frequency of 4 and a block size of 4K:
Before: WRITE: bw=28.3MiB/s (29.7MB/s), 28.3MiB/s-28.3MiB/s (29.7MB/s-29.7MB/s), io=2048MiB (2147MB), run=72297-72297msec
After: WRITE: bw=28.7MiB/s (30.1MB/s), 28.7MiB/s-28.7MiB/s (30.1MB/s-30.1MB/s), io=2048MiB (2147MB), run=71411-71411msec
+1.4% throughput, -1.2% runtime
With 16 jobs, file size 256M, fsync frequency of 4 and a block size of 4K:
Before: WRITE: bw=40.0MiB/s (42.0MB/s), 40.0MiB/s-40.0MiB/s (42.0MB/s-42.0MB/s), io=4096MiB (4295MB), run=99980-99980msec
After: WRITE: bw=40.9MiB/s (42.9MB/s), 40.9MiB/s-40.9MiB/s (42.9MB/s-42.9MB/s), io=4096MiB (4295MB), run=97933-97933msec
+2.2% throughput, -2.1% runtime
The changes are small but it's possible to be better on faster hardware as
in the test machine used disk utilization was pretty much 100% during the
whole time the tests were running (observed with 'iostat -xz 1').
The tests also included the previous patch with the subject of:
"btrfs: avoid unnecessary log mutex contention when syncing log".
So they compared a branch without that patch and without this patch versus
a branch with these two patches applied.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Filipe Manana
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e68107e51f |
btrfs: remove unnecessary list head initialization when syncing log
One of the last steps of syncing the log is to remove all log contexts from the root's list of contexts, done at btrfs_remove_all_log_ctxs(). There we iterate over all the contexts in the list and delete each one from the list, and after that we call INIT_LIST_HEAD() on the list. That is unnecessary since at that point the list is empty. So just remove the INIT_LIST_HEAD() call. It's not needed, increases code size (bloat-o-meter reported a delta of -122 for btrfs_sync_log() after this change) and increases two critical sections delimited by log mutexes. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
Filipe Manana
|
e1a6d26483 |
btrfs: avoid unnecessary log mutex contention when syncing log
When syncing the log we acquire the root's log mutex just to update the root's last_log_commit. This is unnecessary because: 1) At this point there can only be one task updating this value, which is the task committing the current log transaction. Any task that enters btrfs_sync_log() has to wait for the previous log transaction to commit and wait for the current log transaction to commit if someone else already started it (in this case it never reaches to the point of updating last_log_commit, as that is done by the committing task); 2) All readers of the root's last_log_commit don't acquire the root's log mutex. This is to avoid blocking the readers, potentially for too long and because getting a stale value of last_log_commit does not cause any functional problem, in the worst case getting a stale value results in logging an inode unnecessarily. Plus it's actually very rare to get a stale value that results in unnecessarily logging the inode. So in order to avoid unnecessary contention on the root's log mutex, which is used for several different purposes, like starting/joining a log transaction and starting writeback of a log transaction, stop acquiring the log mutex for updating the root's last_log_commit. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
Filipe Manana
|
ecc64fab7d |
btrfs: fix lost inode on log replay after mix of fsync, rename and inode eviction
When checking if we need to log the new name of a renamed inode, we are checking if the inode and its parent inode have been logged before, and if not we don't log the new name. The check however is buggy, as it directly compares the logged_trans field of the inodes versus the ID of the current transaction. The problem is that logged_trans is a transient field, only stored in memory and never persisted in the inode item, so if an inode was logged before, evicted and reloaded, its logged_trans field is set to a value of 0, meaning the check will return false and the new name of the renamed inode is not logged. If the old parent directory was previously fsynced and we deleted the logged directory entries corresponding to the old name, we end up with a log that when replayed will delete the renamed inode. The following example triggers the problem: $ mkfs.btrfs -f /dev/sdc $ mount /dev/sdc /mnt $ mkdir /mnt/A $ mkdir /mnt/B $ echo -n "hello world" > /mnt/A/foo $ sync # Add some new file to A and fsync directory A. $ touch /mnt/A/bar $ xfs_io -c "fsync" /mnt/A # Now trigger inode eviction. We are only interested in triggering # eviction for the inode of directory A. $ echo 2 > /proc/sys/vm/drop_caches # Move foo from directory A to directory B. # This deletes the directory entries for foo in A from the log, and # does not add the new name for foo in directory B to the log, because # logged_trans of A is 0, which is less than the current transaction ID. $ mv /mnt/A/foo /mnt/B/foo # Now make an fsync to anything except A, B or any file inside them, # like for example create a file at the root directory and fsync this # new file. This syncs the log that contains all the changes done by # previous rename operation. $ touch /mnt/baz $ xfs_io -c "fsync" /mnt/baz <power fail> # Mount the filesystem and replay the log. $ mount /dev/sdc /mnt # Check the filesystem content. $ ls -1R /mnt /mnt/: A B baz /mnt/A: bar /mnt/B: $ # File foo is gone, it's neither in A/ nor in B/. Fix this by using the inode_logged() helper at btrfs_log_new_name(), which safely checks if an inode was logged before in the current transaction. A test case for fstests will follow soon. CC: stable@vger.kernel.org # 4.14+ Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
Filipe Manana
|
9acc8103ab |
btrfs: fix unpersisted i_size on fsync after expanding truncate
If we have an inode that does not have the full sync flag set, was changed in the current transaction, then it is logged while logging some other inode (like its parent directory for example), its i_size is increased by a truncate operation, the log is synced through an fsync of some other inode and then finally we explicitly call fsync on our inode, the new i_size is not persisted. The following example shows how to trigger it, with comments explaining how and why the issue happens: $ mkfs.btrfs -f /dev/sdc $ mount /dev/sdc /mnt $ touch /mnt/foo $ xfs_io -f -c "pwrite -S 0xab 0 1M" /mnt/bar $ sync # Fsync bar, this will be a noop since the file has not yet been # modified in the current transaction. The goal here is to clear # BTRFS_INODE_NEEDS_FULL_SYNC from the inode's runtime flags. $ xfs_io -c "fsync" /mnt/bar # Now rename both files, without changing their parent directory. $ mv /mnt/bar /mnt/bar2 $ mv /mnt/foo /mnt/foo2 # Increase the size of bar2 with a truncate operation. $ xfs_io -c "truncate 2M" /mnt/bar2 # Now fsync foo2, this results in logging its parent inode (the root # directory), and logging the parent results in logging the inode of # file bar2 (its inode item and the new name). The inode of file bar2 # is logged with an i_size of 0 bytes since it's logged in # LOG_INODE_EXISTS mode, meaning we are only logging its names (and # xattrs if it had any) and the i_size of the inode will not be changed # when the log is replayed. $ xfs_io -c "fsync" /mnt/foo2 # Now explicitly fsync bar2. This resulted in doing nothing, not # logging the inode with the new i_size of 2M and the hole from file # offset 1M to 2M. Because the inode did not have the flag # BTRFS_INODE_NEEDS_FULL_SYNC set, when it was logged through the # fsync of file foo2, its last_log_commit field was updated, # resulting in this explicit of file bar2 not doing anything. $ xfs_io -c "fsync" /mnt/bar2 # File bar2 content and size before a power failure. $ od -A d -t x1 /mnt/bar2 0000000 ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab * 1048576 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 * 2097152 <power failure> # Mount the filesystem to replay the log. $ mount /dev/sdc /mnt # Read the file again, should have the same content and size as before # the power failure happened, but it doesn't, i_size is still at 1M. $ od -A d -t x1 /mnt/bar2 0000000 ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab * 1048576 This started to happen after commit |
||
|
Filipe Manana
|
ea32af47f0 |
btrfs: zoned: fix wrong mutex unlock on failure to allocate log root tree
When syncing the log, if we fail to allocate the root node for the log
root tree:
1) We are unlocking fs_info->tree_log_mutex, but at this point we have
not yet locked this mutex;
2) We have locked fs_info->tree_root->log_mutex, but we end up not
unlocking it;
So fix this by unlocking fs_info->tree_root->log_mutex instead of
fs_info->tree_log_mutex.
Fixes:
|
||
|
Filipe Manana
|
b590b83972 |
btrfs: avoid unnecessary logging of xattrs during fast fsyncs
When logging an inode we always log all its xattrs, so that we are able
to figure out which ones should be deleted during log replay. However this
is unnecessary when we are doing a fast fsync and no xattrs were added,
changed or deleted since the last time we logged the inode in the current
transaction.
So skip the logging of xattrs when the inode was previously logged in the
current transaction and no xattrs were added, changed or deleted. If any
changes to xattrs happened, than the inode has BTRFS_INODE_COPY_EVERYTHING
set in its runtime flags and the xattrs get logged. This saves time on
scanning for xattrs, allocating memory, COWing log tree extent buffers and
adding more lock contention on the extent buffers when there are multiple
tasks logging in parallel.
The use of xattrs is common when using ACLs, some applications, or when
using security modules like SELinux where every inode gets a security
xattr added to it.
The following test script, using fio, was used on a box with 12 cores, 64G
of RAM, a NVMe device and the default non-debug kernel config from Debian.
It uses 8 concurrent jobs each writing in blocks of 64K to its own 4G file,
each file with a single xattr of 50 bytes (about the same size for an ACL
or SELinux xattr), doing random buffered writes with an fsync after each
write.
$ cat test.sh
#!/bin/bash
DEV=/dev/nvme0n1
MNT=/mnt/test
MOUNT_OPTIONS="-o ssd"
MKFS_OPTIONS="-d single -m single"
NUM_JOBS=8
FILE_SIZE=4G
cat <<EOF > /tmp/fio-job.ini
[writers]
rw=randwrite
fsync=1
fallocate=none
group_reporting=1
direct=0
bs=64K
ioengine=sync
size=$FILE_SIZE
directory=$MNT
numjobs=$NUM_JOBS
EOF
echo "performance" | \
tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
mkfs.btrfs -f $MKFS_OPTIONS $DEV > /dev/null
mount $MOUNT_OPTIONS $DEV $MNT
echo "Creating files before fio runs, each with 1 xattr of 50 bytes"
for ((i = 0; i < $NUM_JOBS; i++)); do
path="$MNT/writers.$i.0"
truncate -s $FILE_SIZE $path
setfattr -n user.xa1 -v $(printf '%0.sX' $(seq 50)) $path
done
fio /tmp/fio-job.ini
umount $MNT
fio output before this change:
WRITE: bw=120MiB/s (126MB/s), 120MiB/s-120MiB/s (126MB/s-126MB/s), io=32.0GiB (34.4GB), run=272145-272145msec
fio output after this change:
WRITE: bw=142MiB/s (149MB/s), 142MiB/s-142MiB/s (149MB/s-149MB/s), io=32.0GiB (34.4GB), run=230408-230408msec
+16.8% throughput, -16.6% runtime
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
||
|
David Sterba
|
1aeb6b563a |
btrfs: clear log tree recovering status if starting transaction fails
When a log recovery is in progress, lots of operations have to take that into account, so we keep this status per tree during the operation. Long time ago error handling revamp patch |
||
|
Filipe Manana
|
0d7d316597 |
btrfs: don't set the full sync flag when truncation does not touch extents
At btrfs_truncate() where we truncate the inode either to the same size or to a smaller size, we always set the full sync flag on the inode. This is needed in case the truncation drops or trims any file extent items that start beyond or cross the new inode size, so that the next fsync drops all inode items from the log and scans again the fs/subvolume tree to find all items that must be logged. However if the truncation does not drop or trims any file extent items, we do not need to set the full sync flag and force the next fsync to use the slow code path. So do not set the full sync flag in such cases. One use case where it is frequent to do truncations that do not change the inode size and do not drop any extents (no prealloc extents beyond i_size) is when running Microsoft's SQL Server inside a Docker container. One example workload is the one Philipp Fent reported recently, in the thread with a link below. In this workload a large number of fsyncs are preceded by such truncate operations. After this change I constantly get the runtime for that workload from Philipp to be reduced by about -12%, for example from 184 seconds down to 162 seconds. Link: https://lore.kernel.org/linux-btrfs/93c4600e-5263-5cba-adf0-6f47526e7561@in.tum.de/ Tested-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
Linus Torvalds
|
cc6cf827dd |
for-5.13-rc5-tag
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||
Josef Bacik
|
165ea85f14 |
btrfs: do not write supers if we have an fs error
Error injection testing uncovered a pretty severe problem where we could end up committing a super that pointed to the wrong tree roots, resulting in transid mismatch errors. The way we commit the transaction is we update the super copy with the current generations and bytenrs of the important roots, and then copy that into our super_for_commit. Then we allow transactions to continue again, we write out the dirty pages for the transaction, and then we write the super. If the write out fails we'll bail and skip writing the supers. However since we've allowed a new transaction to start, we can have a log attempting to sync at this point, which would be blocked on fs_info->tree_log_mutex. Once the commit fails we're allowed to do the log tree commit, which uses super_for_commit, which now points at fs tree's that were not written out. Fix this by checking BTRFS_FS_STATE_ERROR once we acquire the tree_log_mutex. This way if the transaction commit fails we're sure to see this bit set and we can skip writing the super out. This patch fixes this specific transid mismatch error I was seeing with this particular error path. CC: stable@vger.kernel.org # 5.12+ Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
Linus Torvalds
|
fd2ff2774e |
for-5.13-rc4-tag
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Merge tag 'for-5.13-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"Error handling improvements, caught by error injection:
- handle errors during checksum deletion
- set error on mapping when ordered extent io cannot be finished
- inode link count fixup in tree-log
- missing return value checks for inode updates in tree-log
- abort transaction in rename exchange if adding second reference
fails
Fixes:
- fix fsync failure after writes to prealloc extents
- fix deadlock when cloning inline extents and low on available space
- fix compressed writes that cross stripe boundary"
* tag 'for-5.13-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
MAINTAINERS: add btrfs IRC link
btrfs: fix deadlock when cloning inline extents and low on available space
btrfs: fix fsync failure and transaction abort after writes to prealloc extents
btrfs: abort in rename_exchange if we fail to insert the second ref
btrfs: check error value from btrfs_update_inode in tree log
btrfs: fixup error handling in fixup_inode_link_counts
btrfs: mark ordered extent and inode with error if we fail to finish
btrfs: return errors from btrfs_del_csums in cleanup_ref_head
btrfs: fix error handling in btrfs_del_csums
btrfs: fix compressed writes that cross stripe boundary
|
||
|
Josef Bacik
|
f96d44743a |
btrfs: check error value from btrfs_update_inode in tree log
Error injection testing uncovered a case where we ended up with invalid link counts on an inode. This happened because we failed to notice an error when updating the inode while replaying the tree log, and committed the transaction with an invalid file system. Fix this by checking the return value of btrfs_update_inode. This resolved the link count errors I was seeing, and we already properly handle passing up the error values in these paths. CC: stable@vger.kernel.org # 4.4+ Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
Josef Bacik
|
011b28acf9 |
btrfs: fixup error handling in fixup_inode_link_counts
This function has the following pattern
while (1) {
ret = whatever();
if (ret)
goto out;
}
ret = 0
out:
return ret;
However several places in this while loop we simply break; when there's
a problem, thus clearing the return value, and in one case we do a
return -EIO, and leak the memory for the path.
Fix this by re-arranging the loop to deal with ret == 1 coming from
btrfs_search_slot, and then simply delete the
ret = 0;
out:
bit so everybody can break if there is an error, which will allow for
proper error handling to occur.
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
||
|
Linus Torvalds
|
45af60e7ce |
for-5.13-rc2-tag
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||
|
Linus Torvalds
|
8ac91e6c60 |
for-5.13-rc2-tag
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Merge tag 'for-5.13-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"A few more fixes:
- fix fiemap to print extents that could get misreported due to
internal extent splitting and logical merging for fiemap output
- fix RCU stalls during delayed iputs
- fix removed dentries still existing after log is synced"
* tag 'for-5.13-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: fix removed dentries still existing after log is synced
btrfs: return whole extents in fiemap
btrfs: avoid RCU stalls while running delayed iputs
btrfs: return 0 for dev_extent_hole_check_zoned hole_start in case of error
|
||
|
Josef Bacik
|
91df99a6eb |
btrfs: do not BUG_ON in link_to_fixup_dir
While doing error injection testing I got the following panic kernel BUG at fs/btrfs/tree-log.c:1862! invalid opcode: 0000 [#1] SMP NOPTI CPU: 1 PID: 7836 Comm: mount Not tainted 5.13.0-rc1+ #305 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014 RIP: 0010:link_to_fixup_dir+0xd5/0xe0 RSP: 0018:ffffb5800180fa30 EFLAGS: 00010216 RAX: fffffffffffffffb RBX: 00000000fffffffb RCX: ffff8f595287faf0 RDX: ffffb5800180fa37 RSI: ffff8f5954978800 RDI: 0000000000000000 RBP: ffff8f5953af9450 R08: 0000000000000019 R09: 0000000000000001 R10: 000151f408682970 R11: 0000000120021001 R12: ffff8f5954978800 R13: ffff8f595287faf0 R14: ffff8f5953c77dd0 R15: 0000000000000065 FS: 00007fc5284c8c40(0000) GS:ffff8f59bbd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc5287f47c0 CR3: 000000011275e002 CR4: 0000000000370ee0 Call Trace: replay_one_buffer+0x409/0x470 ? btree_read_extent_buffer_pages+0xd0/0x110 walk_up_log_tree+0x157/0x1e0 walk_log_tree+0xa6/0x1d0 btrfs_recover_log_trees+0x1da/0x360 ? replay_one_extent+0x7b0/0x7b0 open_ctree+0x1486/0x1720 btrfs_mount_root.cold+0x12/0xea ? __kmalloc_track_caller+0x12f/0x240 legacy_get_tree+0x24/0x40 vfs_get_tree+0x22/0xb0 vfs_kern_mount.part.0+0x71/0xb0 btrfs_mount+0x10d/0x380 ? vfs_parse_fs_string+0x4d/0x90 legacy_get_tree+0x24/0x40 vfs_get_tree+0x22/0xb0 path_mount+0x433/0xa10 __x64_sys_mount+0xe3/0x120 do_syscall_64+0x3d/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae We can get -EIO or any number of legitimate errors from btrfs_search_slot(), panicing here is not the appropriate response. The error path for this code handles errors properly, simply return the error. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
Filipe Manana
|
54a40fc3a1 |
btrfs: fix removed dentries still existing after log is synced
When we move one inode from one directory to another and both the inode
and its previous parent directory were logged before, we are not supposed
to have the dentry for the old parent if we have a power failure after the
log is synced. Only the new dentry is supposed to exist.
Generally this works correctly, however there is a scenario where this is
not currently working, because the old parent of the file/directory that
was moved is not authoritative for a range that includes the dir index and
dir item keys of the old dentry. This case is better explained with the
following example and reproducer:
# The test requires a very specific layout of keys and items in the
# fs/subvolume btree to trigger the bug. So we want to make sure that
# on whatever platform we are, we have the same leaf/node size.
#
# Currently in btrfs the node/leaf size can not be smaller than the page
# size (but it can be greater than the page size). So use the largest
# supported node/leaf size (64K).
$ mkfs.btrfs -f -n 65536 /dev/sdc
$ mount /dev/sdc /mnt
# "testdir" is inode 257.
$ mkdir /mnt/testdir
$ chmod 755 /mnt/testdir
# Create several empty files to have the directory "testdir" with its
# items spread over several leaves (7 in this case).
$ for ((i = 1; i <= 1200; i++)); do
echo -n > /mnt/testdir/file$i
done
# Create our test directory "dira", inode number 1458, which gets all
# its items in leaf 7.
#
# The BTRFS_DIR_ITEM_KEY item for inode 257 ("testdir") that points to
# the entry named "dira" is in leaf 2, while the BTRFS_DIR_INDEX_KEY
# item that points to that entry is in leaf 3.
#
# For this particular filesystem node size (64K), file count and file
# names, we endup with the directory entry items from inode 257 in
# leaves 2 and 3, as previously mentioned - what matters for triggering
# the bug exercised by this test case is that those items are not placed
# in leaf 1, they must be placed in a leaf different from the one
# containing the inode item for inode 257.
#
# The corresponding BTRFS_DIR_ITEM_KEY and BTRFS_DIR_INDEX_KEY items for
# the parent inode (257) are the following:
#
# item 460 key (257 DIR_ITEM 3724298081) itemoff 48344 itemsize 34
# location key (1458 INODE_ITEM 0) type DIR
# transid 6 data_len 0 name_len 4
# name: dira
#
# and:
#
# item 771 key (257 DIR_INDEX 1202) itemoff 36673 itemsize 34
# location key (1458 INODE_ITEM 0) type DIR
# transid 6 data_len 0 name_len 4
# name: dira
$ mkdir /mnt/testdir/dira
# Make sure everything done so far is durably persisted.
$ sync
# Now do a change to inode 257 ("testdir") that does not result in
# COWing leaves 2 and 3 - the leaves that contain the directory items
# pointing to inode 1458 (directory "dira").
#
# Changing permissions, the owner/group, updating or adding a xattr,
# etc, will not change (COW) leaves 2 and 3. So for the sake of
# simplicity change the permissions of inode 257, which results in
# updating its inode item and therefore change (COW) only leaf 1.
$ chmod 700 /mnt/testdir
# Now fsync directory inode 257.
#
# Since only the first leaf was changed/COWed, we log the inode item of
# inode 257 and only the dentries found in the first leaf, all have a
# key type of BTRFS_DIR_ITEM_KEY, and no keys of type
# BTRFS_DIR_INDEX_KEY, because they sort after the former type and none
# exist in the first leaf.
#
# We also log 3 items that represent ranges for dir items and dir
# indexes for which the log is authoritative:
#
# 1) a key of type BTRFS_DIR_LOG_ITEM_KEY, which indicates the log is
# authoritative for all BTRFS_DIR_ITEM_KEY keys that have an offset
# in the range [0, 2285968570] (the offset here is the crc32c of the
# dentry's name). The value 2285968570 corresponds to the offset of
# the first key of leaf 2 (which is of type BTRFS_DIR_ITEM_KEY);
#
# 2) a key of type BTRFS_DIR_LOG_ITEM_KEY, which indicates the log is
# authoritative for all BTRFS_DIR_ITEM_KEY keys that have an offset
# in the range [4293818216, (u64)-1] (the offset here is the crc32c
# of the dentry's name). The value 4293818216 corresponds to the
# offset of the highest key of type BTRFS_DIR_ITEM_KEY plus 1
# (4293818215 + 1), which is located in leaf 2;
#
# 3) a key of type BTRFS_DIR_LOG_INDEX_KEY, with an offset of 1203,
# which indicates the log is authoritative for all keys of type
# BTRFS_DIR_INDEX_KEY that have an offset in the range
# [1203, (u64)-1]. The value 1203 corresponds to the offset of the
# last key of type BTRFS_DIR_INDEX_KEY plus 1 (1202 + 1), which is
# located in leaf 3;
#
# Also, because "testdir" is a directory and inode 1458 ("dira") is a
# child directory, we log inode 1458 too.
$ xfs_io -c "fsync" /mnt/testdir
# Now move "dira", inode 1458, to be a child of the root directory
# (inode 256).
#
# Because this inode was previously logged, when "testdir" was fsynced,
# the log is updated so that the old inode reference, referring to inode
# 257 as the parent, is deleted and the new inode reference, referring
# to inode 256 as the parent, is added to the log.
$ mv /mnt/testdir/dira /mnt
# Now change some file and fsync it. This guarantees the log changes
# made by the previous move/rename operation are persisted. We do not
# need to do any special modification to the file, just any change to
# any file and sync the log.
$ xfs_io -c "pwrite -S 0xab 0 64K" -c "fsync" /mnt/testdir/file1
# Simulate a power failure and then mount again the filesystem to
# replay the log tree. We want to verify that we are able to mount the
# filesystem, meaning log replay was successful, and that directory
# inode 1458 ("dira") only has inode 256 (the filesystem's root) as
# its parent (and no longer a child of inode 257).
#
# It used to happen that during log replay we would end up having
# inode 1458 (directory "dira") with 2 hard links, being a child of
# inode 257 ("testdir") and inode 256 (the filesystem's root). This
# resulted in the tree checker detecting the issue and causing the
# mount operation to fail (with -EIO).
#
# This happened because in the log we have the new name/parent for
# inode 1458, which results in adding the new dentry with inode 256
# as the parent, but the previous dentry, under inode 257 was never
# removed - this is because the ranges for dir items and dir indexes
# of inode 257 for which the log is authoritative do not include the
# old dir item and dir index for the dentry of inode 257 referring to
# inode 1458:
#
# - for dir items, the log is authoritative for the ranges
# [0, 2285968570] and [4293818216, (u64)-1]. The dir item at inode 257
# pointing to inode 1458 has a key of (257 DIR_ITEM 3724298081), as
# previously mentioned, so the dir item is not deleted when the log
# replay procedure processes the authoritative ranges, as 3724298081
# is outside both ranges;
#
# - for dir indexes, the log is authoritative for the range
# [1203, (u64)-1], and the dir index item of inode 257 pointing to
# inode 1458 has a key of (257 DIR_INDEX 1202), as previously
# mentioned, so the dir index item is not deleted when the log
# replay procedure processes the authoritative range.
<power failure>
$ mount /dev/sdc /mnt
mount: /mnt: can't read superblock on /dev/sdc.
$ dmesg
(...)
[87849.840509] BTRFS info (device sdc): start tree-log replay
[87849.875719] BTRFS critical (device sdc): corrupt leaf: root=5 block=30539776 slot=554 ino=1458, invalid nlink: has 2 expect no more than 1 for dir
[87849.878084] BTRFS info (device sdc): leaf 30539776 gen 7 total ptrs 557 free space 2092 owner 5
[87849.879516] BTRFS info (device sdc): refs 1 lock_owner 0 current 2099108
[87849.880613] item 0 key (1181 1 0) itemoff 65275 itemsize 160
[87849.881544] inode generation 6 size 0 mode 100644
[87849.882692] item 1 key (1181 12 257) itemoff 65258 itemsize 17
(...)
[87850.562549] item 556 key (1458 12 257) itemoff 16017 itemsize 14
[87850.563349] BTRFS error (device dm-0): block=30539776 write time tree block corruption detected
[87850.564386] ------------[ cut here ]------------
[87850.564920] WARNING: CPU: 3 PID: 2099108 at fs/btrfs/disk-io.c:465 csum_one_extent_buffer+0xed/0x100 [btrfs]
[87850.566129] Modules linked in: btrfs dm_zero dm_snapshot (...)
[87850.573789] CPU: 3 PID: 2099108 Comm: mount Not tainted 5.12.0-rc8-btrfs-next-86 #1
(...)
[87850.587481] Call Trace:
[87850.587768] btree_csum_one_bio+0x244/0x2b0 [btrfs]
[87850.588354] ? btrfs_bio_fits_in_stripe+0xd8/0x110 [btrfs]
[87850.589003] btrfs_submit_metadata_bio+0xb7/0x100 [btrfs]
[87850.589654] submit_one_bio+0x61/0x70 [btrfs]
[87850.590248] submit_extent_page+0x91/0x2f0 [btrfs]
[87850.590842] write_one_eb+0x175/0x440 [btrfs]
[87850.591370] ? find_extent_buffer_nolock+0x1c0/0x1c0 [btrfs]
[87850.592036] btree_write_cache_pages+0x1e6/0x610 [btrfs]
[87850.592665] ? free_debug_processing+0x1d5/0x240
[87850.593209] do_writepages+0x43/0xf0
[87850.593798] ? __filemap_fdatawrite_range+0xa4/0x100
[87850.594391] __filemap_fdatawrite_range+0xc5/0x100
[87850.595196] btrfs_write_marked_extents+0x68/0x160 [btrfs]
[87850.596202] btrfs_write_and_wait_transaction.isra.0+0x4d/0xd0 [btrfs]
[87850.597377] btrfs_commit_transaction+0x794/0xca0 [btrfs]
[87850.598455] ? _raw_spin_unlock_irqrestore+0x32/0x60
[87850.599305] ? kmem_cache_free+0x15a/0x3d0
[87850.600029] btrfs_recover_log_trees+0x346/0x380 [btrfs]
[87850.601021] ? replay_one_extent+0x7d0/0x7d0 [btrfs]
[87850.601988] open_ctree+0x13c9/0x1698 [btrfs]
[87850.602846] btrfs_mount_root.cold+0x13/0xed [btrfs]
[87850.603771] ? kmem_cache_alloc_trace+0x7c9/0x930
[87850.604576] ? vfs_parse_fs_string+0x5d/0xb0
[87850.605293] ? kfree+0x276/0x3f0
[87850.605857] legacy_get_tree+0x30/0x50
[87850.606540] vfs_get_tree+0x28/0xc0
[87850.607163] fc_mount+0xe/0x40
[87850.607695] vfs_kern_mount.part.0+0x71/0x90
[87850.608440] btrfs_mount+0x13b/0x3e0 [btrfs]
(...)
[87850.629477] ---[ end trace 68802022b99a1ea0 ]---
[87850.630849] BTRFS: error (device sdc) in btrfs_commit_transaction:2381: errno=-5 IO failure (Error while writing out transaction)
[87850.632422] BTRFS warning (device sdc): Skipping commit of aborted transaction.
[87850.633416] BTRFS: error (device sdc) in cleanup_transaction:1978: errno=-5 IO failure
[87850.634553] BTRFS: error (device sdc) in btrfs_replay_log:2431: errno=-5 IO failure (Failed to recover log tree)
[87850.637529] BTRFS error (device sdc): open_ctree failed
In this example the inode we moved was a directory, so it was easy to
detect the problem because directories can only have one hard link and
the tree checker immediately detects that. If the moved inode was a file,
then the log replay would succeed and we would end up having both the
new hard link (/mnt/foo) and the old hard link (/mnt/testdir/foo) present,
but only the new one should be present.
Fix this by forcing re-logging of the old parent directory when logging
the new name during a rename operation. This ensures we end up with a log
that is authoritative for a range covering the keys for the old dentry,
therefore causing the old dentry do be deleted when replaying the log.
A test case for fstests will follow up soon.
Fixes:
|
||
|
Linus Torvalds
|
142b507f91 |
for-5.13-rc1-tag
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||
|
Filipe Manana
|
626e9f41f7 |
btrfs: fix race leading to unpersisted data and metadata on fsync
When doing a fast fsync on a file, there is a race which can result in the
fsync returning success to user space without logging the inode and without
durably persisting new data.
The following example shows one possible scenario for this:
$ mkfs.btrfs -f /dev/sdc
$ mount /dev/sdc /mnt
$ touch /mnt/bar
$ xfs_io -f -c "pwrite -S 0xab 0 1M" -c "fsync" /mnt/baz
# Now we have:
# file bar == inode 257
# file baz == inode 258
$ mv /mnt/baz /mnt/foo
# Now we have:
# file bar == inode 257
# file foo == inode 258
$ xfs_io -c "pwrite -S 0xcd 0 1M" /mnt/foo
# fsync bar before foo, it is important to trigger the race.
$ xfs_io -c "fsync" /mnt/bar
$ xfs_io -c "fsync" /mnt/foo
# After this:
# inode 257, file bar, is empty
# inode 258, file foo, has 1M filled with 0xcd
<power failure>
# Replay the log:
$ mount /dev/sdc /mnt
# After this point file foo should have 1M filled with 0xcd and not 0xab
The following steps explain how the race happens:
1) Before the first fsync of inode 258, when it has the "baz" name, its
->logged_trans is 0, ->last_sub_trans is 0 and ->last_log_commit is -1.
The inode also has the full sync flag set;
2) After the first fsync, we set inode 258 ->logged_trans to 6, which is
the generation of the current transaction, and set ->last_log_commit
to 0, which is the current value of ->last_sub_trans (done at
btrfs_log_inode()).
The full sync flag is cleared from the inode during the fsync.
The log sub transaction that was committed had an ID of 0 and when we
synced the log, at btrfs_sync_log(), we incremented root->log_transid
from 0 to 1;
3) During the rename:
We update inode 258, through btrfs_update_inode(), and that causes its
->last_sub_trans to be set to 1 (the current log transaction ID), and
->last_log_commit remains with a value of 0.
After updating inode 258, because we have previously logged the inode
in the previous fsync, we log again the inode through the call to
btrfs_log_new_name(). This results in updating the inode's
->last_log_commit from 0 to 1 (the current value of its
->last_sub_trans).
The ->last_sub_trans of inode 257 is updated to 1, which is the ID of
the next log transaction;
4) Then a buffered write against inode 258 is made. This leaves the value
of ->last_sub_trans as 1 (the ID of the current log transaction, stored
at root->log_transid);
5) Then an fsync against inode 257 (or any other inode other than 258),
happens. This results in committing the log transaction with ID 1,
which results in updating root->last_log_commit to 1 and bumping
root->log_transid from 1 to 2;
6) Then an fsync against inode 258 starts. We flush delalloc and wait only
for writeback to complete, since the full sync flag is not set in the
inode's runtime flags - we do not wait for ordered extents to complete.
Then, at btrfs_sync_file(), we call btrfs_inode_in_log() before the
ordered extent completes. The call returns true:
static inline bool btrfs_inode_in_log(...)
{
bool ret = false;
spin_lock(&inode->lock);
if (inode->logged_trans == generation &&
inode->last_sub_trans <= inode->last_log_commit &&
inode->last_sub_trans <= inode->root->last_log_commit)
ret = true;
spin_unlock(&inode->lock);
return ret;
}
generation has a value of 6 (fs_info->generation), ->logged_trans also
has a value of 6 (set when we logged the inode during the first fsync
and when logging it during the rename), ->last_sub_trans has a value
of 1, set during the rename (step 3), ->last_log_commit also has a
value of 1 (set in step 3) and root->last_log_commit has a value of 1,
which was set in step 5 when fsyncing inode 257.
As a consequence we don't log the inode, any new extents and do not
sync the log, resulting in a data loss if a power failure happens
after the fsync and before the current transaction commits.
Also, because we do not log the inode, after a power failure the mtime
and ctime of the inode do not match those we had before.
When the ordered extent completes before we call btrfs_inode_in_log(),
then the call returns false and we log the inode and sync the log,
since at the end of ordered extent completion we update the inode and
set ->last_sub_trans to 2 (the value of root->log_transid) and
->last_log_commit to 1.
This problem is found after removing the check for the emptiness of the
inode's list of modified extents in the recent commit
|
||
|
Linus Torvalds
|
57fa2369ab |
CFI on arm64 series for v5.13-rc1
- Clean up list_sort prototypes (Sami Tolvanen) - Introduce CONFIG_CFI_CLANG for arm64 (Sami Tolvanen) -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEpcP2jyKd1g9yPm4TiXL039xtwCYFAmCHCR8ACgkQiXL039xt wCZyFQ//fnUZaXR2K354zDyW6CJljMf+d94RF6rH+J6eMTH2/HXa5v0iJokwABLf ussP6qF4k5wtmI22Gm9A5Zc3e4iiry5pC0jOdk0mk4gzWwFN9MdgNxJZIGA3xqhS bsBK4AGrVKjtZl48G1/ZxJuNDeJhVp6GNK2n6/Gl4rZF6R7D/Upz0XelyJRdDpcM HIGma7jZl6xfGU0mdWCzpOGK1zdMca1WVs7A4YuurSbLn5PZJrcNVWLouDqt/Si2 AduSri1gyPClicgvqWjMOzhUpuw/nJtBLRl1x1EsWk/KSZ1/uNVjlewfzdN4fZrr zbtFr2gLubYLK6JOX7/LqoHlOTgE3tYLL+WIVN75DsOGZBKgHhmebTmWLyqzV0SL oqcyM5d3ucC6msdtAK5Fv4MSp8rpjqlK1Ha4SGRT6kC2wut7AhZ3KD7eyRIz8mV9 Sa9mhignGFJnTEUp+LSbYdrAudgSKxB40WyXPmswAXX4VJFRD4ONrrcAON/SzkUT Hw/JdFRCKkJjgwNQjIQoZcUNMTbFz2PlNIEnjJWm38YImQKQlCb2mXaZKCwBkf45 aheCZk17eKoxTCXFMd+KxlyNEtS2yBfq/PpZgvw7GW/pfFbWUg1+2O41LnihIe5v zu0hN1wNCQqgfxiMZqX1OTb9C/2vybzGsXILt+9nppjZ8EBU7iU= =wU6U -----END PGP SIGNATURE----- Merge tag 'cfi-v5.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux Pull CFI on arm64 support from Kees Cook: "This builds on last cycle's LTO work, and allows the arm64 kernels to be built with Clang's Control Flow Integrity feature. This feature has happily lived in Android kernels for almost 3 years[1], so I'm excited to have it ready for upstream. The wide diffstat is mainly due to the treewide fixing of mismatched list_sort prototypes. Other things in core kernel are to address various CFI corner cases. The largest code portion is the CFI runtime implementation itself (which will be shared by all architectures implementing support for CFI). The arm64 pieces are Acked by arm64 maintainers rather than coming through the arm64 tree since carrying this tree over there was going to be awkward. CFI support for x86 is still under development, but is pretty close. There are a handful of corner cases on x86 that need some improvements to Clang and objtool, but otherwise works well. Summary: - Clean up list_sort prototypes (Sami Tolvanen) - Introduce CONFIG_CFI_CLANG for arm64 (Sami Tolvanen)" * tag 'cfi-v5.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: arm64: allow CONFIG_CFI_CLANG to be selected KVM: arm64: Disable CFI for nVHE arm64: ftrace: use function_nocfi for ftrace_call arm64: add __nocfi to __apply_alternatives arm64: add __nocfi to functions that jump to a physical address arm64: use function_nocfi with __pa_symbol arm64: implement function_nocfi psci: use function_nocfi for cpu_resume lkdtm: use function_nocfi treewide: Change list_sort to use const pointers bpf: disable CFI in dispatcher functions kallsyms: strip ThinLTO hashes from static functions kthread: use WARN_ON_FUNCTION_MISMATCH workqueue: use WARN_ON_FUNCTION_MISMATCH module: ensure __cfi_check alignment mm: add generic function_nocfi macro cfi: add __cficanonical add support for Clang CFI |
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Josef Bacik
|
2002ae112a |
btrfs: handle btrfs_record_root_in_trans failure in btrfs_recover_log_trees
btrfs_record_root_in_trans will return errors in the future, so handle the error properly in btrfs_recover_log_trees. This appears tricky, however we have a reference count on the destination root, so if this fails we need to continue on in the loop to make sure the proper cleanup is done. Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> [ add comment ] Signed-off-by: David Sterba <dsterba@suse.com> |
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Naohiro Aota
|
e75f9fd194 |
btrfs: zoned: move log tree node allocation out of log_root_tree->log_mutex
Commit |
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Sami Tolvanen
|
4f0f586bf0 |
treewide: Change list_sort to use const pointers
list_sort() internally casts the comparison function passed to it to a different type with constant struct list_head pointers, and uses this pointer to call the functions, which trips indirect call Control-Flow Integrity (CFI) checking. Instead of removing the consts, this change defines the list_cmp_func_t type and changes the comparison function types of all list_sort() callers to use const pointers, thus avoiding type mismatches. Suggested-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Kees Cook <keescook@chromium.org> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20210408182843.1754385-10-samitolvanen@google.com |
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Filipe Manana
|
e3d3b41576 |
btrfs: zoned: fix linked list corruption after log root tree allocation failure
When using a zoned filesystem, while syncing the log, if we fail to
allocate the root node for the log root tree, we are not removing the
log context we allocated on stack from the list of log contexts of the
log root tree. This means after the return from btrfs_sync_log() we get
a corrupted linked list.
Fix this by allocating the node before adding our stack allocated context
to the list of log contexts of the log root tree.
Fixes:
|
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Johannes Thumshirn
|
6e37d24599 |
btrfs: zoned: fix deadlock on log sync
Lockdep with fstests test case btrfs/041 detected a unsafe locking
scenario when we allocate the log node on a zoned filesystem.
btrfs/041
============================================
WARNING: possible recursive locking detected
5.11.0-rc7+ #939 Not tainted
--------------------------------------------
xfs_io/698 is trying to acquire lock:
ffff88810cd673a0 (&root->log_mutex){+.+.}-{3:3}, at: btrfs_sync_log+0x3d1/0xee0 [btrfs]
but task is already holding lock:
ffff88810b0fc3a0 (&root->log_mutex){+.+.}-{3:3}, at: btrfs_sync_log+0x313/0xee0 [btrfs]
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&root->log_mutex);
lock(&root->log_mutex);
*** DEADLOCK ***
May be due to missing lock nesting notation
2 locks held by xfs_io/698:
#0: ffff88810cd66620 (sb_internal){.+.+}-{0:0}, at: btrfs_sync_file+0x2c3/0x570 [btrfs]
#1: ffff88810b0fc3a0 (&root->log_mutex){+.+.}-{3:3}, at: btrfs_sync_log+0x313/0xee0 [btrfs]
stack backtrace:
CPU: 0 PID: 698 Comm: xfs_io Not tainted 5.11.0-rc7+ #939
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4-rebuilt.opensuse.org 04/01/2014
Call Trace:
dump_stack+0x77/0x97
__lock_acquire.cold+0xb9/0x32a
lock_acquire+0xb5/0x400
? btrfs_sync_log+0x3d1/0xee0 [btrfs]
__mutex_lock+0x7b/0x8d0
? btrfs_sync_log+0x3d1/0xee0 [btrfs]
? btrfs_sync_log+0x3d1/0xee0 [btrfs]
? find_first_extent_bit+0x9f/0x100 [btrfs]
? __mutex_unlock_slowpath+0x35/0x270
btrfs_sync_log+0x3d1/0xee0 [btrfs]
btrfs_sync_file+0x3a8/0x570 [btrfs]
__x64_sys_fsync+0x34/0x60
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xa9
This happens, because we are taking the ->log_mutex albeit it has already
been locked.
Also while at it, fix the bogus unlock of the tree_log_mutex in the error
handling.
Fixes:
|
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Naohiro Aota
|
b528f46713 |
btrfs: zoned: deal with holes writing out tree-log pages
Since the zoned filesystem requires sequential write out of metadata, we cannot proceed with a hole in tree-log pages. When such a hole exists, btree_write_cache_pages() will return -EAGAIN. This happens when someone, e.g., a concurrent transaction commit, writes a dirty extent in this tree-log commit. If we are not going to wait for the extents, we can hope the concurrent writing fills the hole for us. So, we can ignore the error in this case and hope the next write will succeed. If we want to wait for them and got the error, we cannot wait for them because it will cause a deadlock. So, let's bail out to a full commit in this case. Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Naohiro Aota
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3ddebf27fc |
btrfs: zoned: reorder log node allocation on zoned filesystem
This is the 3/3 patch to enable tree-log on zoned filesystems. The allocation order of nodes of "fs_info->log_root_tree" and nodes of "root->log_root" is not the same as the writing order of them. So, the writing causes unaligned write errors. Reorder the allocation of them by delaying allocation of the root node of "fs_info->log_root_tree," so that the node buffers can go out sequentially to devices. Cc: Filipe Manana <fdmanana@gmail.com> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Naohiro Aota
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fa1a0f42a0 |
btrfs: zoned: serialize log transaction on zoned filesystems
This is the 2/3 patch to enable tree-log on zoned filesystems. Since we can start more than one log transactions per subvolume simultaneously, nodes from multiple transactions can be allocated interleaved. Such mixed allocation results in non-sequential writes at the time of a log transaction commit. The nodes of the global log root tree (fs_info->log_root_tree), also have the same problem with mixed allocation. Serializes log transactions by waiting for a committing transaction when someone tries to start a new transaction, to avoid the mixed allocation problem. We must also wait for running log transactions from another subvolume, but there is no easy way to detect which subvolume root is running a log transaction. So, this patch forbids starting a new log transaction when other subvolumes already allocated the global log root tree. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Naohiro Aota
|
d3575156f6 |
btrfs: zoned: redirty released extent buffers
Tree manipulating operations like merging nodes often release once-allocated tree nodes. Such nodes are cleaned so that pages in the node are not uselessly written out. On zoned volumes, however, such optimization blocks the following IOs as the cancellation of the write out of the freed blocks breaks the sequential write sequence expected by the device. Introduce a list of clean and unwritten extent buffers that have been released in a transaction. Redirty the buffers so that btree_write_cache_pages() can send proper bios to the devices. Besides it clears the entire content of the extent buffer not to confuse raw block scanners e.g. 'btrfs check'. By clearing the content, csum_dirty_buffer() complains about bytenr mismatch, so avoid the checking and checksum using newly introduced buffer flag EXTENT_BUFFER_NO_CHECK. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
|
64d6b281ba |
btrfs: remove unnecessary check_parent_dirs_for_sync()
Whenever we fsync an inode, if it is a directory, a regular file that was created in the current transaction or has last_unlink_trans set to the generation of the current transaction, we check if any of its ancestor inodes (and the inode itself if it is a directory) can not be logged and need a fallback to a full transaction commit - if so, we return with a value of 1 in order to fallback to a transaction commit. However we often do not need to fallback to a transaction commit because: 1) The ancestor inode is not an immediate parent, and therefore there is not an explicit request to log it and it is not needed neither to guarantee the consistency of the inode originally asked to be logged (fsynced) nor its immediate parent; 2) The ancestor inode was already logged before, in which case any link, unlink or rename operation updates the log as needed. So for these two cases we can avoid an unnecessary transaction commit. Therefore remove check_parent_dirs_for_sync() and add a check at the top of btrfs_log_inode() to make us fallback immediately to a transaction commit when we are logging a directory inode that can not be logged and needs a full transaction commit. All we need to protect is the case where after renaming a file someone fsyncs only the old directory, which would result is losing the renamed file after a log replay. This patch is part of a patchset comprised of the following patches: btrfs: remove unnecessary directory inode item update when deleting dir entry btrfs: stop setting nbytes when filling inode item for logging btrfs: avoid logging new ancestor inodes when logging new inode btrfs: skip logging directories already logged when logging all parents btrfs: skip logging inodes already logged when logging new entries btrfs: remove unnecessary check_parent_dirs_for_sync() btrfs: make concurrent fsyncs wait less when waiting for a transaction commit Performance results, after applying all patches, are mentioned in the change log of the last patch. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
|
0e44cb3f94 |
btrfs: skip logging inodes already logged when logging new entries
When logging new directory entries of a directory, we log the inodes of new dentries and the inodes of dentries pointing to directories that may have been created in past transactions. For the case of directories we log in full mode, which can be particularly expensive for large directories. We do use btrfs_inode_in_log() to skip already logged inodes, however for that helper to return true, it requires that the log transaction used to log the inode to be already committed. This means that when we have more than one task using the same log transaction we can end up logging an inode multiple times, which is a waste of time and not necessary since the log will be committed by one of the tasks and the others will wait for the log transaction to be committed before returning to user space. So simply replace the use of btrfs_inode_in_log() with the new helper function need_log_inode(), introduced in a previous commit. This patch is part of a patchset comprised of the following patches: btrfs: remove unnecessary directory inode item update when deleting dir entry btrfs: stop setting nbytes when filling inode item for logging btrfs: avoid logging new ancestor inodes when logging new inode btrfs: skip logging directories already logged when logging all parents btrfs: skip logging inodes already logged when logging new entries btrfs: remove unnecessary check_parent_dirs_for_sync() btrfs: make concurrent fsyncs wait less when waiting for a transaction commit Performance results, after applying all patches, are mentioned in the change log of the last patch. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
|
3e6a86a193 |
btrfs: skip logging directories already logged when logging all parents
Some times when we fsync an inode we need to do a full log of all its ancestors (due to unlink, link or rename operations), which can be an expensive operation, specially if the directories are large. However if we find an ancestor directory inode that is already logged in the current transaction, and has no inserted/updated/deleted xattrs since it was last logged, we can skip logging the directory again. We are safe to skip that since we know that for logged directories, any link, unlink or rename operations that implicate the directory will update the log as necessary. So use the helper need_log_dir(), introduced in a previous commit, to detect already logged directories that can be skipped. This patch is part of a patchset comprised of the following patches: btrfs: remove unnecessary directory inode item update when deleting dir entry btrfs: stop setting nbytes when filling inode item for logging btrfs: avoid logging new ancestor inodes when logging new inode btrfs: skip logging directories already logged when logging all parents btrfs: skip logging inodes already logged when logging new entries btrfs: remove unnecessary check_parent_dirs_for_sync() btrfs: make concurrent fsyncs wait less when waiting for a transaction commit Performance results, after applying all patches, are mentioned in the change log of the last patch. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
|
ab12313a9f |
btrfs: avoid logging new ancestor inodes when logging new inode
When we fsync a new file, created in the current transaction, we check all its ancestor inodes and always log them if they were created in the current transaction - even if we have already logged them before, which is a waste of time. So avoid logging new ancestor inodes if they were already logged before and have no xattrs added/updated/removed since they were last logged. This patch is part of a patchset comprised of the following patches: btrfs: remove unnecessary directory inode item update when deleting dir entry btrfs: stop setting nbytes when filling inode item for logging btrfs: avoid logging new ancestor inodes when logging new inode btrfs: skip logging directories already logged when logging all parents btrfs: skip logging inodes already logged when logging new entries btrfs: remove unnecessary check_parent_dirs_for_sync() btrfs: make concurrent fsyncs wait less when waiting for a transaction commit Performance results, after applying all patches, are mentioned in the change log of the last patch. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
|
e593e54ed1 |
btrfs: stop setting nbytes when filling inode item for logging
When we fill an inode item for logging we are setting its nbytes field with the value returned by inode_get_bytes() (a VFS API), however we do not need it because it is not used during log replay. In fact, for fast fsyncs, when we call inode_get_bytes() we may even get an outdated value for nbytes because the nbytes field of the inode is only updated when ordered extents complete, and a fast fsync only waits for writeback to complete, it does not wait for ordered extent completion. So just remove the setup of nbytes and add an explicit comment mentioning why we do not set it. This also avoids adding contention on the inode's i_lock (VFS) with concurrent stat() calls, since that spinlock is used by inode_get_bytes() which is also called by our stat callback (btrfs_getattr()). This patch is part of a patchset comprised of the following patches: btrfs: remove unnecessary directory inode item update when deleting dir entry btrfs: stop setting nbytes when filling inode item for logging btrfs: avoid logging new ancestor inodes when logging new inode btrfs: skip logging directories already logged when logging all parents btrfs: skip logging inodes already logged when logging new entries btrfs: remove unnecessary check_parent_dirs_for_sync() btrfs: make concurrent fsyncs wait less when waiting for a transaction commit Performance results, after applying all patches, are mentioned in the change log of the last patch. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
|
ddffcf6fb5 |
btrfs: remove unnecessary directory inode item update when deleting dir entry
When we remove a directory entry, as part of an unlink operation, if the
directory was logged before we must remove the directory index items from
the log. We are also updating the inode item of the directory to update
its i_size, but that is not necessary because during log replay we do not
need it and we correctly adjust the i_size in the inode item of the
subvolume as we process directory index items and replay deletes.
This is not needed since commit
|
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Nikolay Borisov
|
453e487386 |
btrfs: rename btrfs_find_highest_objectid to btrfs_init_root_free_objectid
This function is used to initialize the in-memory btrfs_root::highest_objectid member, which is used to get an available objectid. Rename it to better reflect its semantics. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Filipe Manana
|
47876f7cef |
btrfs: do not block inode logging for so long during transaction commit
Early on during a transaction commit we acquire the tree_log_mutex and
hold it until after we write the super blocks. But before writing the
extent buffers dirtied by the transaction and the super blocks we unblock
the transaction by setting its state to TRANS_STATE_UNBLOCKED and setting
fs_info->running_transaction to NULL.
This means that after that and before writing the super blocks, new
transactions can start. However if any transaction wants to log an inode,
it will block waiting for the transaction commit to write its dirty
extent buffers and the super blocks because the tree_log_mutex is only
released after those operations are complete, and starting a new log
transaction blocks on that mutex (at start_log_trans()).
Writing the dirty extent buffers and the super blocks can take a very
significant amount of time to complete, but we could allow the tasks
wanting to log an inode to proceed with most of their steps:
1) create the log trees
2) log metadata in the trees
3) write their dirty extent buffers
They only need to wait for the previous transaction commit to complete
(write its super blocks) before they attempt to write their super blocks,
otherwise we could end up with a corrupt filesystem after a crash.
So change start_log_trans() to use the root tree's log_mutex to serialize
for the creation of the log root tree instead of using the tree_log_mutex,
and make btrfs_sync_log() acquire the tree_log_mutex before writing the
super blocks. This allows for inode logging to wait much less time when
there is a previous transaction that is still committing, often not having
to wait at all, as by the time when we try to sync the log the previous
transaction already wrote its super blocks.
This patch belongs to a patch set that is comprised of the following
patches:
btrfs: fix race causing unnecessary inode logging during link and rename
btrfs: fix race that results in logging old extents during a fast fsync
btrfs: fix race that causes unnecessary logging of ancestor inodes
btrfs: fix race that makes inode logging fallback to transaction commit
btrfs: fix race leading to unnecessary transaction commit when logging inode
btrfs: do not block inode logging for so long during transaction commit
The following script that uses dbench was used to measure the impact of
the whole patchset:
$ cat test-dbench.sh
#!/bin/bash
DEV=/dev/nvme0n1
MNT=/mnt/btrfs
MOUNT_OPTIONS="-o ssd"
echo "performance" | \
tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
mkfs.btrfs -f -m single -d single $DEV
mount $MOUNT_OPTIONS $DEV $MNT
dbench -D $MNT -t 300 64
umount $MNT
The test was run on a machine with 12 cores, 64G of ram, using a NVMe
device and a non-debug kernel configuration (Debian's default).
Before patch set:
Operation Count AvgLat MaxLat
----------------------------------------
NTCreateX 11277211 0.250 85.340
Close 8283172 0.002 6.479
Rename 477515 1.935 86.026
Unlink 2277936 0.770 87.071
Deltree 256 15.732 81.379
Mkdir 128 0.003 0.009
Qpathinfo 10221180 0.056 44.404
Qfileinfo 1789967 0.002 4.066
Qfsinfo 1874399 0.003 9.176
Sfileinfo 918589 0.061 10.247
Find 3951758 0.341 54.040
WriteX 5616547 0.047 85.079
ReadX 17676028 0.005 9.704
LockX 36704 0.003 1.800
UnlockX 36704 0.002 0.687
Flush 790541 14.115 676.236
Throughput 1179.19 MB/sec 64 clients 64 procs max_latency=676.240 ms
After patch set:
Operation Count AvgLat MaxLat
----------------------------------------
NTCreateX 12687926 0.171 86.526
Close 9320780 0.002 8.063
Rename 537253 1.444 78.576
Unlink 2561827 0.559 87.228
Deltree 374 11.499 73.549
Mkdir 187 0.003 0.005
Qpathinfo 11500300 0.061 36.801
Qfileinfo 2017118 0.002 7.189
Qfsinfo 2108641 0.003 4.825
Sfileinfo 1033574 0.008 8.065
Find 4446553 0.408 47.835
WriteX 6335667 0.045 84.388
ReadX 19887312 0.003 9.215
LockX 41312 0.003 1.394
UnlockX 41312 0.002 1.425
Flush 889233 13.014 623.259
Throughput 1339.32 MB/sec 64 clients 64 procs max_latency=623.265 ms
+12.7% throughput, -8.2% max latency
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
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|
Filipe Manana
|
639bd575b7 |
btrfs: fix race leading to unnecessary transaction commit when logging inode
When logging an inode we may often have to fallback to a full transaction
commit, either because a new block group was allocated, there is some case
we can not deal with without a transaction commit or some error like an
ENOMEM happened. However after we fallback to a transaction commit, we
have a time window where we can make the next attempt to log any inode
commit the next transaction unnecessarily, adding additional overhead and
increasing latency.
A sequence of steps that leads to this issue is the following:
1) The current open transaction has a generation of 1000;
2) A new block group is allocated, and as a consequence we must make sure
any attempts to commit a log fallback to a transaction commit, so
btrfs_set_log_full_commit() is called from btrfs_make_block_group().
This sets fs_info->last_trans_log_full_commit to 1000;
3) Task A is holding a handle on transaction 1000 and tries to log inode X.
Once it gets to start_log_trans(), it calls btrfs_need_log_full_commit()
which returns true, since fs_info->last_trans_log_full_commit has a
value of 1000. So we end up returning EAGAIN and propagating it up to
btrfs_sync_file(), where we commit transaction 1000;
4) The transaction commit task (task A) sets the transaction state to
unblocked (TRANS_STATE_UNBLOCKED);
5) Some other task, task B, starts a new transaction with a generation of
1001;
6) Some stuff is done with transaction 1001, some btree blocks COWed, etc;
7) Transaction 1000 has not fully committed yet, we are still writing all
the extent buffers it created;
8) Some new task, task C, starts an fsync of inode Y, gets a handle for
transaction 1001, and it gets to btrfs_log_inode_parent() which does
the following check:
if (fs_info->last_trans_log_full_commit > last_committed) {
ret = 1;
goto end_no_trans;
}
At that point last_trans_log_full_commit has a value of 1000 and
last_committed (value of fs_info->last_trans_committed) has a value of
999, since transaction 1000 has not yet committed - it is either still
writing out dirty extent buffers, its super blocks or unpinning
extents.
As a consequence we return 1, which gets propagated up to
btrfs_sync_file(), which will then call btrfs_commit_transaction()
for transaction 1001.
As a consequence we have an unnecessary second transaction commit, we
previously committed transaction 1000 and now commit transaction 1001
as well, resulting in more overhead and increased latency.
So fix this double transaction commit issue simply by removing that check,
because all we need to do is wait for the previous transaction to finish
its commit, which we already do later when starting the log transaction at
start_log_trans(), because there we acquire the tree_log_mutex lock, which
is held by a transaction commit and only released after the transaction
commits its super blocks.
Another issue that check has is that it reads last_trans_log_full_commit
without using READ_ONCE(), which is incorrect since that member of
struct btrfs_fs_info is always updated with WRITE_ONCE() through the
helper btrfs_set_log_full_commit().
This double transaction commit issue can actually be triggered quite often
in long runs of dbench, since besides the creation of new block groups
that force inode logging to fallback to a transaction commit, there are
cases where dbench asks to fsync a directory which had files in it that
were previously renamed or subdirectories that were removed, resulting in
the inode logging to fallback to a full transaction commit.
This patch belongs to a patch set that is comprised of the following
patches:
btrfs: fix race causing unnecessary inode logging during link and rename
btrfs: fix race that results in logging old extents during a fast fsync
btrfs: fix race that causes unnecessary logging of ancestor inodes
btrfs: fix race that makes inode logging fallback to transaction commit
btrfs: fix race leading to unnecessary transaction commit when logging inode
btrfs: do not block inode logging for so long during transaction commit
Performance results are mentioned in the change log of the last patch.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
||
|
Filipe Manana
|
47d3db41e1 |
btrfs: fix race that makes inode logging fallback to transaction commit
When logging an inode and the previous transaction is still committing, we
have a time window where we can end up incorrectly think an inode has its
last_unlink_trans field with a value greater than the last transaction
committed, which results in the logging to fallback to a full transaction
commit, which is usually much more expensive than doing a log commit.
The race is described by the following steps:
1) We are at transaction 1000;
2) We modify an inode X (a directory) using transaction 1000 and set its
last_unlink_trans field to 1000, because for example we removed one
of its subdirectories;
3) We create a new inode Y with a dentry in inode X using transaction 1000,
so its generation field is set to 1000;
4) The commit for transaction 1000 is started by task A;
5) The task committing transaction 1000 sets the transaction state to
unblocked, writes the dirty extent buffers and the super blocks, then
unlocks tree_log_mutex;
6) Some task starts a new transaction with a generation of 1001;
7) We do some modification to inode Y (using transaction 1001);
8) The transaction 1000 commit starts unpinning extents. At this point
fs_info->last_trans_committed still has a value of 999;
9) Task B starts an fsync on inode Y, and gets a handle for transaction
1001. When it gets to check_parent_dirs_for_sync() it does the checking
of the ancestor dentries because the following check does not evaluate
to true:
if (S_ISREG(inode->vfs_inode.i_mode) &&
inode->generation <= last_committed &&
inode->last_unlink_trans <= last_committed)
goto out;
The generation value for inode Y is 1000 and last_committed, which has
the value read from fs_info->last_trans_committed, has a value of 999,
so that check evaluates to false and we proceed to check the ancestor
inodes.
Once we get to the first ancestor, inode X, we call
btrfs_must_commit_transaction() on it, which evaluates to true:
static bool btrfs_must_commit_transaction(...)
{
struct btrfs_fs_info *fs_info = inode->root->fs_info;
bool ret = false;
mutex_lock(&inode->log_mutex);
if (inode->last_unlink_trans > fs_info->last_trans_committed) {
/*
* Make sure any commits to the log are forced to be full
* commits.
*/
btrfs_set_log_full_commit(trans);
ret = true;
}
(...)
because inode's X last_unlink_trans has a value of 1000 and
fs_info->last_trans_committed still has a value of 999, it returns
true to check_parent_dirs_for_sync(), making it return 1 which is
propagated up to btrfs_sync_file(), causing it to fallback to a full
transaction commit of transaction 1001.
We should have not fallen back to commit transaction 1001, since inode
X had last_unlink_trans set to 1000 and the super blocks for
transaction 1000 were already written. So while not resulting in a
functional problem, it leads to a lot more work and higher latencies
for a fsync since committing a transaction is usually more expensive
than committing a log (if other filesystem changes happened under that
transaction).
Similar problem happens when logging directories, for the same reason as
btrfs_must_commit_transaction() returns true on an inode with its
last_unlink_trans having the generation of the previous transaction and
that transaction is still committing, unpinning its freed extents.
So fix this by comparing last_unlink_trans with the id of the current
transaction instead of fs_info->last_trans_committed.
This case is often hit when running dbench for a long enough duration, as
it does lots of rename and rmdir operations (both update the field
last_unlink_trans of an inode) and fsyncs of files and directories.
This patch belongs to a patch set that is comprised of the following
patches:
btrfs: fix race causing unnecessary inode logging during link and rename
btrfs: fix race that results in logging old extents during a fast fsync
btrfs: fix race that causes unnecessary logging of ancestor inodes
btrfs: fix race that makes inode logging fallback to transaction commit
btrfs: fix race leading to unnecessary transaction commit when logging inode
btrfs: do not block inode logging for so long during transaction commit
Performance results are mentioned in the change log of the last patch.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
||
|
Filipe Manana
|
4d6221d7d8 |
btrfs: fix race that causes unnecessary logging of ancestor inodes
When logging an inode and we are checking if we need to log ancestors that
are new, if the previous transaction is still committing we have a time
window where we can unnecessarily log ancestor inodes that were created in
the previous transaction.
The race is described by the following steps:
1) We are at transaction 1000;
2) Directory inode X is created, its generation is set to 1000;
3) The commit for transaction 1000 is started by task A;
4) The task committing transaction 1000 sets the transaction state to
unblocked, writes the dirty extent buffers and the super blocks, then
unlocks tree_log_mutex;
5) Inode Y, a regular file, is created under directory inode X, this
results in starting a new transaction with a generation of 1001;
6) The transaction 1000 commit is unpinning extents. At this point
fs_info->last_trans_committed still has a value of 999;
7) Task B calls fsync on inode Y and gets a handle for transaction 1001;
8) Task B ends up at log_all_new_ancestors() and then because inode Y has
only one hard link, ends up at log_new_ancestors_fast(). There it reads
a value of 999 from fs_info->last_trans_committed, and sees that the
parent inode X has a generation of 1000, so we end up logging inode X:
if (inode->generation > fs_info->last_trans_committed) {
ret = btrfs_log_inode(trans, root, inode,
LOG_INODE_EXISTS, ctx);
(...)
which is not necessary since it was created in the past transaction,
with a generation of 1000, and that transaction has already committed
its super blocks - it's still unpinning extents so it has not yet
updated fs_info->last_trans_committed from 999 to 1000.
So this just causes us to spend more time logging and allocating and
writing more tree blocks for the log tree.
So fix this by comparing an inode's generation with the generation of the
transaction our transaction handle refers to - if the inode's generation
matches the generation of the current transaction than we know it is a
new inode we need to log, otherwise don't log it.
This case is often hit when running dbench for a long enough duration.
This patch belongs to a patch set that is comprised of the following
patches:
btrfs: fix race causing unnecessary inode logging during link and rename
btrfs: fix race that results in logging old extents during a fast fsync
btrfs: fix race that causes unnecessary logging of ancestor inodes
btrfs: fix race that makes inode logging fallback to transaction commit
btrfs: fix race leading to unnecessary transaction commit when logging inode
btrfs: do not block inode logging for so long during transaction commit
Performance results are mentioned in the change log of the last patch.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
||
|
Filipe Manana
|
5f96bfb763 |
btrfs: fix race that results in logging old extents during a fast fsync
When logging the extents of an inode during a fast fsync, we have a time window where we can log extents that are from the previous transaction and already persisted. This only makes us waste time unnecessarily. The following sequence of steps shows how this can happen: 1) We are at transaction 1000; 2) An ordered extent E from inode I completes, that is it has gone through btrfs_finish_ordered_io(), and it set the extent maps' generation to 1000 when we unpin the extent, which is the generation of the current transaction; 3) The commit for transaction 1000 starts by task A; 4) The task committing transaction 1000 sets the transaction state to unblocked, writes the dirty extent buffers and the super blocks, then unlocks tree_log_mutex; 5) Some change is made to inode I, resulting in creation of a new transaction with a generation of 1001; 6) The transaction 1000 commit starts unpinning extents. At this point fs_info->last_trans_committed still has a value of 999; 7) Task B starts an fsync on inode I, and when it gets to btrfs_log_changed_extents() sees the extent map for extent E in the list of modified extents. It sees the extent map has a generation of 1000 and fs_info->last_trans_committed has a value of 999, so it proceeds to logging the respective file extent item and all the checksums covering its range. So we end up wasting time since the extent was already persisted and is reachable through the trees pointed to by the super block committed by transaction 1000. So just fix this by comparing the extent maps generation against the generation of the transaction handle - if it is smaller then the id in the handle, we know the extent was already persisted and we do not need to log it. This patch belongs to a patch set that is comprised of the following patches: btrfs: fix race causing unnecessary inode logging during link and rename btrfs: fix race that results in logging old extents during a fast fsync btrfs: fix race that causes unnecessary logging of ancestor inodes btrfs: fix race that makes inode logging fallback to transaction commit btrfs: fix race leading to unnecessary transaction commit when logging inode btrfs: do not block inode logging for so long during transaction commit Performance results are mentioned in the change log of the last patch. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
Filipe Manana
|
de53d892e5 |
btrfs: fix race causing unnecessary inode logging during link and rename
When we are doing a rename or a link operation for an inode that was logged in the previous transaction and that transaction is still committing, we have a time window where we incorrectly consider that the inode was logged previously in the current transaction and therefore decide to log it to update it in the log. The following steps give an example on how this happens during a link operation: 1) Inode X is logged in transaction 1000, so its logged_trans field is set to 1000; 2) Task A starts to commit transaction 1000; 3) The state of transaction 1000 is changed to TRANS_STATE_UNBLOCKED; 4) Task B starts a link operation for inode X, and as a consequence it starts transaction 1001; 5) Task A is still committing transaction 1000, therefore the value stored at fs_info->last_trans_committed is still 999; 6) Task B calls btrfs_log_new_name(), it reads a value of 999 from fs_info->last_trans_committed and because the logged_trans field of inode X has a value of 1000, the function does not return immediately, instead it proceeds to logging the inode, which should not happen because the inode was logged in the previous transaction (1000) and not in the current one (1001). This is not a functional problem, just wasted time and space logging an inode that does not need to be logged, contributing to higher latency for link and rename operations. So fix this by comparing the inodes' logged_trans field with the generation of the current transaction instead of comparing with the value stored in fs_info->last_trans_committed. This case is often hit when running dbench for a long enough duration, as it does lots of rename operations. This patch belongs to a patch set that is comprised of the following patches: btrfs: fix race causing unnecessary inode logging during link and rename btrfs: fix race that results in logging old extents during a fast fsync btrfs: fix race that causes unnecessary logging of ancestor inodes btrfs: fix race that makes inode logging fallback to transaction commit btrfs: fix race leading to unnecessary transaction commit when logging inode btrfs: do not block inode logging for so long during transaction commit Performance results are mentioned in the change log of the last patch. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
Nikolay Borisov
|
5297199a8b |
btrfs: remove inode number cache feature
It's been deprecated since commit
|
||
|
Filipe Manana
|
bc5b5b1e51 |
btrfs: stop incrementing log batch when joining log transaction
When joining a log transaction we acquire the root's log mutex, then increment the root's log batch and log writers counters while holding the mutex. However we don't need to increment the log batch there, because we are holding the mutex and incremented the log writers counter as well, so any other task trying to sync log will wait for the current task to finish its logging and still achieve the desired log batching. Since the log batch counter is an atomic counter and is incremented twice at the very beginning of the fsync callback (btrfs_sync_file()), once before flushing delalloc and once again after waiting for writeback to complete, eliminating its increment when joining the log transaction may provide some performance gains in case we have multiple concurrent tasks doing fsyncs against different files in the same subvolume, as it reduces contention on the atomic (locking the cacheline and bouncing it). When testing fio with 32 jobs, on a 8 cores VM, doing fsyncs against different files of the same subvolume, on top of a zram device, I could consistently see gains (higher throughput) between 1% to 2%, which is a very low value and possibly hard to be observed with a real device (I couldn't observe consistent gains with my low/mid end NVMe device). So this change is mostly motivated to just simplify the logic, as updating the log batch counter is only relevant when an fsync starts and while not holding the root's log mutex. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
Filipe Manana
|
f2f121ab50 |
btrfs: skip unnecessary searches for xattrs when logging an inode
Every time we log an inode we lookup in the fs/subvol tree for xattrs and if we have any, log them into the log tree. However it is very common to have inodes without any xattrs, so doing the search wastes times, but more importantly it adds contention on the fs/subvol tree locks, either making the logging code block and wait for tree locks or making the logging code making other concurrent operations block and wait. The most typical use cases where xattrs are used are when capabilities or ACLs are defined for an inode, or when SELinux is enabled. This change makes the logging code detect when an inode does not have xattrs and skip the xattrs search the next time the inode is logged, unless the inode is evicted and loaded again or a xattr is added to the inode. Therefore skipping the search for xattrs on inodes that don't ever have xattrs and are fsynced with some frequency. The following script that calls dbench was used to measure the impact of this change on a VM with 8 CPUs, 16Gb of ram, using a raw NVMe device directly (no intermediary filesystem on the host) and using a non-debug kernel (default configuration on Debian distributions): $ cat test.sh #!/bin/bash DEV=/dev/sdk MNT=/mnt/sdk MOUNT_OPTIONS="-o ssd" mkfs.btrfs -f -m single -d single $DEV mount $MOUNT_OPTIONS $DEV $MNT dbench -D $MNT -t 200 40 umount $MNT The results before this change: Operation Count AvgLat MaxLat ---------------------------------------- NTCreateX 5761605 0.172 312.057 Close 4232452 0.002 10.927 Rename 243937 1.406 277.344 Unlink 1163456 0.631 298.402 Deltree 160 11.581 221.107 Mkdir 80 0.003 0.005 Qpathinfo 5221410 0.065 122.309 Qfileinfo 915432 0.001 3.333 Qfsinfo 957555 0.003 3.992 Sfileinfo 469244 0.023 20.494 Find 2018865 0.448 123.659 WriteX 2874851 0.049 118.529 ReadX 9030579 0.004 21.654 LockX 18754 0.003 4.423 UnlockX 18754 0.002 0.331 Flush 403792 10.944 359.494 Throughput 908.444 MB/sec 40 clients 40 procs max_latency=359.500 ms The results after this change: Operation Count AvgLat MaxLat ---------------------------------------- NTCreateX 6442521 0.159 230.693 Close 4732357 0.002 10.972 Rename 272809 1.293 227.398 Unlink 1301059 0.563 218.500 Deltree 160 7.796 54.887 Mkdir 80 0.008 0.478 Qpathinfo 5839452 0.047 124.330 Qfileinfo 1023199 0.001 4.996 Qfsinfo 1070760 0.003 5.709 Sfileinfo 524790 0.033 21.765 Find 2257658 0.314 125.611 WriteX 3211520 0.040 232.135 ReadX 10098969 0.004 25.340 LockX 20974 0.003 1.569 UnlockX 20974 0.002 3.475 Flush 451553 10.287 331.037 Throughput 1011.77 MB/sec 40 clients 40 procs max_latency=331.045 ms +10.8% throughput, -8.2% max latency Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
Nikolay Borisov
|
9a56fcd15a |
btrfs: make btrfs_update_inode take btrfs_inode
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
Nikolay Borisov
|
507433985c |
btrfs: make btrfs_truncate_inode_items take btrfs_inode
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
Filipe Manana
|
2766ff6176 |
btrfs: update the number of bytes used by an inode atomically
There are several occasions where we do not update the inode's number of used bytes atomically, resulting in a concurrent stat(2) syscall to report a value of used blocks that does not correspond to a valid value, that is, a value that does not match neither what we had before the operation nor what we get after the operation completes. In extreme cases it can result in stat(2) reporting zero used blocks, which can cause problems for some userspace tools where they can consider a file with a non-zero size and zero used blocks as completely sparse and skip reading data, as reported/discussed a long time ago in some threads like the following: https://lists.gnu.org/archive/html/bug-tar/2016-07/msg00001.html The cases where this can happen are the following: -> Case 1 If we do a write (buffered or direct IO) against a file region for which there is already an allocated extent (or multiple extents), then we have a short time window where we can report a number of used blocks to stat(2) that does not take into account the file region being overwritten. This short time window happens when completing the ordered extent(s). This happens because when we drop the extents in the write range we decrement the inode's number of bytes and later on when we insert the new extent(s) we increment the number of bytes in the inode, resulting in a short time window where a stat(2) syscall can get an incorrect number of used blocks. If we do writes that overwrite an entire file, then we have a short time window where we report 0 used blocks to stat(2). Example reproducer: $ cat reproducer-1.sh #!/bin/bash MNT=/mnt/sdi DEV=/dev/sdi stat_loop() { trap "wait; exit" SIGTERM local filepath=$1 local expected=$2 local got while :; do got=$(stat -c %b $filepath) if [ $got -ne $expected ]; then echo -n "ERROR: unexpected used blocks" echo " (got: $got expected: $expected)" fi done } mkfs.btrfs -f $DEV > /dev/null # mkfs.xfs -f $DEV > /dev/null # mkfs.ext4 -F $DEV > /dev/null # mkfs.f2fs -f $DEV > /dev/null # mkfs.reiserfs -f $DEV > /dev/null mount $DEV $MNT xfs_io -f -s -c "pwrite -b 64K 0 64K" $MNT/foobar >/dev/null expected=$(stat -c %b $MNT/foobar) # Create a process to keep calling stat(2) on the file and see if the # reported number of blocks used (disk space used) changes, it should # not because we are not increasing the file size nor punching holes. stat_loop $MNT/foobar $expected & loop_pid=$! for ((i = 0; i < 50000; i++)); do xfs_io -s -c "pwrite -b 64K 0 64K" $MNT/foobar >/dev/null done kill $loop_pid &> /dev/null wait umount $DEV $ ./reproducer-1.sh ERROR: unexpected used blocks (got: 0 expected: 128) ERROR: unexpected used blocks (got: 0 expected: 128) (...) Note that since this is a short time window where the race can happen, the reproducer may not be able to always trigger the bug in one run, or it may trigger it multiple times. -> Case 2 If we do a buffered write against a file region that does not have any allocated extents, like a hole or beyond EOF, then during ordered extent completion we have a short time window where a concurrent stat(2) syscall can report a number of used blocks that does not correspond to the value before or after the write operation, a value that is actually larger than the value after the write completes. This happens because once we start a buffered write into an unallocated file range we increment the inode's 'new_delalloc_bytes', to make sure any stat(2) call gets a correct used blocks value before delalloc is flushed and completes. However at ordered extent completion, after we inserted the new extent, we increment the inode's number of bytes used with the size of the new extent, and only later, when clearing the range in the inode's iotree, we decrement the inode's 'new_delalloc_bytes' counter with the size of the extent. So this results in a short time window where a concurrent stat(2) syscall can report a number of used blocks that accounts for the new extent twice. Example reproducer: $ cat reproducer-2.sh #!/bin/bash MNT=/mnt/sdi DEV=/dev/sdi stat_loop() { trap "wait; exit" SIGTERM local filepath=$1 local expected=$2 local got while :; do got=$(stat -c %b $filepath) if [ $got -ne $expected ]; then echo -n "ERROR: unexpected used blocks" echo " (got: $got expected: $expected)" fi done } mkfs.btrfs -f $DEV > /dev/null # mkfs.xfs -f $DEV > /dev/null # mkfs.ext4 -F $DEV > /dev/null # mkfs.f2fs -f $DEV > /dev/null # mkfs.reiserfs -f $DEV > /dev/null mount $DEV $MNT touch $MNT/foobar write_size=$((64 * 1024)) for ((i = 0; i < 16384; i++)); do offset=$(($i * $write_size)) xfs_io -c "pwrite -S 0xab $offset $write_size" $MNT/foobar >/dev/null blocks_used=$(stat -c %b $MNT/foobar) # Fsync the file to trigger writeback and keep calling stat(2) on it # to see if the number of blocks used changes. stat_loop $MNT/foobar $blocks_used & loop_pid=$! xfs_io -c "fsync" $MNT/foobar kill $loop_pid &> /dev/null wait $loop_pid done umount $DEV $ ./reproducer-2.sh ERROR: unexpected used blocks (got: 265472 expected: 265344) ERROR: unexpected used blocks (got: 284032 expected: 283904) (...) Note that since this is a short time window where the race can happen, the reproducer may not be able to always trigger the bug in one run, or it may trigger it multiple times. -> Case 3 Another case where such problems happen is during other operations that replace extents in a file range with other extents. Those operations are extent cloning, deduplication and fallocate's zero range operation. The cause of the problem is similar to the first case. When we drop the extents from a range, we decrement the inode's number of bytes, and later on, after inserting the new extents we increment it. Since this is not done atomically, a concurrent stat(2) call can see and return a number of used blocks that is smaller than it should be, does not match the number of used blocks before or after the clone/deduplication/zero operation. Like for the first case, when doing a clone, deduplication or zero range operation against an entire file, we end up having a time window where we can report 0 used blocks to a stat(2) call. Example reproducer: $ cat reproducer-3.sh #!/bin/bash MNT=/mnt/sdi DEV=/dev/sdi mkfs.btrfs -f $DEV > /dev/null # mkfs.xfs -f -m reflink=1 $DEV > /dev/null mount $DEV $MNT extent_size=$((64 * 1024)) num_extents=16384 file_size=$(($extent_size * $num_extents)) # File foo has many small extents. xfs_io -f -s -c "pwrite -S 0xab -b $extent_size 0 $file_size" $MNT/foo \ > /dev/null # File bar has much less extents and has exactly the same data as foo. xfs_io -f -c "pwrite -S 0xab 0 $file_size" $MNT/bar > /dev/null expected=$(stat -c %b $MNT/foo) # Now deduplicate bar into foo. While the deduplication is in progres, # the number of used blocks/file size reported by stat should not change xfs_io -c "dedupe $MNT/bar 0 0 $file_size" $MNT/foo > /dev/null & dedupe_pid=$! while [ -n "$(ps -p $dedupe_pid -o pid=)" ]; do used=$(stat -c %b $MNT/foo) if [ $used -ne $expected ]; then echo "Unexpected blocks used: $used (expected: $expected)" fi done umount $DEV $ ./reproducer-3.sh Unexpected blocks used: 2076800 (expected: 2097152) Unexpected blocks used: 2097024 (expected: 2097152) Unexpected blocks used: 2079872 (expected: 2097152) (...) Note that since this is a short time window where the race can happen, the reproducer may not be able to always trigger the bug in one run, or it may trigger it multiple times. So fix this by: 1) Making btrfs_drop_extents() not decrement the VFS inode's number of bytes, and instead return the number of bytes; 2) Making any code that drops extents and adds new extents update the inode's number of bytes atomically, while holding the btrfs inode's spinlock, which is also used by the stat(2) callback to get the inode's number of bytes; 3) For ranges in the inode's iotree that are marked as 'delalloc new', corresponding to previously unallocated ranges, increment the inode's number of bytes when clearing the 'delalloc new' bit from the range, in the same critical section that decrements the inode's 'new_delalloc_bytes' counter, delimited by the btrfs inode's spinlock. An alternative would be to have btrfs_getattr() wait for any IO (ordered extents in progress) and locking the whole range (0 to (u64)-1) while it it computes the number of blocks used. But that would mean blocking stat(2), which is a very used syscall and expected to be fast, waiting for writes, clone/dedupe, fallocate, page reads, fiemap, etc. CC: stable@vger.kernel.org # 5.4+ Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
Filipe Manana
|
5893dfb98f |
btrfs: refactor btrfs_drop_extents() to make it easier to extend
There are many arguments for __btrfs_drop_extents() and its wrapper
btrfs_drop_extents(), which makes it hard to add more arguments to it and
requires changing every caller. I have added a couple myself back in 2014
commit
|
||
|
Josef Bacik
|
3fbaf25817 |
btrfs: pass the owner_root and level to alloc_extent_buffer
Now that we've plumbed all of the callers to have the owner root and the level, plumb it down into alloc_extent_buffer(). Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
Josef Bacik
|
ac5887c8e0 |
btrfs: locking: remove all the blocking helpers
Now that we're using a rw_semaphore we no longer need to indicate if a lock is blocking or not, nor do we need to flip the entire path from blocking to spinning. Remove these helpers and all the places they are called. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
Nikolay Borisov
|
ecdcf3c259 |
btrfs: open code insert_orphan_item
Just open code it in its sole caller and remove a level of indirection. Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
Filipe Manana
|
bb56f02f26 |
btrfs: reschedule if necessary when logging directory items
Logging directories with many entries can take a significant amount of time, and in some cases monopolize a cpu/core for a long time if the logging task doesn't happen to block often enough. Johannes and Lu Fengqi reported test case generic/041 triggering a soft lockup when the kernel has CONFIG_SOFTLOCKUP_DETECTOR=y. For this test case we log an inode with 3002 hard links, and because the test removed one hard link before fsyncing the file, the inode logging causes the parent directory do be logged as well, which has 6004 directory items to log (3002 BTRFS_DIR_ITEM_KEY items plus 3002 BTRFS_DIR_INDEX_KEY items), so it can take a significant amount of time and trigger the soft lockup. So just make tree-log.c:log_dir_items() reschedule when necessary, releasing the current search path before doing so and then resume from where it was before the reschedule. The stack trace produced when the soft lockup happens is the following: [10480.277653] watchdog: BUG: soft lockup - CPU#2 stuck for 22s! [xfs_io:28172] [10480.279418] Modules linked in: dm_thin_pool dm_persistent_data (...) [10480.284915] irq event stamp: 29646366 [10480.285987] hardirqs last enabled at (29646365): [<ffffffff85249b66>] __slab_alloc.constprop.0+0x56/0x60 [10480.288482] hardirqs last disabled at (29646366): [<ffffffff8579b00d>] irqentry_enter+0x1d/0x50 [10480.290856] softirqs last enabled at (4612): [<ffffffff85a00323>] __do_softirq+0x323/0x56c [10480.293615] softirqs last disabled at (4483): [<ffffffff85800dbf>] asm_call_on_stack+0xf/0x20 [10480.296428] CPU: 2 PID: 28172 Comm: xfs_io Not tainted 5.9.0-rc4-default+ #1248 [10480.298948] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba527-rebuilt.opensuse.org 04/01/2014 [10480.302455] RIP: 0010:__slab_alloc.constprop.0+0x19/0x60 [10480.304151] Code: 86 e8 31 75 21 00 66 66 2e 0f 1f 84 00 00 00 (...) [10480.309558] RSP: 0018:ffffadbe09397a58 EFLAGS: 00000282 [10480.311179] RAX: ffff8a495ab92840 RBX: 0000000000000282 RCX: 0000000000000006 [10480.313242] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff85249b66 [10480.315260] RBP: ffff8a497d04b740 R08: 0000000000000001 R09: 0000000000000001 [10480.317229] R10: ffff8a497d044800 R11: ffff8a495ab93c40 R12: 0000000000000000 [10480.319169] R13: 0000000000000000 R14: 0000000000000c40 R15: ffffffffc01daf70 [10480.321104] FS: 00007fa1dc5c0e40(0000) GS:ffff8a497da00000(0000) knlGS:0000000000000000 [10480.323559] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [10480.325235] CR2: 00007fa1dc5befb8 CR3: 0000000004f8a006 CR4: 0000000000170ea0 [10480.327259] Call Trace: [10480.328286] ? overwrite_item+0x1f0/0x5a0 [btrfs] [10480.329784] __kmalloc+0x831/0xa20 [10480.331009] ? btrfs_get_32+0xb0/0x1d0 [btrfs] [10480.332464] overwrite_item+0x1f0/0x5a0 [btrfs] [10480.333948] log_dir_items+0x2ee/0x570 [btrfs] [10480.335413] log_directory_changes+0x82/0xd0 [btrfs] [10480.336926] btrfs_log_inode+0xc9b/0xda0 [btrfs] [10480.338374] ? init_once+0x20/0x20 [btrfs] [10480.339711] btrfs_log_inode_parent+0x8d3/0xd10 [btrfs] [10480.341257] ? dget_parent+0x97/0x2e0 [10480.342480] btrfs_log_dentry_safe+0x3a/0x50 [btrfs] [10480.343977] btrfs_sync_file+0x24b/0x5e0 [btrfs] [10480.345381] do_fsync+0x38/0x70 [10480.346483] __x64_sys_fsync+0x10/0x20 [10480.347703] do_syscall_64+0x2d/0x70 [10480.348891] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [10480.350444] RIP: 0033:0x7fa1dc80970b [10480.351642] Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 (...) [10480.356952] RSP: 002b:00007fffb3d081d0 EFLAGS: 00000293 ORIG_RAX: 000000000000004a [10480.359458] RAX: ffffffffffffffda RBX: 0000562d93d45e40 RCX: 00007fa1dc80970b [10480.361426] RDX: 0000562d93d44ab0 RSI: 0000562d93d45e60 RDI: 0000000000000003 [10480.363367] RBP: 0000000000000001 R08: 0000000000000000 R09: 00007fa1dc7b2a40 [10480.365317] R10: 0000562d93d0e366 R11: 0000000000000293 R12: 0000000000000001 [10480.367299] R13: 0000562d93d45290 R14: 0000562d93d45e40 R15: 0000562d93d45e60 Link: https://lore.kernel.org/linux-btrfs/20180713090216.GC575@fnst.localdomain/ Reported-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> CC: stable@vger.kernel.org # 4.4+ Tested-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
Filipe Manana
|
487781796d |
btrfs: make fast fsyncs wait only for writeback
Currently regardless of a full or a fast fsync we always wait for ordered
extents to complete, and then start logging the inode after that. However
for fast fsyncs we can just wait for the writeback to complete, we don't
need to wait for the ordered extents to complete since we use the list of
modified extents maps to figure out which extents we must log and we can
get their checksums directly from the ordered extents that are still in
flight, otherwise look them up from the checksums tree.
Until commit
|
||
|
Filipe Manana
|
75b463d2b4 |
btrfs: do not commit logs and transactions during link and rename operations
Since commit
|
||
|
Filipe Manana
|
5522a27e59 |
btrfs: do not take the log_mutex of the subvolume when pinning the log
During a rename we pin the log to make sure no one commits a log that
reflects an ongoing rename operation, as it might result in a committed
log where it recorded the unlink of the old name without having recorded
the new name. However we are taking the subvolume's log_mutex before
incrementing the log_writers counter, which is not necessary since that
counter is atomic and we only remove the old name from the log and add
the new name to the log after we have incremented log_writers, ensuring
that no one can commit the log after we have removed the old name from
the log and before we added the new name to the log.
By taking the log_mutex lock we are just adding unnecessary contention on
the lock, which can become visible for workloads that mix renames with
fsyncs, writes for files opened with O_SYNC and unlink operations (if the
inode or its parent were fsynced before in the current transaction).
So just remove the lock and unlock of the subvolume's log_mutex at
btrfs_pin_log_trans().
Using dbench, which mixes different types of operations that end up taking
that mutex (fsyncs, renames, unlinks and writes into files opened with
O_SYNC) revealed some small gains. The following script that calls dbench
was used:
#!/bin/bash
DEV=/dev/nvme0n1
MNT=/mnt/btrfs
MOUNT_OPTIONS="-o ssd -o space_cache=v2"
MKFS_OPTIONS="-m single -d single"
THREADS=32
echo "performance" | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
mkfs.btrfs -f $MKFS_OPTIONS $DEV
mount $MOUNT_OPTIONS $DEV $MNT
dbench -s -t 600 -D $MNT $THREADS
umount $MNT
The test was run on bare metal, no virtualization, on a box with 12 cores
(Intel i7-8700), 64Gb of RAM and using a NVMe device, with a kernel
configuration that is the default of typical distributions (debian in this
case), without debug options enabled (kasan, kmemleak, slub debug, debug
of page allocations, lock debugging, etc).
Results before this patch:
Operation Count AvgLat MaxLat
----------------------------------------
NTCreateX 4410848 0.017 738.640
Close 3240222 0.001 0.834
Rename 186850 7.478 1272.476
Unlink 890875 0.128 785.018
Deltree 128 2.846 12.081
Mkdir 64 0.002 0.003
Qpathinfo 3997659 0.009 11.171
Qfileinfo 701307 0.001 0.478
Qfsinfo 733494 0.002 1.103
Sfileinfo 359362 0.004 3.266
Find
|
||
Randy Dunlap
|
260db43cd2 |
btrfs: delete duplicated words + other fixes in comments
Delete repeated words in fs/btrfs/.
{to, the, a, and old}
and change "into 2 part" to "into 2 parts".
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
||
|
Josef Bacik
|
fb2fecbad5 |
btrfs: check the right error variable in btrfs_del_dir_entries_in_log
With my new locking code dbench is so much faster that I tripped over a
transaction abort from ENOSPC. This turned out to be because
btrfs_del_dir_entries_in_log was checking for ret == -ENOSPC, but this
function sets err on error, and returns err. So instead of properly
marking the inode as needing a full commit, we were returning -ENOSPC
and aborting in __btrfs_unlink_inode. Fix this by checking the proper
variable so that we return the correct thing in the case of ENOSPC.
The ENOENT needs to be checked, because btrfs_lookup_dir_item_index()
can return -ENOENT if the dir item isn't in the tree log (which would
happen if we hadn't fsync'ed this guy). We actually handle that case in
__btrfs_unlink_inode, so it's an expected error to get back.
Fixes:
|
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|
Filipe Manana
|
4f26433e9b |
btrfs: fix memory leaks after failure to lookup checksums during inode logging
While logging an inode, at copy_items(), if we fail to lookup the checksums
for an extent we release the destination path, free the ins_data array and
then return immediately. However a previous iteration of the for loop may
have added checksums to the ordered_sums list, in which case we leak the
memory used by them.
So fix this by making sure we iterate the ordered_sums list and free all
its checksums before returning.
Fixes:
|
||
|
Filipe Manana
|
3ebac17ce5 |
btrfs: reduce contention on log trees when logging checksums
The possibility of extents being shared (through clone and deduplication operations) requires special care when logging data checksums, to avoid having a log tree with different checksum items that cover ranges which overlap (which resulted in missing checksums after replaying a log tree). Such problems were fixed in the past by the following commits: commit |
||
|
Filipe Manana
|
a93e01682e |
btrfs: remove no longer needed use of log_writers for the log root tree
When syncing the log, we used to update the log root tree without holding
neither the log_mutex of the subvolume root nor the log_mutex of log root
tree.
We used to have two critical sections delimited by the log_mutex of the
log root tree, so in the first one we incremented the log_writers of the
log root tree and on the second one we decremented it and waited for the
log_writers counter to go down to zero. This was because the update of
the log root tree happened between the two critical sections.
The use of two critical sections allowed a little bit more of parallelism
and required the use of the log_writers counter, necessary to make sure
we didn't miss any log root tree update when we have multiple tasks trying
to sync the log in parallel.
However after commit
|
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|
Filipe Manana
|
28a9579561 |
btrfs: stop incremening log_batch for the log root tree when syncing log
We are incrementing the log_batch atomic counter of the root log tree but
we never use that counter, it's used only for the log trees of subvolume
roots. We started doing it when we moved the log_batch and log_write
counters from the global, per fs, btrfs_fs_info structure, into the
btrfs_root structure in commit
|
||
|
Filipe Manana
|
5aa7d1a7f4 |
btrfs: only commit delayed items at fsync if we are logging a directory
When logging an inode we are committing its delayed items if either the
inode is a directory or if it is a new inode, created in the current
transaction.
We need to do it for directories, since new directory indexes are stored
as delayed items of the inode and when logging a directory we need to be
able to access all indexes from the fs/subvolume tree in order to figure
out which index ranges need to be logged.
However for new inodes that are not directories, we do not need to do it
because the only type of delayed item they can have is the inode item, and
we are guaranteed to always log an up to date version of the inode item:
*) for a full fsync we do it by committing the delayed inode and then
copying the item from the fs/subvolume tree with
copy_inode_items_to_log();
*) for a fast fsync we always log the inode item based on the contents of
the in-memory struct btrfs_inode. We guarantee this is always done since
commit
|
||
|
Filipe Manana
|
8c8648dd1f |
btrfs: only commit the delayed inode when doing a full fsync
Commit |
||
|
Nikolay Borisov
|
906c448c3d |
btrfs: make __btrfs_drop_extents take btrfs_inode
It has only 4 uses of a vfs_inode for inode_sub_bytes but unifies the interface with the non __ prefixed version. Will also makes converting its callers to btrfs_inode easier. Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
Filipe Manana
|
e7a79811d0 |
btrfs: check if a log root exists before locking the log_mutex on unlink
This brings back an optimization that commit |
||
|
Filipe Manana
|
e289f03ea7 |
btrfs: fix corrupt log due to concurrent fsync of inodes with shared extents
When we have extents shared amongst different inodes in the same subvolume, if we fsync them in parallel we can end up with checksum items in the log tree that represent ranges which overlap. For example, consider we have inodes A and B, both sharing an extent that covers the logical range from X to X + 64KiB: 1) Task A starts an fsync on inode A; 2) Task B starts an fsync on inode B; 3) Task A calls btrfs_csum_file_blocks(), and the first search in the log tree, through btrfs_lookup_csum(), returns -EFBIG because it finds an existing checksum item that covers the range from X - 64KiB to X; 4) Task A checks that the checksum item has not reached the maximum possible size (MAX_CSUM_ITEMS) and then releases the search path before it does another path search for insertion (through a direct call to btrfs_search_slot()); 5) As soon as task A releases the path and before it does the search for insertion, task B calls btrfs_csum_file_blocks() and gets -EFBIG too, because there is an existing checksum item that has an end offset that matches the start offset (X) of the checksum range we want to log; 6) Task B releases the path; 7) Task A does the path search for insertion (through btrfs_search_slot()) and then verifies that the checksum item that ends at offset X still exists and extends its size to insert the checksums for the range from X to X + 64KiB; 8) Task A releases the path and returns from btrfs_csum_file_blocks(), having inserted the checksums into an existing checksum item that got its size extended. At this point we have one checksum item in the log tree that covers the logical range from X - 64KiB to X + 64KiB; 9) Task B now does a search for insertion using btrfs_search_slot() too, but it finds that the previous checksum item no longer ends at the offset X, it now ends at an of offset X + 64KiB, so it leaves that item untouched. Then it releases the path and calls btrfs_insert_empty_item() that inserts a checksum item with a key offset corresponding to X and a size for inserting a single checksum (4 bytes in case of crc32c). Subsequent iterations end up extending this new checksum item so that it contains the checksums for the range from X to X + 64KiB. So after task B returns from btrfs_csum_file_blocks() we end up with two checksum items in the log tree that have overlapping ranges, one for the range from X - 64KiB to X + 64KiB, and another for the range from X to X + 64KiB. Having checksum items that represent ranges which overlap, regardless of being in the log tree or in the chekcsums tree, can lead to problems where checksums for a file range end up not being found. This type of problem has happened a few times in the past and the following commits fixed them and explain in detail why having checksum items with overlapping ranges is problematic: |
||
|
David Sterba
|
0202e83fda |
btrfs: simplify iget helpers
The inode lookup starting at btrfs_iget takes the full location key, while only the objectid is used to match the inode, because the lookup happens inside the given root thus the inode number is unique. The entire location key is properly set up in btrfs_init_locked_inode. Simplify the helpers and pass only inode number, renaming it to 'ino' instead of 'objectid'. This allows to remove temporary variables key, saving some stack space. Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
David Sterba
|
56e9357a1e |
btrfs: simplify root lookup by id
The main function to lookup a root by its id btrfs_get_fs_root takes the whole key, while only using the objectid. The value of offset is preset to (u64)-1 but not actually used until btrfs_find_root that does the actual search. Switch btrfs_get_fs_root to use only objectid and remove all local variables that existed just for the lookup. The actual key for search is set up in btrfs_get_fs_root, reusing another key variable. Signed-off-by: David Sterba <dsterba@suse.com> |
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|
David Sterba
|
60d48e2e45 |
btrfs: don't use set/get token for single assignment in overwrite_item
The set/get token is supposed to cache the last page that was accessed so it speeds up subsequential access to the eb. It does not make sense to use that for just one change, which is the case of inode size in overwrite_item. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
David Sterba
|
cc4c13d55c |
btrfs: drop eb parameter from set/get token helpers
Now that all set/get helpers use the eb from the token, we don't need to pass it to many btrfs_token_*/btrfs_set_token_* helpers, saving some stack space. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
Filipe Manana
|
0bc2d3c08e |
btrfs: remove useless check for copy_items() return value
At btrfs_log_prealloc_extents() we are checking if copy_items() returns a
value greater than 0. That used to happen in the past to signal the caller
that the path given to it was released and reused for other searches, but
as of commit
|
||
Qu Wenruo
|
e3b8336117 |
btrfs: remove the redundant parameter level in btrfs_bin_search()
All callers pass the eb::level so we can get read it directly inside the btrfs_bin_search and key_search. This is inspired by the work of Marek in U-boot. CC: Marek Behun <marek.behun@nic.cz> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
Filipe Manana
|
f135cea30d |
btrfs: fix partial loss of prealloc extent past i_size after fsync
When we have an inode with a prealloc extent that starts at an offset
lower than the i_size and there is another prealloc extent that starts at
an offset beyond i_size, we can end up losing part of the first prealloc
extent (the part that starts at i_size) and have an implicit hole if we
fsync the file and then have a power failure.
Consider the following example with comments explaining how and why it
happens.
$ mkfs.btrfs -f /dev/sdb
$ mount /dev/sdb /mnt
# Create our test file with 2 consecutive prealloc extents, each with a
# size of 128Kb, and covering the range from 0 to 256Kb, with a file
# size of 0.
$ xfs_io -f -c "falloc -k 0 128K" /mnt/foo
$ xfs_io -c "falloc -k 128K 128K" /mnt/foo
# Fsync the file to record both extents in the log tree.
$ xfs_io -c "fsync" /mnt/foo
# Now do a redudant extent allocation for the range from 0 to 64Kb.
# This will merely increase the file size from 0 to 64Kb. Instead we
# could also do a truncate to set the file size to 64Kb.
$ xfs_io -c "falloc 0 64K" /mnt/foo
# Fsync the file, so we update the inode item in the log tree with the
# new file size (64Kb). This also ends up setting the number of bytes
# for the first prealloc extent to 64Kb. This is done by the truncation
# at btrfs_log_prealloc_extents().
# This means that if a power failure happens after this, a write into
# the file range 64Kb to 128Kb will not use the prealloc extent and
# will result in allocation of a new extent.
$ xfs_io -c "fsync" /mnt/foo
# Now set the file size to 256K with a truncate and then fsync the file.
# Since no changes happened to the extents, the fsync only updates the
# i_size in the inode item at the log tree. This results in an implicit
# hole for the file range from 64Kb to 128Kb, something which fsck will
# complain when not using the NO_HOLES feature if we replay the log
# after a power failure.
$ xfs_io -c "truncate 256K" -c "fsync" /mnt/foo
So instead of always truncating the log to the inode's current i_size at
btrfs_log_prealloc_extents(), check first if there's a prealloc extent
that starts at an offset lower than the i_size and with a length that
crosses the i_size - if there is one, just make sure we truncate to a
size that corresponds to the end offset of that prealloc extent, so
that we don't lose the part of that extent that starts at i_size if a
power failure happens.
A test case for fstests follows soon.
Fixes:
|
||
|
Filipe Manana
|
7af597433d |
btrfs: make full fsyncs always operate on the entire file again
This is a revert of commit |
||
|
Josef Bacik
|
8c38938c7b |
btrfs: move the root freeing stuff into btrfs_put_root
There are a few different ways to free roots, either you allocated them yourself and you just do free_extent_buffer(root->node); free_extent_buffer(root->commit_node); btrfs_put_root(root); Which is the pattern for log roots. Or for snapshots/subvolumes that are being dropped you simply call btrfs_free_fs_root() which does all the cleanup for you. Unify this all into btrfs_put_root(), so that we don't free up things associated with the root until the last reference is dropped. This makes the root freeing code much more significant. The only caveat is at close_ctree() time we have to free the extent buffers for all of our main roots (extent_root, chunk_root, etc) because we have to drop the btree_inode and we'll run into issues if we hold onto those nodes until ->kill_sb() time. This will be addressed in the future when we kill the btree_inode. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|
Filipe Manana
|
0a8068a3dd |
btrfs: make ranged full fsyncs more efficient
Commit |