From: xuw2015@gmail.com
To: xfs@oss.sgi.com
Cc: George Wang <xuw2015@gmail.com>
Subject: [PATCH] xfs: use percpu_counter_compare instead of naive comparing
Date: Fri, 17 Apr 2015 10:22:24 +0800 [thread overview]
Message-ID: <1429237344-5668-1-git-send-email-xuw2015@gmail.com> (raw)
From: George Wang <xuw2015@gmail.com>
Function percpu_counter_read just return the current counter, regardless of
every cpu's count. This counter can be negative value, which will cause the
checking of "allocated inode counts <= m_maxicount" false positive.
Commit 501ab3238753 "xfs: use generic percpu counters for inode counter
" introduced this problem.
Use the percpu_counter_compare, which will first do stuff in current cpu for
performance; if can not get the result, it will get the exactly counter
based on the count of every cpu.
Signed-off-by: George Wang <xuw2015@gmail.com>
---
fs/xfs/libxfs/xfs_ialloc.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
index 07349a1..af9e7d2 100644
--- a/fs/xfs/libxfs/xfs_ialloc.c
+++ b/fs/xfs/libxfs/xfs_ialloc.c
@@ -376,8 +376,8 @@ xfs_ialloc_ag_alloc(
*/
newlen = args.mp->m_ialloc_inos;
if (args.mp->m_maxicount &&
- percpu_counter_read(&args.mp->m_icount) + newlen >
- args.mp->m_maxicount)
+ percpu_counter_compare(&args.mp->m_icount,
+ args.mp->m_maxicount - newlen) > 0)
return -ENOSPC;
args.minlen = args.maxlen = args.mp->m_ialloc_blks;
/*
@@ -1341,8 +1341,8 @@ xfs_dialloc(
* inode.
*/
if (mp->m_maxicount &&
- percpu_counter_read(&mp->m_icount) + mp->m_ialloc_inos >
- mp->m_maxicount) {
+ percpu_counter_compare(&mp->m_icount,
+ mp->m_maxicount - mp->m_ialloc_inos) > 0) {
noroom = 1;
okalloc = 0;
}
--
1.9.3
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next reply other threads:[~2015-04-17 2:22 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-17 2:22 xuw2015 [this message]
2015-04-17 4:06 ` [PATCH] xfs: use percpu_counter_compare instead of naive comparing Dave Chinner
2015-04-17 7:15 ` 王旭
2015-04-17 8:15 ` Dave Chinner
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