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653b704e7d
linux-stable/fs
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Qu Wenruo 653b704e7d btrfs: fix mount failure due to remount races 
[ Upstream commit 951a3f59d2 ]

[BUG]
The following reproducer can cause btrfs mount to fail:

  dev="/dev/test/scratch1"
  mnt1="/mnt/test"
  mnt2="/mnt/scratch"

  mkfs.btrfs -f $dev
  mount $dev $mnt1
  btrfs subvolume create $mnt1/subvol1
  btrfs subvolume create $mnt1/subvol2
  umount $mnt1

  mount $dev $mnt1 -o subvol=subvol1
  while mount -o remount,ro $mnt1; do mount -o remount,rw $mnt1; done &
  bg=$!

  while mount $dev $mnt2 -o subvol=subvol2; do umount $mnt2; done

  kill $bg
  wait
  umount -R $mnt1
  umount -R $mnt2

The script will fail with the following error:

  mount: /mnt/scratch: /dev/mapper/test-scratch1 already mounted on /mnt/test.
        dmesg(1) may have more information after failed mount system call.
  umount: /mnt/test: target is busy.
  umount: /mnt/scratch/: not mounted

And there is no kernel error message.

[CAUSE]
During the btrfs mount, to support mounting different subvolumes with
different RO/RW flags, we need to detect that and retry if needed:

  Retry with matching RO flags if the initial mount fail with -EBUSY.

The problem is, during that retry we do not hold any super block lock
(s_umount), this means there can be a remount process changing the RO
flags of the original fs super block.

If so, we can have an EBUSY error during retry.  And this time we treat
any failure as an error, without any retry and cause the above EBUSY
mount failure.

[FIX]
The current retry behavior is racy because we do not have a super block
thus no way to hold s_umount to prevent the race with remount.

Solve the root problem by allowing fc->sb_flags to mismatch from the
sb->s_flags at btrfs_get_tree_super().

Then at the re-entry point btrfs_get_tree_subvol(), manually check the
fc->s_flags against sb->s_flags, if it's a RO->RW mismatch, then
reconfigure with s_umount lock hold.

Reported-by: Enno Gotthold <egotthold@suse.com>
Reported-by: Fabian Vogt <fvogt@suse.com>
[ Special thanks for the reproducer and early analysis pointing to btrfs. ]
Fixes: f044b31867 ("btrfs: handle the ro->rw transition for mounting different subvolumes")
Link: https://bugzilla.suse.com/show_bug.cgi?id=1231836
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-12-14 20:04:13 +01:00
..
9p Revert patches causing inode collision problems 2024-10-25 15:25:02 -07:00
adfs move asm/unaligned.h to linux/unaligned.h 2024-10-02 17:23:23 -04:00
affs affs-for-6.12-tag 2024-09-16 13:07:59 +02:00
afs vfs-6.12-rc6.fixes 2024-11-01 07:37:10 -10:00
autofs autofs: fix thinko in validate_dev_ioctl() 2024-10-28 13:16:56 +01:00
bcachefs bcachefs: Fix assertion pop in bch2_ptr_swab() 2024-11-12 03:46:57 -05:00
befs befs: Convert befs_symlink_read_folio() to use folio_end_read() 2024-05-31 12:31:39 +02:00
bfs fs: Convert aops->write_begin to take a folio 2024-08-07 11:33:21 +02:00
btrfs btrfs: fix mount failure due to remount races 2024-12-14 20:04:13 +01:00
cachefiles cachefiles: Fix NULL pointer dereference in object->file 2024-12-05 14:01:14 +01:00
ceph ceph: fix cred leak in ceph_mds_check_access() 2024-12-09 10:41:05 +01:00
coda coda: use param->file for FSCONFIG_SET_FD 2024-08-19 13:45:03 +02:00
configfs fs/configfs: Add a callback to determine attribute visibility 2024-06-17 20:42:57 +02:00
cramfs vfs-6.11.module.description 2024-07-15 11:14:59 -07:00
crypto move asm/unaligned.h to linux/unaligned.h 2024-10-02 17:23:23 -04:00
debugfs [tree-wide] finally take no_llseek out 2024-09-27 08:18:43 -07:00
devpts
dlm dlm: fix possible lkb_resource null dereference 2024-12-14 20:03:44 +01:00
ecryptfs move asm/unaligned.h to linux/unaligned.h 2024-10-02 17:23:23 -04:00
efivarfs [tree-wide] finally take no_llseek out 2024-09-27 08:18:43 -07:00
efs efs: fix the efs new mount api implementation 2024-12-05 14:01:10 +01:00
erofs erofs: handle NONHEAD !delta[1] lclusters gracefully 2024-12-05 14:02:00 +01:00
exfat exfat: fix out-of-bounds access of directory entries 2024-12-05 14:02:47 +01:00
exportfs fhandle: relax open_by_handle_at() permission checks 2024-05-28 15:57:23 +02:00
ext2 vfs-6.12.file 2024-09-16 09:14:02 +02:00
ext4 ext4: partial zero eof block on unaligned inode size extension 2024-12-14 20:03:36 +01:00
f2fs f2fs: add a sysfs node to limit max read extent count per-inode 2024-12-14 20:04:06 +01:00
fat fat: fix uninitialized variable 2024-10-17 00:28:06 -07:00
freevxfs
fuse virtiofs: use pages instead of pointer for kernel direct IO 2024-12-05 14:02:21 +01:00
gfs2 KMSAN: uninit-value in inode_go_dump (5) 2024-12-14 20:04:03 +01:00
hfs fs: Convert aops->write_begin to take a folio 2024-08-07 11:33:21 +02:00
hfsplus hfsplus: don't query the device logical block size multiple times 2024-12-05 14:01:15 +01:00
hostfs hostfs: Fix the NULL vs IS_ERR() bug for __filemap_get_folio() 2024-12-05 14:03:04 +01:00
hpfs move asm/unaligned.h to linux/unaligned.h 2024-10-02 17:23:23 -04:00
hugetlbfs fs: Convert aops->write_begin to take a folio 2024-08-07 11:33:21 +02:00
iomap vfs-6.12-rc6.iomap 2024-11-01 07:45:00 -10:00
isofs isofs: avoid memory leak in iocharset 2024-12-05 14:01:54 +01:00
jbd2 jbd2: remove unneeded check of ret in jbd2_fc_get_buf 2024-08-26 23:49:15 -04:00
jffs2 jffs2: fix use of uninitialized variable 2024-12-05 14:03:04 +01:00
jfs jfs: add a check to prevent array-index-out-of-bounds in dbAdjTree 2024-12-14 20:03:52 +01:00
kernfs kernfs: mount: Remove unnecessary ‘NULL’ values from knparent 2024-05-04 19:02:39 +02:00
lockd move asm/unaligned.h to linux/unaligned.h 2024-10-02 17:23:23 -04:00
minix buffer: Convert __block_write_begin() to take a folio 2024-08-07 11:33:36 +02:00
netfs netfs/fscache: Add a memory barrier for FSCACHE_VOLUME_CREATING 2024-12-05 14:01:14 +01:00
nfs nfs/blocklayout: Limit repeat device registration on failure 2024-12-05 14:03:09 +01:00
nfs_common nfs_common: must not hold RCU while calling nfsd_file_put_local 2024-12-05 14:02:27 +01:00
nfsd nfsd: fix nfs4_openowner leak when concurrent nfsd4_open occur 2024-12-09 10:41:09 +01:00
nilfs2 nilfs2: fix potential out-of-bounds memory access in nilfs_find_entry() 2024-12-14 20:03:25 +01:00
nls move asm/unaligned.h to linux/unaligned.h 2024-10-02 17:23:23 -04:00
notify fanotify: allow reporting errors on failure to open fd 2024-12-14 20:03:48 +01:00
ntfs3 fs/ntfs3: Fix case when unmarked clusters intersect with zone 2024-12-14 20:04:06 +01:00
ocfs2 ocfs2: update seq_file index in ocfs2_dlm_seq_next 2024-12-14 20:03:31 +01:00
omfs fs: Convert aops->write_begin to take a folio 2024-08-07 11:33:21 +02:00
openpromfs openpromfs: add missing MODULE_DESCRIPTION() macro 2024-06-20 09:46:01 +02:00
orangefs move asm/unaligned.h to linux/unaligned.h 2024-10-02 17:23:23 -04:00
overlayfs ovl: properly handle large files in ovl_security_fileattr 2024-12-09 10:41:08 +01:00
proc fs/proc/kcore.c: Clear ret value in read_kcore_iter after successful iov_iter_zero 2024-12-09 10:41:07 +01:00
pstore drm next for 6.12-rc1 2024-09-19 10:18:15 +02:00
qnx4 qnx4: add MODULE_DESCRIPTION() 2024-05-28 11:52:53 +02:00
qnx6 qnx6: Convert directory handling to use kmap_local 2024-08-07 11:31:56 +02:00
quota quota: flush quota_release_work upon quota writeback 2024-12-09 10:40:55 +01:00
ramfs mm: switch mm->get_unmapped_area() to a flag 2024-04-25 20:56:25 -07:00
reiserfs move asm/unaligned.h to linux/unaligned.h 2024-10-02 17:23:23 -04:00
romfs romfs: fix romfs_read_folio() 2024-08-21 22:32:58 +02:00
smb smb: client: don't try following DFS links in cifs_tree_connect() 2024-12-14 20:04:10 +01:00
squashfs Squashfs: fix variable overflow in squashfs_readpage_block 2024-10-30 20:14:12 -07:00
sysfs
sysv buffer: Convert __block_write_begin() to take a folio 2024-08-07 11:33:36 +02:00
tests execve: Move KUnit tests to tests/ subdirectory 2024-07-22 18:25:47 -07:00
tracefs tracing: Fix tracefs mount options 2024-11-01 08:38:14 -04:00
ubifs ubifs: authentication: Fix use-after-free in ubifs_tnc_end_commit 2024-12-05 14:03:04 +01:00
udf udf: fix uninit-value use in udf_get_fileshortad 2024-10-02 14:32:37 +02:00
ufs ufs_rename(): fix bogus argument of folio_release_kmap() 2024-10-02 00:05:09 -04:00
unicode unicode: Fix utf8_load() error path 2024-12-05 14:02:01 +01:00
vboxsf fs: Convert aops->write_end to take a folio 2024-08-07 11:32:02 +02:00
verity fsverity: expose verified fsverity built-in signatures to LSMs 2024-08-20 14:03:18 -04:00
xfs xfs: remove unknown compat feature check in superblock write validation 2024-12-09 10:40:55 +01:00
zonefs zonefs fixes for 6.12-rc2 2024-10-02 12:02:15 -07:00
aio.c fs/aio: Fix __percpu annotation of *cpu pointer in struct kioctx 2024-08-19 13:45:03 +02:00
anon_inodes.c fs: Create anon_inode_getfile_fmode() 2024-04-26 10:33:05 +02:00
attr.c nfsd-6.11 fixes: 2024-08-29 06:20:44 +12:00
backing-file.c fs: pass offset and result to backing_file end_write() callback 2024-10-16 13:17:45 +02:00
bad_inode.c
binfmt_elf_fdpic.c Revert "fs: don't block i_writecount during exec" 2024-12-05 14:02:50 +01:00
binfmt_elf.c Revert "fs: don't block i_writecount during exec" 2024-12-05 14:02:50 +01:00
binfmt_flat.c move asm/unaligned.h to linux/unaligned.h 2024-10-02 17:23:23 -04:00
binfmt_misc.c Revert "fs: don't block i_writecount during exec" 2024-12-05 14:02:50 +01:00
binfmt_script.c fs: binfmt: add missing MODULE_DESCRIPTION() macros 2024-05-28 12:06:51 +02:00
bpf_fs_kfuncs.c bpf: Add kfunc bpf_get_dentry_xattr() to read xattr from dentry 2024-08-07 11:26:54 -07:00
buffer.c vfs-6.12.folio 2024-09-16 08:54:30 +02:00
char_dev.c
compat_binfmt_elf.c
coredump.c Revert "binfmt_elf, coredump: Log the reason of the failed core dumps" 2024-09-26 11:39:02 -07:00
d_path.c
dax.c fsdax: dax_unshare_iter needs to copy entire blocks 2024-10-07 13:51:47 +02:00
dcache.c vfs-6.12.misc 2024-09-16 08:35:09 +02:00
direct-io.c fs/direct-io: Remove linux/prefetch.h include 2024-08-19 13:45:02 +02:00
drop_caches.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
eventfd.c introduce fd_file(), convert all accessors to it. 2024-08-12 22:00:43 -04:00
eventpoll.c epoll: annotate racy check 2024-12-14 20:03:35 +01:00
exec.c Revert "fs: don't block i_writecount during exec" 2024-12-05 14:02:50 +01:00
fcntl.c fcntl: make F_DUPFD_QUERY associative 2024-12-05 14:02:47 +01:00
fhandle.c struct fd layout change (and conversion to accessor helpers) 2024-09-23 09:35:36 -07:00
file_table.c slab updates for 6.12 2024-09-18 08:53:53 +02:00
file.c close_range(): fix the logics in descriptor table trimming 2024-09-29 21:52:29 -04:00
filesystems.c
fs_context.c
fs_parser.c fs_parse: add uid & gid option option parsing helpers 2024-07-02 06:20:49 +02:00
fs_pin.c
fs_struct.c
fs_types.c
fs-writeback.c inode: port __I_SYNC to var event 2024-08-30 08:22:39 +02:00
fsopen.c [tree-wide] finally take no_llseek out 2024-09-27 08:18:43 -07:00
init.c
inode.c bcachefs: do not use PF_MEMALLOC_NORECLAIM 2024-10-09 12:47:18 -07:00
internal.h file: reclaim 24 bytes from f_owner 2024-08-28 13:05:39 +02:00
ioctl.c introduce fd_file(), convert all accessors to it. 2024-08-12 22:00:43 -04:00
Kconfig nfs_common: fix Kconfig for NFS_COMMON_LOCALIO_SUPPORT 2024-10-03 16:19:51 -04:00
Kconfig.binfmt exec: Add KUnit test for bprm_stack_limits() 2024-06-19 13:13:55 -07:00
kernel_read_file.c introduce fd_file(), convert all accessors to it. 2024-08-12 22:00:43 -04:00
libfs.c vfs-6.12.folio 2024-09-16 08:54:30 +02:00
locks.c struct fd layout change (and conversion to accessor helpers) 2024-09-23 09:35:36 -07:00
Makefile bpf: introduce new VFS based BPF kfuncs 2024-08-06 09:01:41 -07:00
mbcache.c
mnt_idmapping.c fuse update for 6.12 2024-09-24 15:29:42 -07:00
mount.h vfs-6.12.mount 2024-09-16 11:15:26 +02:00
mpage.c buffer: Remove calls to set and clear the folio error flag 2024-05-31 12:31:43 +02:00
namei.c struct fd layout change (and conversion to accessor helpers) 2024-09-23 09:35:36 -07:00
namespace.c fs: don't try and remove empty rbtree node 2024-10-17 15:33:43 +02:00
nsfs.c [tree-wide] finally take no_llseek out 2024-09-27 08:18:43 -07:00
open.c openat2: explicitly return -E2BIG for (usize > PAGE_SIZE) 2024-10-10 12:09:03 +02:00
pidfs.c pidfs: check for valid pid namespace 2024-09-27 18:29:19 +02:00
pipe.c [tree-wide] finally take no_llseek out 2024-09-27 08:18:43 -07:00
pnode.c
pnode.h
posix_acl.c fs: Use in_group_or_capable() helper to simplify the code 2024-08-30 08:22:37 +02:00
proc_namespace.c fs: rename show_mnt_opts -> show_vfsmnt_opts 2024-06-28 14:36:43 +02:00
read_write.c fs/block: Check for IOCB_DIRECT in generic_atomic_write_valid() 2024-12-05 14:01:11 +01:00
readdir.c introduce fd_file(), convert all accessors to it. 2024-08-12 22:00:43 -04:00
remap_range.c introduce fd_file(), convert all accessors to it. 2024-08-12 22:00:43 -04:00
select.c struct fd layout change (and conversion to accessor helpers) 2024-09-23 09:35:36 -07:00
seq_file.c seq_file: Simplify __seq_puts() 2024-05-02 16:28:20 +02:00
signalfd.c struct fd layout change (and conversion to accessor helpers) 2024-09-23 09:35:36 -07:00
splice.c introduce fd_file(), convert all accessors to it. 2024-08-12 22:00:43 -04:00
stack.c
stat.c introduce fd_file(), convert all accessors to it. 2024-08-12 22:00:43 -04:00
statfs.c introduce fd_file(), convert all accessors to it. 2024-08-12 22:00:43 -04:00
super.c fs/super.c: introduce get_tree_bdev_flags() 2024-10-21 14:30:26 +02:00
sync.c introduce fd_file(), convert all accessors to it. 2024-08-12 22:00:43 -04:00
sysctls.c
timerfd.c introduce fd_file(), convert all accessors to it. 2024-08-12 22:00:43 -04:00
userfaultfd.c fork: do not invoke uffd on fork if error occurs 2024-10-28 21:40:38 -07:00
utimes.c introduce fd_file(), convert all accessors to it. 2024-08-12 22:00:43 -04:00
xattr.c introduce fd_file(), convert all accessors to it. 2024-08-12 22:00:43 -04:00