From: Stuart Brodsky <sbrodsky@xxxxxxx> Because of delayed updates to sb_icount field in the super block, it is possible to allocate over maxicount number of inodes. This causes the arithmetic to calculate a negative number of free inodes in user commands like df or stat -f. Since maxicount is a somewhat arbitrary number, a slight over allocation is not critical but user commands should be displayed as 0 or greater and never go negative. To do this the value in the stats buffer f_ffree is capped to never go negative. [ Modified to use max_t as per Christoph's comment. ] Signed-off-by: Stu Brodsky <sbrodsky@xxxxxxx> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx> --- fs/xfs/linux-2.6/xfs_super.c | 7 ++++++- 1 files changed, 6 insertions(+), 1 deletions(-) diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c index d09cd14..a4e0797 100644 --- a/fs/xfs/linux-2.6/xfs_super.c +++ b/fs/xfs/linux-2.6/xfs_super.c @@ -1226,6 +1226,7 @@ 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; @@ -1249,7 +1250,11 @@ xfs_fs_statfs( statp->f_files = min_t(typeof(statp->f_files), statp->f_files, mp->m_maxicount); - statp->f_ffree = statp->f_files - (sbp->sb_icount - sbp->sb_ifree); + + /* 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); + spin_unlock(&mp->m_sb_lock); if ((ip->i_d.di_flags & XFS_DIFLAG_PROJINHERIT) || -- 1.7.1 _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
