On Wed, Mar 13, 2019 at 06:33:50PM +0800, Anand Jain wrote:
>
>
>
> On 3/13/19 1:36 PM, Anand Jain wrote:
> > 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.j...@oracle.com>
> > ---
> > 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 ef6502a94712..7aa362c2fbcf 100644
> > --- a/fs/btrfs/props.c
> > +++ b/fs/btrfs/props.c
> > @@ -277,11 +277,11 @@ static int prop_compression_validate(struct inode
> > *inode, const char *value,
> > 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;
> >
>
>
> Nack.
> Now some junk value after expected string is not an error.
> such as..
>
> btrfs prop set /btrfs compression lzo110
This was intentional when the zlib levels were introduced so older
kernels can understand newer compression specifier but still have a sane
fallback (ie use the default level). Now it would be better to extend
the validation to parse the method:level format at least. But as
mentioned in the other mail, the level needs to be propagated elsewhere
too so it's not just a change to the validation.
