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btrfs: prevent remounting to v1 space cache for subpage mount

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commit 0591f04036 upstream.

Upstream commit 9f73f1aef9 ("btrfs: force v2 space cache usage for
subpage mount") forces subpage mount to use v2 cache, to avoid
deprecated v1 cache which doesn't support subpage properly.

But there is a loophole that user can still remount to v1 cache.

The existing check will only give users a warning, but does not really
prevent to do the remount.

Although remounting to v1 will not cause any problems since the v1 cache
will always be marked invalid when mounted with a different page size,
it's still better to prevent v1 cache at all for subpage mounts.

Fixes: 9f73f1aef9 ("btrfs: force v2 space cache usage for subpage mount")
CC: stable@vger.kernel.org # 5.15+
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Qu Wenruo 2022-05-18 13:03:09 +08:00 committed by Greg Kroah-Hartman
parent 341d33128a
commit 82e3769c02
1 changed files with 8 additions and 0 deletions
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8
fs/btrfs/super.c
View file

@ -1917,6 +1917,14 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data)
if (ret)
goto restore;
/* V1 cache is not supported for subpage mount. */
if (fs_info->sectorsize < PAGE_SIZE && btrfs_test_opt(fs_info, SPACE_CACHE)) {
btrfs_warn(fs_info,
"v1 space cache is not supported for page size %lu with sectorsize %u",
PAGE_SIZE, fs_info->sectorsize);
ret = -EINVAL;
goto restore;
}
btrfs_remount_begin(fs_info, old_opts, *flags);
btrfs_resize_thread_pool(fs_info,
fs_info->thread_pool_size, old_thread_pool_size);