1 #include <linux/reiserfs_fs.h>
2 #include <linux/mutex.h>
5 * The previous reiserfs locking scheme was heavily based on
6 * the tricky properties of the Bkl:
8 * - it was acquired recursively by a same task
9 * - the performances relied on the release-while-schedule() property
11 * Now that we replace it by a mutex, we still want to keep the same
12 * recursive property to avoid big changes in the code structure.
13 * We use our own lock_owner here because the owner field on a mutex
14 * is only available in SMP or mutex debugging, also we only need this field
15 * for this mutex, no need for a system wide mutex facility.
17 * Also this lock is often released before a call that could block because
18 * reiserfs performances were partialy based on the release while schedule()
19 * property of the Bkl.
21 void reiserfs_write_lock(struct super_block *s)
23 struct reiserfs_sb_info *sb_i = REISERFS_SB(s);
25 if (sb_i->lock_owner != current) {
26 mutex_lock(&sb_i->lock);
27 sb_i->lock_owner = current;
30 /* No need to protect it, only the current task touches it */
34 void reiserfs_write_unlock(struct super_block *s)
36 struct reiserfs_sb_info *sb_i = REISERFS_SB(s);
39 * Are we unlocking without even holding the lock?
40 * Such a situation could even raise a BUG() if we don't
41 * want the data become corrupted
43 WARN_ONCE(sb_i->lock_owner != current,
44 "Superblock write lock imbalance");
46 if (--sb_i->lock_depth == -1) {
47 sb_i->lock_owner = NULL;
48 mutex_unlock(&sb_i->lock);
53 * If we already own the lock, just exit and don't increase the depth.
54 * Useful when we don't want to lock more than once.
56 * We always return the lock_depth we had before calling
59 int reiserfs_write_lock_once(struct super_block *s)
61 struct reiserfs_sb_info *sb_i = REISERFS_SB(s);
63 if (sb_i->lock_owner != current) {
64 mutex_lock(&sb_i->lock);
65 sb_i->lock_owner = current;
66 return sb_i->lock_depth++;
69 return sb_i->lock_depth;
72 void reiserfs_write_unlock_once(struct super_block *s, int lock_depth)
75 reiserfs_write_unlock(s);
79 * Utility function to force a BUG if it is called without the superblock
80 * write lock held. caller is the string printed just before calling BUG()
82 void reiserfs_check_lock_depth(struct super_block *sb, char *caller)
84 struct reiserfs_sb_info *sb_i = REISERFS_SB(sb);
86 if (sb_i->lock_depth < 0)
87 reiserfs_panic(sb, "%s called without kernel lock held %d",