From: George Wang Date: Thu, 28 May 2015 21:39:34 +0000 (+1000) Subject: xfs: use percpu_counter_read_positive for mp->m_icount X-Git-Tag: v4.14-rc1~5139^2~13 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=74f9ce1cf2830b94e189f4e99678dbf19aa3bc90;p=platform%2Fkernel%2Flinux-rpi.git 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 Reviewed-by: Dave Chinner Signed-off-by: Dave Chinner --- diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c index 07349a1..1c9e755 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; }