This function currently takes 7 parameters, most of which are proxies
for values from btrfs_delayed_ref_node struct which is not passed. This
patch simplifies the interface of the function by simply passing said
delayed ref node struct to the function. This enables us to:
1. Move locals variables and init code related to them from
run_delayed_tree_ref which should only be used inside
alloc_reserved_tree_block, such as skinny_metadata and the btrfs_key,
representing the extent being inserted. This removes the need for the
"ins" argument. Instead, it's replaced by a local var with a more
verbose name - extent_key.
2. Now that we have a reference to the node in alloc_reserved_tree_block
the delayed_tree_ref struct can be referenced inside the function and
this enable removing the "ref->level", "parent" and "ref_root"
arguments.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This function already takes a transaction handle which contains a
reference to the fs_info. So use this and remove the extra argument.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The test failures are not clearly visible in the system log as they're
printed at INFO level. Add a new helper that is level ERROR. As this
touches almost all strings, I took the opportunity to unify them:
- decapitalize the first letter as there's a prefix and the text
continues after ":"
- glue strings split to more lines and un-indent so they fit to 80
columns
- use %llu instead of %Lu
- drop \n from the modified messages (test_msg is left untouched)
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_read_fs_root_no_name() may return ERR_PTR(-ENOENT) or
ERR_PTR(-ENOMEM) and therefore search_ioctl() and
btrfs_search_path_in_tree() should use PTR_ERR() instead of -ENOENT,
which all other callers of btrfs_read_fs_root_no_name() do.
Drop the error message as it would be confusing, the caller of ioctl
will likely interpret the error code and not look into the syslog.
Signed-off-by: Tomohiro Misono <misono.tomohiro@jp.fujitsu.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
I got a report that after upgrading to 4.16, someone's filesystems
weren't mounting:
[ 23.845852] BTRFS info (device loop0): unrecognized mount option 'subvol='
Before 4.16, this mounted the default subvolume. It turns out that this
empty "subvol=" is actually an application bug, but it was causing the
application to fail, so it's an ABI break if you squint.
The generic parsing code we use for mount options (match_token())
doesn't match an empty string as "%s". Previously, setup_root_args()
removed the "subvol=" string, but the mount path was cleaned up to not
need that. Add a dummy Opt_subvol_empty to fix this.
The simple workaround is to use / or . for the value of 'subvol=' .
Fixes: 312c89fbca ("btrfs: cleanup btrfs_mount() using btrfs_mount_root()")
CC: stable@vger.kernel.org # 4.16+
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Looks like the original idea was to print the hex of the flags which is
not coded with their flag name. So use the current buf pointer bp
instead of buf.
Reaching the uknown flags should never happen, it's there just in case.
Fixes: ebce0e01b9 ("btrfs: make block group flags in balance printks human-readable")
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The dedupe range is 16 MiB, with 4 KiB pages and 8 byte pointers, the
arrays can be 32KiB large. To avoid allocation failures due to
fragmented memory, use the allocation with fallback to vmalloc.
The arrays are allocated and freed only inside btrfs_extent_same and
reused for all the ranges.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We support big dedup requests by splitting range to smaller parts, and
call dedupe logic on each of them.
Instead of repeated allocation and deallocation, allocate once at the
beginning and reuse in the iteration.
Signed-off-by: Timofey Titovets <nefelim4ag@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently btrfs_dedupe_file_range silently restricts the dedupe range to
to 16MiB to limit locking and working memory size and is documented in
manual page as implementation specific.
Let's remove that restriction by iterating over the dedup range in 16MiB
steps. This is backward compatible and will not change anything for
requests smaller then 16MiB.
Signed-off-by: Timofey Titovets <nefelim4ag@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Split btrfs_extent_same() to two parts where one is the main EXTENT_SAME
entry and a helper that can be repeatedly called on a range. This will
be used in following patches.
Signed-off-by: Timofey Titovets <nefelim4ag@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_link() calls btrfs_orphan_del() if it's linking an O_TMPFILE but
it doesn't reserve space to do so. Even before the removal of the
orphan_block_rsv it wasn't using it.
Fixes: ef3b9af50b ("Btrfs: implement inode_operations callback tmpfile")
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We got rid of BTRFS_INODE_HAS_ORPHAN_ITEM and
BTRFS_INODE_ORPHAN_META_RESERVED, so we can renumber the flags to make
them consecutive again.
Signed-off-by: Omar Sandoval <osandov@fb.com>
[ switch them enums so we don't have to do that again ]
Signed-off-by: David Sterba <dsterba@suse.com>
Now that we don't keep long-standing reservations for orphan items,
root->orphan_block_rsv isn't used. We can git rid of it, along with:
- root->orphan_lock, which was used to protect root->orphan_block_rsv
- root->orphan_inodes, which was used as a refcount for root->orphan_block_rsv
- BTRFS_INODE_ORPHAN_META_RESERVED, which was used to track reservations
in root->orphan_block_rsv
- btrfs_orphan_commit_root(), which was the last user of any of these
and does nothing else
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently, we keep space reserved for all inode orphan items until the
inode is evicted (i.e., all references to it are dropped). We hit an
issue where an application would keep a bunch of deleted files open (by
design) and thus keep a large amount of space reserved, causing ENOSPC
errors when other operations tried to reserve space. This long-standing
reservation isn't absolutely necessary for a couple of reasons:
- We can almost always make the reservation we need or steal from the
global reserve for the orphan item
- If we can't, it's not the end of the world if we drop the orphan item
on the floor and let the next mount clean it up
So, get rid of persistent reservation and just reserve space in
btrfs_evict_inode().
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The truncate loop in btrfs_evict_inode() does two things at once:
- It refills the temporary block reserve, potentially stealing from the
global reserve or committing
- It calls btrfs_truncate_inode_items()
The tangle of continues hides the fact that these two steps are actually
separate. Split the first step out into a separate function both for
clarity and so that we can reuse it in a later patch.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In btrfs_evict_inode(), if btrfs_truncate_inode_items() fails, the inode
item will still be in the tree but we still return the ino to the ino
cache. That will blow up later when someone tries to allocate that ino,
so don't return it to the cache.
Fixes: 581bb05094 ("Btrfs: Cache free inode numbers in memory")
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_orphan_commit_root() tries to delete an orphan item for a
subvolume in the tree root, but we don't actually insert that item in
the first place. See commit 0a0d4415e3 ("Btrfs: delete dead code in
btrfs_orphan_add()"). We can get rid of it.
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Now that we don't add orphan items for truncate, there can't be races on
adding or deleting an orphan item, so this bit is unnecessary.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently, we insert an orphan item during a truncate so that if there's
a crash, we don't leak extents past the on-disk i_size. However, since
commit 7f4f6e0a3f ("Btrfs: only update disk_i_size as we remove
extents"), we keep disk_i_size in sync with the extent items as we
truncate, so orphan cleanup will never have any extents to remove. Don't
bother with the superfluous orphan item.
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_free_extent() can fail because of ENOMEM. There's no reason to
panic here, we can just abort the transaction.
Fixes: f4b9aa8d3b ("btrfs_truncate")
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_truncate_inode_items() uses two variables for error handling, ret
and err. These are not handled consistently, leading to a couple of
bugs.
- Errors from btrfs_del_items() are handled but not propagated to the
caller
- If btrfs_run_delayed_refs() fails and aborts the transaction, we
continue running
Just use ret everywhere and simplify things a bit, fixing both of these
issues.
Fixes: 79787eaab4 ("btrfs: replace many BUG_ONs with proper error handling")
Fixes: 1262133b8d ("Btrfs: account for crcs in delayed ref processing")
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Commit a41ad394a0 ("Btrfs: convert to the new truncate sequence")
changed btrfs_setsize() to call truncate_setsize() instead of
vmtruncate() but didn't update the comment above it. truncate_setsize()
never fails (the IS_SWAPFILE() check happens elsewhere), so remove the
comment.
Additionally, the comment above btrfs_page_mkwrite() references
vmtruncate(), but truncate_setsize() does the size write and page
locking now.
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
select_delayed_ref really just gets the next delayed ref which has to
be processed - either an add ref or drop ref. We never go back for
anything. So the comment is actually bogus, just remove it.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Deletion of a subvolume by rmdir(2) has become allowed by the
'commit cd2decf640b1 ("btrfs: Allow rmdir(2) to delete an empty
subvolume")'.
It is a kind of new feature and this commits add a sysfs entry
/sys/fs/btrfs/features/rmdir_subvol
to indicate the availability of the feature so that a user program
(e.g. fstests) can detect it.
Prior to this commit, all entries in /sys/fs/btrfs/features are feature
which depend on feature bits of superblock (i.e. each feature affects
on-disk format) and managed by attribute_group "btrfs_feature_attr_group".
For each fs, entries in /sys/fs/btrfs/UUID/features indicate which
features are enabled (or can be changed online) for the fs.
However, rmdir_subvol feature only depends on kernel module. Therefore
new attribute_group "btrfs_static_feature_attr_group" is introduced and
sysfs_merge_group() is used to share /sys/fs/btrfs/features directory.
Features in "btrfs_static_feature_attr_group" won't be listed in each
/sys/fs/btrfs/UUID/features.
Signed-off-by: Tomohiro Misono <misono.tomohiro@jp.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Use existing named values instead of the raw numbers.
Signed-off-by: Tomohiro Misono <misono.tomohiro@jp.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Kernel logs are very important for the forensic investigations of the
issues in general make it easy to use it. This patch adds 'balance:'
prefix so that it can be easily searched.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
* The simple 'flags' refer to the btrfs inode
* ... that's in 'binode
* the FS_*_FL variables are 'fsflags'
* the old copies of the variable are prefixed by 'old_'
* Struct inode flags contain 'i_flags'.
Signed-off-by: David Sterba <dsterba@suse.com>
The new ioctl is an extension to the FS_IOC_SETFLAGS and adds new
flags and is extensible. Don't get fooled by the XATTR in the name, it
does not have anything in common with the extended attributes,
incidentally also abbreviated as XATTRs.
This patch allows to set the xflags portion of the fsxattr structure,
other items have no meaning and non-zero values will result in
EOPNOTSUPP.
Currently supported xflags:
- APPEND
- IMMUTABLE
- NOATIME
- NODUMP
- SYNC
The structure of btrfs_ioctl_fssetxattr copies btrfs_ioctl_setflags but
is simpler on the flag setting side.
The original patch was written by Chandan Jay Sharma but was incomplete
and no further revision has been sent.
Based-on-patches-by: Chandan Jay Sharma <chandansbg@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The new ioctl is an extension to the FS_IOC_GETFLAGS and adds new
flags and is extensible. This patch allows to return the xflags portion
of the fsxattr structure, other items have no meaning for btrfs or can
be added later.
The original patch was written by Chandan Jay Sharma but was incomplete
and no further revision has been sent. Several cleanups were necessary
to avoid confusion with other ioctls, as we have another flavor of
flags.
Based-on-patches-by: Chandan Jay Sharma <chandansbg@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The FS_*_FL flags cannot be easily identified by a prefix but we still
need to recognize them so the 'fsflags' should be closer to the naming
scheme but again the 'fs' part sounds like it's a filesystem flag. I
don't have a better idea for now.
Signed-off-by: David Sterba <dsterba@suse.com>
The FS_*_FL flags cannot be easily identified by a variable name prefix
but we still need to recognize them so the 'fsflags' should be closer to
the naming scheme but again the 'fs' part sounds like it's a filesystem
flag. I don't have a better idea for now.
Signed-off-by: David Sterba <dsterba@suse.com>
Use a local btrfs_fs_devices variable to access the structure.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Delete the uuid_mutex lock here as this thread accesses the
btrfs_fs_devices::devices only (counters or called functions do a list
traversal). And the device_list_mutex lock is already taken.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_dev_replace_finishing updates devices (soruce and target) which
are within the btrfs_fs_devices::devices or withint the cloned seed
devices (btrfs_fs_devices::seed::devices), so we don't need the global
uuid_mutex.
The device replace context is also locked by its own locks.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_open_devices() is using the uuid_mutex, but as btrfs_open_devices
is just limited to openning all the devices under for given fsid, so we
don't need uuid_mutex.
Instead it should hold the device_list_mutex as it updates the members
of the btrfs_fs_devices and btrfs_device and not the whole fs_devs list.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
read_chunk_tree() calls read_one_dev(), but for seed device we have
to search the fs_uuids list, so we need the uuid_mutex. Add a comment
comment, so that we can improve this part.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Instead of de-referencing the device->fs_devices use cur_devices
which points to the same fs_devices and does not change.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The generic block device lookup or cleanup does not need the uuid mutex,
that's only for the device_list_add.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
This function is no longer used outside of inode.c so just make it
static. At the same time give a more becoming name, since it's not
really invalidating the inodes but just calling d_prune_alias. Last,
but not least - move the function above the sole caller to avoid
introducing yet-another-pointless forward declaration.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Use the wrappers and reduce the amount of low-level details about the
waitqueue management.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently the code assumes that there's an implied barrier by the
sequence of code preceding the wakeup, namely the mutex unlock.
As Nikolay pointed out:
I think this is wrong (not your code) but the original assumption that
the RELEASE semantics provided by mutex_unlock is sufficient.
According to memory-barriers.txt:
Section 'LOCK ACQUISITION FUNCTIONS' states:
(2) RELEASE operation implication:
Memory operations issued before the RELEASE will be completed before the
RELEASE operation has completed.
Memory operations issued after the RELEASE *may* be completed before the
RELEASE operation has completed.
(I've bolded the may portion)
The example given there:
As an example, consider the following:
*A = a;
*B = b;
ACQUIRE
*C = c;
*D = d;
RELEASE
*E = e;
*F = f;
The following sequence of events is acceptable:
ACQUIRE, {*F,*A}, *E, {*C,*D}, *B, RELEASE
So if we assume that *C is modifying the flag which the waitqueue is checking,
and *E is the actual wakeup, then those accesses can be re-ordered...
IMHO this code should be considered broken...
---
To be on the safe side, add the barriers. The synchronization logic
around log using the mutexes and several other threads does not make it
easy to reason for/against the barrier.
CC: Nikolay Borisov <nborisov@suse.com>
Link: https://lkml.kernel.org/r/6ee068d8-1a69-3728-00d1-d86293d43c9f@suse.com
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Add convenience wrappers for the waitqueue management that involves
memory barriers to prevent deadlocks. The helpers will let us remove
barriers and the necessary comments in several places.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Under the following case, qgroup rescan can double account cowed tree
blocks:
In this case, extent tree only has one tree block.
-
| transid=5 last committed=4
| btrfs_qgroup_rescan_worker()
| |- btrfs_start_transaction()
| | transid = 5
| |- qgroup_rescan_leaf()
| |- btrfs_search_slot_for_read() on extent tree
| Get the only extent tree block from commit root (transid = 4).
| Scan it, set qgroup_rescan_progress to the last
| EXTENT/META_ITEM + 1
| now qgroup_rescan_progress = A + 1.
|
| fs tree get CoWed, new tree block is at A + 16K
| transid 5 get committed
-
| transid=6 last committed=5
| btrfs_qgroup_rescan_worker()
| btrfs_qgroup_rescan_worker()
| |- btrfs_start_transaction()
| | transid = 5
| |- qgroup_rescan_leaf()
| |- btrfs_search_slot_for_read() on extent tree
| Get the only extent tree block from commit root (transid = 5).
| scan it using qgroup_rescan_progress (A + 1).
| found new tree block beyong A, and it's fs tree block,
| account it to increase qgroup numbers.
-
In above case, tree block A, and tree block A + 16K get accounted twice,
while qgroup rescan should stop when it already reach the last leaf,
other than continue using its qgroup_rescan_progress.
Such case could happen by just looping btrfs/017 and with some
possibility it can hit such double qgroup accounting problem.
Fix it by checking the path to determine if we should finish qgroup
rescan, other than relying on next loop to exit.
Reported-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When doing qgroup rescan using the following script (modified from
btrfs/017 test case), we can sometimes hit qgroup corruption.
------
umount $dev &> /dev/null
umount $mnt &> /dev/null
mkfs.btrfs -f -n 64k $dev
mount $dev $mnt
extent_size=8192
xfs_io -f -d -c "pwrite 0 $extent_size" $mnt/foo > /dev/null
btrfs subvolume snapshot $mnt $mnt/snap
xfs_io -f -c "reflink $mnt/foo" $mnt/foo-reflink > /dev/null
xfs_io -f -c "reflink $mnt/foo" $mnt/snap/foo-reflink > /dev/null
xfs_io -f -c "reflink $mnt/foo" $mnt/snap/foo-reflink2 > /dev/unll
btrfs quota enable $mnt
# -W is the new option to only wait rescan while not starting new one
btrfs quota rescan -W $mnt
btrfs qgroup show -prce $mnt
umount $mnt
# Need to patch btrfs-progs to report qgroup mismatch as error
btrfs check $dev || _fail
------
For fast machine, we can hit some corruption which missed accounting
tree blocks:
------
qgroupid rfer excl max_rfer max_excl parent child
-------- ---- ---- -------- -------- ------ -----
0/5 8.00KiB 0.00B none none --- ---
0/257 8.00KiB 0.00B none none --- ---
------
This is due to the fact that we're always searching commit root for
btrfs_find_all_roots() at qgroup_rescan_leaf(), but the leaf we get is
from current transaction, not commit root.
And if our tree blocks get modified in current transaction, we won't
find any owner in commit root, thus causing the corruption.
Fix it by searching commit root for extent tree for
qgroup_rescan_leaf().
Reported-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[spotted while going through ->d_fsdata handling around d_splice_alias();
don't really care which tree that goes through]
The only thing even looking at ->d_fsdata in there (since 2012)
had been kfree(dentry->d_fsdata) in btrfs_dentry_delete(). Which,
incidentally, is all btrfs_dentry_delete() does.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There are already 2 reports about strangely corrupted super blocks,
where csum still matches but extra garbage gets slipped into super block.
The corruption would looks like:
------
superblock: bytenr=65536, device=/dev/sdc1
---------------------------------------------------------
csum_type 41700 (INVALID)
csum 0x3b252d3a [match]
bytenr 65536
flags 0x1
( WRITTEN )
magic _BHRfS_M [match]
...
incompat_flags 0x5b22400000000169
( MIXED_BACKREF |
COMPRESS_LZO |
BIG_METADATA |
EXTENDED_IREF |
SKINNY_METADATA |
unknown flag: 0x5b22400000000000 )
...
------
Or
------
superblock: bytenr=65536, device=/dev/mapper/x
---------------------------------------------------------
csum_type 35355 (INVALID)
csum_size 32
csum 0xf0dbeddd [match]
bytenr 65536
flags 0x1
( WRITTEN )
magic _BHRfS_M [match]
...
incompat_flags 0x176d200000000169
( MIXED_BACKREF |
COMPRESS_LZO |
BIG_METADATA |
EXTENDED_IREF |
SKINNY_METADATA |
unknown flag: 0x176d200000000000 )
------
Obviously, csum_type and incompat_flags get some garbage, but its csum
still matches, which means kernel calculates the csum based on corrupted
super block memory.
And after manually fixing these values, the filesystem is completely
healthy without any problem exposed by btrfs check.
Although the cause is still unknown, at least detect it and prevent further
corruption.
Both reports have same symptoms, there's an overwrite on offset 192 of
the superblock, by 4 bytes. The superblock structure is not allocated or
freed and stays in the memory for the whole filesystem lifetime, so it's
not a use-after-free kind of error on someone else's leaked page.
As a vague point for the problable cause is mentioning of other system
freezing related to graphic card drivers.
Reported-by: Ken Swenson <flat@imo.uto.moe>
Reported-by: Ben Parsons <9parsonsb@gmail.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add brief analysis of the reports ]
Signed-off-by: David Sterba <dsterba@suse.com>
