bcachefs: Factor out two_state_shared_lock

We have a unique lock used for controlling adding to the pagecache: the
lock has two states, where both states are shared - the lock may be held
multiple times for either state - but not both states at the same time.

This is exactly what we need for nocow mode locking, so this patch pulls
it out of fs.c into its own file.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

1 files changed, 1 insertions, 53 deletions

diff --git a/fs/bcachefs/fs.c b/fs/bcachefs/fs.c
index 485cb9cbcd51..90297cfc7934 100644
--- a/fs/bcachefs/fs.c
+++ b/fs/bcachefs/fs.c
@@ -43,58 +43,6 @@ static void bch2_vfs_inode_init(struct btree_trans *, subvol_inum,
 				struct bch_inode_unpacked *,
 				struct bch_subvolume *);
 
-static void __pagecache_lock_put(struct pagecache_lock *lock, long i)
-{
-	BUG_ON(atomic_long_read(&lock->v) == 0);
-
-	if (atomic_long_sub_return_release(i, &lock->v) == 0)
-		wake_up_all(&lock->wait);
-}
-
-static bool __pagecache_lock_tryget(struct pagecache_lock *lock, long i)
-{
-	long v = atomic_long_read(&lock->v), old;
-
-	do {
-		old = v;
-
-		if (i > 0 ? v < 0 : v > 0)
-			return false;
-	} while ((v = atomic_long_cmpxchg_acquire(&lock->v,
-					old, old + i)) != old);
-	return true;
-}
-
-static void __pagecache_lock_get(struct pagecache_lock *lock, long i)
-{
-	wait_event(lock->wait, __pagecache_lock_tryget(lock, i));
-}
-
-void bch2_pagecache_add_put(struct pagecache_lock *lock)
-{
-	__pagecache_lock_put(lock, 1);
-}
-
-bool bch2_pagecache_add_tryget(struct pagecache_lock *lock)
-{
-	return __pagecache_lock_tryget(lock, 1);
-}
-
-void bch2_pagecache_add_get(struct pagecache_lock *lock)
-{
-	__pagecache_lock_get(lock, 1);
-}
-
-void bch2_pagecache_block_put(struct pagecache_lock *lock)
-{
-	__pagecache_lock_put(lock, -1);
-}
-
-void bch2_pagecache_block_get(struct pagecache_lock *lock)
-{
-	__pagecache_lock_get(lock, -1);
-}
-
 void bch2_inode_update_after_write(struct btree_trans *trans,
 				   struct bch_inode_info *inode,
 				   struct bch_inode_unpacked *bi,
@@ -1410,7 +1358,7 @@ static struct inode *bch2_alloc_inode(struct super_block *sb)
 
 	inode_init_once(&inode->v);
 	mutex_init(&inode->ei_update_lock);
-	pagecache_lock_init(&inode->ei_pagecache_lock);
+	two_state_lock_init(&inode->ei_pagecache_lock);
 	mutex_init(&inode->ei_quota_lock);
 
 	return &inode->v;