From 278f6679f454bf185a07d9a4ca355b153482d17a Mon Sep 17 00:00:00 2001 From: Jeff Mahoney Date: Thu, 8 Aug 2013 17:34:46 -0400 Subject: 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 --- fs/reiserfs/lock.c | 43 +++++++++++++++++++++++-------------------- 1 file changed, 23 insertions(+), 20 deletions(-) (limited to 'fs/reiserfs/lock.c') 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 -- cgit v1.2.3-55-g7522