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

To: xfs-oss <xfs@xxxxxxxxxxx>
Subject: [PATCH] xfs: be honest about used inodes in statfs
From: Eric Sandeen <sandeen@xxxxxxxxxx>
Date: Thu, 20 Feb 2014 16:12:16 -0600
Delivered-to: xfs@xxxxxxxxxxx
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:24.0) Gecko/20100101 Thunderbird/24.3.0
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@xxxxxxxxxx>
---

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);
 
        spin_unlock(&mp->m_sb_lock);
 

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