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authorGeorge Wang <xuw2015@gmail.com>2015-05-29 07:39:34 +1000
committerDave Chinner <david@fromorbit.com>2015-05-29 07:39:34 +1000
commit74f9ce1cf2830b94e189f4e99678dbf19aa3bc90 (patch)
treefda31de04c0e47f9ddfe5b9ef4d0a17106233491
parent5ebe6afaf0057ac3eaeb98defd5456894b446d22 (diff)
downloadkernel-74f9ce1cf2830b94e189f4e99678dbf19aa3bc90.tar.gz
xfs: use percpu_counter_read_positive for mp->m_icount
Function percpu_counter_read just return the current counter, which can be negative. This will cause the checking of "allocated inode counts <= m_maxicount" false positive. Use percpu_counter_read_positive can solve this problem, and be consistent with the purpose to introduce percpu mechanism to xfs. Signed-off-by: George Wang <xuw2015@gmail.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
-rw-r--r--fs/xfs/libxfs/xfs_ialloc.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
index 07349a183a11..1c9e75521250 100644
--- a/fs/xfs/libxfs/xfs_ialloc.c
+++ b/fs/xfs/libxfs/xfs_ialloc.c
@@ -376,7 +376,7 @@ xfs_ialloc_ag_alloc(
*/
newlen = args.mp->m_ialloc_inos;
if (args.mp->m_maxicount &&
- percpu_counter_read(&args.mp->m_icount) + newlen >
+ percpu_counter_read_positive(&args.mp->m_icount) + newlen >
args.mp->m_maxicount)
return -ENOSPC;
args.minlen = args.maxlen = args.mp->m_ialloc_blks;
@@ -1339,10 +1339,13 @@ xfs_dialloc(
* If we have already hit the ceiling of inode blocks then clear
* okalloc so we scan all available agi structures for a free
* inode.
+ *
+ * Read rough value of mp->m_icount by percpu_counter_read_positive,
+ * which will sacrifice the preciseness but improve the performance.
*/
if (mp->m_maxicount &&
- percpu_counter_read(&mp->m_icount) + mp->m_ialloc_inos >
- mp->m_maxicount) {
+ percpu_counter_read_positive(&mp->m_icount) + mp->m_ialloc_inos
+ > mp->m_maxicount) {
noroom = 1;
okalloc = 0;
}