Commit ada5c1da authored by NeilBrown's avatar NeilBrown Committed by Jeff Layton
Browse files

fs/locks: rename some lists and pointers. 



struct file lock contains an 'fl_next' pointer which
is used to point to the lock that this request is blocked
waiting for.  So rename it to fl_blocker.

The fl_blocked list_head in an active lock is the head of a list of
blocked requests.  In a request it is a node in that list.
These are two distinct uses, so replace with two list_heads
with different names.
fl_blocked_requests is the head of a list of blocked requests
fl_blocked_member is a node in a member of that list.

The two different list_heads are never used at the same time, but that
will change in a future patch.

Note that a tracepoint is changed to report fl_blocker instead
of fl_next.

Signed-off-by: default avatarNeilBrown <neilb@suse.com>
Reviewed-by: default avatarJ. Bruce Fields <bfields@redhat.com>
Signed-off-by: default avatarJeff Layton <jlayton@kernel.org>
parent ccda4af0

fs/cifs/file.c

+1 −1
Original line number Diff line number Diff line
@@ -1103,7 +1103,7 @@ try_again: 
	rc = posix_lock_file(file, flock, NULL);

	up_write(&cinode->lock_sem);

	if (rc == FILE_LOCK_DEFERRED) {

		rc = wait_event_interruptible(flock->fl_wait, !flock->fl_next);

		rc = wait_event_interruptible(flock->fl_wait, !flock->fl_blocker);

		if (!rc)

			goto try_again;

		posix_unblock_lock(flock);

fs/locks.c

+31 −28
Original line number Diff line number Diff line
@@ -189,9 +189,9 @@ static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS); 
 * This lock protects the blocked_hash. Generally, if you're accessing it, you

 * want to be holding this lock.

 *

 * In addition, it also protects the fl->fl_block list, and the fl->fl_next

 * pointer for file_lock structures that are acting as lock requests (in

 * contrast to those that are acting as records of acquired locks).

 * In addition, it also protects the fl->fl_blocked_requests list, and the

 * fl->fl_blocker pointer for file_lock structures that are acting as lock

 * requests (in contrast to those that are acting as records of acquired locks).

 *

 * Note that when we acquire this lock in order to change the above fields,

 * we often hold the flc_lock as well. In certain cases, when reading the fields
@@ -293,7 +293,8 @@ static void locks_init_lock_heads(struct file_lock *fl) 
{

	INIT_HLIST_NODE(&fl->fl_link);

	INIT_LIST_HEAD(&fl->fl_list);

	INIT_LIST_HEAD(&fl->fl_block);

	INIT_LIST_HEAD(&fl->fl_blocked_requests);

	INIT_LIST_HEAD(&fl->fl_blocked_member);

	init_waitqueue_head(&fl->fl_wait);

}
@@ -332,7 +333,8 @@ void locks_free_lock(struct file_lock *fl) 
{

	BUG_ON(waitqueue_active(&fl->fl_wait));

	BUG_ON(!list_empty(&fl->fl_list));

	BUG_ON(!list_empty(&fl->fl_block));

	BUG_ON(!list_empty(&fl->fl_blocked_requests));

	BUG_ON(!list_empty(&fl->fl_blocked_member));

	BUG_ON(!hlist_unhashed(&fl->fl_link));



	locks_release_private(fl);
@@ -666,8 +668,8 @@ static void locks_delete_global_blocked(struct file_lock *waiter) 
static void __locks_delete_block(struct file_lock *waiter)

{

	locks_delete_global_blocked(waiter);

	list_del_init(&waiter->fl_block);

	waiter->fl_next = NULL;

	list_del_init(&waiter->fl_blocked_member);

	waiter->fl_blocker = NULL;

}



static void locks_delete_block(struct file_lock *waiter)
@@ -683,16 +685,17 @@ static void locks_delete_block(struct file_lock *waiter) 
 * it seems like the reasonable thing to do.

 *

 * Must be called with both the flc_lock and blocked_lock_lock held. The

 * fl_block list itself is protected by the blocked_lock_lock, but by ensuring

 * that the flc_lock is also held on insertions we can avoid taking the

 * blocked_lock_lock in some cases when we see that the fl_block list is empty.

 * fl_blocked_requests list itself is protected by the blocked_lock_lock,

 * but by ensuring that the flc_lock is also held on insertions we can avoid

 * taking the blocked_lock_lock in some cases when we see that the

 * fl_blocked_requests list is empty.

 */

static void __locks_insert_block(struct file_lock *blocker,

					struct file_lock *waiter)

{

	BUG_ON(!list_empty(&waiter->fl_block));

	waiter->fl_next = blocker;

	list_add_tail(&waiter->fl_block, &blocker->fl_block);

	BUG_ON(!list_empty(&waiter->fl_blocked_member));

	waiter->fl_blocker = blocker;

	list_add_tail(&waiter->fl_blocked_member, &blocker->fl_blocked_requests);

	if (IS_POSIX(blocker) && !IS_OFDLCK(blocker))

		locks_insert_global_blocked(waiter);

}
@@ -716,19 +719,19 @@ static void locks_wake_up_blocks(struct file_lock *blocker) 
	/*

	 * Avoid taking global lock if list is empty. This is safe since new

	 * blocked requests are only added to the list under the flc_lock, and

	 * the flc_lock is always held here. Note that removal from the fl_block

	 * list does not require the flc_lock, so we must recheck list_empty()

	 * after acquiring the blocked_lock_lock.

	 * the flc_lock is always held here. Note that removal from the

	 * fl_blocked_requests list does not require the flc_lock, so we must

	 * recheck list_empty() after acquiring the blocked_lock_lock.

	 */

	if (list_empty(&blocker->fl_block))

	if (list_empty(&blocker->fl_blocked_requests))

		return;



	spin_lock(&blocked_lock_lock);

	while (!list_empty(&blocker->fl_block)) {

	while (!list_empty(&blocker->fl_blocked_requests)) {

		struct file_lock *waiter;



		waiter = list_first_entry(&blocker->fl_block,

				struct file_lock, fl_block);

		waiter = list_first_entry(&blocker->fl_blocked_requests,

				struct file_lock, fl_blocked_member);

		__locks_delete_block(waiter);

		if (waiter->fl_lmops && waiter->fl_lmops->lm_notify)

			waiter->fl_lmops->lm_notify(waiter);
@@ -878,7 +881,7 @@ static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl) 


	hash_for_each_possible(blocked_hash, fl, fl_link, posix_owner_key(block_fl)) {

		if (posix_same_owner(fl, block_fl))

			return fl->fl_next;

			return fl->fl_blocker;

	}

	return NULL;

}
@@ -1237,7 +1240,7 @@ static int posix_lock_inode_wait(struct inode *inode, struct file_lock *fl) 
		error = posix_lock_inode(inode, fl, NULL);

		if (error != FILE_LOCK_DEFERRED)

			break;

		error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);

		error = wait_event_interruptible(fl->fl_wait, !fl->fl_blocker);

		if (!error)

			continue;
@@ -1324,7 +1327,7 @@ int locks_mandatory_area(struct inode *inode, struct file *filp, loff_t start, 
		error = posix_lock_inode(inode, &fl, NULL);

		if (error != FILE_LOCK_DEFERRED)

			break;

		error = wait_event_interruptible(fl.fl_wait, !fl.fl_next);

		error = wait_event_interruptible(fl.fl_wait, !fl.fl_blocker);

		if (!error) {

			/*

			 * If we've been sleeping someone might have
@@ -1518,7 +1521,7 @@ restart: 


	locks_dispose_list(&dispose);

	error = wait_event_interruptible_timeout(new_fl->fl_wait,

						!new_fl->fl_next, break_time);

						!new_fl->fl_blocker, break_time);



	percpu_down_read_preempt_disable(&file_rwsem);

	spin_lock(&ctx->flc_lock);
@@ -1931,7 +1934,7 @@ static int flock_lock_inode_wait(struct inode *inode, struct file_lock *fl) 
		error = flock_lock_inode(inode, fl);

		if (error != FILE_LOCK_DEFERRED)

			break;

		error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);

		error = wait_event_interruptible(fl->fl_wait, !fl->fl_blocker);

		if (!error)

			continue;
@@ -2210,7 +2213,7 @@ static int do_lock_file_wait(struct file *filp, unsigned int cmd, 
		error = vfs_lock_file(filp, cmd, fl, NULL);

		if (error != FILE_LOCK_DEFERRED)

			break;

		error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);

		error = wait_event_interruptible(fl->fl_wait, !fl->fl_blocker);

		if (!error)

			continue;
@@ -2581,7 +2584,7 @@ posix_unblock_lock(struct file_lock *waiter) 
	int status = 0;



	spin_lock(&blocked_lock_lock);

	if (waiter->fl_next)

	if (waiter->fl_blocker)

		__locks_delete_block(waiter);

	else

		status = -ENOENT;
@@ -2707,7 +2710,7 @@ static int locks_show(struct seq_file *f, void *v) 


	lock_get_status(f, fl, iter->li_pos, "");



	list_for_each_entry(bfl, &fl->fl_block, fl_block)

	list_for_each_entry(bfl, &fl->fl_blocked_requests, fl_blocked_member)

		lock_get_status(f, bfl, iter->li_pos, " ->");



	return 0;

include/linux/fs.h

+7 −2
Original line number Diff line number Diff line
@@ -1044,10 +1044,15 @@ bool opens_in_grace(struct net *); 
 * Obviously, the last two criteria only matter for POSIX locks.

 */

struct file_lock {

	struct file_lock *fl_next;	/* singly linked list for this inode  */

	struct file_lock *fl_blocker;	/* The lock, that is blocking us */

	struct list_head fl_list;	/* link into file_lock_context */

	struct hlist_node fl_link;	/* node in global lists */

	struct list_head fl_block;	/* circular list of blocked processes */

	struct list_head fl_blocked_requests;	/* list of requests with

						 * ->fl_blocker pointing here

						 */

	struct list_head fl_blocked_member;	/* node in

						 * ->fl_blocker->fl_blocked_requests

						 */

	fl_owner_t fl_owner;

	unsigned int fl_flags;

	unsigned char fl_type;

include/trace/events/filelock.h

+8 −8
Original line number Diff line number Diff line
@@ -68,7 +68,7 @@ DECLARE_EVENT_CLASS(filelock_lock, 
		__field(struct file_lock *, fl)

		__field(unsigned long, i_ino)

		__field(dev_t, s_dev)

		__field(struct file_lock *, fl_next)

		__field(struct file_lock *, fl_blocker)

		__field(fl_owner_t, fl_owner)

		__field(unsigned int, fl_pid)

		__field(unsigned int, fl_flags)
@@ -82,7 +82,7 @@ DECLARE_EVENT_CLASS(filelock_lock, 
		__entry->fl = fl ? fl : NULL;

		__entry->s_dev = inode->i_sb->s_dev;

		__entry->i_ino = inode->i_ino;

		__entry->fl_next = fl ? fl->fl_next : NULL;

		__entry->fl_blocker = fl ? fl->fl_blocker : NULL;

		__entry->fl_owner = fl ? fl->fl_owner : NULL;

		__entry->fl_pid = fl ? fl->fl_pid : 0;

		__entry->fl_flags = fl ? fl->fl_flags : 0;
@@ -92,9 +92,9 @@ DECLARE_EVENT_CLASS(filelock_lock, 
		__entry->ret = ret;

	),



	TP_printk("fl=0x%p dev=0x%x:0x%x ino=0x%lx fl_next=0x%p fl_owner=0x%p fl_pid=%u fl_flags=%s fl_type=%s fl_start=%lld fl_end=%lld ret=%d",

	TP_printk("fl=0x%p dev=0x%x:0x%x ino=0x%lx fl_blocker=0x%p fl_owner=0x%p fl_pid=%u fl_flags=%s fl_type=%s fl_start=%lld fl_end=%lld ret=%d",

		__entry->fl, MAJOR(__entry->s_dev), MINOR(__entry->s_dev),

		__entry->i_ino, __entry->fl_next, __entry->fl_owner,

		__entry->i_ino, __entry->fl_blocker, __entry->fl_owner,

		__entry->fl_pid, show_fl_flags(__entry->fl_flags),

		show_fl_type(__entry->fl_type),

		__entry->fl_start, __entry->fl_end, __entry->ret)
@@ -125,7 +125,7 @@ DECLARE_EVENT_CLASS(filelock_lease, 
		__field(struct file_lock *, fl)

		__field(unsigned long, i_ino)

		__field(dev_t, s_dev)

		__field(struct file_lock *, fl_next)

		__field(struct file_lock *, fl_blocker)

		__field(fl_owner_t, fl_owner)

		__field(unsigned int, fl_flags)

		__field(unsigned char, fl_type)
@@ -137,7 +137,7 @@ DECLARE_EVENT_CLASS(filelock_lease, 
		__entry->fl = fl ? fl : NULL;

		__entry->s_dev = inode->i_sb->s_dev;

		__entry->i_ino = inode->i_ino;

		__entry->fl_next = fl ? fl->fl_next : NULL;

		__entry->fl_blocker = fl ? fl->fl_blocker : NULL;

		__entry->fl_owner = fl ? fl->fl_owner : NULL;

		__entry->fl_flags = fl ? fl->fl_flags : 0;

		__entry->fl_type = fl ? fl->fl_type : 0;
@@ -145,9 +145,9 @@ DECLARE_EVENT_CLASS(filelock_lease, 
		__entry->fl_downgrade_time = fl ? fl->fl_downgrade_time : 0;

	),



	TP_printk("fl=0x%p dev=0x%x:0x%x ino=0x%lx fl_next=0x%p fl_owner=0x%p fl_flags=%s fl_type=%s fl_break_time=%lu fl_downgrade_time=%lu",

	TP_printk("fl=0x%p dev=0x%x:0x%x ino=0x%lx fl_blocker=0x%p fl_owner=0x%p fl_flags=%s fl_type=%s fl_break_time=%lu fl_downgrade_time=%lu",

		__entry->fl, MAJOR(__entry->s_dev), MINOR(__entry->s_dev),

		__entry->i_ino, __entry->fl_next, __entry->fl_owner,

		__entry->i_ino, __entry->fl_blocker, __entry->fl_owner,

		show_fl_flags(__entry->fl_flags),

		show_fl_type(__entry->fl_type),

		__entry->fl_break_time, __entry->fl_downgrade_time)

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