| Age | Commit message (Collapse) | Author | Files | Lines |
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When btrfs balance is interrupted with umount, the background balance
resumes on the next mount. There is a potential deadlock with FS freezing
here like as described in commit 26559780b953 ("btrfs: zoned: mark
relocation as writing"). Mark the process as sb_writing to avoid it.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
CC: stable@vger.kernel.org # 4.9+
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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[BUG]
There is a report that a btrfs has a bad super block num devices.
This makes btrfs to reject the fs completely.
BTRFS error (device sdd3): super_num_devices 3 mismatch with num_devices 2 found here
BTRFS error (device sdd3): failed to read chunk tree: -22
BTRFS error (device sdd3): open_ctree failed
[CAUSE]
During btrfs device removal, chunk tree and super block num devs are
updated in two different transactions:
btrfs_rm_device()
|- btrfs_rm_dev_item(device)
| |- trans = btrfs_start_transaction()
| | Now we got transaction X
| |
| |- btrfs_del_item()
| | Now device item is removed from chunk tree
| |
| |- btrfs_commit_transaction()
| Transaction X got committed, super num devs untouched,
| but device item removed from chunk tree.
| (AKA, super num devs is already incorrect)
|
|- cur_devices->num_devices--;
|- cur_devices->total_devices--;
|- btrfs_set_super_num_devices()
All those operations are not in transaction X, thus it will
only be written back to disk in next transaction.
So after the transaction X in btrfs_rm_dev_item() committed, but before
transaction X+1 (which can be minutes away), a power loss happen, then
we got the super num mismatch.
[FIX]
Instead of starting and committing a transaction inside
btrfs_rm_dev_item(), start a transaction in side btrfs_rm_device() and
pass it to btrfs_rm_dev_item().
And only commit the transaction after everything is done.
Reported-by: Luca Béla Palkovics <luca.bela.palkovics@gmail.com>
Link: https://lore.kernel.org/linux-btrfs/CA+8xDSpvdm_U0QLBAnrH=zqDq_cWCOH5TiV46CKmp3igr44okQ@mail.gmail.com/
CC: stable@vger.kernel.org # 4.14+
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Syzbot reported a possible use-after-free in printing information
in device_list_add.
Very similar with the bug fixed by commit 0697d9a61099 ("btrfs: don't
access possibly stale fs_info data for printing duplicate device"),
but this time the use occurs in btrfs_info_in_rcu.
Call Trace:
kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
btrfs_printk+0x395/0x425 fs/btrfs/super.c:244
device_list_add.cold+0xd7/0x2ed fs/btrfs/volumes.c:957
btrfs_scan_one_device+0x4c7/0x5c0 fs/btrfs/volumes.c:1387
btrfs_control_ioctl+0x12a/0x2d0 fs/btrfs/super.c:2409
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl fs/ioctl.c:860 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
Fix this by modifying device->fs_info to NULL too.
Reported-and-tested-by: syzbot+82650a4e0ed38f218363@syzkaller.appspotmail.com
CC: stable@vger.kernel.org # 4.19+
Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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There is a hung_task issue with running generic/068 on an SMR
device. The hang occurs while a process is trying to thaw the
filesystem. The process is trying to take sb->s_umount to thaw the
FS. The lock is held by fsstress, which calls btrfs_sync_fs() and is
waiting for an ordered extent to finish. However, as the FS is frozen,
the ordered extents never finish.
Having an ordered extent while the FS is frozen is the root cause of
the hang. The ordered extent is initiated from btrfs_relocate_chunk()
which is called from btrfs_reclaim_bgs_work().
This commit adds sb_*_write() around btrfs_relocate_chunk() call
site. For the usual "btrfs balance" command, we already call it with
mnt_want_file() in btrfs_ioctl_balance().
Fixes: 18bb8bbf13c1 ("btrfs: zoned: automatically reclaim zones")
CC: stable@vger.kernel.org # 5.13+
Link: https://github.com/naota/linux/issues/56
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Device add, remove, and replace all require balance, which doesn't work
right now on extent tree v2, so disable these for now.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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With global root id's it makes it problematic to do backref lookups for
balance. This isn't hard to deal with, but future changes are going to
make it impossible to lookup backrefs on any COWonly roots, so go ahead
and disable balance for now on extent tree v2 until we can add balance
support back in future patches.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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The pointer to struct request_queue is used only to get device type
rotating or the non-rotating. So use it directly.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Commit "btrfs: add device major-minor info in the struct btrfs_device"
saved the device major-minor number in the struct btrfs_device upon
discovering it.
So no need to lookup_bdev() again just match, which means
device_matched() can go away.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Internally it is common to use the major-minor number to identify a
device and, at a few locations in btrfs, we use the major-minor number
to match the device.
So when we identify a new btrfs device through device add or device
replace or device-scan/ready save the device's major-minor (dev_t) in the
struct btrfs_device so that we don't have to call lookup_bdev() again.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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After the commit "btrfs: harden identification of the stale device", we
don't have to match the device path anymore. Instead, we match the dev_t.
So pass in the dev_t instead of the device path, in the call chain
btrfs_forget_devices()->btrfs_free_stale_devices().
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Identifying and removing the stale device from the fs_uuids list is done
by btrfs_free_stale_devices(). btrfs_free_stale_devices() in turn
depends on device_path_matched() to check if the device appears in more
than one btrfs_device structure.
The matching of the device happens by its path, the device path. However,
when device mapper is in use, the dm device paths are nothing but a link
to the actual block device, which leads to the device_path_matched()
failing to match.
Fix this by matching the dev_t as provided by lookup_bdev() instead of
plain string compare of the device paths.
Reported-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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This simplifies the code flow in read_one_chunk and makes error handling
when handling missing devices a bit simpler by reducing it to a single
check if something went wrong. No functional changes.
Reviewed-by: Su Yue <l@damenly.su>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Currently there is only one user for btrfs metadata readahead, and
that's scrub.
But even for the single user, it's not providing the correct
functionality it needs, as scrub needs reada for commit root, which
current readahead can't provide. (Although it's pretty easy to add such
feature).
Despite this, there are some extra problems related to metadata
readahead:
- Duplicated feature with btrfs_path::reada
- Partly duplicated feature of btrfs_fs_info::buffer_radix
Btrfs already caches its metadata in buffer_radix, while readahead
tries to read the tree block no matter if it's already cached.
- Poor layer separation
Metadata readahead works kinda at device level.
This is definitely not the correct layer it should be, since metadata
is at btrfs logical address space, it should not bother device at all.
This brings extra chance for bugs to sneak in, while brings
unnecessary complexity.
- Dead code
In the very beginning of scrub.c we have #undef DEBUG, rendering all
the debug related code useless and unable to test.
Thus here I purpose to remove the metadata readahead mechanism
completely.
[BENCHMARK]
There is a full benchmark for the scrub performance difference using the
old btrfs_reada_add() and btrfs_path::reada.
For the worst case (no dirty metadata, slow HDD), there could be a 5%
performance drop for scrub.
For other cases (even SATA SSD), there is no distinguishable performance
difference.
The number is reported scrub speed, in MiB/s.
The resolution is limited by the reported duration, which only has a
resolution of 1 second.
Old New Diff
SSD 455.3 466.332 +2.42%
HDD 103.927 98.012 -5.69%
Comprehensive test methodology is in the cover letter of the patch.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Sink zone check into btrfs_repair_one_zone() so we don't need to do it
in all callers.
Also as btrfs_repair_one_zone() doesn't return a sensible error, make it
a boolean function and return false in case it got called on a non-zoned
filesystem and true on a zoned filesystem.
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>
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Current set of exclusive operation states is not sufficient to handle
all practical use cases. In particular there is a need to be able to add
a device to a filesystem that have paused balance. Currently there is no
way to distinguish between a running and a paused balance. Fix this by
introducing BTRFS_EXCLOP_BALANCE_PAUSED which is going to be set in 2
occasions:
1. When a filesystem is mounted with skip_balance and there is an
unfinished balance it will now be into BALANCE_PAUSED instead of
simply BALANCE state.
2. When a running balance is paused.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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We're just using the extent_root to set the chunk owner to
root_key->objectid, which is BTRFS_EXTENT_TREE_OBJECTID, so use that
directly instead of using the root.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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[BUG]
When debugging calc_bio_boundaries(), I found that even for RAID1
metadata, we're following stripe length to calculate stripe boundary.
# mkfs.btrfs -m raid1 -d raid1 /dev/test/scratch[12]
# mount /dev/test/scratch /mnt/btrfs
# xfs_io -f -c "pwrite 0 64K" /mnt/btrfs/file
# umount
Above very basic operations will make calc_bio_boundaries() to report
the following result:
submit_extent_page: r/i=1/1 file_offset=22036480 len_to_stripe_boundary=49152
submit_extent_page: r/i=1/1 file_offset=30474240 len_to_stripe_boundary=65536
...
submit_extent_page: r/i=1/1 file_offset=30523392 len_to_stripe_boundary=16384
submit_extent_page: r/i=1/1 file_offset=30457856 len_to_stripe_boundary=16384
submit_extent_page: r/i=5/257 file_offset=0 len_to_stripe_boundary=65536
submit_extent_page: r/i=5/257 file_offset=65536 len_to_stripe_boundary=65536
submit_extent_page: r/i=1/1 file_offset=30490624 len_to_stripe_boundary=49152
submit_extent_page: r/i=1/1 file_offset=30507008 len_to_stripe_boundary=32768
Where "r/i" is the rootid and inode, 1/1 means they metadata.
The remaining names match the member used in kernel.
Even all data/metadata are using RAID1, we're still following stripe
length.
[CAUSE]
This behavior is caused by a wrong condition in btrfs_get_io_geometry():
if (map->type & BTRFS_BLOCK_GROUP_PROFILE_MASK) {
/* Fill using stripe_len */
len = min_t(u64, em->len - offset, max_len);
} else {
len = em->len - offset;
}
This means, only for SINGLE we will not follow stripe_len.
However for profiles like RAID1*, DUP, they don't need to bother
stripe_len.
This can lead to unnecessary bio split for RAID1*/DUP profiles, and can
even be a blockage for future zoned RAID support.
[FIX]
Introduce one single-use macro, BTRFS_BLOCK_GROUP_STRIPE_MASK, and
change the condition to only calculate the length using stripe length
for stripe based profiles.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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When mounting a device, we are reporting the zones twice: once for
checking the zone attributes in btrfs_get_dev_zone_info and once for
loading block groups' zone info in
btrfs_load_block_group_zone_info(). With a lot of block groups, that
leads to a lot of REPORT ZONE commands and slows down the mount
process.
This patch introduces a zone info cache in struct
btrfs_zoned_device_info. The cache is populated while in
btrfs_get_dev_zone_info() and used for
btrfs_load_block_group_zone_info() to reduce the number of REPORT ZONE
commands. The zone cache is then released after loading the block
groups, as it will not be much effective during the run time.
Benchmark: Mount an HDD with 57,007 block groups
Before patch: 171.368 seconds
After patch: 64.064 seconds
While it still takes a minute due to the slowness of loading all the
block groups, the patch reduces the mount time by 1/3.
Link: https://lore.kernel.org/linux-btrfs/CAHQ7scUiLtcTqZOMMY5kbWUBOhGRwKo6J6wYPT5WY+C=cD49nQ@mail.gmail.com/
Fixes: 5b316468983d ("btrfs: get zone information of zoned block devices")
CC: stable@vger.kernel.org
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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btrfs_prepare_sprout() splices seed devices into its own struct fs_devices,
so that its parent function btrfs_init_new_device() can add the new sprout
device to fs_info->fs_devices.
Both btrfs_prepare_sprout() and btrfs_init_new_device() need
device_list_mutex. But they are holding it separately, thus create a
small race window. Close it and hold device_list_mutex across both
functions btrfs_init_new_device() and btrfs_prepare_sprout().
Split btrfs_prepare_sprout() into btrfs_init_sprout() and
btrfs_setup_sprout(). This split is essential because device_list_mutex
must not be held for allocations in btrfs_init_sprout() but must be held
for btrfs_setup_sprout(). So now a common device_list_mutex can be used
between btrfs_init_new_device() and btrfs_setup_sprout().
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Declare int seeding_dev as a bool. Also, move its declaration a line
below to adjust packing.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Now that all call sites are using the slot number to modify item values,
rename the SETGET helpers to raw_item_*(), and then rework the _nr()
helpers to be the btrfs_item_*() btrfs_set_item_*() helpers, and then
rename all of the callers to the new helpers.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"A few more fixes, almost all error handling one-liners and for stable.
- regression fix in directory logging items
- regression fix of extent buffer status bits handling after an error
- fix memory leak in error handling path in tree-log
- fix freeing invalid anon device number when handling errors during
subvolume creation
- fix warning when freeing leaf after subvolume creation failure
- fix missing blkdev put in device scan error handling
- fix invalid delayed ref after subvolume creation failure"
* tag 'for-5.16-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: fix missing blkdev_put() call in btrfs_scan_one_device()
btrfs: fix warning when freeing leaf after subvolume creation failure
btrfs: fix invalid delayed ref after subvolume creation failure
btrfs: check WRITE_ERR when trying to read an extent buffer
btrfs: fix missing last dir item offset update when logging directory
btrfs: fix double free of anon_dev after failure to create subvolume
btrfs: fix memory leak in __add_inode_ref()
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The function btrfs_scan_one_device() calls blkdev_get_by_path() and
blkdev_put() to get and release its target block device. However, when
btrfs_sb_log_location_bdev() fails, blkdev_put() is not called and the
block device is left without clean up. This triggered failure of fstests
generic/085. Fix the failure path of btrfs_sb_log_location_bdev() to
call blkdev_put().
Fixes: 12659251ca5df ("btrfs: implement log-structured superblock for ZONED mode")
CC: stable@vger.kernel.org # 5.15+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"Several xes and one old ioctl deprecation. Namely there's fix for
crashes/warnings with lzo compression that was suspected to be caused
by first pull merge resolution, but it was a different bug.
Summary:
- regression fix for a crash in lzo due to missing boundary checks of
the page array
- fix crashes on ARM64 due to missing barriers when synchronizing
status bits between work queues
- silence lockdep when reading chunk tree during mount
- fix false positive warning in integrity checker on devices with
disabled write caching
- fix signedness of bitfields in scrub
- start deprecation of balance v1 ioctl"
* tag 'for-5.16-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: deprecate BTRFS_IOC_BALANCE ioctl
btrfs: make 1-bit bit-fields of scrub_page unsigned int
btrfs: check-integrity: fix a warning on write caching disabled disk
btrfs: silence lockdep when reading chunk tree during mount
btrfs: fix memory ordering between normal and ordered work functions
btrfs: fix a out-of-bound access in copy_compressed_data_to_page()
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Often some test cases like btrfs/161 trigger lockdep splats that complain
about possible unsafe lock scenario due to the fact that during mount,
when reading the chunk tree we end up calling blkdev_get_by_path() while
holding a read lock on a leaf of the chunk tree. That produces a lockdep
splat like the following:
[ 3653.683975] ======================================================
[ 3653.685148] WARNING: possible circular locking dependency detected
[ 3653.686301] 5.15.0-rc7-btrfs-next-103 #1 Not tainted
[ 3653.687239] ------------------------------------------------------
[ 3653.688400] mount/447465 is trying to acquire lock:
[ 3653.689320] ffff8c6b0c76e528 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev.part.0+0xe7/0x320
[ 3653.691054]
but task is already holding lock:
[ 3653.692155] ffff8c6b0a9f39e0 (btrfs-chunk-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x24/0x110 [btrfs]
[ 3653.693978]
which lock already depends on the new lock.
[ 3653.695510]
the existing dependency chain (in reverse order) is:
[ 3653.696915]
-> #3 (btrfs-chunk-00){++++}-{3:3}:
[ 3653.698053] down_read_nested+0x4b/0x140
[ 3653.698893] __btrfs_tree_read_lock+0x24/0x110 [btrfs]
[ 3653.699988] btrfs_read_lock_root_node+0x31/0x40 [btrfs]
[ 3653.701205] btrfs_search_slot+0x537/0xc00 [btrfs]
[ 3653.702234] btrfs_insert_empty_items+0x32/0x70 [btrfs]
[ 3653.703332] btrfs_init_new_device+0x563/0x15b0 [btrfs]
[ 3653.704439] btrfs_ioctl+0x2110/0x3530 [btrfs]
[ 3653.705405] __x64_sys_ioctl+0x83/0xb0
[ 3653.706215] do_syscall_64+0x3b/0xc0
[ 3653.706990] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 3653.708040]
-> #2 (sb_internal#2){.+.+}-{0:0}:
[ 3653.708994] lock_release+0x13d/0x4a0
[ 3653.709533] up_write+0x18/0x160
[ 3653.710017] btrfs_sync_file+0x3f3/0x5b0 [btrfs]
[ 3653.710699] __loop_update_dio+0xbd/0x170 [loop]
[ 3653.711360] lo_ioctl+0x3b1/0x8a0 [loop]
[ 3653.711929] block_ioctl+0x48/0x50
[ 3653.712442] __x64_sys_ioctl+0x83/0xb0
[ 3653.712991] do_syscall_64+0x3b/0xc0
[ 3653.713519] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 3653.714233]
-> #1 (&lo->lo_mutex){+.+.}-{3:3}:
[ 3653.715026] __mutex_lock+0x92/0x900
[ 3653.715648] lo_open+0x28/0x60 [loop]
[ 3653.716275] blkdev_get_whole+0x28/0x90
[ 3653.716867] blkdev_get_by_dev.part.0+0x142/0x320
[ 3653.717537] blkdev_open+0x5e/0xa0
[ 3653.718043] do_dentry_open+0x163/0x390
[ 3653.718604] path_openat+0x3f0/0xa80
[ 3653.719128] do_filp_open+0xa9/0x150
[ 3653.719652] do_sys_openat2+0x97/0x160
[ 3653.720197] __x64_sys_openat+0x54/0x90
[ 3653.720766] do_syscall_64+0x3b/0xc0
[ 3653.721285] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 3653.721986]
-> #0 (&disk->open_mutex){+.+.}-{3:3}:
[ 3653.722775] __lock_acquire+0x130e/0x2210
[ 3653.723348] lock_acquire+0xd7/0x310
[ 3653.723867] __mutex_lock+0x92/0x900
[ 3653.724394] blkdev_get_by_dev.part.0+0xe7/0x320
[ 3653.725041] blkdev_get_by_path+0xb8/0xd0
[ 3653.725614] btrfs_get_bdev_and_sb+0x1b/0xb0 [btrfs]
[ 3653.726332] open_fs_devices+0xd7/0x2c0 [btrfs]
[ 3653.726999] btrfs_read_chunk_tree+0x3ad/0x870 [btrfs]
[ 3653.727739] open_ctree+0xb8e/0x17bf [btrfs]
[ 3653.728384] btrfs_mount_root.cold+0x12/0xde [btrfs]
[ 3653.729130] legacy_get_tree+0x30/0x50
[ 3653.729676] vfs_get_tree+0x28/0xc0
[ 3653.730192] vfs_kern_mount.part.0+0x71/0xb0
[ 3653.730800] btrfs_mount+0x11d/0x3a0 [btrfs]
[ 3653.731427] legacy_get_tree+0x30/0x50
[ 3653.731970] vfs_get_tree+0x28/0xc0
[ 3653.732486] path_mount+0x2d4/0xbe0
[ 3653.732997] __x64_sys_mount+0x103/0x140
[ 3653.733560] do_syscall_64+0x3b/0xc0
[ 3653.734080] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 3653.734782]
other info that might help us debug this:
[ 3653.735784] Chain exists of:
&disk->open_mutex --> sb_internal#2 --> btrfs-chunk-00
[ 3653.737123] Possible unsafe locking scenario:
[ 3653.737865] CPU0 CPU1
[ 3653.738435] ---- ----
[ 3653.739007] lock(btrfs-chunk-00);
[ 3653.739449] lock(sb_internal#2);
[ 3653.740193] lock(btrfs-chunk-00);
[ 3653.740955] lock(&disk->open_mutex);
[ 3653.741431]
*** DEADLOCK ***
[ 3653.742176] 3 locks held by mount/447465:
[ 3653.742739] #0: ffff8c6acf85c0e8 (&type->s_umount_key#44/1){+.+.}-{3:3}, at: alloc_super+0xd5/0x3b0
[ 3653.744114] #1: ffffffffc0b28f70 (uuid_mutex){+.+.}-{3:3}, at: btrfs_read_chunk_tree+0x59/0x870 [btrfs]
[ 3653.745563] #2: ffff8c6b0a9f39e0 (btrfs-chunk-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x24/0x110 [btrfs]
[ 3653.747066]
stack backtrace:
[ 3653.747723] CPU: 4 PID: 447465 Comm: mount Not tainted 5.15.0-rc7-btrfs-next-103 #1
[ 3653.748873] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
[ 3653.750592] Call Trace:
[ 3653.750967] dump_stack_lvl+0x57/0x72
[ 3653.751526] check_noncircular+0xf3/0x110
[ 3653.752136] ? stack_trace_save+0x4b/0x70
[ 3653.752748] __lock_acquire+0x130e/0x2210
[ 3653.753356] lock_acquire+0xd7/0x310
[ 3653.753898] ? blkdev_get_by_dev.part.0+0xe7/0x320
[ 3653.754596] ? lock_is_held_type+0xe8/0x140
[ 3653.755125] ? blkdev_get_by_dev.part.0+0xe7/0x320
[ 3653.755729] ? blkdev_get_by_dev.part.0+0xe7/0x320
[ 3653.756338] __mutex_lock+0x92/0x900
[ 3653.756794] ? blkdev_get_by_dev.part.0+0xe7/0x320
[ 3653.757400] ? do_raw_spin_unlock+0x4b/0xa0
[ 3653.757930] ? _raw_spin_unlock+0x29/0x40
[ 3653.758437] ? bd_prepare_to_claim+0x129/0x150
[ 3653.758999] ? trace_module_get+0x2b/0xd0
[ 3653.759508] ? try_module_get.part.0+0x50/0x80
[ 3653.760072] blkdev_get_by_dev.part.0+0xe7/0x320
[ 3653.760661] ? devcgroup_check_permission+0xc1/0x1f0
[ 3653.761288] blkdev_get_by_path+0xb8/0xd0
[ 3653.761797] btrfs_get_bdev_and_sb+0x1b/0xb0 [btrfs]
[ 3653.762454] open_fs_devices+0xd7/0x2c0 [btrfs]
[ 3653.763055] ? clone_fs_devices+0x8f/0x170 [btrfs]
[ 3653.763689] btrfs_read_chunk_tree+0x3ad/0x870 [btrfs]
[ 3653.764370] ? kvm_sched_clock_read+0x14/0x40
[ 3653.764922] open_ctree+0xb8e/0x17bf [btrfs]
[ 3653.765493] ? super_setup_bdi_name+0x79/0xd0
[ 3653.766043] btrfs_mount_root.cold+0x12/0xde [btrfs]
[ 3653.766780] ? rcu_read_lock_sched_held+0x3f/0x80
[ 3653.767488] ? kfree+0x1f2/0x3c0
[ 3653.767979] legacy_get_tree+0x30/0x50
[ 3653.768548] vfs_get_tree+0x28/0xc0
[ 3653.769076] vfs_kern_mount.part.0+0x71/0xb0
[ 3653.769718] btrfs_mount+0x11d/0x3a0 [btrfs]
[ 3653.770381] ? rcu_read_lock_sched_held+0x3f/0x80
[ 3653.771086] ? kfree+0x1f2/0x3c0
[ 3653.771574] legacy_get_tree+0x30/0x50
[ 3653.772136] vfs_get_tree+0x28/0xc0
[ 3653.772673] path_mount+0x2d4/0xbe0
[ 3653.773201] __x64_sys_mount+0x103/0x140
[ 3653.773793] do_syscall_64+0x3b/0xc0
[ 3653.774333] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 3653.775094] RIP: 0033:0x7f648bc45aaa
This happens because through btrfs_read_chunk_tree(), which is called only
during mount, ends up acquiring the mutex open_mutex of a block device
while holding a read lock on a leaf of the chunk tree while other paths
need to acquire other locks before locking extent buffers of the chunk
tree.
Since at mount time when we call btrfs_read_chunk_tree() we know that
we don't have other tasks running in parallel and modifying the chunk
tree, we can simply skip locking of chunk tree extent buffers. So do
that and move the assertion that checks the fs is not yet mounted to the
top block of btrfs_read_chunk_tree(), with a comment before doing it.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs updates from David Sterba:
"The updates this time are more under the hood and enhancing existing
features (subpage with compression and zoned namespaces).
Performance related:
- misc small inode logging improvements (+3% throughput, -11% latency
on sample dbench workload)
- more efficient directory logging: bulk item insertion, less tree
searches and locking
- speed up bulk insertion of items into a b-tree, which is used when
logging directories, when running delayed items for directories
(fsync and transaction commits) and when running the slow path
(full sync) of an fsync (bulk creation run time -4%, deletion -12%)
Core:
- continued subpage support
- make defragmentation work
- make compression write work
- zoned mode
- support ZNS (zoned namespaces), zone capacity is number of
usable blocks in each zone
- add dedicated block group (zoned) for relocation, to prevent
out of order writes in some cases
- greedy block group reclaim, pick the ones with least usable
space first
- preparatory work for send protocol updates
- error handling improvements
- cleanups and refactoring
Fixes:
- lockdep warnings
- in show_devname callback, on seeding device
- device delete on loop device due to conversions to workqueues
- fix deadlock between chunk allocation and chunk btree modifications
- fix tracking of missing device count and status"
* tag 'for-5.16-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (140 commits)
btrfs: remove root argument from check_item_in_log()
btrfs: remove root argument from add_link()
btrfs: remove root argument from btrfs_unlink_inode()
btrfs: remove root argument from drop_one_dir_item()
btrfs: clear MISSING device status bit in btrfs_close_one_device
btrfs: call btrfs_check_rw_degradable only if there is a missing device
btrfs: send: prepare for v2 protocol
btrfs: fix comment about sector sizes supported in 64K systems
btrfs: update device path inode time instead of bd_inode
fs: export an inode_update_time helper
btrfs: fix deadlock when defragging transparent huge pages
btrfs: sysfs: convert scnprintf and snprintf to sysfs_emit
btrfs: make btrfs_super_block size match BTRFS_SUPER_INFO_SIZE
btrfs: update comments for chunk allocation -ENOSPC cases
btrfs: fix deadlock between chunk allocation and chunk btree modifications
btrfs: zoned: use greedy gc for auto reclaim
btrfs: check-integrity: stop storing the block device name in btrfsic_dev_state
btrfs: use btrfs_get_dev_args_from_path in dev removal ioctls
btrfs: add a btrfs_get_dev_args_from_path helper
btrfs: handle device lookup with btrfs_dev_lookup_args
...
|
|
Pull block inode sync updates from Jens Axboe:
"This contains improvements to how bdev inode syncing is handled,
unifying the API"
* tag 'for-5.16/inode-sync-2021-10-29' of git://git.kernel.dk/linux-block:
block: simplify the block device syncing code
ntfs3: use sync_blockdev_nowait
fat: use sync_blockdev_nowait
btrfs: use sync_blockdev
xen-blkback: use sync_blockdev
block: remove __sync_blockdev
fs: remove __sync_filesystem
|
|
Reported bug: https://github.com/kdave/btrfs-progs/issues/389
There's a problem with scrub reporting aborted status but returning
error code 0, on a filesystem with missing and readded device.
Roughly these steps:
- mkfs -d raid1 dev1 dev2
- fill with data
- unmount
- make dev1 disappear
- mount -o degraded
- copy more data
- make dev1 appear again
Running scrub afterwards reports that the command was aborted, but the
system log message says the exit code was 0.
It seems that the cause of the error is decrementing
fs_devices->missing_devices but not clearing device->dev_state. Every
time we umount filesystem, it would call close_ctree, And it would
eventually involve btrfs_close_one_device to close the device, but it
only decrements fs_devices->missing_devices but does not clear the
device BTRFS_DEV_STATE_MISSING bit. Worse, this bug will cause Integer
Overflow, because every time umount, fs_devices->missing_devices will
decrease. If fs_devices->missing_devices value hit 0, it would overflow.
With added debugging:
loop1: detected capacity change from 0 to 20971520
BTRFS: device fsid 56ad51f1-5523-463b-8547-c19486c51ebb devid 1 transid 21 /dev/loop1 scanned by systemd-udevd (2311)
loop2: detected capacity change from 0 to 20971520
BTRFS: device fsid 56ad51f1-5523-463b-8547-c19486c51ebb devid 2 transid 17 /dev/loop2 scanned by systemd-udevd (2313)
BTRFS info (device loop1): flagging fs with big metadata feature
BTRFS info (device loop1): allowing degraded mounts
BTRFS info (device loop1): using free space tree
BTRFS info (device loop1): has skinny extents
BTRFS info (device loop1): before clear_missing.00000000f706684d /dev/loop1 0
BTRFS warning (device loop1): devid 2 uuid 6635ac31-56dd-4852-873b-c60f5e2d53d2 is missing
BTRFS info (device loop1): before clear_missing.0000000000000000 /dev/loop2 1
BTRFS info (device loop1): flagging fs with big metadata feature
BTRFS info (device loop1): allowing degraded mounts
BTRFS info (device loop1): using free space tree
BTRFS info (device loop1): has skinny extents
BTRFS info (device loop1): before clear_missing.00000000f706684d /dev/loop1 0
BTRFS warning (device loop1): devid 2 uuid 6635ac31-56dd-4852-873b-c60f5e2d53d2 is missing
BTRFS info (device loop1): before clear_missing.0000000000000000 /dev/loop2 0
BTRFS info (device loop1): flagging fs with big metadata feature
BTRFS info (device loop1): allowing degraded mounts
BTRFS info (device loop1): using free space tree
BTRFS info (device loop1): has skinny extents
BTRFS info (device loop1): before clear_missing.00000000f706684d /dev/loop1 18446744073709551615
BTRFS warning (device loop1): devid 2 uuid 6635ac31-56dd-4852-873b-c60f5e2d53d2 is missing
BTRFS info (device loop1): before clear_missing.0000000000000000 /dev/loop2 18446744073709551615
If fs_devices->missing_devices is 0, next time it would be 18446744073709551615
After apply this patch, the fs_devices->missing_devices seems to be
right:
$ truncate -s 10g test1
$ truncate -s 10g test2
$ losetup /dev/loop1 test1
$ losetup /dev/loop2 test2
$ mkfs.btrfs -draid1 -mraid1 /dev/loop1 /dev/loop2 -f
$ losetup -d /dev/loop2
$ mount -o degraded /dev/loop1 /mnt/1
$ umount /mnt/1
$ mount -o degraded /dev/loop1 /mnt/1
$ umount /mnt/1
$ mount -o degraded /dev/loop1 /mnt/1
$ umount /mnt/1
$ dmesg
loop1: detected capacity change from 0 to 20971520
loop2: detected capacity change from 0 to 20971520
BTRFS: device fsid 15aa1203-98d3-4a66-bcae-ca82f629c2cd devid 1 transid 5 /dev/loop1 scanned by mkfs.btrfs (1863)
BTRFS: device fsid 15aa1203-98d3-4a66-bcae-ca82f629c2cd devid 2 transid 5 /dev/loop2 scanned by mkfs.btrfs (1863)
BTRFS info (device loop1): flagging fs with big metadata feature
BTRFS info (device loop1): allowing degraded mounts
BTRFS info (device loop1): disk space caching is enabled
BTRFS info (device loop1): has skinny extents
BTRFS info (device loop1): before clear_missing.00000000975bd577 /dev/loop1 0
BTRFS warning (device loop1): devid 2 uuid 8b333791-0b3f-4f57-b449-1c1ab6b51f38 is missing
BTRFS info (device loop1): before clear_missing.0000000000000000 /dev/loop2 1
BTRFS info (device loop1): checking UUID tree
BTRFS info (device loop1): flagging fs with big metadata feature
BTRFS info (device loop1): allowing degraded mounts
BTRFS info (device loop1): disk space caching is enabled
BTRFS info (device loop1): has skinny extents
BTRFS info (device loop1): before clear_missing.00000000975bd577 /dev/loop1 0
BTRFS warning (device loop1): devid 2 uuid 8b333791-0b3f-4f57-b449-1c1ab6b51f38 is missing
BTRFS info (device loop1): before clear_missing.0000000000000000 /dev/loop2 1
BTRFS info (device loop1): flagging fs with big metadata feature
BTRFS info (device loop1): allowing degraded mounts
BTRFS info (device loop1): disk space caching is enabled
BTRFS info (device loop1): has skinny extents
BTRFS info (device loop1): before clear_missing.00000000975bd577 /dev/loop1 0
BTRFS warning (device loop1): devid 2 uuid 8b333791-0b3f-4f57-b449-1c1ab6b51f38 is missing
BTRFS info (device loop1): before clear_missing.0000000000000000 /dev/loop2 1
CC: stable@vger.kernel.org # 4.19+
Signed-off-by: Li Zhang <zhanglikernel@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
Christoph pointed out that I'm updating bdev->bd_inode for the device
time when we remove block devices from a btrfs file system, however this
isn't actually exposed to anything. The inode we want to update is the
one that's associated with the path to the device, usually on devtmpfs,
so that blkid notices the difference.
We still don't want to do the blkdev_open, so use kern_path() to get the
path to the given device and do the update time on that inode.
Fixes: 8f96a5bfa150 ("btrfs: update the bdev time directly when closing")
Reported-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
When a task is doing some modification to the chunk btree and it is not in
the context of a chunk allocation or a chunk removal, it can deadlock with
another task that is currently allocating a new data or metadata chunk.
These contexts are the following:
* When relocating a system chunk, when we need to COW the extent buffers
that belong to the chunk btree;
* When adding a new device (ioctl), where we need to add a new device item
to the chunk btree;
* When removing a device (ioctl), where we need to remove a device item
from the chunk btree;
* When resizing a device (ioctl), where we need to update a device item in
the chunk btree and may need to relocate a system chunk that lies beyond
the new device size when shrinking a device.
The problem happens due to a sequence of steps like the following:
1) Task A starts a data or metadata chunk allocation and it locks the
chunk mutex;
2) Task B is relocating a system chunk, and when it needs to COW an extent
buffer of the chunk btree, it has locked both that extent buffer as
well as its parent extent buffer;
3) Since there is not enough available system space, either because none
of the existing system block groups have enough free space or because
the only one with enough free space is in RO mode due to the relocation,
task B triggers a new system chunk allocation. It blocks when trying to
acquire the chunk mutex, currently held by task A;
4) Task A enters btrfs_chunk_alloc_add_chunk_item(), in order to insert
the new chunk item into the chunk btree and update the existing device
items there. But in order to do that, it has to lock the extent buffer
that task B locked at step 2, or its parent extent buffer, but task B
is waiting on the chunk mutex, which is currently locked by task A,
therefore resulting in a deadlock.
One example report when the deadlock happens with system chunk relocation:
INFO: task kworker/u9:5:546 blocked for more than 143 seconds.
Not tainted 5.15.0-rc3+ #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u9:5 state:D stack:25936 pid: 546 ppid: 2 flags:0x00004000
Workqueue: events_unbound btrfs_async_reclaim_metadata_space
Call Trace:
context_switch kernel/sched/core.c:4940 [inline]
__schedule+0xcd9/0x2530 kernel/sched/core.c:6287
schedule+0xd3/0x270 kernel/sched/core.c:6366
rwsem_down_read_slowpath+0x4ee/0x9d0 kernel/locking/rwsem.c:993
__down_read_common kernel/locking/rwsem.c:1214 [inline]
__down_read kernel/locking/rwsem.c:1223 [inline]
down_read_nested+0xe6/0x440 kernel/locking/rwsem.c:1590
__btrfs_tree_read_lock+0x31/0x350 fs/btrfs/locking.c:47
btrfs_tree_read_lock fs/btrfs/locking.c:54 [inline]
btrfs_read_lock_root_node+0x8a/0x320 fs/btrfs/locking.c:191
btrfs_search_slot_get_root fs/btrfs/ctree.c:1623 [inline]
btrfs_search_slot+0x13b4/0x2140 fs/btrfs/ctree.c:1728
btrfs_update_device+0x11f/0x500 fs/btrfs/volumes.c:2794
btrfs_chunk_alloc_add_chunk_item+0x34d/0xea0 fs/btrfs/volumes.c:5504
do_chunk_alloc fs/btrfs/block-group.c:3408 [inline]
btrfs_chunk_alloc+0x84d/0xf50 fs/btrfs/block-group.c:3653
flush_space+0x54e/0xd80 fs/btrfs/space-info.c:670
btrfs_async_reclaim_metadata_space+0x396/0xa90 fs/btrfs/space-info.c:953
process_one_work+0x9df/0x16d0 kernel/workqueue.c:2297
worker_thread+0x90/0xed0 kernel/workqueue.c:2444
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
INFO: task syz-executor:9107 blocked for more than 143 seconds.
Not tainted 5.15.0-rc3+ #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor state:D stack:23200 pid: 9107 ppid: 7792 flags:0x00004004
Call Trace:
context_switch kernel/sched/core.c:4940 [inline]
__schedule+0xcd9/0x2530 kernel/sched/core.c:6287
schedule+0xd3/0x270 kernel/sched/core.c:6366
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6425
__mutex_lock_common kernel/locking/mutex.c:669 [inline]
__mutex_lock+0xc96/0x1680 kernel/locking/mutex.c:729
btrfs_chunk_alloc+0x31a/0xf50 fs/btrfs/block-group.c:3631
find_free_extent_update_loop fs/btrfs/extent-tree.c:3986 [inline]
find_free_extent+0x25cb/0x3a30 fs/btrfs/extent-tree.c:4335
btrfs_reserve_extent+0x1f1/0x500 fs/btrfs/extent-tree.c:4415
btrfs_alloc_tree_block+0x203/0x1120 fs/btrfs/extent-tree.c:4813
__btrfs_cow_block+0x412/0x1620 fs/btrfs/ctree.c:415
btrfs_cow_block+0x2f6/0x8c0 fs/btrfs/ctree.c:570
btrfs_search_slot+0x1094/0x2140 fs/btrfs/ctree.c:1768
relocate_tree_block fs/btrfs/relocation.c:2694 [inline]
relocate_tree_blocks+0xf73/0x1770 fs/btrfs/relocation.c:2757
relocate_block_group+0x47e/0xc70 fs/btrfs/relocation.c:3673
btrfs_relocate_block_group+0x48a/0xc60 fs/btrfs/relocation.c:4070
btrfs_relocate_chunk+0x96/0x280 fs/btrfs/volumes.c:3181
__btrfs_balance fs/btrfs/volumes.c:3911 [inline]
btrfs_balance+0x1f03/0x3cd0 fs/btrfs/volumes.c:4301
btrfs_ioctl_balance+0x61e/0x800 fs/btrfs/ioctl.c:4137
btrfs_ioctl+0x39ea/0x7b70 fs/btrfs/ioctl.c:4949
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl fs/ioctl.c:860 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
So fix this by making sure that whenever we try to modify the chunk btree
and we are neither in a chunk allocation context nor in a chunk remove
context, we reserve system space before modifying the chunk btree.
Reported-by: Hao Sun <sunhao.th@gmail.com>
Link: https://lore.kernel.org/linux-btrfs/CACkBjsax51i4mu6C0C3vJqQN3NR_iVuucoeG3U1HXjrgzn5FFQ@mail.gmail.com/
Fixes: 79bd37120b1495 ("btrfs: rework chunk allocation to avoid exhaustion of the system chunk array")
CC: stable@vger.kernel.org # 5.14+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
For device removal and replace we call btrfs_find_device_by_devspec,
which if we give it a device path and nothing else will call
btrfs_get_dev_args_from_path, which opens the block device and reads the
super block and then looks up our device based on that.
However at this point we're holding the sb write "lock", so reading the
block device pulls in the dependency of ->open_mutex, which produces the
following lockdep splat
======================================================
WARNING: possible circular locking dependency detected
5.14.0-rc2+ #405 Not tainted
------------------------------------------------------
losetup/11576 is trying to acquire lock:
ffff9bbe8cded938 ((wq_completion)loop0){+.+.}-{0:0}, at: flush_workqueue+0x67/0x5e0
but task is already holding lock:
ffff9bbe88e4fc68 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x41/0x660 [loop]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #4 (&lo->lo_mutex){+.+.}-{3:3}:
__mutex_lock+0x7d/0x750
lo_open+0x28/0x60 [loop]
blkdev_get_whole+0x25/0xf0
blkdev_get_by_dev.part.0+0x168/0x3c0
blkdev_open+0xd2/0xe0
do_dentry_open+0x161/0x390
path_openat+0x3cc/0xa20
do_filp_open+0x96/0x120
do_sys_openat2+0x7b/0x130
__x64_sys_openat+0x46/0x70
do_syscall_64+0x38/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #3 (&disk->open_mutex){+.+.}-{3:3}:
__mutex_lock+0x7d/0x750
blkdev_get_by_dev.part.0+0x56/0x3c0
blkdev_get_by_path+0x98/0xa0
btrfs_get_bdev_and_sb+0x1b/0xb0
btrfs_find_device_by_devspec+0x12b/0x1c0
btrfs_rm_device+0x127/0x610
btrfs_ioctl+0x2a31/0x2e70
__x64_sys_ioctl+0x80/0xb0
do_syscall_64+0x38/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #2 (sb_writers#12){.+.+}-{0:0}:
lo_write_bvec+0xc2/0x240 [loop]
loop_process_work+0x238/0xd00 [loop]
process_one_work+0x26b/0x560
worker_thread+0x55/0x3c0
kthread+0x140/0x160
ret_from_fork+0x1f/0x30
-> #1 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}:
process_one_work+0x245/0x560
worker_thread+0x55/0x3c0
kthread+0x140/0x160
ret_from_fork+0x1f/0x30
-> #0 ((wq_completion)loop0){+.+.}-{0:0}:
__lock_acquire+0x10ea/0x1d90
lock_acquire+0xb5/0x2b0
flush_workqueue+0x91/0x5e0
drain_workqueue+0xa0/0x110
destroy_workqueue+0x36/0x250
__loop_clr_fd+0x9a/0x660 [loop]
block_ioctl+0x3f/0x50
__x64_sys_ioctl+0x80/0xb0
do_syscall_64+0x38/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
other info that might help us debug this:
Chain exists of:
(wq_completion)loop0 --> &disk->open_mutex --> &lo->lo_mutex
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&lo->lo_mutex);
lock(&disk->open_mutex);
lock(&lo->lo_mutex);
lock((wq_completion)loop0);
*** DEADLOCK ***
1 lock held by losetup/11576:
#0: ffff9bbe88e4fc68 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x41/0x660 [loop]
stack backtrace:
CPU: 0 PID: 11576 Comm: losetup Not tainted 5.14.0-rc2+ #405
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
Call Trace:
dump_stack_lvl+0x57/0x72
check_noncircular+0xcf/0xf0
? stack_trace_save+0x3b/0x50
__lock_acquire+0x10ea/0x1d90
lock_acquire+0xb5/0x2b0
? flush_workqueue+0x67/0x5e0
? lockdep_init_map_type+0x47/0x220
flush_workqueue+0x91/0x5e0
? flush_workqueue+0x67/0x5e0
? verify_cpu+0xf0/0x100
drain_workqueue+0xa0/0x110
destroy_workqueue+0x36/0x250
__loop_clr_fd+0x9a/0x660 [loop]
? blkdev_ioctl+0x8d/0x2a0
block_ioctl+0x3f/0x50
__x64_sys_ioctl+0x80/0xb0
do_syscall_64+0x38/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f31b02404cb
Instead what we want to do is populate our device lookup args before we
grab any locks, and then pass these args into btrfs_rm_device(). From
there we can find the device and do the appropriate removal.
Suggested-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
We are going to want to populate our device lookup args outside of any
locks and then do the actual device lookup later, so add a helper to do
this work and make btrfs_find_device_by_devspec() use this helper for
now.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
We have a lot of device lookup functions that all do something slightly
different. Clean this up by adding a struct to hold the different
lookup criteria, and then pass this around to btrfs_find_device() so it
can do the proper matching based on the lookup criteria.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
There's a subtle case where if we're removing the seed device from a
file system we need to free its private copy of the fs_devices. However
we do not need to call close_fs_devices(), because at this point there
are no devices left to close as we've closed the last one. The only
thing that close_fs_devices() does is decrement ->opened, which should
be 1. We want to avoid calling close_fs_devices() here because it has a
lockdep_assert_held(&uuid_mutex), and we are going to stop holding the
uuid_mutex in this path.
So simply decrement the ->opened counter like we should, and then clean
up like normal. Also add a comment explaining what we're doing here as
I initially removed this code erroneously.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
For both sprout and seed fsids,
btrfs_fs_devices::num_devices provides device count including missing
btrfs_fs_devices::open_devices provides device count excluding missing
We create a dummy struct btrfs_device for the missing device, so
num_devices != open_devices when there is a missing device.
In btrfs_rm_devices() we wrongly check for %cur_devices->open_devices
before freeing the seed fs_devices. Instead we should check for
%cur_devices->num_devices.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
We can grab fs_info reliably from btrfs_raid_bio::bioc, as the bioc is
always passed into alloc_rbio(), and only get released when the raid bio
is released.
Remove btrfs_raid_bio::fs_info member, and cleanup all the @fs_info
parameters for alloc_rbio() callers.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
Currently btrfs_io_context::fs_info is only initialized in
btrfs_map_bio, but there are call sites like btrfs_map_sblock() which
calls __btrfs_map_block() directly, leaving bioc::fs_info uninitialized
(NULL).
Currently this is fine, but later cleanup will rely on bioc::fs_info to
grab fs_info, and this can be a hidden problem for such usage.
This patch will remove such hidden uninitialized member by always
assigning bioc::fs_info at alloc_btrfs_io_context().
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
We got the following lockdep splat while running fstests (specifically
btrfs/003 and btrfs/020 in a row) with the new rc. This was uncovered
by 87579e9b7d8d ("loop: use worker per cgroup instead of kworker") which
converted loop to using workqueues, which comes with lockdep
annotations that don't exist with kworkers. The lockdep splat is as
follows:
WARNING: possible circular locking dependency detected
5.14.0-rc2-custom+ #34 Not tainted
------------------------------------------------------
losetup/156417 is trying to acquire lock:
ffff9c7645b02d38 ((wq_completion)loop0){+.+.}-{0:0}, at: flush_workqueue+0x84/0x600
but task is already holding lock:
ffff9c7647395468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x41/0x650 [loop]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #5 (&lo->lo_mutex){+.+.}-{3:3}:
__mutex_lock+0xba/0x7c0
lo_open+0x28/0x60 [loop]
blkdev_get_whole+0x28/0xf0
blkdev_get_by_dev.part.0+0x168/0x3c0
blkdev_open+0xd2/0xe0
do_dentry_open+0x163/0x3a0
path_openat+0x74d/0xa40
do_filp_open+0x9c/0x140
do_sys_openat2+0xb1/0x170
__x64_sys_openat+0x54/0x90
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #4 (&disk->open_mutex){+.+.}-{3:3}:
__mutex_lock+0xba/0x7c0
blkdev_get_by_dev.part.0+0xd1/0x3c0
blkdev_get_by_path+0xc0/0xd0
btrfs_scan_one_device+0x52/0x1f0 [btrfs]
btrfs_control_ioctl+0xac/0x170 [btrfs]
__x64_sys_ioctl+0x83/0xb0
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #3 (uuid_mutex){+.+.}-{3:3}:
__mutex_lock+0xba/0x7c0
btrfs_rm_device+0x48/0x6a0 [btrfs]
btrfs_ioctl+0x2d1c/0x3110 [btrfs]
__x64_sys_ioctl+0x83/0xb0
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #2 (sb_writers#11){.+.+}-{0:0}:
lo_write_bvec+0x112/0x290 [loop]
loop_process_work+0x25f/0xcb0 [loop]
process_one_work+0x28f/0x5d0
worker_thread+0x55/0x3c0
kthread+0x140/0x170
ret_from_fork+0x22/0x30
-> #1 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}:
process_one_work+0x266/0x5d0
worker_thread+0x55/0x3c0
kthread+0x140/0x170
ret_from_fork+0x22/0x30
-> #0 ((wq_completion)loop0){+.+.}-{0:0}:
__lock_acquire+0x1130/0x1dc0
lock_acquire+0xf5/0x320
flush_workqueue+0xae/0x600
drain_workqueue+0xa0/0x110
destroy_workqueue+0x36/0x250
__loop_clr_fd+0x9a/0x650 [loop]
lo_ioctl+0x29d/0x780 [loop]
block_ioctl+0x3f/0x50
__x64_sys_ioctl+0x83/0xb0
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
other info that might help us debug this:
Chain exists of:
(wq_completion)loop0 --> &disk->open_mutex --> &lo->lo_mutex
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&lo->lo_mutex);
lock(&disk->open_mutex);
lock(&lo->lo_mutex);
lock((wq_completion)loop0);
*** DEADLOCK ***
1 lock held by losetup/156417:
#0: ffff9c7647395468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x41/0x650 [loop]
stack backtrace:
CPU: 8 PID: 156417 Comm: losetup Not tainted 5.14.0-rc2-custom+ #34
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
Call Trace:
dump_stack_lvl+0x57/0x72
check_noncircular+0x10a/0x120
__lock_acquire+0x1130/0x1dc0
lock_acquire+0xf5/0x320
? flush_workqueue+0x84/0x600
flush_workqueue+0xae/0x600
? flush_workqueue+0x84/0x600
drain_workqueue+0xa0/0x110
destroy_workqueue+0x36/0x250
__loop_clr_fd+0x9a/0x650 [loop]
lo_ioctl+0x29d/0x780 [loop]
? __lock_acquire+0x3a0/0x1dc0
? update_dl_rq_load_avg+0x152/0x360
? lock_is_held_type+0xa5/0x120
? find_held_lock.constprop.0+0x2b/0x80
block_ioctl+0x3f/0x50
__x64_sys_ioctl+0x83/0xb0
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f645884de6b
Usually the uuid_mutex exists to protect the fs_devices that map
together all of the devices that match a specific uuid. In rm_device
we're messing with the uuid of a device, so it makes sense to protect
that here.
However in doing that it pulls in a whole host of lockdep dependencies,
as we call mnt_may_write() on the sb before we grab the uuid_mutex, thus
we end up with the dependency chain under the uuid_mutex being added
under the normal sb write dependency chain, which causes problems with
loop devices.
We don't need the uuid mutex here however. If we call
btrfs_scan_one_device() before we scratch the super block we will find
the fs_devices and not find the device itself and return EBUSY because
the fs_devices is open. If we call it after the scratch happens it will
not appear to be a valid btrfs file system.
We do not need to worry about other fs_devices modifying operations here
because we're protected by the exclusive operations locking.
So drop the uuid_mutex here in order to fix the lockdep splat.
A more detailed explanation from the discussion:
We are worried about rm and scan racing with each other, before this
change we'll zero the device out under the UUID mutex so when scan does
run it'll make sure that it can go through the whole device scan thing
without rm messing with us.
We aren't worried if the scratch happens first, because the result is we
don't think this is a btrfs device and we bail out.
The only case we are concerned with is we scratch _after_ scan is able
to read the superblock and gets a seemingly valid super block, so lets
consider this case.
Scan will call device_list_add() with the device we're removing. We'll
call find_fsid_with_metadata_uuid() and get our fs_devices for this
UUID. At this point we lock the fs_devices->device_list_mutex. This is
what protects us in this case, but we have two cases here.
1. We aren't to the device removal part of the RM. We found our device,
and device name matches our path, we go down and we set total_devices
to our super number of devices, which doesn't affect anything because
we haven't done the remove yet.
2. We are past the device removal part, which is protected by the
device_list_mutex. Scan doesn't find the device, it goes down and
does the
if (fs_devices->opened)
return -EBUSY;
check and we bail out.
Nothing about this situation is ideal, but the lockdep splat is real,
and the fix is safe, tho admittedly a bit scary looking.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ copy more from the discussion ]
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
Previously we had "struct btrfs_bio", which records IO context for
mirrored IO and RAID56, and "strcut btrfs_io_bio", which records extra
btrfs specific info for logical bytenr bio.
With "btrfs_bio" renamed to "btrfs_io_context", we are safe to rename
"btrfs_io_bio" to "btrfs_bio" which is a more suitable name now.
The struct btrfs_bio changes meaning by this commit. There was a
suggested name like btrfs_logical_bio but it's a bit long and we'd
prefer to use a shorter name.
This could be a concern for backports to older kernels where the
different meaning could possibly cause confusion or bugs. Comparing the
new and old structures, there's no overlap among the struct members so a
build would break in case of incorrect backport.
We haven't had many backports to bio code anyway so this is more of a
theoretical cause of bugs and a matter of precaution but we'll need to
keep the semantic change in mind.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
The structure btrfs_bio is used by two different sites:
- bio->bi_private for mirror based profiles
For those profiles (SINGLE/DUP/RAID1*/RAID10), this structures records
how many mirrors are still pending, and save the original endio
function of the bio.
- RAID56 code
In that case, RAID56 only utilize the stripes info, and no long uses
that to trace the pending mirrors.
So btrfs_bio is not always bind to a bio, and contains more info for IO
context, thus renaming it will make the naming less confusing.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
There were few lockdep warnings because btrfs_show_devname() was using
device_list_mutex as recorded in the commits:
0ccd05285e7f ("btrfs: fix a possible umount deadlock")
779bf3fefa83 ("btrfs: fix lock dep warning, move scratch dev out of device_list_mutex and uuid_mutex")
And finally, commit 88c14590cdd6 ("btrfs: use RCU in btrfs_show_devname
for device list traversal") removed the device_list_mutex from
btrfs_show_devname for performance reasons.
This patch removes a stale comment about the function
btrfs_show_devname and device_list_mutex.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
When we add a device to the seed filesystem (sprouting) it is a new
filesystem (and fsid) on the device added. Update the latest_dev so
that /proc/self/mounts shows the correct device.
Example:
$ btrfstune -S1 /dev/vg/seed
$ mount /dev/vg/seed /btrfs
mount: /btrfs: WARNING: device write-protected, mounted read-only.
$ cat /proc/self/mounts | grep btrfs
/dev/mapper/vg-seed /btrfs btrfs ro,relatime,space_cache,subvolid=5,subvol=/ 0 0
$ btrfs dev add -f /dev/vg/new /btrfs
Before:
$ cat /proc/self/mounts | grep btrfs
/dev/mapper/vg-seed /btrfs btrfs ro,relatime,space_cache,subvolid=5,subvol=/ 0 0
After:
$ cat /proc/self/mounts | grep btrfs
/dev/mapper/vg-new /btrfs btrfs ro,relatime,space_cache,subvolid=5,subvol=/ 0 0
Tested-by: Su Yue <l@damenly.su>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
In preparation to fix a bug in btrfs_show_devname().
Convert fs_devices::latest_bdev type from struct block_device to struct
btrfs_device and, rename the member to fs_devices::latest_dev.
So that btrfs_show_devname() can use fs_devices::latest_dev::name.
Tested-by: Su Yue <l@damenly.su>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
btrfs_chunk_readonly() checks if the given chunk is writeable. It
returns 1 for readonly, and 0 for writeable. So the return argument type
bool shall suffice instead of the current type int.
Also, rename btrfs_chunk_readonly() to btrfs_chunk_writeable() as we
check if the bg is writeable, and helps to keep the logic at the parent
function simpler to understand.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
Update it since commit 944d3f9fac61 ("btrfs: switch seed device to
list api") did conversion from fs_devices::seed to fs_devices::seed_list.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Su Yue <l@damenly.su>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
The user facing function used to allocate new chunks is
btrfs_chunk_alloc, unfortunately there is yet another similar sounding
function - btrfs_alloc_chunk. This creates confusion, especially since
the latter function can be considered "private" in the sense that it
implements the first stage of chunk creation and as such is called by
btrfs_chunk_alloc.
To avoid the awkwardness that comes with having similarly named but
distinctly different in their purpose function rename btrfs_alloc_chunk
to btrfs_create_chunk, given that the main purpose of this function is
to orchestrate the whole process of allocating a chunk - reserving space
into devices, deciding on characteristics of the stripe size and
creating the in-memory structures.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
Use sync_blockdev instead of opencoding it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Acked-by: David Sterba <dsterba@suse.com>
Link: https://lore.kernel.org/r/20211019062530.2174626-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Use the proper helper to read the block device size.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Acked-by: David Sterba <dsterba@suse.com>
Link: https://lore.kernel.org/r/20211018101130.1838532-13-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
When we get an error flushing one device, during a super block commit, we
record the error in the device structure, in the field 'last_flush_error'.
This is used to later check if we should error out the super block commit,
depending on whether the number of flush errors is greater than or equals
to the maximum tolerated device failures for a raid profile.
However if we get a transient device flush error, unmount the filesystem
and later try to mount it, we can fail the mount because we treat that
past error as critical and consider the device is missing. Even if it's
very likely that the error will happen again, as it's probably due to a
hardware related problem, there may be cases where the error might not
happen again. One example is during testing, and a test case like the
new generic/648 from fstests always triggers this. The test cases
generic/019 and generic/475 also trigger this scenario, but very
sporadically.
When this happens we get an error like this:
$ mount /dev/sdc /mnt
mount: /mnt wrong fs type, bad option, bad superblock on /dev/sdc, missing codepage or helper program, or other error.
$ dmesg
(...)
[12918.886926] BTRFS warning (device sdc): chunk 13631488 missing 1 devices, max tolerance is 0 for writable mount
[12918.888293] BTRFS warning (device sdc): writable mount is not allowed due to too many missing devices
[12918.890853] BTRFS error (device sdc): open_ctree failed
The failure happens because when btrfs_check_rw_degradable() is called at
mount time, or at remount from RO to RW time, is sees a non zero value in
a device's ->last_flush_error attribute, and therefore considers that the
device is 'missing'.
Fix this by setting a device's ->last_flush_error to zero when we close a
device, making sure the error is not seen on the next mount attempt. We
only need to track flush errors during the current mount, so that we never
commit a super block if such errors happened.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
Following test case reproduces lockdep warning.
Test case:
$ mkfs.btrfs -f <dev1>
$ btrfstune -S 1 <dev1>
$ mount <dev1> <mnt>
$ btrfs device add <dev2> <mnt> -f
$ umount <mnt>
$ mount <dev2> <mnt>
$ umount <mnt>
The warning claims a possible ABBA deadlock between the threads
initiated by [#1] btrfs device add and [#0] the mount.
[ 540.743122] WARNING: possible circular locking dependency detected
[ 540.743129] 5.11.0-rc7+ #5 Not tainted
[ 540.743135] ------------------------------------------------------
[ 540.743142] mount/2515 is trying to acquire lock:
[ 540.743149] ffffa0c5544c2ce0 (&fs_devs->device_list_mutex){+.+.}-{4:4}, at: clone_fs_devices+0x6d/0x210 [btrfs]
[ 540.743458] but task is already holding lock:
[ 540.743461] ffffa0c54a7932b8 (btrfs-chunk-00){++++}-{4:4}, at: __btrfs_tree_read_lock+0x32/0x200 [btrfs]
[ 540.743541] which lock already depends on the new lock.
[ 540.743543] the existing dependency chain (in reverse order) is:
[ 540.743546] -> #1 (btrfs-chunk-00){++++}-{4:4}:
[ 540.743566] down_read_nested+0x48/0x2b0
[ 540.743585] __btrfs_tree_read_lock+0x32/0x200 [btrfs]
[ 540.743650] btrfs_read_lock_root_node+0x70/0x200 [btrfs]
[ 540.743733] btrfs_search_slot+0x6c6/0xe00 [btrfs]
[ 540.743785] btrfs_update_device+0x83/0x260 [btrfs]
[ 540.743849] btrfs_finish_chunk_alloc+0x13f/0x660 [btrfs] <--- device_list_mutex
[ 540.743911] btrfs_create_pending_block_groups+0x18d/0x3f0 [btrfs]
[ 540.743982] btrfs_commit_transaction+0x86/0x1260 [btrfs]
[ 540.744037] btrfs_init_new_device+0x1600/0x1dd0 [btrfs]
[ 540.744101] btrfs_ioctl+0x1c77/0x24c0 [btrfs]
[ 540.744166] __x64_sys_ioctl+0xe4/0x140
[ 540.744170] do_syscall_64+0x4b/0x80
[ 540.744174] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 540.744180] -> #0 (&fs_devs->device_list_mutex){+.+.}-{4:4}:
[ 540.744184] __lock_acquire+0x155f/0x2360
[ 540.744188] lock_acquire+0x10b/0x5c0
[ 540.744190] __mutex_lock+0xb1/0xf80
[ 540.744193] mutex_lock_nested+0x27/0x30
[ 540.744196] clone_fs_devices+0x6d/0x210 [btrfs]
[ 540.744270] btrfs_read_chunk_tree+0x3c7/0xbb0 [btrfs]
[ 540.744336] open_ctree+0xf6e/0x2074 [btrfs]
[ 540.744406] btrfs_mount_root.cold.72+0x16/0x127 [btrfs]
[ 540.744472] legacy_get_tree+0x38/0x90
[ 540.744475] vfs_get_tree+0x30/0x140
[ 540.744478] fc_mount+0x16/0x60
[ 540.744482] vfs_kern_mount+0x91/0x100
[ 540.744484] btrfs_mount+0x1e6/0x670 [btrfs]
[ 540.744536] legacy_get_tree+0x38/0x90
[ 540.744537] vfs_get_tree+0x30/0x140
[ 540.744539] path_mount+0x8d8/0x1070
[ 540.744541] do_mount+0x8d/0xc0
[ 540.744543] __x64_sys_mount+0x125/0x160
[ 540.744545] do_syscall_64+0x4b/0x80
[ 540.744547] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 540.744551] other info that might help us debug this:
[ 540.744552] Possible unsafe locking scenario:
[ 540.744553] CPU0 CPU1
[ 540.744554] ---- ----
[ 540.744555] lock(btrfs-chunk-00);
[ 540.744557] lock(&fs_devs->device_list_mutex);
[ 540.744560] lock(btrfs-chunk-00);
[ 540.744562] lock(&fs_devs->device_list_mutex);
[ 540.744564]
*** DEADLOCK ***
[ 540.744565] 3 locks held by mount/2515:
[ 540.744567] #0: ffffa0c56bf7a0e0 (&type->s_umount_key#42/1){+.+.}-{4:4}, at: alloc_super.isra.16+0xdf/0x450
[ 540.744574] #1: ffffffffc05a9628 (uuid_mutex){+.+.}-{4:4}, at: btrfs_read_chunk_tree+0x63/0xbb0 [btrfs]
[ 540.744640] #2: ffffa0c54a7932b8 (btrfs-chunk-00){++++}-{4:4}, at: __btrfs_tree_read_lock+0x32/0x200 [btrfs]
[ 540.744708]
stack backtrace:
[ 540.744712] CPU: 2 PID: 2515 Comm: mount Not tainted 5.11.0-rc7+ #5
But the device_list_mutex in clone_fs_devices() is redundant, as
explained below. Two threads [1] and [2] (below) could lead to
clone_fs_device().
[1]
open_ctree <== mount sprout fs
btrfs_read_chunk_tree()
mutex_lock(&uuid_mutex) <== global lock
read_one_dev()
open_seed_devices()
clone_fs_devices() <== seed fs_devices
mutex_lock(&orig->device_list_mutex) <== seed fs_devices
[2]
btrfs_init_new_device() <== sprouting
mutex_lock(&uuid_mutex); <== global lock
btrfs_prepare_sprout()
lockdep_assert_held(&uuid_mutex)
clone_fs_devices(seed_fs_device) <== seed fs_devices
Both of these threads hold uuid_mutex which is sufficient to protect
getting the seed device(s) freed while we are trying to clone it for
sprouting [2] or mounting a sprout [1] (as above). A mounted seed device
can not free/write/replace because it is read-only. An unmounted seed
device can be freed by btrfs_free_stale_devices(), but it needs
uuid_mutex. So this patch removes the unnecessary device_list_mutex in
clone_fs_devices(). And adds a lockdep_assert_held(&uuid_mutex) in
clone_fs_devices().
Reported-by: Su Yue <l@damenly.su>
Tested-by: Su Yue <l@damenly.su>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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