[PATCH] fix overflow in xfs_growfs_data_private

[Felix Blyakher]

On May 23, 2009, at 2:30 PM, Eric Sandeen wrote:

> In the case where growing a filesystem would leave the last AG
> too small, the fixup code has an overflow in the calculation
> of the new size with one fewer ag, because "nagcount" is a 32
> bit number.  If the new filesystem has > 2^32 blocks in it
> this causes a problem resulting in an EINVAL return from growfs:
>
> # xfs_io -f -c "truncate 19998630180864" fsfile
> # mkfs.xfs -f -bsize=4096 -dagsize=76288719b,size=3905982455b fsfile
> # mount -o loop fsfile mnt/
> # xfs_growfs mnt/

Is it really 'mnt/', not '/mnt'?

>
> meta-data=/dev/loop0             isize=256    agcount=52,
> agsize=76288719 blks
>         =                       sectsz=512   attr=2
> data     =                       bsize=4096   blocks=3905982455,  
> imaxpct=5
>         =                       sunit=0      swidth=0 blks
> naming   =version 2              bsize=4096   ascii-ci=0
> log      =internal               bsize=4096   blocks=32768, version=2
>         =                       sectsz=512   sunit=0 blks, lazy- 
> count=0
> realtime =none                   extsz=4096   blocks=0, rtextents=0
> xfs_growfs: XFS_IOC_FSGROWFSDATA xfsctl failed: Invalid argument
>
> Reported-by: richard.ems at cape-horn-eng.com
> Signed-off-by: Eric Sandeen <sandeen at sandeen.net>

Nice find and the neat fix, Eric.

Reviewed-by: Felix Blyakher <felixb at sgi.com>