The compression property resets to NULL, instead of the old value if we
fail to set the new compression parameter.
btrfs prop get /btrfs compression
compression=lzo
btrfs prop set /btrfs compression zli
ERROR: failed to set compression for /btrfs: Invalid argument
btrfs prop get /btrfs compression
This is because the compression property ->validate() is successful for
'zli' as the strncmp() used the len passed from the userland.
Fix it by using the expected string length in strncmp().
Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
Reviewed-by: Nikolay Borisov <nborisov@xxxxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
---
Please note:
This patch also fixes the bug that generation number gets updated when
property validation fails. As the reason its reason is weak validate(),
which lets the bad set pass untill ->apply().
fs/btrfs/props.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/btrfs/props.c b/fs/btrfs/props.c
index b324a5fd7864..64b5f4695d4c 100644
--- a/fs/btrfs/props.c
+++ b/fs/btrfs/props.c
@@ -255,11 +255,11 @@ static int prop_compression_validate(const char *value, size_t len)
if (!value)
return 0;
- if (!strncmp("lzo", value, len))
+ if (!strncmp("lzo", value, 3))
return 0;
- else if (!strncmp("zlib", value, len))
+ else if (!strncmp("zlib", value, 4))
return 0;
- else if (!strncmp("zstd", value, len))
+ else if (!strncmp("zstd", value, 4))
return 0;
return -EINVAL;
--
2.17.1
