GitHub-Mirror/Star64_linux
2
0
Fork 0
mirror of https://github.com/Fishwaldo/Star64_linux.git synced 2025-06-19 13:11:14 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

locks: give the blocked_hash its own spinlock

Browse source 
There's no reason we have to protect the blocked_hash and file_lock_list
with the same spinlock. With the tests I have, breaking it in two gives
a barely measurable performance benefit, but it seems reasonable to make
this locking as granular as possible.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Jeff Layton 2013-06-21 08:58:20 -04:00 • committed by Al Viro
parent 3999e49364
commit 7b2296afb3
2 changed files with 30 additions and 27 deletions
Download patch file Download diff file Expand all files Collapse all files

41
fs/locks.c
View file

@ -159,10 +159,11 @@ int lease_break_time = 45;
* by the file_lock_lock.
*/
static HLIST_HEAD(file_lock_list);
static DEFINE_SPINLOCK(file_lock_lock);
/*
* The blocked_hash is used to find POSIX lock loops for deadlock detection.
* It is protected by file_lock_lock.
* It is protected by blocked_lock_lock.
*
* We hash locks by lockowner in order to optimize searching for the lock a
* particular lockowner is waiting on.
@ -175,8 +176,8 @@ static HLIST_HEAD(file_lock_list);
static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS);
/*
* This lock protects the blocked_hash and the file_lock_list. Generally, if
* you're accessing one of those lists, you want to be holding this lock.
* 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
@ -191,7 +192,7 @@ static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS);
* both the i_lock and the blocked_lock_lock (acquired in that order). Deleting
* an entry from the list however only requires the file_lock_lock.
*/
static DEFINE_SPINLOCK(file_lock_lock);
static DEFINE_SPINLOCK(blocked_lock_lock);
static struct kmem_cache *filelock_cache __read_mostly;
@ -544,7 +545,7 @@ locks_delete_global_blocked(struct file_lock *waiter)
/* Remove waiter from blocker's block list.
* When blocker ends up pointing to itself then the list is empty.
*
* Must be called with file_lock_lock held.
* Must be called with blocked_lock_lock held.
*/
static void __locks_delete_block(struct file_lock *waiter)
{
@ -555,9 +556,9 @@ static void __locks_delete_block(struct file_lock *waiter)
static void locks_delete_block(struct file_lock *waiter)
{
spin_lock(&file_lock_lock);
spin_lock(&blocked_lock_lock);
__locks_delete_block(waiter);
spin_unlock(&file_lock_lock);
spin_unlock(&blocked_lock_lock);
}
/* Insert waiter into blocker's block list.
@ -565,9 +566,9 @@ static void locks_delete_block(struct file_lock *waiter)
* the order they blocked. The documentation doesn't require this but
* it seems like the reasonable thing to do.
*
* Must be called with both the i_lock and file_lock_lock held. The fl_block
* Must be called with both the i_lock and blocked_lock_lock held. The fl_block
* list itself is protected by the file_lock_list, but by ensuring that the
* i_lock is also held on insertions we can avoid taking the file_lock_lock
* i_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.
*/
static void __locks_insert_block(struct file_lock *blocker,
@ -584,9 +585,9 @@ static void __locks_insert_block(struct file_lock *blocker,
static void locks_insert_block(struct file_lock *blocker,
struct file_lock *waiter)
{
spin_lock(&file_lock_lock);
spin_lock(&blocked_lock_lock);
__locks_insert_block(blocker, waiter);
spin_unlock(&file_lock_lock);
spin_unlock(&blocked_lock_lock);
}
/*
@ -601,12 +602,12 @@ static void locks_wake_up_blocks(struct file_lock *blocker)
* blocked requests are only added to the list under the i_lock, and
* the i_lock is always held here. Note that removal from the fl_block
* list does not require the i_lock, so we must recheck list_empty()
* after acquiring the file_lock_lock.
* after acquiring the blocked_lock_lock.
*/
if (list_empty(&blocker->fl_block))
return;
spin_lock(&file_lock_lock);
spin_lock(&blocked_lock_lock);
while (!list_empty(&blocker->fl_block)) {
struct file_lock *waiter;
@ -618,7 +619,7 @@ static void locks_wake_up_blocks(struct file_lock *blocker)
else
wake_up(&waiter->fl_wait);
}
spin_unlock(&file_lock_lock);
spin_unlock(&blocked_lock_lock);
}
/* Insert file lock fl into an inode's lock list at the position indicated
@ -772,7 +773,7 @@ static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
return NULL;
}
/* Must be called with the file_lock_lock held! */
/* Must be called with the blocked_lock_lock held! */
static int posix_locks_deadlock(struct file_lock *caller_fl,
struct file_lock *block_fl)
{
@ -920,12 +921,12 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
* locks list must be done while holding the same lock!
*/
error = -EDEADLK;
spin_lock(&file_lock_lock);
spin_lock(&blocked_lock_lock);
if (likely(!posix_locks_deadlock(request, fl))) {
error = FILE_LOCK_DEFERRED;
__locks_insert_block(fl, request);
}
spin_unlock(&file_lock_lock);
spin_unlock(&blocked_lock_lock);
goto out;
}
}
@ -2212,12 +2213,12 @@ posix_unblock_lock(struct file_lock *waiter)
{
int status = 0;
spin_lock(&file_lock_lock);
spin_lock(&blocked_lock_lock);
if (waiter->fl_next)
__locks_delete_block(waiter);
else
status = -ENOENT;
spin_unlock(&file_lock_lock);
spin_unlock(&blocked_lock_lock);
return status;
}
EXPORT_SYMBOL(posix_unblock_lock);
@ -2332,6 +2333,7 @@ static void *locks_start(struct seq_file *f, loff_t *pos)
loff_t *p = f->private;
spin_lock(&file_lock_lock);
spin_lock(&blocked_lock_lock);
*p = (*pos + 1);
return seq_hlist_start(&file_lock_list, *pos);
}
@ -2345,6 +2347,7 @@ static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
static void locks_stop(struct seq_file *f, void *v)
{
spin_unlock(&blocked_lock_lock);
spin_unlock(&file_lock_lock);
}