diff options
author | Jeff Mahoney <jeffm@suse.com> | 2013-08-08 17:34:46 -0400 |
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committer | Jeff Mahoney <jeffm@suse.de> | 2013-08-08 17:34:46 -0400 |
commit | 278f6679f454bf185a07d9a4ca355b153482d17a (patch) | |
tree | ffead073e67cfdc1ddfc3949ebc93c06dcaaab8f /fs/reiserfs/lock.c | |
parent | 4c05141df57f4ffc1a9a28f1925434924179bfe4 (diff) | |
download | linux-next-278f6679f454bf185a07d9a4ca355b153482d17a.tar.gz |
reiserfs: locking, handle nested locks properly
The reiserfs write lock replaced the BKL and uses similar semantics.
Frederic's locking code makes a distinction between when the lock is nested
and when it's being acquired/released, but I don't think that's the right
distinction to make.
The right distinction is between the lock being released at end-of-use and
the lock being released for a schedule. The unlock should return the depth
and the lock should restore it, rather than the other way around as it is now.
This patch implements that and adds a number of places where the lock
should be dropped.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Diffstat (limited to 'fs/reiserfs/lock.c')
-rw-r--r-- | fs/reiserfs/lock.c | 43 |
1 files changed, 23 insertions, 20 deletions
diff --git a/fs/reiserfs/lock.c b/fs/reiserfs/lock.c index d735bc8470e3..045b83ef9fd9 100644 --- a/fs/reiserfs/lock.c +++ b/fs/reiserfs/lock.c @@ -48,30 +48,35 @@ void reiserfs_write_unlock(struct super_block *s) } } -/* - * If we already own the lock, just exit and don't increase the depth. - * Useful when we don't want to lock more than once. - * - * We always return the lock_depth we had before calling - * this function. - */ -int reiserfs_write_lock_once(struct super_block *s) +int __must_check reiserfs_write_unlock_nested(struct super_block *s) { struct reiserfs_sb_info *sb_i = REISERFS_SB(s); + int depth; - if (sb_i->lock_owner != current) { - mutex_lock(&sb_i->lock); - sb_i->lock_owner = current; - return sb_i->lock_depth++; - } + /* this can happen when the lock isn't always held */ + if (sb_i->lock_owner != current) + return -1; + + depth = sb_i->lock_depth; + + sb_i->lock_depth = -1; + sb_i->lock_owner = NULL; + mutex_unlock(&sb_i->lock); - return sb_i->lock_depth; + return depth; } -void reiserfs_write_unlock_once(struct super_block *s, int lock_depth) +void reiserfs_write_lock_nested(struct super_block *s, int depth) { - if (lock_depth == -1) - reiserfs_write_unlock(s); + struct reiserfs_sb_info *sb_i = REISERFS_SB(s); + + /* this can happen when the lock isn't always held */ + if (depth == -1) + return; + + mutex_lock(&sb_i->lock); + sb_i->lock_owner = current; + sb_i->lock_depth = depth; } /* @@ -82,9 +87,7 @@ void reiserfs_check_lock_depth(struct super_block *sb, char *caller) { struct reiserfs_sb_info *sb_i = REISERFS_SB(sb); - if (sb_i->lock_depth < 0) - reiserfs_panic(sb, "%s called without kernel lock held %d", - caller); + WARN_ON(sb_i->lock_depth < 0); } #ifdef CONFIG_REISERFS_CHECK |