On Tue, May 05, 2015 at 03:02:08PM -0700, Darrick J. Wong wrote:
> When per-CPU superblock counters are enabled (i.e. SMP=y), we don't
> update the in-core superblock's sb_icount value prior to checking if
> we're already at maximum inodes. Therefore, it's possible for a tight
> file creation loop (e.g. "for i in {0..100000}; do touch /mnt/$i;
> done") to allocate far more inodes than the administrator specified at
> mkfs time. Fix this by synchronizing the counters every time we think
> we need to allocate another chunk of inodes.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
> fs/xfs/libxfs/xfs_ialloc.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
> index 116ef1d..a8aaab6 100644
> --- a/fs/xfs/libxfs/xfs_ialloc.c
> +++ b/fs/xfs/libxfs/xfs_ialloc.c
> @@ -375,6 +375,8 @@ xfs_ialloc_ag_alloc(
> * at one time.
> */
> newlen = args.mp->m_ialloc_inos;
> + if (args.mp->m_maxicount)
> + xfs_icsb_sync_counters(args.mp, 0);
> if (args.mp->m_maxicount &&
> args.mp->m_sb.sb_icount + newlen > args.mp->m_maxicount)
> return -ENOSPC;
> @@ -1339,6 +1341,8 @@ xfs_dialloc(
> * okalloc so we scan all available agi structures for a free
> * inode.
> */
> + if (mp->m_maxicount)
> + xfs_icsb_sync_counters(mp, 0);
> if (mp->m_maxicount &&
> mp->m_sb.sb_icount + mp->m_ialloc_inos > mp->m_maxicount) {
> noroom = 1;
As i mentioned on IRC, sb_icount is now using the generic percpu
counter infrastrcture, so shouldn't have this problem - overshoot
should be, at maximum, (Ncpus * 32).
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
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