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| author | Omar Sandoval <osandov@osandov.com> | 2015-06-03 02:31:00 +0200 |
|---|---|---|
| committer | Chris Mason <clm@fb.com> | 2015-06-03 04:34:33 +0200 |
| commit | 64ad6c488975d7516230cf7849190a991fd615ae (patch) | |
| tree | 49867e1daa030b8839ba0b8a83d7bac32452a6f0 /fs/btrfs/ioctl.c | |
| parent | Linux 4.1-rc6 (diff) | |
| download | linux-64ad6c488975d7516230cf7849190a991fd615ae.tar.xz linux-64ad6c488975d7516230cf7849190a991fd615ae.zip | |
Btrfs: don't invalidate root dentry when subvolume deletion fails
Since commit bafc9b754f75 ("vfs: More precise tests in d_invalidate"),
mounted subvolumes can be deleted because d_invalidate() won't fail.
However, we run into problems when we attempt to delete the default
subvolume while it is mounted as the root filesystem:
# btrfs subvol list /
ID 257 gen 306 top level 5 path rootvol
ID 267 gen 334 top level 5 path snap1
# btrfs subvol get-default /
ID 267 gen 334 top level 5 path snap1
# btrfs inspect-internal rootid /
267
# mount -o subvol=/ /dev/vda1 /mnt
# btrfs subvol del /mnt/snap1
Delete subvolume (no-commit): '/mnt/snap1'
ERROR: cannot delete '/mnt/snap1' - Operation not permitted
# findmnt /
findmnt: can't read /proc/mounts: No such file or directory
# ls /proc
#
Markus reported that this same scenario simply led to a kernel oops.
This happens because in btrfs_ioctl_snap_destroy(), we call
d_invalidate() before we check may_destroy_subvol(), which means that we
detach the submounts and drop the dentry before erroring out. Instead,
we should only invalidate the dentry once the deletion has succeeded.
Additionally, the shrink_dcache_sb() isn't necessary; d_invalidate()
will prune the dcache for the deleted subvolume.
Cc: <stable@vger.kernel.org>
Fixes: bafc9b754f75 ("vfs: More precise tests in d_invalidate")
Reported-by: Markus Schauler <mschauler@gmail.com>
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to 'fs/btrfs/ioctl.c')
| -rw-r--r-- | fs/btrfs/ioctl.c | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 1c22c6518504..6f790bcddfc1 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2413,8 +2413,6 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file, goto out_unlock_inode; } - d_invalidate(dentry); - down_write(&root->fs_info->subvol_sem); err = may_destroy_subvol(dest); @@ -2508,7 +2506,7 @@ out_up_write: out_unlock_inode: mutex_unlock(&inode->i_mutex); if (!err) { - shrink_dcache_sb(root->fs_info->sb); + d_invalidate(dentry); btrfs_invalidate_inodes(dest); d_delete(dentry); ASSERT(dest->send_in_progress == 0); |