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| author | Oleg Nesterov <oleg@redhat.com> | 2015-08-11 16:28:29 +0200 |
|---|---|---|
| committer | Oleg Nesterov <oleg@redhat.com> | 2015-08-15 13:52:09 +0200 |
| commit | 0e28e01f1e73015d8e1b8fa1cda071d0bd9a2600 (patch) | |
| tree | ae83a5c9f212e85db4dbd00279880a6ce24f575d | |
| parent | fix the broken lockdep logic in __sb_start_write() (diff) | |
| download | linux-0e28e01f1e73015d8e1b8fa1cda071d0bd9a2600.tar.xz linux-0e28e01f1e73015d8e1b8fa1cda071d0bd9a2600.zip | |
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>
| -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) { s64 writers; + rwsem_acquire(&sb->s_writers.lock_map[level-1], 0, 0, _THIS_IP_); /* - * We just cycle-through lockdep here so that it does not complain - * about returning with lock to userspace + * We are going to return to userspace and forget about this lock, the + * ownership goes to the caller of thaw_super() which does unlock. + * + * FIXME: we should do this before return from freeze_super() after we + * called sync_filesystem(sb) and s_op->freeze_fs(sb), and thaw_super() + * should re-acquire these locks before s_op->unfreeze_fs(sb). However + * this leads to lockdep false-positives, so currently we do the early + * release right after acquire. */ - rwsem_acquire(&sb->s_writers.lock_map[level-1], 0, 0, _THIS_IP_); rwsem_release(&sb->s_writers.lock_map[level-1], 1, _THIS_IP_); do { |