Revert "mm: pagecache add lock"

This reverts commit 8675f74ac343b24c14b3991dc6f999c138723eec.

5 files changed, 1 insertions, 111 deletions

diff --git a/fs/inode.c b/fs/inode.c
index 6dec6f6336ce..36792cd800e5 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -351,7 +351,6 @@ EXPORT_SYMBOL(inc_nlink);
 static void __address_space_init_once(struct address_space *mapping)
 {
 	INIT_RADIX_TREE(&mapping->i_pages, GFP_ATOMIC | __GFP_ACCOUNT);
-	pagecache_lock_init(&mapping->add_lock);
 	init_rwsem(&mapping->i_mmap_rwsem);
 	INIT_LIST_HEAD(&mapping->private_list);
 	spin_lock_init(&mapping->private_lock);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 207ccf1b9bfe..73dc9d477447 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -412,28 +412,6 @@ int pagecache_write_end(struct file *, struct address_space *mapping,
 				loff_t pos, unsigned len, unsigned copied,
 				struct page *page, void *fsdata);
 
-/*
- * 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 pagecache_add_put(struct pagecache_lock *);
-void pagecache_add_get(struct pagecache_lock *);
-void __pagecache_block_put(struct pagecache_lock *);
-void __pagecache_block_get(struct pagecache_lock *);
-void pagecache_block_put(struct pagecache_lock *);
-void pagecache_block_get(struct pagecache_lock *);
-
 struct address_space {
 	struct inode		*host;		/* owner: inode, block_device */
 	struct radix_tree_root	i_pages;	/* cached pages */
@@ -452,8 +430,6 @@ struct address_space {
 	struct list_head	private_list;	/* for use by the address_space */
 	void			*private_data;	/* ditto */
 	errseq_t		wb_err;
-	struct pagecache_lock	add_lock
-		____cacheline_aligned_in_smp;	/* protects adding new pages */
 } __attribute__((aligned(sizeof(long)))) __randomize_layout;
 	/*
 	 * On most architectures that alignment is already the case; but
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 80629ad3d05a..c69f308f3a53 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -41,7 +41,6 @@ struct io_context;
 struct mempolicy;
 struct nameidata;
 struct nsproxy;
-struct pagecache_lock;
 struct perf_event_context;
 struct pid_namespace;
 struct pipe_inode_info;
@@ -941,9 +940,6 @@ struct task_struct {
 	unsigned int			in_ubsan;
 #endif
 
-	/* currently held lock, for avoiding recursing in fault path: */
-	struct pagecache_lock *pagecache_lock;
-
 	/* Journalling filesystem info: */
 	void				*journal_info;
 
diff --git a/init/init_task.c b/init/init_task.c
index f4be590da394..5aebe3be4d7c 100644
--- a/init/init_task.c
+++ b/init/init_task.c
@@ -114,7 +114,6 @@ struct task_struct init_task
 	},
 	.blocked	= {{0}},
 	.alloc_lock	= __SPIN_LOCK_UNLOCKED(init_task.alloc_lock),
-	.pagecache_lock = NULL,
 	.journal_info	= NULL,
 	INIT_CPU_TIMERS(init_task)
 	.pi_lock	= __RAW_SPIN_LOCK_UNLOCKED(init_task.pi_lock),
diff --git a/mm/filemap.c b/mm/filemap.c
index 37e16bd7b0fd..7e0dee304b54 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -111,73 +111,6 @@
  *   ->tasklist_lock            (memory_failure, collect_procs_ao)
  */
 
-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 pagecache_add_put(struct pagecache_lock *lock)
-{
-	__pagecache_lock_put(lock, 1);
-}
-EXPORT_SYMBOL(pagecache_add_put);
-
-void pagecache_add_get(struct pagecache_lock *lock)
-{
-	__pagecache_lock_get(lock, 1);
-}
-EXPORT_SYMBOL(pagecache_add_get);
-
-void __pagecache_block_put(struct pagecache_lock *lock)
-{
-	__pagecache_lock_put(lock, -1);
-}
-EXPORT_SYMBOL(__pagecache_block_put);
-
-void __pagecache_block_get(struct pagecache_lock *lock)
-{
-	__pagecache_lock_get(lock, -1);
-}
-EXPORT_SYMBOL(__pagecache_block_get);
-
-void pagecache_block_put(struct pagecache_lock *lock)
-{
-	BUG_ON(current->pagecache_lock != lock);
-	current->pagecache_lock = NULL;
-	__pagecache_lock_put(lock, -1);
-}
-EXPORT_SYMBOL(pagecache_block_put);
-
-void pagecache_block_get(struct pagecache_lock *lock)
-{
-	__pagecache_lock_get(lock, -1);
-	BUG_ON(current->pagecache_lock);
-	current->pagecache_lock = lock;
-}
-EXPORT_SYMBOL(pagecache_block_get);
-
 static int page_cache_tree_insert_vec(struct address_space *mapping,
 				      struct page *pages[],
 				      unsigned nr_pages,
@@ -982,9 +915,6 @@ static int add_to_page_cache_vec(struct page **pages,
 		page->index = offset + i;
 	}
 
-	if (current->pagecache_lock != &mapping->add_lock)
-		pagecache_add_get(&mapping->add_lock);
-
 	while (nr_added < nr_charged) {
 		error = radix_tree_maybe_preload(gfp_mask & GFP_RECLAIM_MASK);
 		if (error)
@@ -1014,9 +944,6 @@ static int add_to_page_cache_vec(struct page **pages,
 		radix_tree_preload_end();
 	}
 
-	if (current->pagecache_lock != &mapping->add_lock)
-		pagecache_add_put(&mapping->add_lock);
-
 	for (i = 0; i < nr_added; i++) {
 		struct page *page = pages[i];
 
@@ -2772,14 +2699,7 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
 	 * Do we have something in the page cache already?
 	 */
 	page = find_get_page(mapping, offset);
-	if (unlikely(current->pagecache_lock == &mapping->add_lock)) {
-		/*
-		 * fault from e.g. dio -> get_user_pages() - _don't_ want to do
-		 * readahead, only read in page we need:
-		 */
-		if (!page)
-			goto no_cached_page;
-	} else if (likely(page) && !(vmf->flags & FAULT_FLAG_TRIED)) {
+	if (likely(page) && !(vmf->flags & FAULT_FLAG_TRIED)) {
 		/*
 		 * We found the page, so try async readahead before
 		 * waiting for the lock.