The btrfs_alloc_dummy_root() uses ERR_PTR as the error return value
rather than NULL, if error happened, there will be a NULL pointer
dereference:
BUG: KASAN: null-ptr-deref in btrfs_free_dummy_root+0x21/0x50 [btrfs]
Read of size 8 at addr 000000000000002c by task insmod/258926
CPU: 2 PID: 258926 Comm: insmod Tainted: G W 6.1.0-rc2+ #5
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1.fc33 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x34/0x44
kasan_report+0xb7/0x140
kasan_check_range+0x145/0x1a0
btrfs_free_dummy_root+0x21/0x50 [btrfs]
btrfs_test_free_space_cache+0x1a8c/0x1add [btrfs]
btrfs_run_sanity_tests+0x65/0x80 [btrfs]
init_btrfs_fs+0xec/0x154 [btrfs]
do_one_initcall+0x87/0x2a0
do_init_module+0xdf/0x320
load_module+0x3006/0x3390
__do_sys_finit_module+0x113/0x1b0
do_syscall_64+0x35/0x80
entry_SYSCALL_64_after_hwframe+0x46/0xb0
Fixes: aaedb55bc0 ("Btrfs: add tests for btrfs_get_extent")
CC: stable@vger.kernel.org # 4.9+
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
syzkaller found a failed assertion:
assertion failed: (args->devid != (u64)-1) || args->missing, in fs/btrfs/volumes.c:6921
This can be triggered when we set devid to (u64)-1 by ioctl. In this
case, the match of devid will be skipped and the match of device may
succeed incorrectly.
Patch 562d7b1512 introduced this function which is used to match device.
This function contains two matching scenarios, we can distinguish them by
checking the value of args->missing rather than check whether args->devid
and args->uuid is default value.
Reported-by: syzbot+031687116258450f9853@syzkaller.appspotmail.com
Fixes: 562d7b1512 ("btrfs: handle device lookup with btrfs_dev_lookup_args")
CC: stable@vger.kernel.org # 5.16+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Signed-off-by: David Sterba <dsterba@suse.com>
During a nowait buffered write, if we fail to balance dirty pages we exit
btrfs_buffered_write() without releasing the delalloc space reserved for
an extent, resulting in leaking space from the inode's block reserve.
So fix that by releasing the delalloc space for the extent when balancing
dirty pages fails.
Reported-by: kernel test robot <yujie.liu@intel.com>
Link: https://lore.kernel.org/all/202210111304.d369bc32-yujie.liu@intel.com
Fixes: 965f47aeb5 ("btrfs: make btrfs_buffered_write nowait compatible")
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If we are doing a buffered write in NOWAIT context and we can't reserve
metadata space due to -ENOSPC, then we should return -EAGAIN so that we
retry the write in a context allowed to block and do metadata reservation
with flushing, which might succeed this time due to the allowed flushing.
Returning -ENOSPC while in NOWAIT context simply makes some writes fail
with -ENOSPC when they would likely succeed after switching from NOWAIT
context to blocking context. That is unexpected behaviour and even fio
complains about it with a warning like this:
fio: io_u error on file /mnt/sdi/task_0.0.0: No space left on device: write offset=1535705088, buflen=65536
fio: pid=592630, err=28/file:io_u.c:1846, func=io_u error, error=No space left on device
The fio's job config is this:
[global]
bs=64K
ioengine=io_uring
iodepth=1
size=2236962133
nr_files=1
filesize=2236962133
direct=0
runtime=10
fallocate=posix
io_size=2236962133
group_reporting
time_based
[task_0]
rw=randwrite
directory=/mnt/sdi
numjobs=4
So fix this by returning -EAGAIN if we are in NOWAIT context and the
metadata reservation failed with -ENOSPC.
Fixes: 304e45acdb ("btrfs: plumb NOWAIT through the write path")
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Several places in the qgroup self tests follow the pattern of freeing the
ulist pointer they passed to btrfs_find_all_roots() if the call to that
function returned an error. That is pointless because that function always
frees the ulist in case it returns an error.
Also In some places like at test_multiple_refs(), after a call to
btrfs_qgroup_account_extent() we also leave "old_roots" and "new_roots"
pointing to ulists that were freed, because btrfs_qgroup_account_extent()
has freed those ulists, and if after that the next call to
btrfs_find_all_roots() fails, we call ulist_free() on the "old_roots"
ulist again, resulting in a double free.
So remove those calls to reduce the code size and avoid double ulist
free in case of an error.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In the test_no_shared_qgroup() and test_multiple_refs() qgroup self tests,
if we fail to add the tree ref, remove the extent item or remove the
extent ref, we are returning from the test function without freeing the
"old_roots" ulist that was allocated by the previous calls to
btrfs_find_all_roots(). Fix that by calling ulist_free() before returning.
Fixes: 442244c963 ("btrfs: qgroup: Switch self test to extent-oriented qgroup mechanism.")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
During backref walking, at find_parent_nodes(), if we are dealing with a
data extent and we get an error while resolving the indirect backrefs, at
resolve_indirect_refs(), or in the while loop that iterates over the refs
in the direct refs rbtree, we end up leaking the inode lists attached to
the direct refs we have in the direct refs rbtree that were not yet added
to the refs ulist passed as argument to find_parent_nodes(). Since they
were not yet added to the refs ulist and prelim_release() does not free
the lists, on error the caller can only free the lists attached to the
refs that were added to the refs ulist, all the remaining refs get their
inode lists never freed, therefore leaking their memory.
Fix this by having prelim_release() always free any attached inode list
to each ref found in the rbtree, and have find_parent_nodes() set the
ref's inode list to NULL once it transfers ownership of the inode list
to a ref added to the refs ulist passed to find_parent_nodes().
Fixes: 86d5f99442 ("btrfs: convert prelimary reference tracking to use rbtrees")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
During backref walking, at resolve_indirect_refs(), if we get an error
we jump to the 'out' label and call ulist_free() on the 'parents' ulist,
which frees all the elements in the ulist - however that does not free
any inode lists that may be attached to elements, through the 'aux' field
of a ulist node, so we end up leaking lists if we have any attached to
the unodes.
Fix this by calling free_leaf_list() instead of ulist_free() when we exit
from resolve_indirect_refs(). The static function free_leaf_list() is
moved up for this to be possible and it's slightly simplified by removing
unnecessary code.
Fixes: 3301958b7c ("Btrfs: add inodes before dropping the extent lock in find_all_leafs")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When doing a direct IO write using a iocb with nowait and dsync set, we
end up not syncing the file once the write completes.
This is because we tell iomap to not call generic_write_sync(), which
would result in calling btrfs_sync_file(), in order to avoid a deadlock
since iomap can call it while we are holding the inode's lock and
btrfs_sync_file() needs to acquire the inode's lock. The deadlock happens
only if the write happens synchronously, when iomap_dio_rw() calls
iomap_dio_complete() before it returns. Instead we do the sync ourselves
at btrfs_do_write_iter().
For a nowait write however we can end up not doing the sync ourselves at
at btrfs_do_write_iter() because the write could have been queued, and
therefore we get -EIOCBQUEUED returned from iomap in such case. That makes
us skip the sync call at btrfs_do_write_iter(), as we don't do it for
any error returned from btrfs_direct_write(). We can't simply do the call
even if -EIOCBQUEUED is returned, since that would block the task waiting
for IO, both for the data since there are bios still in progress as well
as potentially blocking when joining a log transaction and when syncing
the log (writing log trees, super blocks, etc).
So let iomap do the sync call itself and in order to avoid deadlocks for
the case of synchronous writes (without nowait), use __iomap_dio_rw() and
have ourselves call iomap_dio_complete() after unlocking the inode.
A test case will later be sent for fstests, after this is fixed in Linus'
tree.
Fixes: 51bd9563b6 ("btrfs: fix deadlock due to page faults during direct IO reads and writes")
Reported-by: Марк Коренберг <socketpair@gmail.com>
Link: https://lore.kernel.org/linux-btrfs/CAEmTpZGRKbzc16fWPvxbr6AfFsQoLmz-Lcg-7OgJOZDboJ+SGQ@mail.gmail.com/
CC: stable@vger.kernel.org # 6.0+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
After allocation 'dip' is tested instead of 'dip->csums'. Fix it.
Fixes: 642c5d34da ("btrfs: allocate the btrfs_dio_private as part of the iomap dio bio")
CC: stable@vger.kernel.org # 5.19+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
There are two reports (the earliest one from LKP, a more recent one from
kernel bugzilla) that we can have some chunks with 0 as sub_stripes.
This will cause divide-by-zero errors at btrfs_rmap_block, which is
introduced by a recent kernel patch ac0677348f ("btrfs: merge
calculations for simple striped profiles in btrfs_rmap_block"):
if (map->type & (BTRFS_BLOCK_GROUP_RAID0 |
BTRFS_BLOCK_GROUP_RAID10)) {
stripe_nr = stripe_nr * map->num_stripes + i;
stripe_nr = div_u64(stripe_nr, map->sub_stripes); <<<
}
[CAUSE]
From the more recent report, it has been proven that we have some chunks
with 0 as sub_stripes, mostly caused by older mkfs.
It turns out that the mkfs.btrfs fix is only introduced in 6718ab4d33aa
("btrfs-progs: Initialize sub_stripes to 1 in btrfs_alloc_data_chunk")
which is included in v5.4 btrfs-progs release.
So there would be quite some old filesystems with such 0 sub_stripes.
[FIX]
Just don't trust the sub_stripes values from disk.
We have a trusted btrfs_raid_array[] to fetch the correct sub_stripes
numbers for each profile and that are fixed.
By this, we can keep the compatibility with older filesystems while
still avoid divide-by-zero bugs.
Reported-by: kernel test robot <oliver.sang@intel.com>
Reported-by: Viktor Kuzmin <kvaster@gmail.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=216559
Fixes: ac0677348f ("btrfs: merge calculations for simple striped profiles in btrfs_rmap_block")
CC: stable@vger.kernel.org # 6.0
Reviewed-by: Su Yue <glass@fydeos.io>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The type of parameter generation has been u32 since the beginning,
however all callers pass a u64 generation, so unify the types to prevent
potential loss.
CC: stable@vger.kernel.org # 4.9+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Commit 9ed0a72e5b ("btrfs: send: fix failures when processing inodes with
no links") tries to fix all incremental send cases of orphan inodes the
send operation will meet. However, there's still a bug causing the corner
subcase fails with a ENOENT error.
Here's shortened steps of that subcase:
$ btrfs subvolume create vol
$ touch vol/foo
$ btrfs subvolume snapshot -r vol snap1
$ btrfs subvolume snapshot -r vol snap2
# Turn the second snapshot to RW mode and delete the file while
# holding an open file descriptor on it
$ btrfs property set snap2 ro false
$ exec 73<snap2/foo
$ rm snap2/foo
# Set the second snapshot back to RO mode and do an incremental send
# with an unusal reverse order
$ btrfs property set snap2 ro true
$ btrfs send -p snap2 snap1 > /dev/null
At subvol snap1
ERROR: send ioctl failed with -2: No such file or directory
It's subcase 3 of BTRFS_COMPARE_TREE_CHANGED in the commit 9ed0a72e5b
("btrfs: send: fix failures when processing inodes with no links"). And
it's not a common case. We still have not met it in the real world.
Theoretically, this case can happen in a batch cascading snapshot backup.
In cascading backups, the receive operation in the middle may cause orphan
inodes to appear because of the open file descriptors on the snapshot files
during receiving. And if we don't do the batch snapshot backups in their
creation order, then we can have an inode, which is an orphan in the parent
snapshot but refers to a file in the send snapshot. Since an orphan inode
has no paths, the send operation will fail with a ENOENT error if it
tries to generate a path for it.
In that patch, this subcase will be treated as an inode with a new
generation. However, when the routine tries to delete the old paths in
the parent snapshot, the function process_all_refs() doesn't check whether
there are paths recorded or not before it calls the function
process_recorded_refs(). And the function process_recorded_refs() try
to get the first path in the parent snapshot in the beginning. Since it has
no paths in the parent snapshot, the send operation fails.
To fix this, we can easily put a link count check to avoid entering the
deletion routine like what we do a link count check to avoid creating a
new one. Moreover, we can assume that the function process_all_refs()
can always collect references to process because we know it has a
positive link count.
Fixes: 9ed0a72e5b ("btrfs: send: fix failures when processing inodes with no links")
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: BingJing Chang <bingjingc@synology.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Previous commit a05d3c9153 ("btrfs: check superblock to ensure the fs
was not modified at thaw time") only checks the content of the super
block, but it doesn't really check if the on-disk super block has a
matching checksum.
This patch will add the checksum verification to thaw time superblock
verification.
This involves the following extra changes:
- Export btrfs_check_super_csum()
As we need to call it in super.c.
- Change the argument list of btrfs_check_super_csum()
Instead of passing a char *, directly pass struct btrfs_super_block *
pointer.
- Verify that our checksum type didn't change before checking the
checksum value, like it's done at mount time
Fixes: a05d3c9153 ("btrfs: check superblock to ensure the fs was not modified at thaw time")
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We have been seeing the following panic in production
kernel BUG at fs/btrfs/tree-mod-log.c:677!
invalid opcode: 0000 [#1] SMP
RIP: 0010:tree_mod_log_rewind+0x1b4/0x200
RSP: 0000:ffffc9002c02f890 EFLAGS: 00010293
RAX: 0000000000000003 RBX: ffff8882b448c700 RCX: 0000000000000000
RDX: 0000000000008000 RSI: 00000000000000a7 RDI: ffff88877d831c00
RBP: 0000000000000002 R08: 000000000000009f R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000100c40 R12: 0000000000000001
R13: ffff8886c26d6a00 R14: ffff88829f5424f8 R15: ffff88877d831a00
FS: 00007fee1d80c780(0000) GS:ffff8890400c0000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fee1963a020 CR3: 0000000434f33002 CR4: 00000000007706e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
btrfs_get_old_root+0x12b/0x420
btrfs_search_old_slot+0x64/0x2f0
? tree_mod_log_oldest_root+0x3d/0xf0
resolve_indirect_ref+0xfd/0x660
? ulist_alloc+0x31/0x60
? kmem_cache_alloc_trace+0x114/0x2c0
find_parent_nodes+0x97a/0x17e0
? ulist_alloc+0x30/0x60
btrfs_find_all_roots_safe+0x97/0x150
iterate_extent_inodes+0x154/0x370
? btrfs_search_path_in_tree+0x240/0x240
iterate_inodes_from_logical+0x98/0xd0
? btrfs_search_path_in_tree+0x240/0x240
btrfs_ioctl_logical_to_ino+0xd9/0x180
btrfs_ioctl+0xe2/0x2ec0
? __mod_memcg_lruvec_state+0x3d/0x280
? do_sys_openat2+0x6d/0x140
? kretprobe_dispatcher+0x47/0x70
? kretprobe_rethook_handler+0x38/0x50
? rethook_trampoline_handler+0x82/0x140
? arch_rethook_trampoline_callback+0x3b/0x50
? kmem_cache_free+0xfb/0x270
? do_sys_openat2+0xd5/0x140
__x64_sys_ioctl+0x71/0xb0
do_syscall_64+0x2d/0x40
Which is this code in tree_mod_log_rewind()
switch (tm->op) {
case BTRFS_MOD_LOG_KEY_REMOVE_WHILE_FREEING:
BUG_ON(tm->slot < n);
This occurs because we replay the nodes in order that they happened, and
when we do a REPLACE we will log a REMOVE_WHILE_FREEING for every slot,
starting at 0. 'n' here is the number of items in this block, which in
this case was 1, but we had 2 REMOVE_WHILE_FREEING operations.
The actual root cause of this was that we were replaying operations for
a block that shouldn't have been replayed. Consider the following
sequence of events
1. We have an already modified root, and we do a btrfs_get_tree_mod_seq().
2. We begin removing items from this root, triggering KEY_REPLACE for
it's child slots.
3. We remove one of the 2 children this root node points to, thus triggering
the root node promotion of the remaining child, and freeing this node.
4. We modify a new root, and re-allocate the above node to the root node of
this other root.
The tree mod log looks something like this
logical 0 op KEY_REPLACE (slot 1) seq 2
logical 0 op KEY_REMOVE (slot 1) seq 3
logical 0 op KEY_REMOVE_WHILE_FREEING (slot 0) seq 4
logical 4096 op LOG_ROOT_REPLACE (old logical 0) seq 5
logical 8192 op KEY_REMOVE_WHILE_FREEING (slot 1) seq 6
logical 8192 op KEY_REMOVE_WHILE_FREEING (slot 0) seq 7
logical 0 op LOG_ROOT_REPLACE (old logical 8192) seq 8
>From here the bug is triggered by the following steps
1. Call btrfs_get_old_root() on the new_root.
2. We call tree_mod_log_oldest_root(btrfs_root_node(new_root)), which is
currently logical 0.
3. tree_mod_log_oldest_root() calls tree_mod_log_search_oldest(), which
gives us the KEY_REPLACE seq 2, and since that's not a
LOG_ROOT_REPLACE we incorrectly believe that we don't have an old
root, because we expect that the most recent change should be a
LOG_ROOT_REPLACE.
4. Back in tree_mod_log_oldest_root() we don't have a LOG_ROOT_REPLACE,
so we don't set old_root, we simply use our existing extent buffer.
5. Since we're using our existing extent buffer (logical 0) we call
tree_mod_log_search(0) in order to get the newest change to start the
rewind from, which ends up being the LOG_ROOT_REPLACE at seq 8.
6. Again since we didn't find an old_root we simply clone logical 0 at
it's current state.
7. We call tree_mod_log_rewind() with the cloned extent buffer.
8. Set n = btrfs_header_nritems(logical 0), which would be whatever the
original nritems was when we COWed the original root, say for this
example it's 2.
9. We start from the newest operation and work our way forward, so we
see LOG_ROOT_REPLACE which we ignore.
10. Next we see KEY_REMOVE_WHILE_FREEING for slot 0, which triggers the
BUG_ON(tm->slot < n), because it expects if we've done this we have a
completely empty extent buffer to replay completely.
The correct thing would be to find the first LOG_ROOT_REPLACE, and then
get the old_root set to logical 8192. In fact making that change fixes
this particular problem.
However consider the much more complicated case. We have a child node
in this tree and the above situation. In the above case we freed one
of the child blocks at the seq 3 operation. If this block was also
re-allocated and got new tree mod log operations we would have a
different problem. btrfs_search_old_slot(orig root) would get down to
the logical 0 root that still pointed at that node. However in
btrfs_search_old_slot() we call tree_mod_log_rewind(buf) directly. This
is not context aware enough to know which operations we should be
replaying. If the block was re-allocated multiple times we may only
want to replay a range of operations, and determining what that range is
isn't possible to determine.
We could maybe solve this by keeping track of which root the node
belonged to at every tree mod log operation, and then passing this
around to make sure we're only replaying operations that relate to the
root we're trying to rewind.
However there's a simpler way to solve this problem, simply disallow
reallocations if we have currently running tree mod log users. We
already do this for leaf's, so we're simply expanding this to nodes as
well. This is a relatively uncommon occurrence, and the problem is
complicated enough I'm worried that we will still have corner cases in
the reallocation case. So fix this in the most straightforward way
possible.
Fixes: bd989ba359 ("Btrfs: add tree modification log functions")
CC: stable@vger.kernel.org # 3.3+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
After changes in commit 917f32a235 ("btrfs: give struct btrfs_bio a
real end_io handler") the layout of btrfs_bio can be improved. There
are two holes and the structure size is 264 bytes on release build. By
reordering the iterator we can get rid of the holes and the size is 256
bytes which fits to slabs much better.
Final layout:
struct btrfs_bio {
unsigned int mirror_num; /* 0 4 */
struct bvec_iter iter; /* 4 20 */
u64 file_offset; /* 24 8 */
struct btrfs_device * device; /* 32 8 */
u8 * csum; /* 40 8 */
u8 csum_inline[64]; /* 48 64 */
/* --- cacheline 1 boundary (64 bytes) was 48 bytes ago --- */
btrfs_bio_end_io_t end_io; /* 112 8 */
void * private; /* 120 8 */
/* --- cacheline 2 boundary (128 bytes) --- */
struct work_struct end_io_work; /* 128 32 */
struct bio bio; /* 160 96 */
/* size: 256, cachelines: 4, members: 10 */
};
Fixes: 917f32a235 ("btrfs: give struct btrfs_bio a real end_io handler")
Signed-off-by: David Sterba <dsterba@suse.com>
Currently if full_stripe_write() failed to allocate the pages for
parity, it will call __free_raid_bio() first, then return -ENOMEM.
But some caller of full_stripe_write() will also call __free_raid_bio()
again, this would cause double freeing.
And it's not a logically sound either, normally we should either free
the memory at the same level where we allocated it, or let endio to
handle everything.
So this patch will solve the double freeing by make
raid56_parity_write() to handle the error and free the rbio.
Just like what we do in raid56_parity_recover().
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In raid56_alloc_missing_rbio(), if we can not determine where the
missing device is inside the full stripe, we just BUG_ON().
This is not necessary especially the only caller inside scrub.c is
already properly checking the return value, and will treat it as a
memory allocation failure.
Fix the error handling by:
- Add an extra warning for the reason
Although personally speaking it may be better to be an ASSERT().
- Properly free the allocated rbio
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The path cache used during fiemap used to determine the sharedness of
extent buffers in a path from a leaf containing a file extent item
pointing to our data extent up to the root node of the tree, is meant to
be used for a single path. Having a single path is by far the most common
case, and therefore worth to optimize for, but it's possible to actually
have multiple paths because we have 2 or more leaves.
If we have multiple leaves, the 'level' variable keeps getting incremented
in each iteration of the while loop at btrfs_is_data_extent_shared(),
which means we will treat the second leaf in the 'tmp' ulist as a level 1
node, and so forth. In the worst case this can lead to getting a level
greater than or equals to BTRFS_MAX_LEVEL (8), which will trigger a
WARN_ON_ONCE() in the functions to lookup from or store in the path cache
(lookup_backref_shared_cache() and store_backref_shared_cache()). If the
current level never goes beyond 8, due to shared nodes in the paths and
a fs tree height smaller than 8, it can still result in incorrectly
marking one leaf as shared because some other leaf is shared and is stored
one level below that other leaf, as when storing a true sharedness value
in the cache results in updating the sharedness to true of all entries in
the cache below the current level.
Having multiple leaves happens in a case like the following:
- We have a file extent item point to data extent at bytenr X, for
a file range [0, 1M[ for example;
- At this moment we have an extent data ref for the extent, with
an offset of 0 and a count of 1;
- A write into the middle of the extent happens, file range [64K, 128K)
so the file extent item is split into two (at btrfs_drop_extents()):
1) One for file range [0, 64K), with a length (num_bytes field) of
64K and an extent offset of 0;
2) Another one for file range [128K, 1M), with a length of 896K
(1M - 128K) and an extent offset of 128K.
- At this moment the two file extent items are located in the same
leaf;
- A new file extent item for the range [64K, 128K), pointing to a new
data extent, is inserted in the leaf. This results in a leaf split
and now those two file extent items pointing to data extent X end
up located in different leaves;
- Once delayed refs are run, we still have a single extent data ref
item for our data extent at bytenr X, for offset 0, but now with a
count of 2 instead of 1;
- So during fiemap, at btrfs_is_data_extent_shared(), after we call
find_parent_nodes() for the data extent, we get two leaves, since
we have two file extent items point to data extent at bytenr X that
are located in two different leaves.
So skip the use of the path cache when we get more than one leaf.
Fixes: 12a824dc67 ("btrfs: speedup checking for extent sharedness during fiemap")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
During backref walking, when processing a delayed reference with a type of
BTRFS_TREE_BLOCK_REF_KEY, we have two bugs there:
1) We are accessing the delayed references extent_op, and its key, without
the protection of the delayed ref head's lock;
2) If there's no extent op for the delayed ref head, we end up with an
uninitialized key in the stack, variable 'tmp_op_key', and then pass
it to add_indirect_ref(), which adds the reference to the indirect
refs rb tree.
This is wrong, because indirect references should have a NULL key
when we don't have access to the key, and in that case they should be
added to the indirect_missing_keys rb tree and not to the indirect rb
tree.
This means that if have BTRFS_TREE_BLOCK_REF_KEY delayed ref resulting
from freeing an extent buffer, therefore with a count of -1, it will
not cancel out the corresponding reference we have in the extent tree
(with a count of 1), since both references end up in different rb
trees.
When using fiemap, where we often need to check if extents are shared
through shared subtrees resulting from snapshots, it means we can
incorrectly report an extent as shared when it's no longer shared.
However this is temporary because after the transaction is committed
the extent is no longer reported as shared, as running the delayed
reference results in deleting the tree block reference from the extent
tree.
Outside the fiemap context, the result is unpredictable, as the key was
not initialized but it's used when navigating the rb trees to insert
and search for references (prelim_ref_compare()), and we expect all
references in the indirect rb tree to have valid keys.
The following reproducer triggers the second bug:
$ cat test.sh
#!/bin/bash
DEV=/dev/sdj
MNT=/mnt/sdj
mkfs.btrfs -f $DEV
mount -o compress $DEV $MNT
# With a compressed 128M file we get a tree height of 2 (level 1 root).
xfs_io -f -c "pwrite -b 1M 0 128M" $MNT/foo
btrfs subvolume snapshot $MNT $MNT/snap
# Fiemap should output 0x2008 in the flags column.
# 0x2000 means shared extent
# 0x8 means encoded extent (because it's compressed)
echo
echo "fiemap after snapshot, range [120M, 120M + 128K):"
xfs_io -c "fiemap -v 120M 128K" $MNT/foo
echo
# Overwrite one extent and fsync to flush delalloc and COW a new path
# in the snapshot's tree.
#
# After this we have a BTRFS_DROP_DELAYED_REF delayed ref of type
# BTRFS_TREE_BLOCK_REF_KEY with a count of -1 for every COWed extent
# buffer in the path.
#
# In the extent tree we have inline references of type
# BTRFS_TREE_BLOCK_REF_KEY, with a count of 1, for the same extent
# buffers, so they should cancel each other, and the extent buffers in
# the fs tree should no longer be considered as shared.
#
echo "Overwriting file range [120M, 120M + 128K)..."
xfs_io -c "pwrite -b 128K 120M 128K" $MNT/snap/foo
xfs_io -c "fsync" $MNT/snap/foo
# Fiemap should output 0x8 in the flags column. The extent in the range
# [120M, 120M + 128K) is no longer shared, it's now exclusive to the fs
# tree.
echo
echo "fiemap after overwrite range [120M, 120M + 128K):"
xfs_io -c "fiemap -v 120M 128K" $MNT/foo
echo
umount $MNT
Running it before this patch:
$ ./test.sh
(...)
wrote 134217728/134217728 bytes at offset 0
128 MiB, 128 ops; 0.1152 sec (1.085 GiB/sec and 1110.5809 ops/sec)
Create a snapshot of '/mnt/sdj' in '/mnt/sdj/snap'
fiemap after snapshot, range [120M, 120M + 128K):
/mnt/sdj/foo:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [245760..246015]: 34304..34559 256 0x2008
Overwriting file range [120M, 120M + 128K)...
wrote 131072/131072 bytes at offset 125829120
128 KiB, 1 ops; 0.0001 sec (683.060 MiB/sec and 5464.4809 ops/sec)
fiemap after overwrite range [120M, 120M + 128K):
/mnt/sdj/foo:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [245760..246015]: 34304..34559 256 0x2008
The extent in the range [120M, 120M + 128K) is still reported as shared
(0x2000 bit set) after overwriting that range and flushing delalloc, which
is not correct - an entire path was COWed in the snapshot's tree and the
extent is now only referenced by the original fs tree.
Running it after this patch:
$ ./test.sh
(...)
wrote 134217728/134217728 bytes at offset 0
128 MiB, 128 ops; 0.1198 sec (1.043 GiB/sec and 1068.2067 ops/sec)
Create a snapshot of '/mnt/sdj' in '/mnt/sdj/snap'
fiemap after snapshot, range [120M, 120M + 128K):
/mnt/sdj/foo:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [245760..246015]: 34304..34559 256 0x2008
Overwriting file range [120M, 120M + 128K)...
wrote 131072/131072 bytes at offset 125829120
128 KiB, 1 ops; 0.0001 sec (694.444 MiB/sec and 5555.5556 ops/sec)
fiemap after overwrite range [120M, 120M + 128K):
/mnt/sdj/foo:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [245760..246015]: 34304..34559 256 0x8
Now the extent is not reported as shared anymore.
So fix this by passing a NULL key pointer to add_indirect_ref() when
processing a delayed reference for a tree block if there's no extent op
for our delayed ref head with a defined key. Also access the extent op
only after locking the delayed ref head's lock.
The reproducer will be converted later to a test case for fstests.
Fixes: 86d5f99442 ("btrfs: convert prelimary reference tracking to use rbtrees")
Fixes: a6dbceafb9 ("btrfs: Remove unused op_key var from add_delayed_refs")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When processing delayed data references during backref walking and we are
using a share context (we are being called through fiemap), whenever we
find a delayed data reference for an inode different from the one we are
interested in, then we immediately exit and consider the data extent as
shared. This is wrong, because:
1) This might be a DROP reference that will cancel out a reference in the
extent tree;
2) Even if it's an ADD reference, it may be followed by a DROP reference
that cancels it out.
In either case we should not exit immediately.
Fix this by never exiting when we find a delayed data reference for
another inode - instead add the reference and if it does not cancel out
other delayed reference, we will exit early when we call
extent_is_shared() after processing all delayed references. If we find
a drop reference, then signal the code that processes references from
the extent tree (add_inline_refs() and add_keyed_refs()) to not exit
immediately if it finds there a reference for another inode, since we
have delayed drop references that may cancel it out. In this later case
we exit once we don't have references in the rb trees that cancel out
each other and have two references for different inodes.
Example reproducer for case 1):
$ cat test-1.sh
#!/bin/bash
DEV=/dev/sdj
MNT=/mnt/sdj
mkfs.btrfs -f $DEV
mount $DEV $MNT
xfs_io -f -c "pwrite 0 64K" $MNT/foo
cp --reflink=always $MNT/foo $MNT/bar
echo
echo "fiemap after cloning:"
xfs_io -c "fiemap -v" $MNT/foo
rm -f $MNT/bar
echo
echo "fiemap after removing file bar:"
xfs_io -c "fiemap -v" $MNT/foo
umount $MNT
Running it before this patch, the extent is still listed as shared, it has
the flag 0x2000 (FIEMAP_EXTENT_SHARED) set:
$ ./test-1.sh
fiemap after cloning:
/mnt/sdj/foo:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..127]: 26624..26751 128 0x2001
fiemap after removing file bar:
/mnt/sdj/foo:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..127]: 26624..26751 128 0x2001
Example reproducer for case 2):
$ cat test-2.sh
#!/bin/bash
DEV=/dev/sdj
MNT=/mnt/sdj
mkfs.btrfs -f $DEV
mount $DEV $MNT
xfs_io -f -c "pwrite 0 64K" $MNT/foo
cp --reflink=always $MNT/foo $MNT/bar
# Flush delayed references to the extent tree and commit current
# transaction.
sync
echo
echo "fiemap after cloning:"
xfs_io -c "fiemap -v" $MNT/foo
rm -f $MNT/bar
echo
echo "fiemap after removing file bar:"
xfs_io -c "fiemap -v" $MNT/foo
umount $MNT
Running it before this patch, the extent is still listed as shared, it has
the flag 0x2000 (FIEMAP_EXTENT_SHARED) set:
$ ./test-2.sh
fiemap after cloning:
/mnt/sdj/foo:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..127]: 26624..26751 128 0x2001
fiemap after removing file bar:
/mnt/sdj/foo:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..127]: 26624..26751 128 0x2001
After this patch, after deleting bar in both tests, the extent is not
reported with the 0x2000 flag anymore, it gets only the flag 0x1
(which is FIEMAP_EXTENT_LAST):
$ ./test-1.sh
fiemap after cloning:
/mnt/sdj/foo:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..127]: 26624..26751 128 0x2001
fiemap after removing file bar:
/mnt/sdj/foo:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..127]: 26624..26751 128 0x1
$ ./test-2.sh
fiemap after cloning:
/mnt/sdj/foo:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..127]: 26624..26751 128 0x2001
fiemap after removing file bar:
/mnt/sdj/foo:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..127]: 26624..26751 128 0x1
These tests will later be converted to a test case for fstests.
Fixes: dc046b10c8 ("Btrfs: make fiemap not blow when you have lots of snapshots")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There are two comments in btrfs_cache_block_group that I left when
resolving conflict between commits ced8ecf026 "btrfs: fix space cache
corruption and potential double allocations" and 527c490f44 "btrfs:
delete btrfs_wait_space_cache_v1_finished".
The former reworked the caching logic to wait until the caching ends in
btrfs_cache_block_group while the latter only open coded the waiting.
Both removed btrfs_wait_space_cache_v1_finished, the correct code is
with the waiting and returning error. Thus the conflict resolution was
OK.
Signed-off-by: David Sterba <dsterba@suse.com>
In production we hit the following deadlock
task 1 task 2 task 3
------ ------ ------
fiemap(file) falloc(file) fsync(file)
write(0, 1MiB)
btrfs_commit_transaction()
wait_on(!pending_ordered)
lock(512MiB, 1GiB)
start_transaction
wait_on_transaction
lock(0, 1GiB)
wait_extent_bit(512MiB)
task 4
------
finish_ordered_extent(0, 1MiB)
lock(0, 1MiB)
**DEADLOCK**
This occurs because when task 1 does it's lock, it locks everything from
0-512MiB, and then waits for the 512MiB chunk to unlock. task 2 will
never unlock because it's waiting on the transaction commit to happen,
the transaction commit is waiting for the outstanding ordered extents,
and then the ordered extent thread is blocked waiting on the 0-1MiB
range to unlock.
To fix this we have to clear anything we've locked so far, wait for the
extent_state that we contended on, and then try to re-lock the entire
range again.
CC: stable@vger.kernel.org # 5.15+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
For a protocol and command compatibility we have a helper that hasn't
been updated for v3 yet. We use it for verity so update where necessary.
Fixes: 38622010a6 ("btrfs: send: add support for fs-verity")
Signed-off-by: David Sterba <dsterba@suse.com>
We haven't finalized send stream v3 yet, so gate the send stream version
behind CONFIG_BTRFS_DEBUG as we want some way to test it.
The original verity send did not check the protocol version, so add that
actual protection as well.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
When looking the stored result for a cached path node, if the stored
result is valid and has a value of true, we must update all the nodes for
all levels below it with a result of true as well. This is necessary when
moving from one leaf in the fs tree to the next one, as well as when
moving from a node at any level to the next node at the same level.
Currently this logic is missing as it was somehow forgotten by a recent
patch with the subject: "btrfs: speedup checking for extent sharedness
during fiemap".
This adds the missing logic, which is the counter part to what we do
when adding a shared node to the cache at store_backref_shared_cache().
Fixes: 12a824dc67 ("btrfs: speedup checking for extent sharedness during fiemap")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
syzbot is reporting uninit-value in btrfs_clean_tree_block() [1], for
commit bc877d285c ("btrfs: Deduplicate extent_buffer init code")
missed that btrfs_set_header_generation() in btrfs_init_new_buffer() must
not be moved to after clean_tree_block() because clean_tree_block() is
calling btrfs_header_generation() since commit 55c69072d6 ("Btrfs:
Fix extent_buffer usage when nodesize != leafsize").
Since memzero_extent_buffer() will reset "struct btrfs_header" part, we
can't move btrfs_set_header_generation() to before memzero_extent_buffer().
Just re-add btrfs_set_header_generation() before btrfs_clean_tree_block().
Link: https://syzkaller.appspot.com/bug?extid=fba8e2116a12609b6c59 [1]
Reported-by: syzbot <syzbot+fba8e2116a12609b6c59@syzkaller.appspotmail.com>
Fixes: bc877d285c ("btrfs: Deduplicate extent_buffer init code")
CC: stable@vger.kernel.org # 4.19+
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently when dropping extent maps for a file range, through
btrfs_drop_extent_map_range(), we do the following non-optimal things:
1) We lookup for extent maps one by one, always starting the search from
the root of the extent map tree. This is not efficient if we have
multiple extent maps in the range;
2) We check on every iteration if we have the 'split' and 'split2' spare
extent maps in case we need to split an extent map that intersects our
range but also crosses its boundaries (to the left, to the right or
both cases). If our target range is for example:
[2M, 8M)
And we have 3 extents maps in the range:
[1M, 3M) [3M, 6M) [6M, 10M[
The on the first iteration we allocate two extent maps for 'split' and
'split2', and use the 'split' to split the first extent map, so after
the split we set 'split' to 'split2' and then set 'split2' to NULL.
On the second iteration, we don't need to split the second extent map,
but because 'split2' is now NULL, we allocate a new extent map for
'split2'.
On the third iteration we need to split the third extent map, so we
use the extent map pointed by 'split'.
So we ended up allocating 3 extent maps for splitting, but all we
needed was 2 extent maps. We never need to allocate more than 2,
because extent maps that need to be split are always the first one
and the last one in the target range.
Improve on this by:
1) Using rb_next() to move on to the next extent map. This results in
iterating over less nodes of the tree and it does not require comparing
the ranges of nodes to our start/end offset;
2) Allocate the 2 extent maps for splitting before entering the loop and
never allocate more than 2. In practice it's very rare to have the
combination of both extent map allocations fail, since we have a
dedicated slab for extent maps, and also have the need to split two
extent maps.
This patch is part of a patchset comprised of the following patches:
btrfs: fix missed extent on fsync after dropping extent maps
btrfs: move btrfs_drop_extent_cache() to extent_map.c
btrfs: use extent_map_end() at btrfs_drop_extent_map_range()
btrfs: use cond_resched_rwlock_write() during inode eviction
btrfs: move open coded extent map tree deletion out of inode eviction
btrfs: add helper to replace extent map range with a new extent map
btrfs: remove the refcount warning/check at free_extent_map()
btrfs: remove unnecessary extent map initializations
btrfs: assert tree is locked when clearing extent map from logging
btrfs: remove unnecessary NULL pointer checks when searching extent maps
btrfs: remove unnecessary next extent map search
btrfs: avoid pointless extent map tree search when flushing delalloc
btrfs: drop extent map range more efficiently
And the following fio test was done before and after applying the whole
patchset, on a non-debug kernel (Debian's default kernel config) on a 12
cores Intel box with 64G of ram:
$ cat test.sh
#!/bin/bash
DEV=/dev/nvme0n1
MNT=/mnt/nvme0n1
MOUNT_OPTIONS="-o ssd"
MKFS_OPTIONS="-R free-space-tree -O no-holes"
cat <<EOF > /tmp/fio-job.ini
[writers]
rw=randwrite
fsync=8
fallocate=none
group_reporting=1
direct=0
bssplit=4k/20:8k/20:16k/20:32k/10:64k/10:128k/5:256k/5:512k/5:1m/5
ioengine=psync
filesize=2G
runtime=300
time_based
directory=$MNT
numjobs=8
thread
EOF
echo performance | \
tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
echo
echo "Using config:"
echo
cat /tmp/fio-job.ini
echo
umount $MNT &> /dev/null
mkfs.btrfs -f $MKFS_OPTIONS $DEV
mount $MOUNT_OPTIONS $DEV $MNT
fio /tmp/fio-job.ini
umount $MNT
Result before applying the patchset:
WRITE: bw=197MiB/s (206MB/s), 197MiB/s-197MiB/s (206MB/s-206MB/s), io=57.7GiB (61.9GB), run=300188-300188msec
Result after applying the patchset:
WRITE: bw=203MiB/s (213MB/s), 203MiB/s-203MiB/s (213MB/s-213MB/s), io=59.5GiB (63.9GB), run=300019-300019msec
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When flushing delalloc, in COW mode at cow_file_range(), before entering
the loop that allocates extents and creates ordered extents, we do a call
to btrfs_drop_extent_map_range() for the whole range. This is pointless
because in the loop we call create_io_em(), which will also call
btrfs_drop_extent_map_range() before inserting the new extent map.
So remove that call at cow_file_range() not only because it is not needed,
but also because it will make the btrfs_drop_extent_map_range() calls made
from create_io_em() waste time searching the extent map tree, and that
tree can be large for files with many extents. It also makes us waste time
at btrfs_drop_extent_map_range() allocating and freeing the split extent
maps for nothing.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
At __tree_search(), and its single caller __lookup_extent_mapping(), there
is no point in finding the next extent map that starts after the search
offset if we were able to find the previous extent map that ends before
our search offset, because __lookup_extent_mapping() ignores the next
acceptable extent map if we were able to find the previous one.
So just return immediately if we were able to find the previous extent
map, therefore avoiding wasting time iterating the tree looking for the
next extent map which will not be used by __lookup_extent_mapping().
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The previous and next pointer arguments passed to __tree_search() are
never NULL as the only caller of this function, __lookup_extent_mapping(),
always passes the address of two on stack pointers. So remove the NULL
checks and add assertions to verify the pointers.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When calling clear_em_logging() we should have a write lock on the extent
map tree, as we will try to merge the extent map with the previous and
next ones in the tree. So assert that we have a write lock.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When allocating an extent map, we use kmem_cache_zalloc() which guarantees
the returned memory is initialized to zeroes, therefore it's pointless
to initialize the generation and flags of the extent map to zero again.
Remove those initializations, as they are pointless and slightly increase
the object text size.
Before removing them:
$ size fs/btrfs/extent_map.o
text data bss dec hex filename
9241 274 24 9539 2543 fs/btrfs/extent_map.o
After removing them:
$ size fs/btrfs/extent_map.o
text data bss dec hex filename
9209 274 24 9507 2523 fs/btrfs/extent_map.o
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
At free_extent_map(), it's pointless to have a WARN_ON() to check if the
refcount of the extent map is zero. Such check is already done by the
refcount_t module and refcount_dec_and_test(), which loudly complains if
we try to decrement a reference count that is currently 0.
The WARN_ON() dates back to the time when used a regular atomic_t type
for the reference counter, before we switched to the refcount_t type.
The main goal of the refcount_t type/module is precisely to catch such
types of bugs and loudly complain if they happen.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We have several places that need to drop all the extent maps in a given
file range and then add a new extent map for that range. Currently they
call btrfs_drop_extent_map_range() to delete all extent maps in the range
and then keep trying to add the new extent map in a loop that keeps
retrying while the insertion of the new extent map fails with -EEXIST.
So instead of repeating this logic, add a helper to extent_map.c that
does these steps and name it btrfs_replace_extent_map_range(). Also add
a comment about why the retry loop is necessary.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Move the loop that removes all the extent maps from the inode's extent
map tree during inode eviction out of inode.c and into extent_map.c, to
btrfs_drop_extent_map_range(). Anything manipulating extent maps or the
extent map tree should be in extent_map.c.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
At evict_inode_truncate_pages(), instead of manually checking if
rescheduling is needed, then unlock the extent map tree, reschedule and
then write lock again the tree, use the helper cond_resched_rwlock_write()
which does all that.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Instead of open coding the end offset calculation of an extent map, use
the helper extent_map_end() and cache its result in a local variable,
since it's used several times.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The function btrfs_drop_extent_cache() doesn't really belong at file.c
because what it does is drop a range of extent maps for a file range.
It directly allocates and manipulates extent maps, by dropping,
splitting and replacing them in an extent map tree, so it should be
located at extent_map.c, where all manipulations of an extent map tree
and its extent maps are supposed to be done.
So move it out of file.c and into extent_map.c. Additionally do the
following changes:
1) Rename it into btrfs_drop_extent_map_range(), as this makes it more
clear about what it does. The term "cache" is a bit confusing as it's
not widely used, "extent maps" or "extent mapping" is much more common;
2) Change its 'skip_pinned' argument from int to bool;
3) Turn several of its local variables from int to bool, since they are
used as booleans;
4) Move the declaration of some variables out of the function's main
scope and into the scopes where they are used;
5) Remove pointless assignment of false to 'modified' early in the while
loop, as later that variable is set and it's not used before that
second assignment;
6) Remove checks for NULL before calling free_extent_map().
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When dropping extent maps for a range, through btrfs_drop_extent_cache(),
if we find an extent map that starts before our target range and/or ends
before the target range, and we are not able to allocate extent maps for
splitting that extent map, then we don't fail and simply remove the entire
extent map from the inode's extent map tree.
This is generally fine, because in case anyone needs to access the extent
map, it can just load it again later from the respective file extent
item(s) in the subvolume btree. However, if that extent map is new and is
in the list of modified extents, then a fast fsync will miss the parts of
the extent that were outside our range (that needed to be split),
therefore not logging them. Fix that by marking the inode for a full
fsync. This issue was introduced after removing BUG_ON()s triggered when
the split extent map allocations failed, done by commit 7014cdb493
("Btrfs: btrfs_drop_extent_cache should never fail"), back in 2012, and
the fast fsync path already existed but was very recent.
Also, in the case where we could allocate extent maps for the split
operations but then fail to add a split extent map to the tree, mark the
inode for a full fsync as well. This is not supposed to ever fail, and we
assert that, but in case assertions are disabled (CONFIG_BTRFS_ASSERT is
not set), it's the correct thing to do to make sure a fast fsync will not
miss a new extent.
CC: stable@vger.kernel.org # 5.15+
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This function no longer exists, was removed in 3c4276936f ("Btrfs: fix
btrfs_write_inode vs delayed iput deadlock").
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Enable nowait async buffered writes in btrfs_do_write_iter() and
btrfs_file_open().
In this version encoded buffered writes have the optimization not
enabled. Encoded writes are enabled by using an ioctl. io_uring
currently does not support ioctls. This might be enabled in the future.
Performance results:
For fio the following results have been obtained with a queue depth of
1 and 4k block size (runtime 600 secs):
sequential writes:
without patch with patch libaio psync
iops: 55k 134k 117K 148K
bw: 221MB/s 538MB/s 469MB/s 592MB/s
clat: 15286ns 82ns 994ns 6340ns
For an io depth of 1, the new patch improves throughput by over two
times (compared to the existing behavior, where buffered writes are
processed by an io-worker process) and also the latency is considerably
reduced. To achieve the same or better performance with the existing
code an io depth of 4 is required. Increasing the iodepth further does
not lead to improvements.
The tests have been run like this:
./fio --name=seq-writers --ioengine=psync --iodepth=1 --rw=write \
--bs=4k --direct=0 --size=100000m --time_based --runtime=600 \
--numjobs=1 --filename=...
./fio --name=seq-writers --ioengine=io_uring --iodepth=1 --rw=write \
--bs=4k --direct=0 --size=100000m --time_based --runtime=600 \
--numjobs=1 --filename=...
./fio --name=seq-writers --ioengine=libaio --iodepth=1 --rw=write \
--bs=4k --direct=0 --size=100000m --time_based --runtime=600 \
--numjobs=1 --filename=...
Testing:
This patch has been tested with xfstests, fsx, fio. xfstests shows no new
diffs compared to running without the patch series.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Stefan Roesch <shr@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Adds nowait asserts to btree search functions which are not used by
buffered IO and direct IO paths.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Stefan Roesch <shr@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We need to avoid unconditionally calling balance_dirty_pages_ratelimited
as it could wait for some reason. Use balance_dirty_pages_ratelimited_flags
with the BDP_ASYNC in case the buffered write is nowait, returning
EAGAIN eventually.
It also moves the function after the again label. This can cause the
function to be called a bit later, but this should have no impact in the
real world.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Stefan Roesch <shr@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We have everywhere setup for nowait, plumb NOWAIT through the write path.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Stefan Roesch <shr@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Add the nowait parameter to lock_and_cleanup_extent_if_need(). If the
nowait parameter is specified we try to lock the extent in nowait mode.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Stefan Roesch <shr@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Add nowait parameter to the prepare_pages function. In case nowait is
specified for an async buffered write request, do a nowait allocation or
return -EAGAIN.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Stefan Roesch <shr@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Now all the helpers that btrfs_check_nocow_lock uses handle nowait, add
a nowait flag to btrfs_check_nocow_lock so it can be used by the write
path.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Stefan Roesch <shr@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
For IOCB_NOWAIT we're going to want to use try lock on the extent lock,
and simply bail if there's an ordered extent in the range because the
only choice there is to wait for the ordered extent to complete.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Stefan Roesch <shr@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In order to accommodate NOWAIT IOCB's we need to be able to do NO_FLUSH
data reservations, so plumb this through the delalloc reservation
system.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Stefan Roesch <shr@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
