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| author | Stuart Brodsky <sbrodsky@sgi.com> | 2010-08-24 11:46:05 +1000 |
|---|---|---|
| committer | Dave Chinner <david@fromorbit.com> | 2010-08-24 11:46:05 +1000 |
| commit | 2fe33661fcd79d4c53022509f7223d526b5fa233 (patch) | |
| tree | 1c26f0ca23372dc7142fa4f9395056c529378801 /fs/xfs | |
| parent | efceab1d563153a2b1a6e7d35376241a48126989 (diff) | |
| download | linux-2fe33661fcd79d4c53022509f7223d526b5fa233.tar.gz linux-2fe33661fcd79d4c53022509f7223d526b5fa233.tar.bz2 linux-2fe33661fcd79d4c53022509f7223d526b5fa233.zip | |
xfs: ensure f_ffree returned by statfs() is non-negative
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@sgi.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Diffstat (limited to 'fs/xfs')
| -rw-r--r-- | 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 15c35b62ff14..c6b24e7c308a 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) || |