xfs: use generic percpu counters for free inode counter
XFS has hand-rolled per-cpu counters for the superblock since before
there was any generic implementation. The free inode counter is not
used for any limit enforcement - the per-AG free inode counters are
used during allocation to determine if there are inode available for
allocation.
Hence we don't need any of the complexity of the hand-rolled
counters and we can simply replace them with generic per-cpu
counters similar to the inode counter.
This version introduces a xfs_mod_ifree() helper function from
Christoph Hellwig.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 0aa4428..0491477 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1086,6 +1086,7 @@
struct xfs_inode *ip = XFS_I(dentry->d_inode);
__uint64_t fakeinos, id;
__uint64_t icount;
+ __uint64_t ifree;
xfs_extlen_t lsize;
__int64_t ffree;
@@ -1098,6 +1099,7 @@
xfs_icsb_sync_counters(mp, XFS_ICSB_LAZY_COUNT);
icount = percpu_counter_sum(&mp->m_icount);
+ ifree = percpu_counter_sum(&mp->m_ifree);
spin_lock(&mp->m_sb_lock);
statp->f_bsize = sbp->sb_blocksize;
@@ -1118,7 +1120,7 @@
sbp->sb_icount);
/* make sure statp->f_ffree does not underflow */
- ffree = statp->f_files - (icount - sbp->sb_ifree);
+ ffree = statp->f_files - (icount - ifree);
statp->f_ffree = max_t(__int64_t, ffree, 0);
spin_unlock(&mp->m_sb_lock);