[mirror_ubuntu-bionic-kernel.git] / fs / reiserfs / lock.c

// SPDX-License-Identifier: GPL-2.0
#include "reiserfs.h"
#include <linux/mutex.h>

/*
 * The previous reiserfs locking scheme was heavily based on
 * the tricky properties of the Bkl:
 *
 * - it was acquired recursively by a same task
 * - the performances relied on the release-while-schedule() property
 *
 * Now that we replace it by a mutex, we still want to keep the same
 * recursive property to avoid big changes in the code structure.
 * We use our own lock_owner here because the owner field on a mutex
 * is only available in SMP or mutex debugging, also we only need this field
 * for this mutex, no need for a system wide mutex facility.
 *
 * Also this lock is often released before a call that could block because
 * reiserfs performances were partially based on the release while schedule()
 * property of the Bkl.
 */
void reiserfs_write_lock(struct super_block *s)
{
	struct reiserfs_sb_info *sb_i = REISERFS_SB(s);

	if (sb_i->lock_owner != current) {
		mutex_lock(&sb_i->lock);
		sb_i->lock_owner = current;
	}

	/* No need to protect it, only the current task touches it */
	sb_i->lock_depth++;
}

void reiserfs_write_unlock(struct super_block *s)
{
	struct reiserfs_sb_info *sb_i = REISERFS_SB(s);

	/*
	 * Are we unlocking without even holding the lock?
	 * Such a situation must raise a BUG() if we don't want
	 * to corrupt the data.
	 */
	BUG_ON(sb_i->lock_owner != current);

	if (--sb_i->lock_depth == -1) {
		sb_i->lock_owner = NULL;
		mutex_unlock(&sb_i->lock);
	}
}

int __must_check reiserfs_write_unlock_nested(struct super_block *s)
{
	struct reiserfs_sb_info *sb_i = REISERFS_SB(s);
	int 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 depth;
}

void reiserfs_write_lock_nested(struct super_block *s, int depth)
{
	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;
}

/*
 * Utility function to force a BUG if it is called without the superblock
 * write lock held.  caller is the string printed just before calling BUG()
 */
void reiserfs_check_lock_depth(struct super_block *sb, char *caller)
{
	struct reiserfs_sb_info *sb_i = REISERFS_SB(sb);

	WARN_ON(sb_i->lock_depth < 0);
}

#ifdef CONFIG_REISERFS_CHECK
void reiserfs_lock_check_recursive(struct super_block *sb)
{
	struct reiserfs_sb_info *sb_i = REISERFS_SB(sb);

	WARN_ONCE((sb_i->lock_depth > 0), "Unwanted recursive reiserfs lock!\n");
}
#endif
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
f466c6fd	2	#include "reiserfs.h"
8ebc4232 FW	3	#include <linux/mutex.h>
	4
	5	/*
	6	* The previous reiserfs locking scheme was heavily based on
	7	* the tricky properties of the Bkl:
	8	*
	9	* - it was acquired recursively by a same task
	10	* - the performances relied on the release-while-schedule() property
	11	*
	12	* Now that we replace it by a mutex, we still want to keep the same
	13	* recursive property to avoid big changes in the code structure.
	14	* We use our own lock_owner here because the owner field on a mutex
	15	* is only available in SMP or mutex debugging, also we only need this field
	16	* for this mutex, no need for a system wide mutex facility.
	17	*
	18	* Also this lock is often released before a call that could block because
25985edc	19	* reiserfs performances were partially based on the release while schedule()
8ebc4232 FW	20	* property of the Bkl.
	21	*/
	22	void reiserfs_write_lock(struct super_block *s)
	23	{
	24	struct reiserfs_sb_info *sb_i = REISERFS_SB(s);
	25
	26	if (sb_i->lock_owner != current) {
	27	mutex_lock(&sb_i->lock);
	28	sb_i->lock_owner = current;
	29	}
	30
	31	/* No need to protect it, only the current task touches it */
	32	sb_i->lock_depth++;
	33	}
	34
	35	void reiserfs_write_unlock(struct super_block *s)
	36	{
	37	struct reiserfs_sb_info *sb_i = REISERFS_SB(s);
	38
	39	/*
	40	* Are we unlocking without even holding the lock?
80503185 FW	41	* Such a situation must raise a BUG() if we don't want
80503185 FW	42	* to corrupt the data.
8ebc4232	43	*/
80503185	44	BUG_ON(sb_i->lock_owner != current);
8ebc4232 FW	45
	46	if (--sb_i->lock_depth == -1) {
	47	sb_i->lock_owner = NULL;
	48	mutex_unlock(&sb_i->lock);
	49	}
	50	}
	51
278f6679	52	int __must_check reiserfs_write_unlock_nested(struct super_block *s)
daf88c89 FW	53	{
daf88c89 FW	54	struct reiserfs_sb_info *sb_i = REISERFS_SB(s);
278f6679	55	int depth;
daf88c89	56
278f6679 JM	57	/* this can happen when the lock isn't always held */
	58	if (sb_i->lock_owner != current)
	59	return -1;
	60
	61	depth = sb_i->lock_depth;
	62
	63	sb_i->lock_depth = -1;
	64	sb_i->lock_owner = NULL;
	65	mutex_unlock(&sb_i->lock);
daf88c89	66
278f6679	67	return depth;
daf88c89 FW	68	}
daf88c89 FW	69
278f6679	70	void reiserfs_write_lock_nested(struct super_block *s, int depth)
daf88c89	71	{
278f6679 JM	72	struct reiserfs_sb_info *sb_i = REISERFS_SB(s);
	73
	74	/* this can happen when the lock isn't always held */
	75	if (depth == -1)
	76	return;
	77
	78	mutex_lock(&sb_i->lock);
	79	sb_i->lock_owner = current;
	80	sb_i->lock_depth = depth;
daf88c89 FW	81	}
daf88c89 FW	82
8ebc4232 FW	83	/*
	84	* Utility function to force a BUG if it is called without the superblock
	85	* write lock held. caller is the string printed just before calling BUG()
	86	*/
	87	void reiserfs_check_lock_depth(struct super_block sb, char caller)
	88	{
	89	struct reiserfs_sb_info *sb_i = REISERFS_SB(sb);
	90
278f6679	91	WARN_ON(sb_i->lock_depth < 0);
8ebc4232	92	}
c4a62ca3 FW	93
	94	#ifdef CONFIG_REISERFS_CHECK
	95	void reiserfs_lock_check_recursive(struct super_block *sb)
	96	{
	97	struct reiserfs_sb_info *sb_i = REISERFS_SB(sb);
	98
	99	WARN_ONCE((sb_i->lock_depth > 0), "Unwanted recursive reiserfs lock!\n");
	100	}
	101	#endif