Re: [PATCH] xfs: be honest about used inodes in statfs

Brian Foster
2014-02-24T16:06:57Z

On Thu, Feb 20, 2014 at 04:12:16PM -0600, Eric Sandeen wrote:
> Because we have lazy counters, it's possible that we over-allocate
> inodes past the maxicount (imaxpct) limit.
>
> A previous commit,
>
> 2fe3366 xfs: ensure f_ffree returned by statfs() is non-negative
>
> stopped statfs from underflowing f_ffree in this case, but that
> only happened when we mis-reported f_files, capped at maxicount.
>
> Change statfs to report the actual number of inodes allocated,
> even if it is greater than maxicount. It's reality.
> Deal with it. ;)
>
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> ---
>
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index f317488..7c7a810 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -1083,7 +1083,6 @@ xfs_fs_statfs(
> struct xfs_inode *ip = XFS_I(dentry->d_inode);
> __uint64_t fakeinos, id;
> xfs_extlen_t lsize;
> - __int64_t ffree;
>
> statp->f_type = XFS_SB_MAGIC;
> statp->f_namelen = MAXNAMELEN - 1;
> @@ -1100,17 +1099,24 @@ xfs_fs_statfs(
> statp->f_blocks = sbp->sb_dblocks - lsize;
> statp->f_bfree = statp->f_bavail =
> sbp->sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
> +
> + /* Potential number of new inodes in free blocks */
> fakeinos = statp->f_bfree << sbp->sb_inopblog;
> + /* Total possible files is current inodes + potential new inodes */
> statp->f_files =
> MIN(sbp->sb_icount + fakeinos, (__uint64_t)XFS_MAXINUMBER);
> + /* Unless we have maxicount! Then cap it at that */
> if (mp->m_maxicount)
> statp->f_files = min_t(typeof(statp->f_files),
> statp->f_files,
> mp->m_maxicount);
>
> - /* make sure statp->f_ffree does not underflow */
> - ffree = statp->f_files - (sbp->sb_icount - sbp->sb_ifree);
> - statp->f_ffree = max_t(__int64_t, ffree, 0);
> + /* But if we already managed to allocate more, let's be honest */
> + statp->f_files = max_t(typeof(statp->f_files),
> + sbp->sb_icount,
> + statp->f_files);
> +
> + statp->f_ffree = statp->f_files - (sbp->sb_icount - sbp->sb_ifree);

Hi Eric,

Would something like the following be equivalent (and accurate?):

/*
* Potential number of new inodes in free blocks, limited by maxicount.
*/
fakeinos = statp->f_bfree << sbp->sb_inopblog;
if (mp->m_maxicount)
fakeinos = mp->m_maxicount > sbp->sb_icount ?
MIN(mp->m_maxicount - sbp->sb_icount, fakeinos) : 0;

/* Total possible files is current inodes + potential new inodes */
statp->f_files = MIN(sbp->sb_icount + fakeinos,
(__uint64_t) XFS_MAXINUMBER);

statp->f_ffree = statp->f_files - (sbp->sb_icount - sbp->sb_ifree);

Brian

>
> spin_unlock(&mp->m_sb_lock);
>
>
> _______________________________________________
> xfs mailing list
> xfs@oss.sgi.com
> http://oss.sgi.com/mailman/listinfo/xfs