Merge branch 'work.splice' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull splice updates from Al Viro:
 "Christoph's assorted splice cleanups"

* 'work.splice' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  fs: rename pipe_buf ->steal to ->try_steal
  fs: make the pipe_buf_operations ->confirm operation optional
  fs: make the pipe_buf_operations ->steal operation optional
  trace: remove tracing_pipe_buf_ops
  pipe: merge anon_pipe_buf*_ops
  fs: simplify do_splice_from
  fs: simplify do_splice_to

Author: torvalds

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,
-			       struct pipe_buffer *buf)
+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) {
-		memcg_kmem_uncharge_page(page, 0);
-		__SetPageLocked(page);
-		return 0;
-	}
-	return 1;
+	if (page_count(page) != 1)
+		return false;
+	memcg_kmem_uncharge_page(page, 0);
+	__SetPageLocked(page);
+	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
  *
@@ -165,8 +164,8 @@ 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,
-			   struct pipe_buffer *buf)
+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
@@ -200,22 +198,6 @@ bool generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
 }
 EXPORT_SYMBOL(generic_pipe_buf_get);
 
-/**
- * generic_pipe_buf_confirm - verify contents of the pipe buffer
- * @info:	the pipe that the buffer belongs to
- * @buf:	the buffer to confirm
- *
- * Description:
- *	This function does nothing, because the generic pipe code uses
- *	pages that are always good when inserted into the pipe.
- */
-int generic_pipe_buf_confirm(struct pipe_inode_info *info,
-			     struct pipe_buffer *buf)
-{
-	return 0;
-}
-EXPORT_SYMBOL(generic_pipe_buf_confirm);
-
 /**
  * generic_pipe_buf_release - put a reference to a &struct pipe_buffer
  * @pipe:	the pipe that the buffer belongs to
@@ -231,48 +213,12 @@ void generic_pipe_buf_release(struct pipe_inode_info *pipe,
 }
 EXPORT_SYMBOL(generic_pipe_buf_release);
 
-/* New data written to a pipe may be appended to a buffer with this type. */
 static const struct pipe_buf_operations anon_pipe_buf_ops = {
-	.confirm = generic_pipe_buf_confirm,
-	.release = anon_pipe_buf_release,
-	.steal = anon_pipe_buf_steal,
-	.get = generic_pipe_buf_get,
-};
-
-static const struct pipe_buf_operations anon_pipe_buf_nomerge_ops = {
-	.confirm = generic_pipe_buf_confirm,
-	.release = anon_pipe_buf_release,
-	.steal = anon_pipe_buf_steal,
-	.get = generic_pipe_buf_get,
-};
-
-static const struct pipe_buf_operations packet_pipe_buf_ops = {
-	.confirm = generic_pipe_buf_confirm,
-	.release = anon_pipe_buf_release,
-	.steal = anon_pipe_buf_steal,
-	.get = generic_pipe_buf_get,
+	.release	= anon_pipe_buf_release,
+	.try_steal	= anon_pipe_buf_try_steal,
+	.get		= generic_pipe_buf_get,
 };
 
-/**
- * pipe_buf_mark_unmergeable - mark a &struct pipe_buffer as unmergeable
- * @buf:	the buffer to mark
- *
- * Description:
- *	This function ensures that no future writes will be merged into the
- *	given &struct pipe_buffer. This is necessary when multiple pipe buffers
- *	share the same backing page.
- */
-void pipe_buf_mark_unmergeable(struct pipe_buffer *buf)
-{
-	if (buf->ops == &anon_pipe_buf_ops)
-		buf->ops = &anon_pipe_buf_nomerge_ops;
-}
-
-static bool pipe_buf_can_merge(struct pipe_buffer *buf)
-{
-	return buf->ops == &anon_pipe_buf_ops;
-}
-
 /* Done while waiting without holding the pipe lock - thus the READ_ONCE() */
 static inline bool pipe_readable(const struct pipe_inode_info *pipe)
 {
@@ -478,7 +424,8 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from)
 		struct pipe_buffer *buf = &pipe->bufs[(head - 1) & mask];
 		int offset = buf->offset + buf->len;
 
-		if (pipe_buf_can_merge(buf) && offset + chars <= PAGE_SIZE) {
+		if ((buf->flags & PIPE_BUF_FLAG_CAN_MERGE) &&
+		    offset + chars <= PAGE_SIZE) {
 			ret = pipe_buf_confirm(pipe, buf);
 			if (ret)
 				goto out;
@@ -541,11 +488,10 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from)
 			buf->ops = &anon_pipe_buf_ops;
 			buf->offset = 0;
 			buf->len = 0;
-			buf->flags = 0;
-			if (is_packetized(filp)) {
-				buf->ops = &packet_pipe_buf_ops;
+			if (is_packetized(filp))
 				buf->flags = PIPE_BUF_FLAG_PACKET;
-			}
+			else
+				buf->flags = PIPE_BUF_FLAG_CAN_MERGE;
 			pipe->tmp_page = NULL;
 
 			copied = copy_page_from_iter(page, 0, PAGE_SIZE, from);

fs/splice.c

@@ -44,8 +44,8 @@
  * 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,
-				     struct pipe_buffer *buf)
+static bool page_cache_pipe_buf_try_steal(struct pipe_inode_info *pipe,
+		struct pipe_buffer *buf)
 {
 	struct page *page = buf->page;
 	struct address_space *mapping;
@@ -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,
@@ -139,27 +139,26 @@ 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,
-	.get = generic_pipe_buf_get,
+	.confirm	= page_cache_pipe_buf_confirm,
+	.release	= page_cache_pipe_buf_release,
+	.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,
-				    struct pipe_buffer *buf)
+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 = {
-	.confirm = generic_pipe_buf_confirm,
-	.release = page_cache_pipe_buf_release,
-	.steal = user_page_pipe_buf_steal,
-	.get = generic_pipe_buf_get,
+	.release	= page_cache_pipe_buf_release,
+	.try_steal	= user_page_pipe_buf_try_steal,
+	.get		= generic_pipe_buf_get,
 };
 
 static void wakeup_pipe_readers(struct pipe_inode_info *pipe)
@@ -331,24 +330,15 @@ ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
 EXPORT_SYMBOL(generic_file_splice_read);
 
 const struct pipe_buf_operations default_pipe_buf_ops = {
-	.confirm = generic_pipe_buf_confirm,
-	.release = generic_pipe_buf_release,
-	.steal = generic_pipe_buf_steal,
-	.get = generic_pipe_buf_get,
+	.release	= generic_pipe_buf_release,
+	.try_steal	= generic_pipe_buf_try_steal,
+	.get		= generic_pipe_buf_get,
 };
 
-int generic_pipe_buf_nosteal(struct pipe_inode_info *pipe,
-			     struct pipe_buffer *buf)
-{
-	return 1;
-}
-
 /* Pipe buffer operations for a socket and similar. */
 const struct pipe_buf_operations nosteal_pipe_buf_ops = {
-	.confirm = generic_pipe_buf_confirm,
-	.release = generic_pipe_buf_release,
-	.steal = generic_pipe_buf_nosteal,
-	.get = generic_pipe_buf_get,
+	.release	= generic_pipe_buf_release,
+	.get		= generic_pipe_buf_get,
 };
 EXPORT_SYMBOL(nosteal_pipe_buf_ops);
 
@@ -852,15 +842,9 @@ EXPORT_SYMBOL(generic_splice_sendpage);
 static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
 			   loff_t *ppos, size_t len, unsigned int flags)
 {
-	ssize_t (*splice_write)(struct pipe_inode_info *, struct file *,
-				loff_t *, size_t, unsigned int);
-
 	if (out->f_op->splice_write)
-		splice_write = out->f_op->splice_write;
-	else
-		splice_write = default_file_splice_write;
-
-	return splice_write(pipe, out, ppos, len, flags);
+		return out->f_op->splice_write(pipe, out, ppos, len, flags);
+	return default_file_splice_write(pipe, out, ppos, len, flags);
 }
 
 /*
@@ -870,8 +854,6 @@ static long do_splice_to(struct file *in, loff_t *ppos,
 			 struct pipe_inode_info *pipe, size_t len,
 			 unsigned int flags)
 {
-	ssize_t (*splice_read)(struct file *, loff_t *,
-			       struct pipe_inode_info *, size_t, unsigned int);
 	int ret;
 
 	if (unlikely(!(in->f_mode & FMODE_READ)))
@@ -885,11 +867,8 @@ static long do_splice_to(struct file *in, loff_t *ppos,
 		len = MAX_RW_COUNT;
 
 	if (in->f_op->splice_read)
-		splice_read = in->f_op->splice_read;
-	else
-		splice_read = default_file_splice_read;
-
-	return splice_read(in, ppos, pipe, len, flags);
+		return in->f_op->splice_read(in, ppos, pipe, len, flags);
+	return default_file_splice_read(in, ppos, pipe, len, flags);
 }
 
 /**
@@ -1626,12 +1605,11 @@ static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
 			*obuf = *ibuf;
 
 			/*
-			 * Don't inherit the gift flag, we need to
+			 * Don't inherit the gift and merge flags, we need to
 			 * prevent multiple steals of this page.
 			 */
 			obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
-
-			pipe_buf_mark_unmergeable(obuf);
+			obuf->flags &= ~PIPE_BUF_FLAG_CAN_MERGE;
 
 			obuf->len = len;
 			ibuf->offset += len;
@@ -1719,12 +1697,11 @@ static int link_pipe(struct pipe_inode_info *ipipe,
 		*obuf = *ibuf;
 
 		/*
-		 * Don't inherit the gift flag, we need to
-		 * prevent multiple steals of this page.
+		 * Don't inherit the gift and merge flag, we need to prevent
+		 * multiple steals of this page.
 		 */
 		obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
-
-		pipe_buf_mark_unmergeable(obuf);
+		obuf->flags &= ~PIPE_BUF_FLAG_CAN_MERGE;
 
 		if (obuf->len > len)
 			obuf->len = len;