From 43b10a20372d9a1c08391f33f1c8bd86179ddc5f Mon Sep 17 00:00:00 2001 From: jiangyiwen Date: Thu, 3 Apr 2014 14:47:13 -0700 Subject: ocfs2: avoid system inode ref confusion by adding mutex lock The following case may lead to the same system inode ref in confusion. A thread B thread ocfs2_get_system_file_inode ->get_local_system_inode ->_ocfs2_get_system_file_inode because of *arr == NULL, ocfs2_get_system_file_inode ->get_local_system_inode ->_ocfs2_get_system_file_inode gets first ref thru _ocfs2_get_system_file_inode, gets second ref thru igrab and set *arr = inode at the moment, B thread also gets two refs, so lead to one more inode ref. So add mutex lock to avoid multi thread set two inode ref once at the same time. Signed-off-by: jiangyiwen Reviewed-by: Joseph Qi Cc: Joel Becker Cc: Mark Fasheh Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/ocfs2/sysfile.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'fs/ocfs2/sysfile.c') diff --git a/fs/ocfs2/sysfile.c b/fs/ocfs2/sysfile.c index f053688d22a3..af155c183123 100644 --- a/fs/ocfs2/sysfile.c +++ b/fs/ocfs2/sysfile.c @@ -113,9 +113,11 @@ struct inode *ocfs2_get_system_file_inode(struct ocfs2_super *osb, } else arr = get_local_system_inode(osb, type, slot); + mutex_lock(&osb->system_file_mutex); if (arr && ((inode = *arr) != NULL)) { /* get a ref in addition to the array ref */ inode = igrab(inode); + mutex_unlock(&osb->system_file_mutex); BUG_ON(!inode); return inode; @@ -129,6 +131,7 @@ struct inode *ocfs2_get_system_file_inode(struct ocfs2_super *osb, *arr = igrab(inode); BUG_ON(!*arr); } + mutex_unlock(&osb->system_file_mutex); return inode; } -- cgit v1.2.3