diff options
author | Oleg Nesterov <oleg@redhat.com> | 2015-08-11 10:28:29 -0400 |
---|---|---|
committer | Oleg Nesterov <oleg@redhat.com> | 2015-08-15 07:52:09 -0400 |
commit | 0e28e01f1e73015d8e1b8fa1cda071d0bd9a2600 (patch) | |
tree | ae83a5c9f212e85db4dbd00279880a6ce24f575d /fs/super.c | |
parent | f4b554af9931585174d4913b482eacab75858964 (diff) |
document rwsem_release() in sb_wait_write()
Not only we need to avoid the warning from lockdep_sys_exit(), the
caller of freeze_super() can never release this lock. Another thread
can do this, so there is another reason for rwsem_release().
Plus the comment should explain why we have to fool lockdep.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Jan Kara <jack@suse.com>
Diffstat (limited to 'fs/super.c')
-rw-r--r-- | fs/super.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/fs/super.c b/fs/super.c index 24a76bcd62a5..8aa3cbc571d1 100644 --- a/fs/super.c +++ b/fs/super.c | |||
@@ -1236,11 +1236,17 @@ static void sb_wait_write(struct super_block *sb, int level) | |||
1236 | { | 1236 | { |
1237 | s64 writers; | 1237 | s64 writers; |
1238 | 1238 | ||
1239 | rwsem_acquire(&sb->s_writers.lock_map[level-1], 0, 0, _THIS_IP_); | ||
1239 | /* | 1240 | /* |
1240 | * We just cycle-through lockdep here so that it does not complain | 1241 | * We are going to return to userspace and forget about this lock, the |
1241 | * about returning with lock to userspace | 1242 | * ownership goes to the caller of thaw_super() which does unlock. |
1243 | * | ||
1244 | * FIXME: we should do this before return from freeze_super() after we | ||
1245 | * called sync_filesystem(sb) and s_op->freeze_fs(sb), and thaw_super() | ||
1246 | * should re-acquire these locks before s_op->unfreeze_fs(sb). However | ||
1247 | * this leads to lockdep false-positives, so currently we do the early | ||
1248 | * release right after acquire. | ||
1242 | */ | 1249 | */ |
1243 | rwsem_acquire(&sb->s_writers.lock_map[level-1], 0, 0, _THIS_IP_); | ||
1244 | rwsem_release(&sb->s_writers.lock_map[level-1], 1, _THIS_IP_); | 1250 | rwsem_release(&sb->s_writers.lock_map[level-1], 1, _THIS_IP_); |
1245 | 1251 | ||
1246 | do { | 1252 | do { |