fs: rename pipe_buf ->steal to ->try_steal

And replace the arcane return value convention with a simple bool
where true means success and false means failure.

[AV: braino fix folded in]

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

drivers/char/virtio_console.c

@@ -871,7 +871,7 @@ static int pipe_to_sg(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
 		return 0;
 
 	/* Try lock this page */
-	if (pipe_buf_steal(pipe, buf) == 0) {
+	if (pipe_buf_try_steal(pipe, buf)) {
 		/* Get reference and unlock page for moving */
 		get_page(buf->page);
 		unlock_page(buf->page);

fs/fuse/dev.c

@@ -805,7 +805,7 @@ static int fuse_try_move_page(struct fuse_copy_state *cs, struct page **pagep)
 	if (cs->len != PAGE_SIZE)
 		goto out_fallback;
 
-	if (pipe_buf_steal(cs->pipe, buf) != 0)
+	if (!pipe_buf_try_steal(cs->pipe, buf))
 		goto out_fallback;
 
 	newpage = buf->page;

fs/pipe.c

@@ -140,21 +140,20 @@ static void anon_pipe_buf_release(struct pipe_inode_info *pipe,
 		put_page(page);
 }
 
-static int anon_pipe_buf_steal(struct pipe_inode_info *pipe,
+static bool anon_pipe_buf_try_steal(struct pipe_inode_info *pipe,
 		struct pipe_buffer *buf)
 {
 	struct page *page = buf->page;
 
-	if (page_count(page) == 1) {
+	if (page_count(page) != 1)
+		return false;
 	memcg_kmem_uncharge_page(page, 0);
 	__SetPageLocked(page);
-		return 0;
-	}
-	return 1;
+	return true;
 }
 
 /**
- * generic_pipe_buf_steal - attempt to take ownership of a &pipe_buffer
+ * generic_pipe_buf_try_steal - attempt to take ownership of a &pipe_buffer
  * @pipe:	the pipe that the buffer belongs to
  * @buf:	the buffer to attempt to steal
  *
@@ -165,7 +164,7 @@ static int anon_pipe_buf_steal(struct pipe_inode_info *pipe,
  *	he wishes; the typical use is insertion into a different file
  *	page cache.
  */
-int generic_pipe_buf_steal(struct pipe_inode_info *pipe,
+bool generic_pipe_buf_try_steal(struct pipe_inode_info *pipe,
 		struct pipe_buffer *buf)
 {
 	struct page *page = buf->page;
@@ -177,12 +176,11 @@ int generic_pipe_buf_steal(struct pipe_inode_info *pipe,
 	 */
 	if (page_count(page) == 1) {
 		lock_page(page);
-		return 0;
+		return true;
 	}
-
-	return 1;
+	return false;
 }
-EXPORT_SYMBOL(generic_pipe_buf_steal);
+EXPORT_SYMBOL(generic_pipe_buf_try_steal);
 
 /**
  * generic_pipe_buf_get - get a reference to a &struct pipe_buffer
@@ -217,7 +215,7 @@ EXPORT_SYMBOL(generic_pipe_buf_release);
 
 static const struct pipe_buf_operations anon_pipe_buf_ops = {
 	.release	= anon_pipe_buf_release,
-	.steal = anon_pipe_buf_steal,
+	.try_steal	= anon_pipe_buf_try_steal,
 	.get		= generic_pipe_buf_get,
 };
 

fs/splice.c

@@ -44,7 +44,7 @@
  * addition of remove_mapping(). If success is returned, the caller may
  * attempt to reuse this page for another destination.
  */
-static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe,
+static bool page_cache_pipe_buf_try_steal(struct pipe_inode_info *pipe,
 		struct pipe_buffer *buf)
 {
 	struct page *page = buf->page;
@@ -76,7 +76,7 @@ static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe,
 		 */
 		if (remove_mapping(mapping, page)) {
 			buf->flags |= PIPE_BUF_FLAG_LRU;
-			return 0;
+			return true;
 		}
 	}
 
@@ -86,7 +86,7 @@ static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe,
 	 */
 out_unlock:
 	unlock_page(page);
-	return 1;
+	return false;
 }
 
 static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe,
@@ -141,23 +141,23 @@ static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe,
 const struct pipe_buf_operations page_cache_pipe_buf_ops = {
 	.confirm	= page_cache_pipe_buf_confirm,
 	.release	= page_cache_pipe_buf_release,
-	.steal = page_cache_pipe_buf_steal,
+	.try_steal	= page_cache_pipe_buf_try_steal,
 	.get		= generic_pipe_buf_get,
 };
 
-static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe,
+static bool user_page_pipe_buf_try_steal(struct pipe_inode_info *pipe,
 		struct pipe_buffer *buf)
 {
 	if (!(buf->flags & PIPE_BUF_FLAG_GIFT))
-		return 1;
+		return false;
 
 	buf->flags |= PIPE_BUF_FLAG_LRU;
-	return generic_pipe_buf_steal(pipe, buf);
+	return generic_pipe_buf_try_steal(pipe, buf);
 }
 
 static const struct pipe_buf_operations user_page_pipe_buf_ops = {
 	.release	= page_cache_pipe_buf_release,
-	.steal = user_page_pipe_buf_steal,
+	.try_steal	= user_page_pipe_buf_try_steal,
 	.get		= generic_pipe_buf_get,
 };
 
@@ -331,7 +331,7 @@ EXPORT_SYMBOL(generic_file_splice_read);
 
 const struct pipe_buf_operations default_pipe_buf_ops = {
 	.release	= generic_pipe_buf_release,
-	.steal = generic_pipe_buf_steal,
+	.try_steal	= generic_pipe_buf_try_steal,
 	.get		= generic_pipe_buf_get,
 };
 

include/linux/pipe_fs_i.h

@@ -70,11 +70,11 @@ struct pipe_inode_info {
  * Note on the nesting of these functions:
  *
  * ->confirm()
- *	->steal()
+ *	->try_steal()
  *
- * That is, ->steal() must be called on a confirmed buffer.
- * See below for the meaning of each operation. Also see kerneldoc
- * in fs/pipe.c for the pipe and generic variants of these hooks.
+ * That is, ->try_steal() must be called on a confirmed buffer.  See below for
+ * the meaning of each operation.  Also see the kerneldoc in fs/pipe.c for the
+ * pipe and generic variants of these hooks.
  */
 struct pipe_buf_operations {
 	/*
@@ -94,13 +94,13 @@ struct pipe_buf_operations {
 
 	/*
 	 * Attempt to take ownership of the pipe buffer and its contents.
-	 * ->steal() returns 0 for success, in which case the contents
-	 * of the pipe (the buf->page) is locked and now completely owned
-	 * by the caller. The page may then be transferred to a different
-	 * mapping, the most often used case is insertion into different
-	 * file address space cache.
+	 * ->try_steal() returns %true for success, in which case the contents
+	 * of the pipe (the buf->page) is locked and now completely owned by the
+	 * caller. The page may then be transferred to a different mapping, the
+	 * most often used case is insertion into different file address space
+	 * cache.
 	 */
-	int (*steal)(struct pipe_inode_info *, struct pipe_buffer *);
+	bool (*try_steal)(struct pipe_inode_info *, struct pipe_buffer *);
 
 	/*
 	 * Get a reference to the pipe buffer.
@@ -201,16 +201,16 @@ static inline int pipe_buf_confirm(struct pipe_inode_info *pipe,
 }
 
 /**
- * pipe_buf_steal - attempt to take ownership of a pipe_buffer
+ * pipe_buf_try_steal - attempt to take ownership of a pipe_buffer
  * @pipe:	the pipe that the buffer belongs to
  * @buf:	the buffer to attempt to steal
  */
-static inline int pipe_buf_steal(struct pipe_inode_info *pipe,
+static inline bool pipe_buf_try_steal(struct pipe_inode_info *pipe,
 		struct pipe_buffer *buf)
 {
-	if (!buf->ops->steal)
-		return 1;
-	return buf->ops->steal(pipe, buf);
+	if (!buf->ops->try_steal)
+		return false;
+	return buf->ops->try_steal(pipe, buf);
 }
 
 /* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
@@ -234,7 +234,7 @@ void free_pipe_info(struct pipe_inode_info *);
 
 /* Generic pipe buffer ops functions */
 bool generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
-int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *);
+bool generic_pipe_buf_try_steal(struct pipe_inode_info *, struct pipe_buffer *);
 void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *);
 
 extern const struct pipe_buf_operations nosteal_pipe_buf_ops;

kernel/relay.c

@@ -1178,7 +1178,7 @@ static void relay_pipe_buf_release(struct pipe_inode_info *pipe,
 
 static const struct pipe_buf_operations relay_pipe_buf_ops = {
 	.release	= relay_pipe_buf_release,
-	.steal = generic_pipe_buf_steal,
+	.try_steal	= generic_pipe_buf_try_steal,
 	.get		= generic_pipe_buf_get,
 };