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

8 files changed, 77 insertions, 170 deletions

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 3cbaec925606..00c5e3acee46 100644
--- a/drivers/char/virtio_console.c
+++ b/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);
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index c7a65cf2bcca..4907e3d1f56c 100644
--- a/fs/fuse/dev.c
+++ b/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;
diff --git a/fs/pipe.c b/fs/pipe.c
index 16fb72e9abf7..c7c4fb5f345f 100644
--- a/fs/pipe.c
+++ b/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
@@ -201,22 +199,6 @@ 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
  * @buf:	the buffer to put a reference 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);
diff --git a/fs/splice.c b/fs/splice.c
index 5013565eb756..6b3c9a018a8e 100644
--- a/fs/splice.c
+++ b/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 @@ error:
 }
 
 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 @@ retry:
 			*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;
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index ae58fad7f1e0..0c31b9461262 100644
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -8,6 +8,7 @@
 #define PIPE_BUF_FLAG_ATOMIC	0x02	/* was atomically mapped */
 #define PIPE_BUF_FLAG_GIFT	0x04	/* page is a gift */
 #define PIPE_BUF_FLAG_PACKET	0x08	/* read() as a packet */
+#define PIPE_BUF_FLAG_CAN_MERGE	0x10	/* can merge buffers */
 
 /**
  *	struct pipe_buffer - a linux kernel pipe buffer
@@ -69,11 +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 {
 	/*
@@ -81,7 +82,7 @@ struct pipe_buf_operations {
 	 * and that the contents are good. If the pages in the pipe belong
 	 * to a file system, we may need to wait for IO completion in this
 	 * hook. Returns 0 for good, or a negative error value in case of
-	 * error.
+	 * error.  If not present all pages are considered good.
 	 */
 	int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *);
 
@@ -93,13 +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.
@@ -194,18 +195,22 @@ static inline void pipe_buf_release(struct pipe_inode_info *pipe,
 static inline int pipe_buf_confirm(struct pipe_inode_info *pipe,
 				   struct pipe_buffer *buf)
 {
+	if (!buf->ops->confirm)
+		return 0;
 	return buf->ops->confirm(pipe, buf);
 }
 
 /**
- * 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,
-				 struct pipe_buffer *buf)
+static inline bool pipe_buf_try_steal(struct pipe_inode_info *pipe,
+		struct pipe_buffer *buf)
 {
-	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
@@ -229,11 +234,8 @@ 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_confirm(struct pipe_inode_info *, struct pipe_buffer *);
-int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *);
-int generic_pipe_buf_nosteal(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 *);
-void pipe_buf_mark_unmergeable(struct pipe_buffer *buf);
 
 extern const struct pipe_buf_operations nosteal_pipe_buf_ops;
 
diff --git a/kernel/relay.c b/kernel/relay.c
index d0c9c287680a..90c7a002436d 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -1177,10 +1177,9 @@ static void relay_pipe_buf_release(struct pipe_inode_info *pipe,
 }
 
 static const struct pipe_buf_operations relay_pipe_buf_ops = {
-	.confirm = generic_pipe_buf_confirm,
-	.release = relay_pipe_buf_release,
-	.steal = generic_pipe_buf_steal,
-	.get = generic_pipe_buf_get,
+	.release	= relay_pipe_buf_release,
+	.try_steal	= generic_pipe_buf_try_steal,
+	.get		= generic_pipe_buf_get,
 };
 
 static void relay_page_release(struct splice_pipe_desc *spd, unsigned int i)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index f12e99b387b2..0b144926bd73 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6305,13 +6305,6 @@ static void tracing_spd_release_pipe(struct splice_pipe_desc *spd,
 	__free_page(spd->pages[idx]);
 }
 
-static const struct pipe_buf_operations tracing_pipe_buf_ops = {
-	.confirm		= generic_pipe_buf_confirm,
-	.release		= generic_pipe_buf_release,
-	.steal			= generic_pipe_buf_steal,
-	.get			= generic_pipe_buf_get,
-};
-
 static size_t
 tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
 {
@@ -6373,7 +6366,7 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
 		.partial	= partial_def,
 		.nr_pages	= 0, /* This gets updated below. */
 		.nr_pages_max	= PIPE_DEF_BUFFERS,
-		.ops		= &tracing_pipe_buf_ops,
+		.ops		= &default_pipe_buf_ops,
 		.spd_release	= tracing_spd_release_pipe,
 	};
 	ssize_t ret;
@@ -7582,9 +7575,7 @@ static bool buffer_pipe_buf_get(struct pipe_inode_info *pipe,
 
 /* Pipe buffer operations for a buffer. */
 static const struct pipe_buf_operations buffer_pipe_buf_ops = {
-	.confirm		= generic_pipe_buf_confirm,
 	.release		= buffer_pipe_buf_release,
-	.steal			= generic_pipe_buf_nosteal,
 	.get			= buffer_pipe_buf_get,
 };
 
diff --git a/net/smc/smc_rx.c b/net/smc/smc_rx.c
index 39d7b34d06d2..fcfac59f8b72 100644
--- a/net/smc/smc_rx.c
+++ b/net/smc/smc_rx.c
@@ -129,16 +129,8 @@ out:
 	sock_put(sk);
 }
 
-static int smc_rx_pipe_buf_nosteal(struct pipe_inode_info *pipe,
-				   struct pipe_buffer *buf)
-{
-	return 1;
-}
-
 static const struct pipe_buf_operations smc_pipe_ops = {
-	.confirm = generic_pipe_buf_confirm,
 	.release = smc_rx_pipe_buf_release,
-	.steal = smc_rx_pipe_buf_nosteal,
 	.get = generic_pipe_buf_get
 };