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, 11 insertions, 24 deletions

diff --git a/fs/bcachefs/fs.h b/fs/bcachefs/fs.h
index 73b96d0b5d83..4164d0669d70 100644
--- a/fs/bcachefs/fs.h
+++ b/fs/bcachefs/fs.h
@@ -6,31 +6,11 @@
 #include "opts.h"
 #include "str_hash.h"
 #include "quota_types.h"
+#include "two_state_shared_lock.h"
 
 #include <linux/seqlock.h>
 #include <linux/stat.h>
 
-/*
- * Two-state lock - can be taken for add or block - both states are shared,
- * like read side of rwsem, but conflict with other state:
- */
-struct pagecache_lock {
-	atomic_long_t		v;
-	wait_queue_head_t	wait;
-};
-
-static inline void pagecache_lock_init(struct pagecache_lock *lock)
-{
-	atomic_long_set(&lock->v, 0);
-	init_waitqueue_head(&lock->wait);
-}
-
-void bch2_pagecache_add_put(struct pagecache_lock *);
-bool bch2_pagecache_add_tryget(struct pagecache_lock *);
-void bch2_pagecache_add_get(struct pagecache_lock *);
-void bch2_pagecache_block_put(struct pagecache_lock *);
-void bch2_pagecache_block_get(struct pagecache_lock *);
-
 struct bch_inode_info {
 	struct inode		v;
 	unsigned long		ei_flags;
@@ -38,7 +18,7 @@ struct bch_inode_info {
 	struct mutex		ei_update_lock;
 	u64			ei_quota_reserved;
 	unsigned long		ei_last_dirtied;
-	struct pagecache_lock	ei_pagecache_lock;
+	two_state_lock_t	ei_pagecache_lock;
 
 	struct mutex		ei_quota_lock;
 	struct bch_qid		ei_qid;
@@ -49,6 +29,13 @@ struct bch_inode_info {
 	struct bch_inode_unpacked ei_inode;
 };
 
+#define bch2_pagecache_add_put(i)	bch2_two_state_unlock(&i->ei_pagecache_lock, 0)
+#define bch2_pagecache_add_tryget(i)	bch2_two_state_trylock(&i->ei_pagecache_lock, 0)
+#define bch2_pagecache_add_get(i)	bch2_two_state_lock(&i->ei_pagecache_lock, 0)
+
+#define bch2_pagecache_block_put(i)	bch2_two_state_unlock(&i->ei_pagecache_lock, 1)
+#define bch2_pagecache_block_get(i)	bch2_two_state_lock(&i->ei_pagecache_lock, 1)
+
 static inline subvol_inum inode_inum(struct bch_inode_info *inode)
 {
 	return (subvol_inum) {
@@ -95,7 +82,7 @@ do {									\
 			if ((_locks) & INODE_LOCK)			\
 				down_write_nested(&a[i]->v.i_rwsem, i);	\
 			if ((_locks) & INODE_PAGECACHE_BLOCK)		\
-				bch2_pagecache_block_get(&a[i]->ei_pagecache_lock);\
+				bch2_pagecache_block_get(a[i]);\
 			if ((_locks) & INODE_UPDATE_LOCK)			\
 				mutex_lock_nested(&a[i]->ei_update_lock, i);\
 		}							\
@@ -113,7 +100,7 @@ do {									\
 			if ((_locks) & INODE_LOCK)			\
 				up_write(&a[i]->v.i_rwsem);		\
 			if ((_locks) & INODE_PAGECACHE_BLOCK)		\
-				bch2_pagecache_block_put(&a[i]->ei_pagecache_lock);\
+				bch2_pagecache_block_put(a[i]);\
 			if ((_locks) & INODE_UPDATE_LOCK)			\
 				mutex_unlock(&a[i]->ei_update_lock);	\
 		}							\