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.
Signed-off-by: Stu Brodsky <sbrodsky@xxxxxxx>
--- a/fs/xfs/linux-2.6/xfs_super.c.orig 2010-07-20
06:06:19.269572013-0500
+++ b/fs/xfs/linux-2.6/xfs_super.c 2010-07-20 08:09:17.773570840 -0500
@@ -1226,6 +1226,7 @@
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 +1250,9 @@
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);
+ ffree = statp->f_files - (sbp->sb_icount - sbp->sb_ifree);
+ statp->f_ffree = (__u64) (ffree < 0 ? 0 : ffree);
+
spin_unlock(&mp->m_sb_lock);
if ((ip->i_d.di_flags & XFS_DIFLAG_PROJINHERIT) ||
--
Stuart Brodsky
2750 Blue Water Road
Eagan, MN. 55121
651-683-7910
<sbrodsky@xxxxxxx>
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