From: jiangyiwen Date: Thu, 3 Apr 2014 21:47:13 +0000 (-0700) Subject: ocfs2: avoid system inode ref confusion by adding mutex lock X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=43b10a20372d9a1c08391f33f1c8bd86179ddc5f;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git 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 --- diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h index a780e20d4fba..8d64a97a9d5e 100644 --- a/fs/ocfs2/ocfs2.h +++ b/fs/ocfs2/ocfs2.h @@ -446,6 +446,8 @@ struct ocfs2_super /* rb tree root for refcount lock. */ struct rb_root osb_rf_lock_tree; struct ocfs2_refcount_tree *osb_ref_tree_lru; + + struct mutex system_file_mutex; }; #define OCFS2_SB(sb) ((struct ocfs2_super *)(sb)->s_fs_info) diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c index 888a1457af96..1aecd626e645 100644 --- a/fs/ocfs2/super.c +++ b/fs/ocfs2/super.c @@ -2100,6 +2100,8 @@ static int ocfs2_initialize_super(struct super_block *sb, spin_lock_init(&osb->osb_xattr_lock); ocfs2_init_steal_slots(osb); + mutex_init(&osb->system_file_mutex); + atomic_set(&osb->alloc_stats.moves, 0); atomic_set(&osb->alloc_stats.local_data, 0); atomic_set(&osb->alloc_stats.bitmap_data, 0); 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; }