Static analysis reports this problem
free-space-cache.c:3965:2: warning: Undefined or garbage value returned
return ret;
^~~~~~~~~~
ret is set in the node handling loop. Treat doing nothing as a success
and initialize ret to 0, although it's unlikely the loop would be
skipped. We always have block groups, but as it could lead to
transaction abort in the caller it's better to be safe.
CC: stable@vger.kernel.org # 5.12+
Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The fstests test case generic/475 creates a dm-linear device that gets
changed to a dm-error device. This leads to errors in loading the block
group's zone information when running on a zoned file system, ultimately
resulting in a list corruption. When running on a kernel with list
debugging enabled this leads to the following crash.
BTRFS: error (device dm-2) in cleanup_transaction:1953: errno=-5 IO failure
kernel BUG at lib/list_debug.c:54!
invalid opcode: 0000 [#1] SMP PTI
CPU: 1 PID: 2433 Comm: umount Tainted: G W 5.12.0+ #1018
RIP: 0010:__list_del_entry_valid.cold+0x1d/0x47
RSP: 0018:ffffc90001473df0 EFLAGS: 00010296
RAX: 0000000000000054 RBX: ffff8881038fd000 RCX: ffffc90001473c90
RDX: 0000000100001a31 RSI: 0000000000000003 RDI: 0000000000000003
RBP: ffff888308871108 R08: 0000000000000003 R09: 0000000000000001
R10: 3961373532383838 R11: 6666666620736177 R12: ffff888308871000
R13: ffff8881038fd088 R14: ffff8881038fdc78 R15: dead000000000100
FS: 00007f353c9b1540(0000) GS:ffff888627d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f353cc2c710 CR3: 000000018e13c000 CR4: 00000000000006a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
btrfs_free_block_groups+0xc9/0x310 [btrfs]
close_ctree+0x2ee/0x31a [btrfs]
? call_rcu+0x8f/0x270
? mutex_lock+0x1c/0x40
generic_shutdown_super+0x67/0x100
kill_anon_super+0x14/0x30
btrfs_kill_super+0x12/0x20 [btrfs]
deactivate_locked_super+0x31/0x90
cleanup_mnt+0x13e/0x1b0
task_work_run+0x63/0xb0
exit_to_user_mode_loop+0xd9/0xe0
exit_to_user_mode_prepare+0x3e/0x60
syscall_exit_to_user_mode+0x1d/0x50
entry_SYSCALL_64_after_hwframe+0x44/0xae
As dm-error has no support for zones, btrfs will run it's zone emulation
mode on this device. The zone emulation mode emulates conventional zones,
so bail out if the zone bitmap that gets populated on mount sees the zone
as sequential while we're thinking it's a conventional zone when creating
a block group.
Note: this scenario is unlikely in a real wold application and can only
happen by this (ab)use of device-mapper targets.
CC: stable@vger.kernel.org # 5.12+
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The following test case reproduces an issue of wrongly freeing in-use
blocks on the readonly seed device when fstrim is called on the rw sprout
device. As shown below.
Create a seed device and add a sprout device to it:
$ mkfs.btrfs -fq -dsingle -msingle /dev/loop0
$ btrfstune -S 1 /dev/loop0
$ mount /dev/loop0 /btrfs
$ btrfs dev add -f /dev/loop1 /btrfs
BTRFS info (device loop0): relocating block group 290455552 flags system
BTRFS info (device loop0): relocating block group 1048576 flags system
BTRFS info (device loop0): disk added /dev/loop1
$ umount /btrfs
Mount the sprout device and run fstrim:
$ mount /dev/loop1 /btrfs
$ fstrim /btrfs
$ umount /btrfs
Now try to mount the seed device, and it fails:
$ mount /dev/loop0 /btrfs
mount: /btrfs: wrong fs type, bad option, bad superblock on /dev/loop0, missing codepage or helper program, or other error.
Block 5292032 is missing on the readonly seed device:
$ dmesg -kt | tail
<snip>
BTRFS error (device loop0): bad tree block start, want 5292032 have 0
BTRFS warning (device loop0): couldn't read-tree root
BTRFS error (device loop0): open_ctree failed
From the dump-tree of the seed device (taken before the fstrim). Block
5292032 belonged to the block group starting at 5242880:
$ btrfs inspect dump-tree -e /dev/loop0 | grep -A1 BLOCK_GROUP
<snip>
item 3 key (5242880 BLOCK_GROUP_ITEM 8388608) itemoff 16169 itemsize 24
block group used 114688 chunk_objectid 256 flags METADATA
<snip>
From the dump-tree of the sprout device (taken before the fstrim).
fstrim used block-group 5242880 to find the related free space to free:
$ btrfs inspect dump-tree -e /dev/loop1 | grep -A1 BLOCK_GROUP
<snip>
item 1 key (5242880 BLOCK_GROUP_ITEM 8388608) itemoff 16226 itemsize 24
block group used 32768 chunk_objectid 256 flags METADATA
<snip>
BPF kernel tracing the fstrim command finds the missing block 5292032
within the range of the discarded blocks as below:
kprobe:btrfs_discard_extent {
printf("freeing start %llu end %llu num_bytes %llu:\n",
arg1, arg1+arg2, arg2);
}
freeing start 5259264 end 5406720 num_bytes 147456
<snip>
Fix this by avoiding the discard command to the readonly seed device.
Reported-by: Chris Murphy <lists@colorremedies.com>
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There are a few exceptional cases where cloning an inline extent needs to
copy the inline extent data into a page of the destination inode.
When this happens, we end up starting a transaction while having a dirty
page for the destination inode and while having the range locked in the
destination's inode iotree too. Because when reserving metadata space
for a transaction we may need to flush existing delalloc in case there is
not enough free space, we have a mechanism in place to prevent a deadlock,
which was introduced in commit 3d45f221ce ("btrfs: fix deadlock when
cloning inline extent and low on free metadata space").
However when using qgroups, a transaction also reserves metadata qgroup
space, which can also result in flushing delalloc in case there is not
enough available space at the moment. When this happens we deadlock, since
flushing delalloc requires locking the file range in the inode's iotree
and the range was already locked at the very beginning of the clone
operation, before attempting to start the transaction.
When this issue happens, stack traces like the following are reported:
[72747.556262] task:kworker/u81:9 state:D stack: 0 pid: 225 ppid: 2 flags:0x00004000
[72747.556268] Workqueue: writeback wb_workfn (flush-btrfs-1142)
[72747.556271] Call Trace:
[72747.556273] __schedule+0x296/0x760
[72747.556277] schedule+0x3c/0xa0
[72747.556279] io_schedule+0x12/0x40
[72747.556284] __lock_page+0x13c/0x280
[72747.556287] ? generic_file_readonly_mmap+0x70/0x70
[72747.556325] extent_write_cache_pages+0x22a/0x440 [btrfs]
[72747.556331] ? __set_page_dirty_nobuffers+0xe7/0x160
[72747.556358] ? set_extent_buffer_dirty+0x5e/0x80 [btrfs]
[72747.556362] ? update_group_capacity+0x25/0x210
[72747.556366] ? cpumask_next_and+0x1a/0x20
[72747.556391] extent_writepages+0x44/0xa0 [btrfs]
[72747.556394] do_writepages+0x41/0xd0
[72747.556398] __writeback_single_inode+0x39/0x2a0
[72747.556403] writeback_sb_inodes+0x1ea/0x440
[72747.556407] __writeback_inodes_wb+0x5f/0xc0
[72747.556410] wb_writeback+0x235/0x2b0
[72747.556414] ? get_nr_inodes+0x35/0x50
[72747.556417] wb_workfn+0x354/0x490
[72747.556420] ? newidle_balance+0x2c5/0x3e0
[72747.556424] process_one_work+0x1aa/0x340
[72747.556426] worker_thread+0x30/0x390
[72747.556429] ? create_worker+0x1a0/0x1a0
[72747.556432] kthread+0x116/0x130
[72747.556435] ? kthread_park+0x80/0x80
[72747.556438] ret_from_fork+0x1f/0x30
[72747.566958] Workqueue: btrfs-flush_delalloc btrfs_work_helper [btrfs]
[72747.566961] Call Trace:
[72747.566964] __schedule+0x296/0x760
[72747.566968] ? finish_wait+0x80/0x80
[72747.566970] schedule+0x3c/0xa0
[72747.566995] wait_extent_bit.constprop.68+0x13b/0x1c0 [btrfs]
[72747.566999] ? finish_wait+0x80/0x80
[72747.567024] lock_extent_bits+0x37/0x90 [btrfs]
[72747.567047] btrfs_invalidatepage+0x299/0x2c0 [btrfs]
[72747.567051] ? find_get_pages_range_tag+0x2cd/0x380
[72747.567076] __extent_writepage+0x203/0x320 [btrfs]
[72747.567102] extent_write_cache_pages+0x2bb/0x440 [btrfs]
[72747.567106] ? update_load_avg+0x7e/0x5f0
[72747.567109] ? enqueue_entity+0xf4/0x6f0
[72747.567134] extent_writepages+0x44/0xa0 [btrfs]
[72747.567137] ? enqueue_task_fair+0x93/0x6f0
[72747.567140] do_writepages+0x41/0xd0
[72747.567144] __filemap_fdatawrite_range+0xc7/0x100
[72747.567167] btrfs_run_delalloc_work+0x17/0x40 [btrfs]
[72747.567195] btrfs_work_helper+0xc2/0x300 [btrfs]
[72747.567200] process_one_work+0x1aa/0x340
[72747.567202] worker_thread+0x30/0x390
[72747.567205] ? create_worker+0x1a0/0x1a0
[72747.567208] kthread+0x116/0x130
[72747.567211] ? kthread_park+0x80/0x80
[72747.567214] ret_from_fork+0x1f/0x30
[72747.569686] task:fsstress state:D stack: 0 pid:841421 ppid:841417 flags:0x00000000
[72747.569689] Call Trace:
[72747.569691] __schedule+0x296/0x760
[72747.569694] schedule+0x3c/0xa0
[72747.569721] try_flush_qgroup+0x95/0x140 [btrfs]
[72747.569725] ? finish_wait+0x80/0x80
[72747.569753] btrfs_qgroup_reserve_data+0x34/0x50 [btrfs]
[72747.569781] btrfs_check_data_free_space+0x5f/0xa0 [btrfs]
[72747.569804] btrfs_buffered_write+0x1f7/0x7f0 [btrfs]
[72747.569810] ? path_lookupat.isra.48+0x97/0x140
[72747.569833] btrfs_file_write_iter+0x81/0x410 [btrfs]
[72747.569836] ? __kmalloc+0x16a/0x2c0
[72747.569839] do_iter_readv_writev+0x160/0x1c0
[72747.569843] do_iter_write+0x80/0x1b0
[72747.569847] vfs_writev+0x84/0x140
[72747.569869] ? btrfs_file_llseek+0x38/0x270 [btrfs]
[72747.569873] do_writev+0x65/0x100
[72747.569876] do_syscall_64+0x33/0x40
[72747.569879] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[72747.569899] task:fsstress state:D stack: 0 pid:841424 ppid:841417 flags:0x00004000
[72747.569903] Call Trace:
[72747.569906] __schedule+0x296/0x760
[72747.569909] schedule+0x3c/0xa0
[72747.569936] try_flush_qgroup+0x95/0x140 [btrfs]
[72747.569940] ? finish_wait+0x80/0x80
[72747.569967] __btrfs_qgroup_reserve_meta+0x36/0x50 [btrfs]
[72747.569989] start_transaction+0x279/0x580 [btrfs]
[72747.570014] clone_copy_inline_extent+0x332/0x490 [btrfs]
[72747.570041] btrfs_clone+0x5b7/0x7a0 [btrfs]
[72747.570068] ? lock_extent_bits+0x64/0x90 [btrfs]
[72747.570095] btrfs_clone_files+0xfc/0x150 [btrfs]
[72747.570122] btrfs_remap_file_range+0x3d8/0x4a0 [btrfs]
[72747.570126] do_clone_file_range+0xed/0x200
[72747.570131] vfs_clone_file_range+0x37/0x110
[72747.570134] ioctl_file_clone+0x7d/0xb0
[72747.570137] do_vfs_ioctl+0x138/0x630
[72747.570140] __x64_sys_ioctl+0x62/0xc0
[72747.570143] do_syscall_64+0x33/0x40
[72747.570146] entry_SYSCALL_64_after_hwframe+0x44/0xa9
So fix this by skipping the flush of delalloc for an inode that is
flagged with BTRFS_INODE_NO_DELALLOC_FLUSH, meaning it is currently under
such a special case of cloning an inline extent, when flushing delalloc
during qgroup metadata reservation.
The special cases for cloning inline extents were added in kernel 5.7 by
by commit 05a5a7621c ("Btrfs: implement full reflink support for
inline extents"), while having qgroup metadata space reservation flushing
delalloc when low on space was added in kernel 5.9 by commit
c53e965360 ("btrfs: qgroup: try to flush qgroup space when we get
-EDQUOT"). So use a "Fixes:" tag for the later commit to ease stable
kernel backports.
Reported-by: Wang Yugui <wangyugui@e16-tech.com>
Link: https://lore.kernel.org/linux-btrfs/20210421083137.31E3.409509F4@e16-tech.com/
Fixes: c53e965360 ("btrfs: qgroup: try to flush qgroup space when we get -EDQUOT")
CC: stable@vger.kernel.org # 5.9+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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 209ecbb858
("btrfs: remove stale comment and logic from btrfs_inode_in_log()"),
added in the 5.13 merge window. However checking the emptiness of the
list is not really the way to solve this problem, and was never intended
to, because while that solves the problem for COW writes, the problem
persists for NOCOW writes because in that case the list is always empty.
In the case of NOCOW writes, even though we wait for the writeback to
complete before returning from btrfs_sync_file(), we end up not logging
the inode, which has a new mtime/ctime, and because we don't sync the log,
we never issue disk barriers (send REQ_PREFLUSH to the device) since that
only happens when we sync the log (when we write super blocks at
btrfs_sync_log()). So effectively, for a NOCOW case, when we return from
btrfs_sync_file() to user space, we are not guaranteeing that the data is
durably persisted on disk.
Also, while the example above uses a rename exchange to show how the
problem happens, it is not the only way to trigger it. An alternative
could be adding a new hard link to inode 258, since that also results
in calling btrfs_log_new_name() and updating the inode in the log.
An example reproducer using the addition of a hard link instead of a
rename operation:
$ mkfs.btrfs -f /dev/sdc
$ mount /dev/sdc /mnt
$ touch /mnt/bar
$ xfs_io -f -c "pwrite -S 0xab 0 1M" -c "fsync" /mnt/foo
$ ln /mnt/foo /mnt/foo_link
$ xfs_io -c "pwrite -S 0xcd 0 1M" /mnt/foo
$ xfs_io -c "fsync" /mnt/bar
$ xfs_io -c "fsync" /mnt/foo
<power failure>
# Replay the log:
$ mount /dev/sdc /mnt
# After this point file foo often has 1M filled with 0xab and not 0xcd
The reasons leading to the final fsync of file foo, inode 258, not
persisting the new data are the same as for the previous example with
a rename operation.
So fix by never skipping logging and log syncing when there are still any
ordered extents in flight. To avoid making the conditional if statement
that checks if logging an inode is needed harder to read, place all the
logic into an helper function with separate if statements to make it more
manageable and easier to read.
A test case for fstests will follow soon.
For NOCOW writes, the problem existed before commit b5e6c3e170
("btrfs: always wait on ordered extents at fsync time"), introduced in
kernel 4.19, then it went away with that commit since we started to always
wait for ordered extent completion before logging.
The problem came back again once the fast fsync path was changed again to
avoid waiting for ordered extent completion, in commit 487781796d
("btrfs: make fast fsyncs wait only for writeback"), added in kernel 5.10.
However, for COW writes, the race only happens after the recent
commit 209ecbb858 ("btrfs: remove stale comment and logic from
btrfs_inode_in_log()"), introduced in the 5.13 merge window. For NOCOW
writes, the bug existed before that commit. So tag 5.10+ as the release
for stable backports.
CC: stable@vger.kernel.org # 5.10+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
At qgroup.c:try_flush_qgroup() we are asserting that current->journal_info
is either NULL or has the value BTRFS_SEND_TRANS_STUB.
However allowing for BTRFS_SEND_TRANS_STUB makes no sense because:
1) It is misleading, because send operations are read-only and do not
ever need to reserve qgroup space;
2) We already assert that current->journal_info != BTRFS_SEND_TRANS_STUB
at transaction.c:start_transaction();
3) On a kernel without CONFIG_BTRFS_ASSERT=y set, it would result in
a crash if try_flush_qgroup() is ever called in a send context, because
at transaction.c:start_transaction we cast current->journal_info into
a struct btrfs_trans_handle pointer and then dereference it.
So just do allow a send context at try_flush_qgroup() and update the
comment about it.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
On a zoned filesystem, sometimes we need to split an ordered extent into 3
different ordered extents. The original ordered extent is shortened, at
the front and at the rear, and we create two other new ordered extents to
represent the trimmed parts of the original ordered extent.
After adjusting the original ordered extent, we create an ordered extent
to represent the pre-range, and that may fail with ENOMEM for example.
After that we always try to create the ordered extent for the post-range,
and if that happens to succeed we end up returning success to the caller
as we overwrite the 'ret' variable which contained the previous error.
This means we end up with a file range for which there is no ordered
extent, which results in the range never getting a new file extent item
pointing to the new data location. And since the split operation did
not return an error, writeback does not fail and the inode's mapping is
not flagged with an error, resulting in a subsequent fsync not reporting
an error either.
It's possibly very unlikely to have the creation of the post-range ordered
extent succeed after the creation of the pre-range ordered extent failed,
but it's not impossible.
So fix this by making sure we only create the post-range ordered extent
if there was no error creating the ordered extent for the pre-range.
Fixes: d22002fd37 ("btrfs: zoned: split ordered extent when bio is sent")
CC: stable@vger.kernel.org # 5.12+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When a file gets deleted on a zoned file system, the space freed is not
returned back into the block group's free space, but is migrated to
zone_unusable.
As this zone_unusable space is behind the current write pointer it is not
possible to use it for new allocations. In the current implementation a
zone is reset once all of the block group's space is accounted as zone
unusable.
This behaviour can lead to premature ENOSPC errors on a busy file system.
Instead of only reclaiming the zone once it is completely unusable,
kick off a reclaim job once the amount of unusable bytes exceeds a user
configurable threshold between 51% and 100%. It can be set per mounted
filesystem via the sysfs tunable bg_reclaim_threshold which is set to 75%
by default.
Similar to reclaiming unused block groups, these dirty block groups are
added to a to_reclaim list and then on a transaction commit, the reclaim
process is triggered but after we deleted unused block groups, which will
free space for the relocation process.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
As a preparation for extending the block group deletion use case, rename
the unused_bgs_mutex to reclaim_bgs_lock.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When relocating a block group the freed up space is not discarded in one
big block, but each extent is discarded on its own with -odisard=sync.
For a zoned filesystem we need to discard the whole block group at once,
so btrfs_discard_extent() will translate the discard into a
REQ_OP_ZONE_RESET operation, which then resets the device's zone.
Failure to reset the zone is not fatal error.
Discussion about the approach and regarding transaction blocking:
https://lore.kernel.org/linux-btrfs/CAL3q7H4SjS_d5rBepfTMhU8Th3bJzdmyYd0g4Z60yUgC_rC_ZA@mail.gmail.com/
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Btrfs uses internally mapped u64 address space for all its metadata.
Due to the page cache limit on 32bit systems, btrfs can't access
metadata at or beyond (ULONG_MAX + 1) << PAGE_SHIFT. See
how MAX_LFS_FILESIZE and page::index are defined. This is 16T for 4K
page size while 256T for 64K page size.
Users can have a filesystem which doesn't have metadata beyond the
boundary at mount time, but later balance can cause it to create
metadata beyond the boundary.
And modification to MM layer is unrealistic just for such minor use
case. We can't do more than to prevent mounting such filesystem or warn
early when the numbers are still within the limits.
To address such problem, this patch will introduce the following checks:
- Mount time rejection
This will reject any fs which has metadata chunk at or beyond the
boundary.
- Mount time early warning
If there is any metadata chunk beyond 5/8th of the boundary, we do an
early warning and hope the end user will see it.
- Runtime extent buffer rejection
If we're going to allocate an extent buffer at or beyond the boundary,
reject such request with EOVERFLOW.
This is definitely going to cause problems like transaction abort, but
we have no better ways.
- Runtime extent buffer early warning
If an extent buffer beyond 5/8th of the max file size is allocated, do
an early warning.
Above error/warning message will only be printed once for each fs to
reduce dmesg flood.
If the mount is rejected, the filesystem will be mountable only on a
64bit host.
Link: https://lore.kernel.org/linux-btrfs/1783f16d-7a28-80e6-4c32-fdf19b705ed0@gmx.com/
Reported-by: Erik Jensen <erikjensen@rkjnsn.net>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When doing a device replace on a zoned filesystem, if we find a block
group with ->to_copy == 0, we jump to the label 'done', which will result
in later calling btrfs_unfreeze_block_group(), even though at this point
we never called btrfs_freeze_block_group().
Since at this point we have neither turned the block group to RO mode nor
made any progress, we don't need to jump to the label 'done'. So fix this
by jumping instead to the label 'skip' and dropping our reference on the
block group before the jump.
Fixes: 78ce9fc269 ("btrfs: zoned: mark block groups to copy for device-replace")
CC: stable@vger.kernel.org # 5.12
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>
Commit dbcc7d57bf ("btrfs: fix race when cloning extent buffer during
rewind of an old root"), fixed a race when we need to rewind the extent
buffer of an old root. It was caused by picking a new mod log operation
for the extent buffer while getting a cloned extent buffer with an outdated
number of items (off by -1), because we cloned the extent buffer without
locking it first.
However there is still another similar race, but in the opposite direction.
The cloned extent buffer has a number of items that does not match the
number of tree mod log operations that are going to be replayed. This is
because right after we got the last (most recent) tree mod log operation to
replay and before locking and cloning the extent buffer, another task adds
a new pointer to the extent buffer, which results in adding a new tree mod
log operation and incrementing the number of items in the extent buffer.
So after cloning we have mismatch between the number of items in the extent
buffer and the number of mod log operations we are going to apply to it.
This results in hitting a BUG_ON() that produces the following stack trace:
------------[ cut here ]------------
kernel BUG at fs/btrfs/tree-mod-log.c:675!
invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 3 PID: 4811 Comm: crawl_1215 Tainted: G W 5.12.0-7d1efdf501f8-misc-next+ #99
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
RIP: 0010:tree_mod_log_rewind+0x3b1/0x3c0
Code: 05 48 8d 74 10 (...)
RSP: 0018:ffffc90001027090 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff8880a8514600 RCX: ffffffffaa9e59b6
RDX: 0000000000000007 RSI: dffffc0000000000 RDI: ffff8880a851462c
RBP: ffffc900010270e0 R08: 00000000000000c0 R09: ffffed1004333417
R10: ffff88802199a0b7 R11: ffffed1004333416 R12: 000000000000000e
R13: ffff888135af8748 R14: ffff88818766ff00 R15: ffff8880a851462c
FS: 00007f29acf62700(0000) GS:ffff8881f2200000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0e6013f718 CR3: 000000010d42e003 CR4: 0000000000170ee0
Call Trace:
btrfs_get_old_root+0x16a/0x5c0
? lock_downgrade+0x400/0x400
btrfs_search_old_slot+0x192/0x520
? btrfs_search_slot+0x1090/0x1090
? free_extent_buffer.part.61+0xd7/0x140
? free_extent_buffer+0x13/0x20
resolve_indirect_refs+0x3e9/0xfc0
? lock_downgrade+0x400/0x400
? __kasan_check_read+0x11/0x20
? add_prelim_ref.part.11+0x150/0x150
? lock_downgrade+0x400/0x400
? __kasan_check_read+0x11/0x20
? lock_acquired+0xbb/0x620
? __kasan_check_write+0x14/0x20
? do_raw_spin_unlock+0xa8/0x140
? rb_insert_color+0x340/0x360
? prelim_ref_insert+0x12d/0x430
find_parent_nodes+0x5c3/0x1830
? stack_trace_save+0x87/0xb0
? resolve_indirect_refs+0xfc0/0xfc0
? fs_reclaim_acquire+0x67/0xf0
? __kasan_check_read+0x11/0x20
? lockdep_hardirqs_on_prepare+0x210/0x210
? fs_reclaim_acquire+0x67/0xf0
? __kasan_check_read+0x11/0x20
? ___might_sleep+0x10f/0x1e0
? __kasan_kmalloc+0x9d/0xd0
? trace_hardirqs_on+0x55/0x120
btrfs_find_all_roots_safe+0x142/0x1e0
? find_parent_nodes+0x1830/0x1830
? trace_hardirqs_on+0x55/0x120
? ulist_free+0x1f/0x30
? btrfs_inode_flags_to_xflags+0x50/0x50
iterate_extent_inodes+0x20e/0x580
? tree_backref_for_extent+0x230/0x230
? release_extent_buffer+0x225/0x280
? read_extent_buffer+0xdd/0x110
? lock_downgrade+0x400/0x400
? __kasan_check_read+0x11/0x20
? lock_acquired+0xbb/0x620
? __kasan_check_write+0x14/0x20
? do_raw_spin_unlock+0xa8/0x140
? _raw_spin_unlock+0x22/0x30
? release_extent_buffer+0x225/0x280
iterate_inodes_from_logical+0x129/0x170
? iterate_inodes_from_logical+0x129/0x170
? btrfs_inode_flags_to_xflags+0x50/0x50
? iterate_extent_inodes+0x580/0x580
? __vmalloc_node+0x92/0xb0
? init_data_container+0x34/0xb0
? init_data_container+0x34/0xb0
? kvmalloc_node+0x60/0x80
btrfs_ioctl_logical_to_ino+0x158/0x230
btrfs_ioctl+0x2038/0x4360
? __kasan_check_write+0x14/0x20
? mmput+0x3b/0x220
? btrfs_ioctl_get_supported_features+0x30/0x30
? __kasan_check_read+0x11/0x20
? __kasan_check_read+0x11/0x20
? lock_release+0xc8/0x650
? __might_fault+0x64/0xd0
? __kasan_check_read+0x11/0x20
? lock_downgrade+0x400/0x400
? lockdep_hardirqs_on_prepare+0x210/0x210
? lockdep_hardirqs_on_prepare+0x13/0x210
? _raw_spin_unlock_irqrestore+0x51/0x63
? __kasan_check_read+0x11/0x20
? do_vfs_ioctl+0xfc/0x9d0
? ioctl_file_clone+0xe0/0xe0
? lock_downgrade+0x400/0x400
? lockdep_hardirqs_on_prepare+0x210/0x210
? __kasan_check_read+0x11/0x20
? lock_release+0xc8/0x650
? __task_pid_nr_ns+0xd3/0x250
? __kasan_check_read+0x11/0x20
? __fget_files+0x160/0x230
? __fget_light+0xf2/0x110
__x64_sys_ioctl+0xc3/0x100
do_syscall_64+0x37/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f29ae85b427
Code: 00 00 90 48 8b (...)
RSP: 002b:00007f29acf5fcf8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f29acf5ff40 RCX: 00007f29ae85b427
RDX: 00007f29acf5ff48 RSI: 00000000c038943b RDI: 0000000000000003
RBP: 0000000001000000 R08: 0000000000000000 R09: 00007f29acf60120
R10: 00005640d5fc7b00 R11: 0000000000000246 R12: 0000000000000003
R13: 00007f29acf5ff48 R14: 00007f29acf5ff40 R15: 00007f29acf5fef8
Modules linked in:
---[ end trace 85e5fce078dfbe04 ]---
(gdb) l *(tree_mod_log_rewind+0x3b1)
0xffffffff819e5b21 is in tree_mod_log_rewind (fs/btrfs/tree-mod-log.c:675).
670 * the modification. As we're going backwards, we do the
671 * opposite of each operation here.
672 */
673 switch (tm->op) {
674 case BTRFS_MOD_LOG_KEY_REMOVE_WHILE_FREEING:
675 BUG_ON(tm->slot < n);
676 fallthrough;
677 case BTRFS_MOD_LOG_KEY_REMOVE_WHILE_MOVING:
678 case BTRFS_MOD_LOG_KEY_REMOVE:
679 btrfs_set_node_key(eb, &tm->key, tm->slot);
(gdb) quit
The following steps explain in more detail how it happens:
1) We have one tree mod log user (through fiemap or the logical ino ioctl),
with a sequence number of 1, so we have fs_info->tree_mod_seq == 1.
This is task A;
2) Another task is at ctree.c:balance_level() and we have eb X currently as
the root of the tree, and we promote its single child, eb Y, as the new
root.
Then, at ctree.c:balance_level(), we call:
ret = btrfs_tree_mod_log_insert_root(root->node, child, true);
3) At btrfs_tree_mod_log_insert_root() we create a tree mod log operation
of type BTRFS_MOD_LOG_KEY_REMOVE_WHILE_FREEING, with a ->logical field
pointing to ebX->start. We only have one item in eb X, so we create
only one tree mod log operation, and store in the "tm_list" array;
4) Then, still at btrfs_tree_mod_log_insert_root(), we create a tree mod
log element of operation type BTRFS_MOD_LOG_ROOT_REPLACE, ->logical set
to ebY->start, ->old_root.logical set to ebX->start, ->old_root.level
set to the level of eb X and ->generation set to the generation of eb X;
5) Then btrfs_tree_mod_log_insert_root() calls tree_mod_log_free_eb() with
"tm_list" as argument. After that, tree_mod_log_free_eb() calls
tree_mod_log_insert(). This inserts the mod log operation of type
BTRFS_MOD_LOG_KEY_REMOVE_WHILE_FREEING from step 3 into the rbtree
with a sequence number of 2 (and fs_info->tree_mod_seq set to 2);
6) Then, after inserting the "tm_list" single element into the tree mod
log rbtree, the BTRFS_MOD_LOG_ROOT_REPLACE element is inserted, which
gets the sequence number 3 (and fs_info->tree_mod_seq set to 3);
7) Back to ctree.c:balance_level(), we free eb X by calling
btrfs_free_tree_block() on it. Because eb X was created in the current
transaction, has no other references and writeback did not happen for
it, we add it back to the free space cache/tree;
8) Later some other task B allocates the metadata extent from eb X, since
it is marked as free space in the space cache/tree, and uses it as a
node for some other btree;
9) The tree mod log user task calls btrfs_search_old_slot(), which calls
btrfs_get_old_root(), and finally that calls tree_mod_log_oldest_root()
with time_seq == 1 and eb_root == eb Y;
10) The first iteration of the while loop finds the tree mod log element
with sequence number 3, for the logical address of eb Y and of type
BTRFS_MOD_LOG_ROOT_REPLACE;
11) Because the operation type is BTRFS_MOD_LOG_ROOT_REPLACE, we don't
break out of the loop, and set root_logical to point to
tm->old_root.logical, which corresponds to the logical address of
eb X;
12) On the next iteration of the while loop, the call to
tree_mod_log_search_oldest() returns the smallest tree mod log element
for the logical address of eb X, which has a sequence number of 2, an
operation type of BTRFS_MOD_LOG_KEY_REMOVE_WHILE_FREEING and
corresponds to the old slot 0 of eb X (eb X had only 1 item in it
before being freed at step 7);
13) We then break out of the while loop and return the tree mod log
operation of type BTRFS_MOD_LOG_ROOT_REPLACE (eb Y), and not the one
for slot 0 of eb X, to btrfs_get_old_root();
14) At btrfs_get_old_root(), we process the BTRFS_MOD_LOG_ROOT_REPLACE
operation and set "logical" to the logical address of eb X, which was
the old root. We then call tree_mod_log_search() passing it the logical
address of eb X and time_seq == 1;
15) But before calling tree_mod_log_search(), task B locks eb X, adds a
key to eb X, which results in adding a tree mod log operation of type
BTRFS_MOD_LOG_KEY_ADD, with a sequence number of 4, to the tree mod
log, and increments the number of items in eb X from 0 to 1.
Now fs_info->tree_mod_seq has a value of 4;
16) Task A then calls tree_mod_log_search(), which returns the most recent
tree mod log operation for eb X, which is the one just added by task B
at the previous step, with a sequence number of 4, a type of
BTRFS_MOD_LOG_KEY_ADD and for slot 0;
17) Before task A locks and clones eb X, task A adds another key to eb X,
which results in adding a new BTRFS_MOD_LOG_KEY_ADD mod log operation,
with a sequence number of 5, for slot 1 of eb X, increments the
number of items in eb X from 1 to 2, and unlocks eb X.
Now fs_info->tree_mod_seq has a value of 5;
18) Task A then locks eb X and clones it. The clone has a value of 2 for
the number of items and the pointer "tm" points to the tree mod log
operation with sequence number 4, not the most recent one with a
sequence number of 5, so there is mismatch between the number of
mod log operations that are going to be applied to the cloned version
of eb X and the number of items in the clone;
19) Task A then calls tree_mod_log_rewind() with the clone of eb X, the
tree mod log operation with sequence number 4 and a type of
BTRFS_MOD_LOG_KEY_ADD, and time_seq == 1;
20) At tree_mod_log_rewind(), we set the local variable "n" with a value
of 2, which is the number of items in the clone of eb X.
Then in the first iteration of the while loop, we process the mod log
operation with sequence number 4, which is targeted at slot 0 and has
a type of BTRFS_MOD_LOG_KEY_ADD. This results in decrementing "n" from
2 to 1.
Then we pick the next tree mod log operation for eb X, which is the
tree mod log operation with a sequence number of 2, a type of
BTRFS_MOD_LOG_KEY_REMOVE_WHILE_FREEING and for slot 0, it is the one
added in step 5 to the tree mod log tree.
We go back to the top of the loop to process this mod log operation,
and because its slot is 0 and "n" has a value of 1, we hit the BUG_ON:
(...)
switch (tm->op) {
case BTRFS_MOD_LOG_KEY_REMOVE_WHILE_FREEING:
BUG_ON(tm->slot < n);
fallthrough;
(...)
Fix this by checking for a more recent tree mod log operation after locking
and cloning the extent buffer of the old root node, and use it as the first
operation to apply to the cloned extent buffer when rewinding it.
Stable backport notes: due to moved code and renames, in =< 5.11 the
change should be applied to ctree.c:get_old_root.
Reported-by: Zygo Blaxell <ce3g8jdj@umail.furryterror.org>
Link: https://lore.kernel.org/linux-btrfs/20210404040732.GZ32440@hungrycats.org/
Fixes: 834328a849 ("Btrfs: tree mod log's old roots could still be part of the tree")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When creating a subvolume we allocate an extent buffer for its root node
after starting a transaction. We setup a root item for the subvolume that
points to that extent buffer and then attempt to insert the root item into
the root tree - however if that fails, due to ENOMEM for example, we do
not free the extent buffer previously allocated and we do not abort the
transaction (as at that point we did nothing that can not be undone).
This means that we effectively do not return the metadata extent back to
the free space cache/tree and we leave a delayed reference for it which
causes a metadata extent item to be added to the extent tree, in the next
transaction commit, without having backreferences. When this happens
'btrfs check' reports the following:
$ btrfs check /dev/sdi
Opening filesystem to check...
Checking filesystem on /dev/sdi
UUID: dce2cb9d-025f-4b05-a4bf-cee0ad3785eb
[1/7] checking root items
[2/7] checking extents
ref mismatch on [30425088 16384] extent item 1, found 0
backref 30425088 root 256 not referenced back 0x564a91c23d70
incorrect global backref count on 30425088 found 1 wanted 0
backpointer mismatch on [30425088 16384]
owner ref check failed [30425088 16384]
ERROR: errors found in extent allocation tree or chunk allocation
[3/7] checking free space cache
[4/7] checking fs roots
[5/7] checking only csums items (without verifying data)
[6/7] checking root refs
[7/7] checking quota groups skipped (not enabled on this FS)
found 212992 bytes used, error(s) found
total csum bytes: 0
total tree bytes: 131072
total fs tree bytes: 32768
total extent tree bytes: 16384
btree space waste bytes: 124669
file data blocks allocated: 65536
referenced 65536
So fix this by freeing the metadata extent if btrfs_insert_root() returns
an error.
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
When running btrfs/071 with inode_need_compress() removed from
compress_file_range(), we got the following crash:
BUG: kernel NULL pointer dereference, address: 0000000000000018
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
Workqueue: btrfs-delalloc btrfs_work_helper [btrfs]
RIP: 0010:compress_file_range+0x476/0x7b0 [btrfs]
Call Trace:
? submit_compressed_extents+0x450/0x450 [btrfs]
async_cow_start+0x16/0x40 [btrfs]
btrfs_work_helper+0xf2/0x3e0 [btrfs]
process_one_work+0x278/0x5e0
worker_thread+0x55/0x400
? process_one_work+0x5e0/0x5e0
kthread+0x168/0x190
? kthread_create_worker_on_cpu+0x70/0x70
ret_from_fork+0x22/0x30
---[ end trace 65faf4eae941fa7d ]---
This is already after the patch "btrfs: inode: fix NULL pointer
dereference if inode doesn't need compression."
[CAUSE]
@pages is firstly created by kcalloc() in compress_file_extent():
pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS);
Then passed to btrfs_compress_pages() to be utilized there:
ret = btrfs_compress_pages(...
pages,
&nr_pages,
...);
btrfs_compress_pages() will initialize each page as output, in
zlib_compress_pages() we have:
pages[nr_pages] = out_page;
nr_pages++;
Normally this is completely fine, but there is a special case which
is in btrfs_compress_pages() itself:
switch (type) {
default:
return -E2BIG;
}
In this case, we didn't modify @pages nor @out_pages, leaving them
untouched, then when we cleanup pages, the we can hit NULL pointer
dereference again:
if (pages) {
for (i = 0; i < nr_pages; i++) {
WARN_ON(pages[i]->mapping);
put_page(pages[i]);
}
...
}
Since pages[i] are all initialized to zero, and btrfs_compress_pages()
doesn't change them at all, accessing pages[i]->mapping would lead to
NULL pointer dereference.
This is not possible for current kernel, as we check
inode_need_compress() before doing pages allocation.
But if we're going to remove that inode_need_compress() in
compress_file_extent(), then it's going to be a problem.
[FIX]
When btrfs_compress_pages() hits its default case, modify @out_pages to
0 to prevent such problem from happening.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=212331
CC: stable@vger.kernel.org # 5.10+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
For zoned btrfs, zone append is mandatory to write to a sequential write
only zone, otherwise parallel writes to the same zone could result in
unaligned write errors.
If a zoned block device does not support zone append (e.g. a dm-crypt
zoned device using a non-NULL IV cypher), fail to mount.
CC: stable@vger.kernel.org # 5.12
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There is a race between a task aborting a transaction during a commit,
a task doing an fsync and the transaction kthread, which leads to an
use-after-free of the log root tree. When this happens, it results in a
stack trace like the following:
BTRFS info (device dm-0): forced readonly
BTRFS warning (device dm-0): Skipping commit of aborted transaction.
BTRFS: error (device dm-0) in cleanup_transaction:1958: errno=-5 IO failure
BTRFS warning (device dm-0): lost page write due to IO error on /dev/mapper/error-test (-5)
BTRFS warning (device dm-0): Skipping commit of aborted transaction.
BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0xa4e8 len 4096 err no 10
BTRFS error (device dm-0): error writing primary super block to device 1
BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0x12e000 len 4096 err no 10
BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0x12e008 len 4096 err no 10
BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0x12e010 len 4096 err no 10
BTRFS: error (device dm-0) in write_all_supers:4110: errno=-5 IO failure (1 errors while writing supers)
BTRFS: error (device dm-0) in btrfs_sync_log:3308: errno=-5 IO failure
general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6b68: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI
CPU: 2 PID: 2458471 Comm: fsstress Not tainted 5.12.0-rc5-btrfs-next-84 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
RIP: 0010:__mutex_lock+0x139/0xa40
Code: c0 74 19 (...)
RSP: 0018:ffff9f18830d7b00 EFLAGS: 00010202
RAX: 6b6b6b6b6b6b6b68 RBX: 0000000000000001 RCX: 0000000000000002
RDX: ffffffffb9c54d13 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff9f18830d7bc0 R08: 0000000000000000 R09: 0000000000000000
R10: ffff9f18830d7be0 R11: 0000000000000001 R12: ffff8c6cd199c040
R13: ffff8c6c95821358 R14: 00000000fffffffb R15: ffff8c6cbcf01358
FS: 00007fa9140c2b80(0000) GS:ffff8c6fac600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa913d52000 CR3: 000000013d2b4003 CR4: 0000000000370ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
? __btrfs_handle_fs_error+0xde/0x146 [btrfs]
? btrfs_sync_log+0x7c1/0xf20 [btrfs]
? btrfs_sync_log+0x7c1/0xf20 [btrfs]
btrfs_sync_log+0x7c1/0xf20 [btrfs]
btrfs_sync_file+0x40c/0x580 [btrfs]
do_fsync+0x38/0x70
__x64_sys_fsync+0x10/0x20
do_syscall_64+0x33/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fa9142a55c3
Code: 8b 15 09 (...)
RSP: 002b:00007fff26278d48 EFLAGS: 00000246 ORIG_RAX: 000000000000004a
RAX: ffffffffffffffda RBX: 0000563c83cb4560 RCX: 00007fa9142a55c3
RDX: 00007fff26278cb0 RSI: 00007fff26278cb0 RDI: 0000000000000005
RBP: 0000000000000005 R08: 0000000000000001 R09: 00007fff26278d5c
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000340
R13: 00007fff26278de0 R14: 00007fff26278d96 R15: 0000563c83ca57c0
Modules linked in: btrfs dm_zero dm_snapshot dm_thin_pool (...)
---[ end trace ee2f1b19327d791d ]---
The steps that lead to this crash are the following:
1) We are at transaction N;
2) We have two tasks with a transaction handle attached to transaction N.
Task A and Task B. Task B is doing an fsync;
3) Task B is at btrfs_sync_log(), and has saved fs_info->log_root_tree
into a local variable named 'log_root_tree' at the top of
btrfs_sync_log(). Task B is about to call write_all_supers(), but
before that...
4) Task A calls btrfs_commit_transaction(), and after it sets the
transaction state to TRANS_STATE_COMMIT_START, an error happens before
it waits for the transaction's 'num_writers' counter to reach a value
of 1 (no one else attached to the transaction), so it jumps to the
label "cleanup_transaction";
5) Task A then calls cleanup_transaction(), where it aborts the
transaction, setting BTRFS_FS_STATE_TRANS_ABORTED on fs_info->fs_state,
setting the ->aborted field of the transaction and the handle to an
errno value and also setting BTRFS_FS_STATE_ERROR on fs_info->fs_state.
After that, at cleanup_transaction(), it deletes the transaction from
the list of transactions (fs_info->trans_list), sets the transaction
to the state TRANS_STATE_COMMIT_DOING and then waits for the number
of writers to go down to 1, as it's currently 2 (1 for task A and 1
for task B);
6) The transaction kthread is running and sees that BTRFS_FS_STATE_ERROR
is set in fs_info->fs_state, so it calls btrfs_cleanup_transaction().
There it sees the list fs_info->trans_list is empty, and then proceeds
into calling btrfs_drop_all_logs(), which frees the log root tree with
a call to btrfs_free_log_root_tree();
7) Task B calls write_all_supers() and, shortly after, under the label
'out_wake_log_root', it deferences the pointer stored in
'log_root_tree', which was already freed in the previous step by the
transaction kthread. This results in a use-after-free leading to a
crash.
Fix this by deleting the transaction from the list of transactions at
cleanup_transaction() only after setting the transaction state to
TRANS_STATE_COMMIT_DOING and waiting for all existing tasks that are
attached to the transaction to release their transaction handles.
This makes the transaction kthread wait for all the tasks attached to
the transaction to be done with the transaction before dropping the
log roots and doing other cleanups.
Fixes: ef67963dac ("btrfs: drop logs when we've aborted a transaction")
CC: stable@vger.kernel.org # 5.10+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The new function, submit_eb_subpage(), will submit all the dirty extent
buffers in the page.
The major difference between submit_eb_page() and submit_eb_subpage()
is:
- How to grab extent buffer
Now we use find_extent_buffer_nospinlock() other than using
page::private.
All other different handling is already done in functions like
lock_extent_buffer_for_io() and write_one_eb().
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
For subpage metadata, we don't use page locking at all. So just skip
the page locking part for subpage. The rest of the function can be
reused.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The new function, write_one_subpage_eb(), as a subroutine for subpage
metadata write, will handle the extent buffer bio submission.
The major differences between the new write_one_subpage_eb() and
write_one_eb() is:
- No page locking
When entering write_one_subpage_eb() the page is no longer locked.
We only lock the page for its status update, and unlock immediately.
Now we completely rely on extent io tree locking.
- Extra bitmap update along with page status update
Now page dirty and writeback is controlled by
btrfs_subpage::dirty_bitmap and btrfs_subpage::writeback_bitmap.
They both follow the schema that any sector is dirty/writeback, then
the full page gets dirty/writeback.
- When to update the nr_written number
Now we take a shortcut, if we have cleared the last dirty bit of the
page, we update nr_written.
This is not completely perfect, but should emulate the old behavior
well enough.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The new function, end_bio_subpage_eb_writepage(), will handle the
metadata writeback endio.
The major differences involved are:
- How to grab extent buffer
Now page::private is a pointer to btrfs_subpage, we can no longer grab
extent buffer directly.
Thus we need to use the bv_offset to locate the extent buffer manually
and iterate through the whole range.
- Use btrfs_subpage_end_writeback() caller
This helper will handle the subpage writeback for us.
Since this function is executed under endio context, when grabbing
extent buffers it can't grab eb->refs_lock as that lock is not designed
to be grabbed under hardirq context.
So here introduce a helper, find_extent_buffer_nolock(), for such
situation, and convert find_extent_buffer() to use that helper.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There are a few places where we don't check the return value of
btrfs_commit_transaction in relocation.c. Thankfully all these places
have straightforward error handling, so simply change all of the sites
at once.
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>
We have a BUG_ON() if we get an error back from btrfs_get_fs_root().
This honestly should never fail, as at this point we have a solid
coordination of fs root to reloc root, and these roots will all be in
memory. But in the name of killing BUG_ON()'s remove these and handle
the error condition properly, ASSERT()'ing for developers.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In corruption cases we could have paths from a block up to no root at
all, and thus we'll BUG_ON(!root) in select_one_root. Handle this by
adding an ASSERT() for developers, and returning an error for normal
users.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This probably can't happen even with a corrupt file system, because we
would have failed much earlier on than here. However there's no reason
we can't just check and bail out as appropriate, so do that and convert
the correctness BUG_ON() to an ASSERT().
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>
If we have a duplicate entry for a reloc root then we could have fs
corruption that resulted in a double allocation. Since this shouldn't
happen unless there is corruption, add an ASSERT(ret != -EEXIST) to all
of the callers of __add_reloc_root() to catch any logic mistakes for
developers, otherwise normal error handling will happen for normal
users.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We can already handle errors appropriately from this function, deal with
an error coming from __add_reloc_root appropriately.
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>
We already handle some errors in this function, and the callers do the
correct error handling, so clean up the rest of the function to do the
appropriate error handling.
There's a little extra work that needs to be done here, as we create the
inode item before we create the orphan item. We could potentially add
the orphan item, but if we failed to create the inode item we would have
to abort the transaction.
Instead add a helper to delete the inode item we created in the case
that we're unable to look up the inode (this would likely be caused by
an ENOMEM), which if it succeeds means we can avoid a transaction abort
in this particular error case.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
These checks are all taken care of for us by the tree checker code:
- the flags don't change or are updated consistently
- the v0 extent item format is invalid and caught in many other places
too
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
We need to validate that a data extent item does not have the
FULL_BACKREF flag set on its flags.
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>
We can already deal with errors appropriately from do_relocation, simply
handle any errors that come from changing the refs at this point
cleanly. We have to abort the transaction if we fail here as we've
modified metadata at this point.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If any of the reference count manipulation stuff fails in replace_path
we need to abort the transaction, as we've modified the blocks already.
We can simply break at this point and everything will be cleaned up.
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>
The search can fail for various reasons, in case of errors there's no
cleanup to be done so we can pass the error to the caller, adjusting for
the case where the key is not found and search slot returns 1.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
If we error out COWing the root node when doing a replace_path then we
simply unlock and free the buffer and return the error.
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>
A few BUG_ON()'s in replace_path are purely to keep us from making
logical mistakes, so replace them with ASSERT()'s.
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>
We call btrfs_update_root in btrfs_update_reloc_root, which can fail for
all sorts of reasons, including IO errors. Instead of panicing the box
lets return the error, now that all callers properly handle those
errors.
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>
btrfs_update_reloc_root will will return errors in the future, so handle
an error properly in prepare_to_merge.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_update_reloc_root will will return errors in the future, so handle
the error properly in insert_dirty_subvol.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This will be able to return errors in the future, so change it to return
an error and handle the errors appropriately.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_update_reloc_root will will return errors in the future, so handle
the error properly in commit_fs_roots.
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>
If we fail to setup a root->reloc_root in a different thread that path
will error out, however it still leaves root->reloc_root NULL but would
still appear set up in the transaction. Subsequent calls to
btrfs_record_root_in_transaction would succeed without attempting to
create the reloc root, as the transid has already been updated.
Handle this case by making sure we have a root->reloc_root set after a
btrfs_record_root_in_transaction call so we don't end up dereferencing a
NULL pointer.
Reported-by: Zygo Blaxell <ce3g8jdj@umail.furryterror.org>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We do memory allocations here, read blocks from disk, all sorts of
operations that could easily fail at any given point. Instead of
panicing the box, simply return the error back up the chain, all callers
at this point have proper error handling.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
create_reloc_root will return errors in the future, and __add_reloc_root
can return ENOMEM or EEXIST, so handle these errors properly.
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>
We can create a reloc root when we record the root in the trans, which
can fail for all sorts of different reasons. Propagate this error up
the chain of callers. Future patches will fix the callers of
btrfs_record_root_in_trans() to handle the error.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
record_root_in_trans can currently fail, so handle this failure
properly.
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>
record_root_in_trans can fail currently, handle this failure properly.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
record_root_in_trans can fail currently, so handle this failure
properly.
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>
btrfs_record_root_in_trans will return errors in the future, so handle
the error properly in start_transaction.
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>
btrfs_record_root_in_trans will return errors in the future, so handle
the error properly in relocate_tree_block.
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>
btrfs_record_root_in_trans will return errors in the future, so handle
the error properly in create_subvol.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
