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Merge tag 'for-7.2-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"Zoned mode:
- fix assertion and handle case of finished zone and truncated extent
- fix zone metadata write pointer on actual zone reset
- fix deadlock caused metadata writeback and transaction commit
- fix return value reuse leading to confusion about chunk
reservations
raid56 scrub:
- fix tracking of sector checksums when there are not checksums found
- fix inverted logic when submitting parity read bio
mount/remount fixes:
- fix leaking 'remount in progress' state which can break other
operations to work (qgroup rescan, autodefrag, reclaim)
- adjust using global block reserve after read-only mount when using
rescue= option
- handle missing raid stripe tree when mounted with 'ignorebadroots'
Misc:
- fix -Wmaybe-uninitialized warning in GET_CSUMS ioctl"
* tag 'for-7.2-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: raid56: fix scrub read assembly submitting no reads
btrfs: zoned: skip fully truncated ordered extents at zone finish
btrfs: initialize 'args' to avoid compiler warning in btrfs_ioctl_get_csums()
btrfs: zoned: fix missing chunk metadata reservation
btrfs: raid56: fix an incorrect csum skip during scrub
btrfs: report missing raid stripe tree root during lookup
btrfs: skip global block reserve accounting for rescue mounts
btrfs: zoned: reset meta_write_pointer on zone reset
btrfs: zoned: fix deadlock between metadata writeback and transaction commit
btrfs: fix leaking BTRFS_FS_STATE_REMOUNTING flag
Commit 0baad6f9b9 ("fs/super: skip non-memcg-aware nr_cached_objects
in memcg slab shrink") added a check in fs/super.c that skipped every
->nr_cached_objects() hook whenever the shrinker was invoked for a
non-root memcg, on the assumption that none of them honour sc->memcg.
That assumption is wrong for XFS, whose inode-reclaim hook is
intentionally driven from per-memcg contexts to free memcg-charged
slab. Encoding a blanket "never memcg-aware" policy in fs/super.c
short-circuits that path.
Push the check down into the callbacks whose counters really are
irrelevant to per-memcg reclaim - btrfs_nr_cached_objects() and
shmem_unused_huge_count() - and drop the fs/super.c gate. Each
filesystem can now lift the restriction independently if its counter
later grows memcg awareness, without touching fs/super.c.
Introduce mem_cgroup_shrink_is_root() in <linux/memcontrol.h> so the
callbacks don't open-code "sc->memcg is NULL or root".
Fixes: 0baad6f9b9 ("fs/super: skip non-memcg-aware nr_cached_objects in memcg slab shrink")
Acked-by: Qi Zheng <qi.zheng@linux.dev>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Usama Arif <usama.arif@linux.dev>
Link: https://patch.msgid.link/20260715103516.2410175-1-usama.arif@linux.dev
Acked-by: David Sterba <dsterba@suse.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
[BUG]
The following script can lead to unexpected qgroup rescan failure:
# mkfs.btrfs -f -O quota $dev
# mount $dev $mnt
# mount -o remount,rescue=ibadroots $mnt
^^^^^ This above command is expected to fail
# btrfs quota rescan -w $mnt
^^^^^ The above qgroup rescan is not expected to fail
# btrfs qgroup show $mnt
WARNING: qgroup data inconsistent, rescan recommended
Qgroupid Referenced Exclusive Path
-------- ---------- --------- ----
0/5 16.00KiB 16.00KiB <toplevel>
The above short script will be converted to a proper fstests case.
[CAUSE]
Inside btrfs_reconfigure(), if either btrfs_check_options() or
btrfs_check_features() failed, we will always have
BTRFS_FS_STATE_REMOUNTING set for the fs until the next successful
remount.
That BTRFS_FS_STATE_REMOUNTING flag will interrupt several operations,
including:
- Qgroup rescan
- Auto defrag
- Space reclaim
[FIX]
Change the error handling of btrfs_check_options() and
btrfs_check_features() to goto restore label.
Fixes: eddb1a433f ("btrfs: add reconfigure callback for fs_context")
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Merge tag 'for-7.2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs updates from David Sterba:
"The most noticeable change is to enable large folios by default, it's
been in testing for a few releases. Related to that is huge folio
support (still under experimental config). Otherwise a few ioctl
updates, performance improvements and usual fixes and core changes.
User visible changes:
- enable large folios by default, added in 6.17 (under experimental
build), no feature limitations, a big change internally
- new ioctl to return raw checksums to userspace (a bit tricky given
compression and tail extents), can be used for mkfs and
deduplication optimizations
- provide stable UUID for e.g. overlayfs and temp_fsid, also
reflected in statvfs() field f_fsid, internal dev_t is hashed in to
allow cloning
- add 32bit compat version of GET_SUBVOL_INFO ioctl
- in experimental build, support huge folios (up to 2M)
Performance related improvements/changes:
- limit bio size to the estimated optimum derived from the queue,
this prevents build up of too much data for writeback, which could
cause latency spikes (reported improvement 15% on sequential
writes)
- don't force direct IO to be serialized, forgotten change during
mount API port, brings back +60% of throughput
- lockless calculation of number of shrinkable extent maps, improve
performance with many memcg allocated objects
Notable fixes:
- in zoned mode, fix a deadlock due to zone reclaim and relocation
when space needs to be flushed
- don't trim device which is internally not tracked as writeable
(e.g. when missing device is being rescanned)
- fix deadlock when cloning inline extent and mounted with
flushoncommit
- fix false IO failures after direct IO falls back to buffered write
in some cases
Core:
- remove COW fixup mechanism completely; detect and fix changes to
pages outside of filesystem tracking, guaranteed since 5.8, grace
period is over
- remove 2K block size support, experimental to test subpage code on
x86_64 but now it would block folio changes
- tree-checker improvements of:
- free-space cache and tree items
- root reference and backref items
- extent state exceptions in reloc tree
- subpage mode updates:
- code optimizations, simplify tracking bitmaps
- re-enable readahead of compressed extent
- extend bitmap size to cover huge folios
- add tracepoints related to sync, tree-log and transactions
- device stats item tracking unification, remove item if there are no
stats recorded, also don't leave stale stats on replaced device
- allow extent buffer pages to be allocated as movable, to help page
migration
- added checks for proper extent buffer release
- btrfs.ko code size reduction due to transaction abort call
simplifications
- several struct size reductions
- more auto free conversions
- more verbose assertions"
* tag 'for-7.2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (130 commits)
btrfs: fix use-after-free after relocation failure with concurrent COW
btrfs: move WARN_ON on unexpected error in __add_tree_block()
btrfs: move locking into btrfs_get_reloc_bg_bytenr()
btrfs: lzo: reject compressed segment that overflows the compressed input
btrfs: retry faulting in the pages after a zero sized short direct write
btrfs: fix incorrect buffered IO fallback for append direct writes
btrfs: fix false IO failure after falling back to buffered write
btrfs: use verbose assertions in backref.c
btrfs: print a message when a missing device re-appears
btrfs: do not trim a device which is not writeable
btrfs: return real error after lookup failure in btrfs_ioctl_default_subvol()
btrfs: use mapping shared locking for reading super block
btrfs: use lockless read in nr_cached_objects shrinker callback
btrfs: switch local indicator variables to bools
btrfs: send: pass bool for pending_move and refs_processed parameters
btrfs: use shifts for sectorsize and nodesize
btrfs: fix deadlock cloning inline extent when using flushoncommit
btrfs: allocate eb-attached btree pages as movable
btrfs: add 32-bit compat ioctl for BTRFS_IOC_GET_SUBVOL_INFO
btrfs: derive f_fsid from on-disk fsid and dev_t
...
Under heavy memcg-driven slab reclaim with many memcgs and CPUs,
shrink_slab_memcg() invokes the per-superblock count callback once per
(memcg, NUMA node) tuple. For btrfs that callback reaches
percpu_counter_sum_positive() on fs_info->evictable_extent_maps, which
takes the percpu_counter's raw spinlock with IRQs disabled and walks
every online CPU. With hundreds of memcgs driving reclaim on a host with
dozens of CPUs, this counter lock becomes a global serialization point:
profiles show CPU pinned in the spin_lock_irqsave acquire under
__percpu_counter_sum, with cross-CPU IPIs hitting csd_lock_wait_toolong
while waiting for spinning vCPUs.
The shrinker count is advisory -- super_cache_count() already notes
"counts can change between super_cache_count and super_cache_scan, so we
really don't need locks here." Use percpu_counter_read_positive(), which
is lockless. Worst-case skew is bounded by batch * num_online_cpus (a
few thousand), negligible compared to the millions of extent maps a busy
filesystem accumulates and well within the noise that the shrinker
already tolerates.
Tested-by: Boris Burkov <boris@bur.io>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Ben Maurer <bmaurer@meta.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The f_fsid was originally derived from fs_devices->fsid and the
subvolume root ID. However, when temp_fsid is active, fs_devices->fsid
is randomized, making the standard derivation inconsistent.
Since metadata_uuid is optional, it is not a reliable alternative. This
patch instead retrieves the on-disk UUID from fs_info->super_copy->fsid.
To prevent f_fsid collisions between original and cloned filesystems,
this implementation hashes the dev_t for single-device btrfs filesystems
to ensure uniqueness. This is limited to single-device filesystems as
cloned mounts are currently only supported for that configuration. Note
that f_fsid will change if the device is replaced.
Additionally, since the kernel cannot distinguish between the original
and the cloned filesystem, this new f_fsid derivation is applied to
both.
Link: https://lore.kernel.org/linux-btrfs/cover.1772095546.git.asj@kernel.org/
Link: https://lore.kernel.org/linux-btrfs/cover.1774092915.git.asj@kernel.org/
Signed-off-by: Anand Jain <asj@kernel.org>
Signed-off-by: David Sterba <dsterba@suse.com>
Don't account the free space in a data relocation space-info sub-group as
usable free space in statfs.
This is misleading as no user allocations can be made in this space-info
sub-group. It is only a target for relocation.
Fixes: f92ee31e03 ("btrfs: introduce btrfs_space_info sub-group")
Reviewed-by: Boris Burkov <boris@bur.io>
Reviewed-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_log_inode() is one of the most important steps called during a fsync,
as well as during rename and link operations on inodes that were previously
logged. Add trace events for when entering and exiting that function.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Before btrfs switched to the new mount API in 2023, we were setting
SB_NOSEC in btrfs_mount_root(). This flag tells the VFS that the
filesystem may have files which don't have security xattrs, enabling it
to do some optimizations.
Unfortunately this was missed in the transition, meaning that IS_NOSEC
will always return false for a btrfs inode. This means that
btrfs_direct_write() calls will always get the inode lock exclusively,
meaning that DIO writes to the same file will be serialized.
On my machine, this one-line change results in a ~59% improvement in DIO
throughput:
Before patch:
test: (g=0): rw=randwrite, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=io_uring, iodepth=64
...
fio-3.39
Starting 32 processes
test: Laying out IO file (1 file / 1024MiB)
Jobs: 32 (f=32): [w(32)][100.0%][w=764MiB/s][w=195k IOPS][eta 00m:00s]
test: (groupid=0, jobs=32): err= 0: pid=586: Wed Apr 22 13:03:04 2026
write: IOPS=202k, BW=787MiB/s (826MB/s)(46.1GiB/60012msec); 0 zone resets
bw ( KiB/s): min=498714, max=1199892, per=100.00%, avg=806659.03, stdev=4229.94, samples=3808
iops : min=124677, max=299971, avg=201661.82, stdev=1057.49, samples=3808
cpu : usr=0.32%, sys=1.27%, ctx=8329204, majf=0, minf=1163
IO depths : 1=0.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=100.0%
submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.1%, >=64=0.0%
issued rwts: total=0,12094328,0,0 short=0,0,0,0 dropped=0,0,0,0
latency : target=0, window=0, percentile=100.00%, depth=64
Run status group 0 (all jobs):
WRITE: bw=787MiB/s (826MB/s), 787MiB/s-787MiB/s (826MB/s-826MB/s), io=46.1GiB (49.5GB), run=60012-60012msec
After patch:
test: (g=0): rw=randwrite, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=io_uring, iodepth=64
...
fio-3.39
Starting 32 processes
test: Laying out IO file (1 file / 1024MiB)
Jobs: 32 (f=32): [w(32)][100.0%][w=1255MiB/s][w=321k IOPS][eta 00m:00s]
test: (groupid=0, jobs=32): err= 0: pid=572: Wed Apr 22 13:13:46 2026
write: IOPS=320k, BW=1250MiB/s (1311MB/s)(73.3GiB/60003msec); 0 zone resets
bw ( MiB/s): min= 619, max= 2289, per=100.00%, avg=1251.28, stdev= 9.64, samples=3808
iops : min=158538, max=586025, avg=320320.80, stdev=2468.97, samples=3808
cpu : usr=0.35%, sys=11.50%, ctx=1584847, majf=0, minf=1160
IO depths : 1=0.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=100.0%
submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.1%, >=64=0.0%
issued rwts: total=0,19203309,0,0 short=0,0,0,0 dropped=0,0,0,0
latency : target=0, window=0, percentile=100.00%, depth=64
Run status group 0 (all jobs):
WRITE: bw=1250MiB/s (1311MB/s), 1250MiB/s-1250MiB/s (1311MB/s-1311MB/s), io=73.3GiB (78.7GB), run=60003-60003msec
The script to reproduce that:
#!/bin/bash
mkfs.btrfs -f /dev/nvme0n1
mount /dev/nvme0n1 /mnt/test
mkdir /mnt/test/nocow
chattr +C /mnt/test/nocow
fio /root/test.fio
# cat /root/test.fio
[global]
rw=randwrite
ioengine=io_uring
iodepth=64
size=1g
direct=1
startdelay=20
force_async=4
ramp_time=5
runtime=60
group_reporting=1
numjobs=32
time_based
disk_util=0
clat_percentiles=0
disable_lat=1
disable_clat=1
disable_slat=1
filename=/mnt/test/nocow/fiofile
[test]
name=test
bs=4k
stonewall
This was on a VM with 8 cores and 8GB of RAM, with a real NVMe exposed
through PCI passthrough. The figures for XFS and ext4 in comparison are
both about ~3GB/s.
Fixes: ad21f15b0f ("btrfs: switch to the new mount API")
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We are currently allocating block groups using the generic slabs, and
given that the size of btrfs_block_group structure is 672 bytes (on a
release kernel), we end up using the kmalloc-1024 slab and therefore
waste quite some memory since on a 4K page system we can only fit 4
block groups per page. The block groups are also allocated and
delallocated with some frequency, specially if we have auto reclaim
enabled.
So use a kmem_cache for block groups, this way on a 4K page system we
can fit 6 block groups per page instead of 4.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There's one use of kmalloc_array() that can be transformed to
kmalloc_objs() in the same way as suggested in commit 69050f8d6d
("treewide: Replace kmalloc with kmalloc_obj for non-scalar types"),
swap the arguments and drop GFP flags. All the other cases of
kmalloc_array() do not use a simple type so this is the only one.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
sget() and sget_fc() have lived side by side as near-duplicate
find-or-create-and-publish helpers for the legacy and fs_context mount
APIs. The three remaining in-tree callers (CIFS plus the ext4 extents
and mballoc KUnit tests) have all been moved to sget_fc(). Nothing
calls sget() anymore.
Delete sget() from fs/super.c and the prototype in <linux/fs.h>.
Update the two comments that referred to "sget()" or "sget{_fc}()" to
just say "sget_fc()".
This removes ~60 lines of code that only existed to be kept in
lockstep with sget_fc() on every superblock publish-path change.
Link: https://patch.msgid.link/20260529-work-sget-v2-4-57bbe08604e4@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Having the filesystem in an error state, meaning we had a transaction
abort, is unexpected. Mark every check for the error state with the
unlikely annotation to convey that and to allow the compiler to generate
better code.
On x86_64, using gcc 14.2.0-19 from Debian, resulted in a slightly
reduced object size and better code.
Before:
$ size fs/btrfs/btrfs.ko
text data bss dec hex filename
2008598 175912 15592 2200102 219226 fs/btrfs/btrfs.ko
After:
$ size fs/btrfs/btrfs.ko
text data bss dec hex filename
2008450 175912 15592 2199954 219192 fs/btrfs/btrfs.ko
Reviewed-by: Anand Jain <asj@kernel.org>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
These two new callbacks have been introduced in v6.19, and it has been
two releases in v7.1.
During that time we have not yet exposed bugs related that two features,
thus it's time to expose them for end users.
It's especially important to expose remove_bdev callback to end users.
That new callback makes btrfs automatically shutdown or go degraded
when a device is missing (depending on if the fs can maintain RW), which
is affecting end users.
We want some feedback from early adopters.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This was done entirely with mindless brute force, using
git grep -l '\<k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'
to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.
Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.
For the same reason the 'flex' versions will be done as a separate
conversion.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:
Single allocations: kmalloc(sizeof(TYPE), ...)
are replaced with: kmalloc_obj(TYPE, ...)
Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with: kmalloc_objs(TYPE, COUNT, ...)
Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...)
(where TYPE may also be *VAR)
The resulting allocations no longer return "void *", instead returning
"TYPE *".
Signed-off-by: Kees Cook <kees@kernel.org>
Make btrfs use the library APIs instead of crypto_shash, for all
checksum computations. This has many benefits:
- Allows future checksum types, e.g. XXH3 or CRC64, to be more easily
supported. Only a library API will be needed, not crypto_shash too.
- Eliminates the overhead of the generic crypto layer, including an
indirect call for every function call and other API overhead. A
microbenchmark of btrfs_check_read_bio() with crc32c checksums shows a
speedup from 658 cycles to 608 cycles per 4096-byte block.
- Decreases the stack usage of btrfs by reducing the size of checksum
contexts from 384 bytes to 240 bytes, and by eliminating the need for
some functions to declare a checksum context at all.
- Increases reliability. The library functions always succeed and
return void. In contrast, crypto_shash can fail and return errors.
Also, the library functions are guaranteed to be available when btrfs
is loaded; there's no longer any need to use module softdeps to try to
work around the crypto modules sometimes not being loaded.
- Fixes a bug where blake2b checksums didn't work on kernels booted with
fips=1. Since btrfs checksums are for integrity only, it's fine for
them to use non-FIPS-approved algorithms.
Note that with having to handle 4 algorithms instead of just 1-2, this
commit does result in a slightly positive diffstat. That being said,
this wouldn't have been the case if btrfs had actually checked for
errors from crypto_shash, which technically it should have been doing.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Neal Gompa <neal@gompa.dev>
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
Currently we only enforcing the free space tree for bs < ps cases, but
with the recently added bs > ps support, we lack the free space tree
enforcing, causing explicit v1 cache mount option to fail on bs > ps
cases:
# mount -o space_cache=v1 /dev/test/scratch1 /mnt/btrfs/
mount: /mnt/btrfs: wrong fs type, bad option, bad superblock on /dev/mapper/test-scratch1, missing codepage or helper program, or other error.
dmesg(1) may have more information after failed mount system call.
# dmesg -t | tail -n7
BTRFS: device fsid ac14a6fa-4ec9-449e-aec9-7d1777bfdc06 devid 1 transid 11 /dev/mapper/test-scratch1 (253:3) scanned by mount (2849)
BTRFS info (device dm-3): first mount of filesystem ac14a6fa-4ec9-449e-aec9-7d1777bfdc06
BTRFS info (device dm-3): using crc32c checksum algorithm
BTRFS warning (device dm-3): support for block size 8192 with page size 4096 is experimental, some features may be missing
BTRFS warning (device dm-3): space cache v1 is being deprecated and will be removed in a future release, please use -o space_cache=v2
BTRFS warning (device dm-3): v1 space cache is not supported for page size 4096 with sectorsize 8192
BTRFS error (device dm-3): open_ctree failed: -22
[FIX]
Just enable the same free space tree for bs > ps cases, aligning the
behavior to bs < ps cases.
Reviewed-by: Filipe Manana <fdmanana@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>
[BUG]
Since the introduction of btrfs bs < ps support, v1 cache was never on
the plan due to its hard coded PAGE_SIZE usage, and the future plan to
properly deprecate it.
However for bs < ps cases, even if 'nospace_cache,clear_cache' mount
option is specified, it's never respected and free space tree is always
enabled:
mkfs.btrfs -f -O ^bgt,fst $dev
mount $dev $mnt -o clear_cache,nospace_cache
umount $mnt
btrfs ins dump-super $dev
...
compat_ro_flags 0x3
( FREE_SPACE_TREE |
FREE_SPACE_TREE_VALID )
...
This means a different behavior compared to bs >= ps cases.
[CAUSE]
The forcing usage of v2 space cache is done inside
btrfs_set_free_space_cache_settings(), however it never checks if we're
even using space cache but always enabling v2 cache.
[FIX]
Instead unconditionally enable v2 cache, only forcing v2 cache if the
old v1 cache is required.
Now v2 space cache can be properly disabled on bs < ps cases:
mkfs.btrfs -f -O ^bgt,fst $dev
mount $dev $mnt -o clear_cache,nospace_cache
umount $mnt
btrfs ins dump-super $dev
...
compat_ro_flags 0x0
...
Fixes: 9f73f1aef9 ("btrfs: force v2 space cache usage for subpage mount")
Reviewed-by: Filipe Manana <fdmanana@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>
Do the remaining btrfs_path conversion to the auto cleaning, this seems
to be the last one. Most of the conversions are trivial, only adding the
declaration and removing the freeing, or changing the goto patterns to
return.
There are some functions with many changes, like __btrfs_free_extent(),
btrfs_remove_from_free_space_tree() or btrfs_add_to_free_space_tree()
but it still follows the same pattern.
Signed-off-by: David Sterba <dsterba@suse.com>
Apply the AUTO_KFREE and AUTO_KVFREE macros wherever it makes
sense. Since this macro is expected to improve code readability, it has
been avoided in places where the lifetime of objects wasn't easy to
follow and a cleanup attribute would've made things worse; or when the
cleanup section of a function involved many other things and thus there
was no readability impact anyways. This change has also not been applied
in extremely short functions where readability was clearly not an issue.
Signed-off-by: Miquel Sabaté Solà <mssola@mssola.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
For the ->remove_bdev() callback, btrfs will:
- Mark the target device as missing
- Go degraded if the fs can afford it
- Return error other wise
Thus falls back to the shutdown callback
For the ->shutdown callback, btrfs will:
- Set the SHUTDOWN flag
Which will reject all new incoming operations, and make all writeback
to fail.
The behavior is the same as the NOLOGFLUSH behavior.
To support the lookup from bdev to a btrfs_device,
btrfs_dev_lookup_args is enhanced to have a new @devt member.
If set, we should be able to use that @devt member to uniquely locating a
btrfs device.
I know the shutdown can be a little overkilled, if one has a RAID1
metadata and RAID0 data, in that case one can still read data with 50%
chance to got some good data.
But a filesystem returning -EIO for half of the time is not really
considered usable.
Further it can also be as bad as the only device went missing for a single
device btrfs.
So here we go safe other than sorry when handling missing device.
And the remove_bdev callback will be hidden behind experimental features
for now, the reasons are:
- There are not enough btrfs specific bdev removal test cases
The existing test cases are all removing the only device, thus only
exercises the ->shutdown() behavior.
- Not yet determined what's the expected behavior
Although the current auto-degrade behavior is no worse than the old
behavior, it may not always be what the end users want.
Before there is a concrete interface, better hide the new feature
from end users.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <asj@kernel.org>
Tested-by: Anand Jain <asj@kernel.org>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
With v6.17-rc kernels, btrfs will always set 'ssd' mount option even if
the block device is not a rotating one:
# cat /sys/block/sdd/queue/rotational
1
# cat /etc/fstab:
LABEL=DATA2 /data2 btrfs rw,relatime,space_cache=v2,subvolid=5,subvol=/,nofail,nosuid,nodev 0 0
# mount
[...]
/dev/sdd on /data2 type btrfs (rw,nosuid,nodev,relatime,ssd,space_cache=v2,subvolid=5,subvol=/)
[CAUSE]
The 'ssd' mount option is set by set_device_specific_options(), and it
expects that if there is any rotating device in the btrfs, it will set
fs_devices::rotating.
However after commit bddf57a707 ("btrfs: delay btrfs_open_devices()
until super block is created"), the device opening is delayed until the
super block is created.
But the timing of set_device_specific_options() is still left as is,
this makes the function be called without any device opened.
Since no device is opened, thus fs_devices::rotating will never be set,
making btrfs incorrectly set 'ssd' mount option.
[FIX]
Only call set_device_specific_options() after btrfs_open_devices().
Also only call set_device_specific_options() after a new mount, if we're
mounting a mounted btrfs, there is no need to set the device specific
mount options again.
Reported-by: HAN Yuwei <hrx@bupt.moe>
Link: https://lore.kernel.org/linux-btrfs/C8FF75669DFFC3C5+5f93bf8a-80a0-48a6-81bf-4ec890abc99a@bupt.moe/
Fixes: bddf57a707 ("btrfs: delay btrfs_open_devices() until super block is created")
CC: stable@vger.kernel.org # 6.17
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The unlikely() annotation is a static prediction hint that compiler may
use to reorder code out of hot path. We use it elsewhere (namely
tree-checker.c) for error branches that almost never happen, where
EUCLEAN (a corruption) is one of them.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Trivial pattern for the auto freeing with goto -> return conversions
if possible.
The following cases are considered trivial in this patch:
1. Cases where there are no operations between btrfs_free_path() and the
function returns.
2. Cases where only simple cleanup operations (such as kfree(), kvfree(),
clear_bit(), and fs_path_free()) are present between
btrfs_free_path() and the function return.
Signed-off-by: Sun YangKai <sunk67188@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Annual typo fixing pass. Strangely codespell found only about 30% of
what is in this patch, the rest was done manually using text
spellchecker with a custom dictionary of acceptable terms.
Reviewed-by: Neal Gompa <neal@gompa.dev>
Signed-off-by: David Sterba <dsterba@suse.com>
The ref_tracker infrastructure aids debugging but is not enabled by
default as it has a performance impact. Add mount option 'ref_tracker'
so it can be selectively enabled on a filesystem. Currently it track
references of 'delayed inodes'.
Signed-off-by: Leo Martins <loemra.dev@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Remove CONFIG_BTRFS_FS_REF_VERIFY Kconfig and add it as part of
CONFIG_BTRFS_DEBUG. This should not be impactful to the performance
of debug. The struct btrfs_ref takes an additional u64, btrfs_fs_info
takes an additional spinlock_t and rb_root. All of the ref_verify logic
is still protected by a mount option.
Signed-off-by: Leo Martins <loemra.dev@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Use the standard error pointer macro to simplify the code.
Reviewed-by: Daniel Vacek <neelx@suse.com>
Signed-off-by: Xichao Zhao <zhao.xichao@vivo.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Merge tag 'for-6.17-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull a few more btrfs fixes from David Sterba:
- in tree-checker, fix wrong size of check for inode ref item
- in ref-verify, handle combination of mount options that allow
partially damaged extent tree (reported by syzbot)
- additional validation of compression mount option to catch invalid
string as level
* tag 'for-6.17-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: reject invalid compression level
btrfs: ref-verify: handle damaged extent root tree
btrfs: tree-checker: fix the incorrect inode ref size check
Inspired by recent changes to compression level parsing in
6db1df415d ("btrfs: accept and ignore compression level for lzo")
it turns out that we do not do any extra validation for compression
level input string, thus allowing things like "compress=lzo:invalid" to
be accepted without warnings.
Although we accept levels that are beyond the supported algorithm
ranges, accepting completely invalid level specification is not correct.
Fix the too loose checks for compression level, by doing proper error
handling of kstrtoint(), so that we will reject not only too large
values (beyond int range) but also completely wrong levels like
"lzo:invalid".
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Merge tag 'for-6.17-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
- fix delayed inode tracking in xarray, eviction can race with
insertion and leave behind a disconnected inode
- on systems with large page (64K) and small block size (4K) fix
compression read that can return partially filled folio
- slightly relax compression option format for backward compatibility,
allow to specify level for LZO although there's only one
- fix simple quota accounting of compressed extents
- validate minimum device size in 'device add'
- update maintainers' entry
* tag 'for-6.17-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: don't allow adding block device of less than 1 MB
MAINTAINERS: update btrfs entry
btrfs: fix subvolume deletion lockup caused by inodes xarray race
btrfs: fix corruption reading compressed range when block size is smaller than page size
btrfs: accept and ignore compression level for lzo
btrfs: fix squota compressed stats leak
The compression level is meaningless for lzo, but before commit
3f093ccb95 ("btrfs: harden parsing of compression mount options"),
it was silently ignored if passed.
After that commit, passing a level with lzo fails to mount:
BTRFS error: unrecognized compression value lzo:1
It seems reasonable for users to expect that lzo would permit a numeric
level option, as all the other algos do, even though the kernel's
implementation of LZO currently only supports a single level. Because it
has always worked to pass a level, it seems likely to me that users in
the real world are relying on doing so.
This patch restores the old behavior, giving "lzo:N" the same semantics
as all of the other compression algos.
To be clear, silly variants like "lzo:one", "lzo:the_first_option", or
"lzo:armageddon" also used to work. This isn't meant to suggest that
any possible mis-interpretation of mount options that once worked must
continue to work forever. This is an exceptional case where it makes
sense to preserve compatibility, both because the mis-interpretation is
reasonable, and because nothing tangible is sacrificed.
Finally update btrfs_show_options() to ignore the level of LZO, as it
is only the default level without any extra meaning.
Fixes: 3f093ccb95 ("btrfs: harden parsing of compression mount options")
Reviewed-by: Daniel Vacek <neelx@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Calvin Owens <calvin@wbinvd.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Merge tag 'for-6.17-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"Several zoned mode fixes, mount option printing fixups, folio state
handling fixes and one log replay fix.
- zoned mode:
- zone activation and finish fixes
- block group reservation fixes
- mount option fixes:
- bring back printing of mount options with key=value that got
accidentally dropped during mount option parsing in 6.8
- fix inverse logic or typos when printing nodatasum/nodatacow
- folio status fixes:
- writeback fixes in zoned mode
- properly reset dirty/writeback if submission fails
- properly handle TOWRITE xarray mark/tag
- do not set mtime/ctime to current time when unlinking for log
replay"
* tag 'for-6.17-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: fix printing of mount info messages for NODATACOW/NODATASUM
btrfs: restore mount option info messages during mount
btrfs: fix incorrect log message for nobarrier mount option
btrfs: fix buffer index in wait_eb_writebacks()
btrfs: subpage: keep TOWRITE tag until folio is cleaned
btrfs: clear TAG_TOWRITE from buffer tree when submitting a tree block
btrfs: do not set mtime/ctime to current time when unlinking for log replay
btrfs: clear block dirty if btrfs_writepage_cow_fixup() failed
btrfs: clear block dirty if submit_one_sector() failed
btrfs: zoned: limit active zones to max_open_zones
btrfs: zoned: fix write time activation failure for metadata block group
btrfs: zoned: fix data relocation block group reservation
btrfs: zoned: skip ZONE FINISH of conventional zones
The NODATASUM message was printed twice by mistake and the NODATACOW was
missing from the 'unset' part. Fix the duplication and make the output
look the same.
Fixes: eddb1a433f ("btrfs: add reconfigure callback for fs_context")
CC: stable@vger.kernel.org # 6.8+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Kyoji Ogasawara <sawara04.o@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
After the fsconfig migration in 6.8, mount option info messages are no
longer displayed during mount operations because btrfs_emit_options() is
only called during remount, not during initial mount.
Fix this by calling btrfs_emit_options() in btrfs_fill_super() after
open_ctree() succeeds. Additionally, prevent log duplication by ensuring
btrfs_check_options() handles validation with warn-level and err-level
messages, while btrfs_emit_options() provides info-level messages.
Fixes: eddb1a433f ("btrfs: add reconfigure callback for fs_context")
CC: stable@vger.kernel.org # 6.8+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Kyoji Ogasawara <sawara04.o@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Fix a wrong log message that appears when the "nobarrier" mount option
is unset. When "nobarrier" is unset, barrier is actually enabled.
However, the log incorrectly stated "turning off barriers".
Fixes: eddb1a433f ("btrfs: add reconfigure callback for fs_context")
CC: stable@vger.kernel.org # 6.12+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Kyoji Ogasawara <sawara04.o@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The basic rules are simple:
* stores to dentry->d_flags are OK under dentry->d_lock.
* stores to dentry->d_flags are OK in the dentry constructor, before
becomes potentially visible to other threads.
Unfortunately, there's a couple of exceptions to that, and that's where the
headache comes from.
Main PITA comes from d_set_d_op(); that primitive sets ->d_op
of dentry and adjusts the flags that correspond to presence of individual
methods. It's very easy to misuse; existing uses _are_ safe, but proof
of correctness is brittle.
Use in __d_alloc() is safe (we are within a constructor), but we
might as well precalculate the initial value of ->d_flags when we set
the default ->d_op for given superblock and set ->d_flags directly
instead of messing with that helper.
The reasons why other uses are safe are bloody convoluted; I'm not going
to reproduce it here. See https://lore.kernel.org/all/20250224010624.GT1977892@ZenIV/
for gory details, if you care. The critical part is using d_set_d_op() only
just prior to d_splice_alias(), which makes a combination of d_splice_alias()
with setting ->d_op, etc. a natural replacement primitive. Better yet, if
we go that way, it's easy to take setting ->d_op and modifying ->d_flags
under ->d_lock, which eliminates the headache as far as ->d_flags exclusion
rules are concerned. Other exceptions are minor and easy to deal with.
What this series does:
* d_set_d_op() is no longer available; new primitive (d_splice_alias_ops())
is provided, equivalent to combination of d_set_d_op() and d_splice_alias().
* new field of struct super_block - ->s_d_flags. Default value of ->d_flags
to be used when allocating dentries on this filesystem.
* new primitive for setting ->s_d_op: set_default_d_op(). Replaces stores
to ->s_d_op at mount time. All in-tree filesystems converted; out-of-tree
ones will get caught by compiler (->s_d_op is renamed, so stores to it will
be caught). ->s_d_flags is set by the same primitive to match the ->s_d_op.
* a lot of filesystems had ->s_d_op->d_delete equal to always_delete_dentry;
that is equivalent to setting DCACHE_DONTCACHE in ->d_flags, so such filesystems
can bloody well set that bit in ->s_d_flags and drop ->d_delete() from
dentry_operations. In quite a few cases that results in empty dentry_operations,
which means that we can get rid of those.
* kill simple_dentry_operations - not needed anymore.
* massage d_alloc_parallel() to get rid of the other exception wrt ->d_flags
stores - we can set DCACHE_PAR_LOOKUP as soon as we allocate the new dentry;
no need to delay that until we commit to using the sucker.
As the result, ->d_flags stores are all either under ->d_lock or done before
the dentry becomes visible in any shared data structures.
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Merge tag 'pull-dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull dentry d_flags updates from Al Viro:
"The current exclusion rules for dentry->d_flags stores are rather
unpleasant. The basic rules are simple:
- stores to dentry->d_flags are OK under dentry->d_lock
- stores to dentry->d_flags are OK in the dentry constructor, before
becomes potentially visible to other threads
Unfortunately, there's a couple of exceptions to that, and that's
where the headache comes from.
The main PITA comes from d_set_d_op(); that primitive sets ->d_op of
dentry and adjusts the flags that correspond to presence of individual
methods. It's very easy to misuse; existing uses _are_ safe, but proof
of correctness is brittle.
Use in __d_alloc() is safe (we are within a constructor), but we might
as well precalculate the initial value of 'd_flags' when we set the
default ->d_op for given superblock and set 'd_flags' directly instead
of messing with that helper.
The reasons why other uses are safe are bloody convoluted; I'm not
going to reproduce it here. See [1] for gory details, if you care. The
critical part is using d_set_d_op() only just prior to
d_splice_alias(), which makes a combination of d_splice_alias() with
setting ->d_op, etc a natural replacement primitive.
Better yet, if we go that way, it's easy to take setting ->d_op and
modifying 'd_flags' under ->d_lock, which eliminates the headache as
far as 'd_flags' exclusion rules are concerned. Other exceptions are
minor and easy to deal with.
What this series does:
- d_set_d_op() is no longer available; instead a new primitive
(d_splice_alias_ops()) is provided, equivalent to combination of
d_set_d_op() and d_splice_alias().
- new field of struct super_block - 's_d_flags'. This sets the
default value of 'd_flags' to be used when allocating dentries on
this filesystem.
- new primitive for setting 's_d_op': set_default_d_op(). This
replaces stores to 's_d_op' at mount time.
All in-tree filesystems converted; out-of-tree ones will get caught
by the compiler ('s_d_op' is renamed, so stores to it will be
caught). 's_d_flags' is set by the same primitive to match the
's_d_op'.
- a lot of filesystems had sb->s_d_op->d_delete equal to
always_delete_dentry; that is equivalent to setting
DCACHE_DONTCACHE in 'd_flags', so such filesystems can bloody well
set that bit in 's_d_flags' and drop 'd_delete()' from
dentry_operations.
In quite a few cases that results in empty dentry_operations, which
means that we can get rid of those.
- kill simple_dentry_operations - not needed anymore
- massage d_alloc_parallel() to get rid of the other exception wrt
'd_flags' stores - we can set DCACHE_PAR_LOOKUP as soon as we
allocate the new dentry; no need to delay that until we commit to
using the sucker.
As the result, 'd_flags' stores are all either under ->d_lock or done
before the dentry becomes visible in any shared data structures"
Link: https://lore.kernel.org/all/20250224010624.GT1977892@ZenIV/ [1]
* tag 'pull-dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (21 commits)
configfs: use DCACHE_DONTCACHE
debugfs: use DCACHE_DONTCACHE
efivarfs: use DCACHE_DONTCACHE instead of always_delete_dentry()
9p: don't bother with always_delete_dentry
ramfs, hugetlbfs, mqueue: set DCACHE_DONTCACHE
kill simple_dentry_operations
devpts, sunrpc, hostfs: don't bother with ->d_op
shmem: no dentry retention past the refcount reaching zero
d_alloc_parallel(): set DCACHE_PAR_LOOKUP earlier
make d_set_d_op() static
simple_lookup(): just set DCACHE_DONTCACHE
tracefs: Add d_delete to remove negative dentries
set_default_d_op(): calculate the matching value for ->d_flags
correct the set of flags forbidden at d_set_d_op() time
split d_flags calculation out of d_set_d_op()
new helper: set_default_d_op()
fuse: no need for special dentry_operations for root dentry
switch procfs from d_set_d_op() to d_splice_alias_ops()
new helper: d_splice_alias_ops()
procfs: kill ->proc_dops
...
[FLAG EXCLUSION]
Commit ead622674d ("btrfs: Do not restrict writes to btrfs devices")
removes the BLK_OPEN_RESTRICT_WRITES flag when opening the devices
during mount. This was an exception at the time as it depended on other
patches.
[REASON TO EXCLUDE THAT FLAG]
Btrfs needs to call btrfs_scan_one_device() to determine the fsid, no
matter if we're mounting a new fs or an existing one.
But if a fs is already mounted and the BLK_OPEN_RESTRICT_WRITES is
honored, meaning no other write open is allowed for the block device.
Then we want to mount a subvolume of the mounted fs to another mount
point, we will call btrfs_scan_one_device() again, but it will fail due
to the BLK_OPEN_RESTRICT_WRITES flag (no more write open allowed),
causing only one mount point for the fs.
Thus at that time, we had to exclude the BLK_OPEN_RESTRICT_WRITES to
allow multiple mount points for one fs.
[WHY IT'S SAFE NOW]
The root problem is, we do not need to nor should use BLK_OPEN_WRITE for
btrfs_scan_one_device().
That function is only to read out the super block, no write at all, and
BLK_OPEN_WRITE is only going to cause problems for such usage.
The root problem has been fixed by patch "btrfs: always open the device
read-only in btrfs_scan_one_device", so btrfs_scan_one_device() will
always work no matter if the device is opened with
BLK_OPEN_RESTRICT_WRITES.
[ENHANCEMENT]
Just remove the btrfs_open_mode(), as the only call site can be replaced
with regular sb_open_mode().
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The file system type is not a very useful holder as it doesn't allow us
to go back to the actual file system instance. Pass the super_block
instead which is useful when passed back to the file system driver.
This matches what is done for all other block device based file systems,
and allows us to remove btrfs_fs_info::bdev_holder completely.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently we always call btrfs_open_devices() before creating the
super block.
It's fine for now because:
- No blk_holder_ops is provided
- btrfs_fs_type is used as a holder
This means no matter who wins the device opening race, the holder will be
the same thus not affecting the later sget_fc() race.
And since no blk_holder_ops is provided, no bdev operation is depending on
the holder.
But this will no longer be true if we want to implement a proper
blk_holder_ops using fs_holder_ops.
This means we will need a proper super block as the bdev holder.
To prepare for such change:
- Add btrfs_fs_devices::holding member
This will prevent btrfs_free_stale_devices() and btrfs_close_device()
from deleting the fs_devices when there is another process trying to
mount the fs.
Along with the new member, here come the two helpers,
btrfs_fs_devices_inc_holding() and btrfs_fs_devices_dec_holding().
This will allow us to hold fs_devices without opening it.
This is needed because we cannot hold uuid_mutex while calling
sget_fc(), this will reverse the lock sequence with s_umount, causing
a lockdep warning.
- Delay btrfs_open_devices() until a super block is returned
This means we have to hold the initial fs_devices first, then unlock
uuid_mutex, call sget_fc(), then re-lock uuid_mutex, and decrease the
holding number.
For new super block case, we continue to btrfs_open_devices() with
uuid_mutex hold.
For existing super block case, we can unlock uuid_mutex and continue.
Although this means a more complex error handling path, as if we
didn't call btrfs_open_devices() (either got an existing sb, or
sget_fc() failed), we cannot let btrfs_put_fs_info() cleanup the
fs_devices, as it can be freed at any time after we decrease the hold
on fs_devices and unlock uuid_mutex.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Although btrfs is not yet implementing blk_holder_ops, there is a
requirement for proper blk_holder_ops:
- blkdev_put() must not be called under sb->s_umount
The blkdev_put()/bdev_fput() must not be called under sb->s_umount to
avoid lock order reversal with disk->open_mutex.
This is for the proper blk_holder_ops callbacks.
Currently we're fine because we call regular fput() which defers the
blk holder reclaiming.
To prepare for the future of blk_holder_ops, move the
btrfs_close_devices() calls into btrfs_free_fs_info().
That will be called from kill_sb() callbacks, which is also called for
error handing during mount failures, or there is already an existing
super block.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When calling sget_fc(), there are 3 different situations:
a) Critical error
No super block created.
b) A new super block is created
The fc->s_fs_info is transferred to the super block, and fc->s_fs_info
is reset to NULL.
In this case sb->s_root should still be NULL, and needs to be properly
initialized later by btrfs_fill_super().
c) An existing super block is returned
The fc->s_fs_info is untouched, and anything related to that fs_info
should be properly cleaned up.
This is not obvious even with the extra comments at sget_fc().
Enhance the situation by:
- Add comments for case b) and c)
Especially for case c), the fs_info and fs_devices cleanup happens at
different timing, thus needs extra explanation.
- Move the comments closer to case b) and case c)
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[EXISTING PROBLEM]
Currently btrfs mount is split into two parts:
- btrfs_get_tree_subvol()
Which sets up the very basic fs_info, and eventually calls
mount_subvol() to mount the target subvolume.
- btrfs_get_tree_super()
This is the part doing super block allocation and if there is no
existing super block, do the real open_ctree() to open the fs.
However currently we're doing this in a complex re-entering way:
vfs_get_tree()
|- btrfs_get_tree()
|- btrfs_get_tree_subvol()
|- vfs_get_tree()
| |- btrfs_get_tree()
| |- btrfs_get_tree_super()
|- mount_subvol()
This is definitely not that easy to grasp.
[ENHANCEMENT]
The function vfs_get_tree() is only doing the following work:
- Call get_tree() call back
- Call super_wake()
- Call security_sb_set_mnt_opts()
In our case, super_wake() can be skipped, as after
btrfs_get_tree_subvol() finishes, vfs_get_tree() will call super_wake()
on the super block we got anyway.
The same applies to security_sb_set_mnt_opts(), as long as we do not
free the security from our original fc in btrfs_get_tree_subvol(), the
first vfs_get_tree() call will handle the security correctly.
So here we only need to:
- Replace vfs_get_tree() call with btrfs_get_tree_super()
- Keep the existing fc->security for vfs_get_tree() to handle the
security
This will remove the re-entering behavior and make thing much easier to
follow.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_scan_one_device() opens the block device only to read the super
block. Instead of passing a blk_mode_t argument to sometimes open
it for writing, just hard code BLK_OPEN_READ as it will never write
to the device or hand the block_device out to someone else.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[CURRENT BEHAVIOR]
Currently inside btrfs_get_tree_subvol(), we call fc_mount() to grab a
tree, then re-lock s_umount inside btrfs_reconfigure_for_mount() to
avoid race with remount.
However fc_mount() itself is just doing two things:
1. Call vfs_get_tree()
2. Release s_umount then call vfs_create_mount()
[ENHANCEMENT]
Instead of calling fc_mount(), we can open-code it with vfs_get_tree()
first.
This provides a benefit that, since we have the full control of
s_umount, we do not need to re-lock that rw_sempahore when calling
btrfs_reconfigure_for_mount(), meaning less race between RO/RW remount.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: Qu Wenruo <wqu@suse.com>
[ Rework the subject and commit message, refactor the error handling ]
Signed-off-by: Qu Wenruo <wqu@suse.com>
Tested-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
