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ocfs2: kill osb->system_file_mutex lock

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Commit 43b10a2037 ("ocfs2: avoid system inode ref confusion by adding
mutex lock") tried to avoid a refcount leak caused by allowing multiple
threads to call igrab(inode).  But addition of osb->system_file_mutex made
locking dependency complicated and is causing lockdep to warn about
possibility of AB-BA deadlock.

Since _ocfs2_get_system_file_inode() returns the same inode for the same
input arguments, we don't need to serialize
_ocfs2_get_system_file_inode().  What we need to make sure is that
igrab(inode) is called for only once().  Therefore, replace
osb->system_file_mutex with cmpxchg()-based locking.

Link: https://lore.kernel.org/fea8d1fd-afb0-4302-a560-c202e2ef7afd@I-love.SAKURA.ne.jp
Fixes: 43b10a2037 ("ocfs2: avoid system inode ref confusion by adding mutex lock")
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Heming Zhao <heming.zhao@suse.com>
Acked-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Tetsuo Handa
2026-05-18 13:23:40 +09:00
committed by Andrew Morton
parent f7ea0d1373
commit f5b1910e23
3 changed files with 3 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
fs/ocfs2/ocfs2.h
View File

@@ -494,8 +494,6 @@ struct ocfs2_super
struct rb_root osb_rf_lock_tree;
struct ocfs2_refcount_tree *osb_ref_tree_lru;
struct mutex system_file_mutex;
/*
* OCFS2 needs to schedule several different types of work which
* require cluster locking, disk I/O, recovery waits, etc. Since these

2
fs/ocfs2/super.c
View File

@@ -1997,8 +1997,6 @@ 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);

9
fs/ocfs2/sysfile.c
View File

@@ -98,11 +98,9 @@ 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;
@@ -112,11 +110,10 @@ struct inode *ocfs2_get_system_file_inode(struct ocfs2_super *osb,
inode = _ocfs2_get_system_file_inode(osb, type, slot);
/* add one more if putting into array for first time */
if (arr && inode) {
*arr = igrab(inode);
BUG_ON(!*arr);
if (inode && arr && !*arr && !cmpxchg(&(*arr), NULL, inode)) {
inode = igrab(inode);
BUG_ON(!inode);
}
mutex_unlock(&osb->system_file_mutex);
return inode;
}