1 files changed, 230 insertions, 42 deletions

diff --git a/fs/splice.c b/fs/splice.c
index e50a460..8d57e89 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -125,12 +125,19 @@ static void page_cache_pipe_buf_unmap(struct pipe_inode_info *info,
 	kunmap(buf->page);
 }
 
+static void page_cache_pipe_buf_get(struct pipe_inode_info *info,
+				    struct pipe_buffer *buf)
+{
+	page_cache_get(buf->page);
+}
+
 static struct pipe_buf_operations page_cache_pipe_buf_ops = {
 	.can_merge = 0,
 	.map = page_cache_pipe_buf_map,
 	.unmap = page_cache_pipe_buf_unmap,
 	.release = page_cache_pipe_buf_release,
 	.steal = page_cache_pipe_buf_steal,
+	.get = page_cache_pipe_buf_get,
 };
 
 /*
@@ -231,8 +238,9 @@ static ssize_t move_to_pipe(struct pipe_inode_info *pipe, struct page **pages,
 }
 
 static int
-__generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe,
-			   size_t len, unsigned int flags)
+__generic_file_splice_read(struct file *in, loff_t *ppos,
+			   struct pipe_inode_info *pipe, size_t len,
+			   unsigned int flags)
 {
 	struct address_space *mapping = in->f_mapping;
 	unsigned int offset, nr_pages;
@@ -241,8 +249,8 @@ __generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe,
 	pgoff_t index;
 	int i, error;
 
-	index = in->f_pos >> PAGE_CACHE_SHIFT;
-	offset = in->f_pos & ~PAGE_CACHE_MASK;
+	index = *ppos >> PAGE_CACHE_SHIFT;
+	offset = *ppos & ~PAGE_CACHE_MASK;
 	nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
 
 	if (nr_pages > PIPE_BUFFERS)
@@ -348,8 +356,9 @@ fill_it:
  *
  * Will read pages from given file and fill them into a pipe.
  */
-ssize_t generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe,
-				 size_t len, unsigned int flags)
+ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
+				 struct pipe_inode_info *pipe, size_t len,
+				 unsigned int flags)
 {
 	ssize_t spliced;
 	int ret;
@@ -358,12 +367,12 @@ ssize_t generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe,
 	spliced = 0;
 
 	while (len) {
-		ret = __generic_file_splice_read(in, pipe, len, flags);
+		ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
 
 		if (ret <= 0)
 			break;
 
-		in->f_pos += ret;
+		*ppos += ret;
 		len -= ret;
 		spliced += ret;
 
@@ -561,7 +570,7 @@ typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
  * to the wanted destination. See pipe_to_file/pipe_to_sendpage above.
  */
 static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out,
-			      size_t len, unsigned int flags,
+			      loff_t *ppos, size_t len, unsigned int flags,
 			      splice_actor *actor)
 {
 	int ret, do_wakeup, err;
@@ -573,7 +582,7 @@ static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out,
 	sd.total_len = len;
 	sd.flags = flags;
 	sd.file = out;
-	sd.pos = out->f_pos;
+	sd.pos = *ppos;
 
 	if (pipe->inode)
 		mutex_lock(&pipe->inode->i_mutex);
@@ -656,9 +665,7 @@ static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out,
 		kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
 	}
 
-	out->f_pos = sd.pos;
 	return ret;
-
 }
 
 /**
@@ -674,12 +681,12 @@ static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out,
  */
 ssize_t
 generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
-			  size_t len, unsigned int flags)
+			  loff_t *ppos, size_t len, unsigned int flags)
 {
 	struct address_space *mapping = out->f_mapping;
 	ssize_t ret;
 
-	ret = move_from_pipe(pipe, out, len, flags, pipe_to_file);
+	ret = move_from_pipe(pipe, out, ppos, len, flags, pipe_to_file);
 
 	/*
 	 * If file or inode is SYNC and we actually wrote some data, sync it.
@@ -715,9 +722,9 @@ EXPORT_SYMBOL(generic_file_splice_write);
  *
  */
 ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
-				size_t len, unsigned int flags)
+				loff_t *ppos, size_t len, unsigned int flags)
 {
-	return move_from_pipe(pipe, out, len, flags, pipe_to_sendpage);
+	return move_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
 }
 
 EXPORT_SYMBOL(generic_splice_sendpage);
@@ -726,9 +733,8 @@ EXPORT_SYMBOL(generic_splice_sendpage);
  * Attempt to initiate a splice from pipe to file.
  */
 static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
-			   size_t len, unsigned int flags)
+			   loff_t *ppos, size_t len, unsigned int flags)
 {
-	loff_t pos;
 	int ret;
 
 	if (unlikely(!out->f_op || !out->f_op->splice_write))
@@ -737,22 +743,21 @@ static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
 	if (unlikely(!(out->f_mode & FMODE_WRITE)))
 		return -EBADF;
 
-	pos = out->f_pos;
-
-	ret = rw_verify_area(WRITE, out, &pos, len);
+	ret = rw_verify_area(WRITE, out, ppos, len);
 	if (unlikely(ret < 0))
 		return ret;
 
-	return out->f_op->splice_write(pipe, out, len, flags);
+	return out->f_op->splice_write(pipe, out, ppos, len, flags);
 }
 
 /*
  * Attempt to initiate a splice from a file to a pipe.
  */
-static long do_splice_to(struct file *in, struct pipe_inode_info *pipe,
-			 size_t len, unsigned int flags)
+static long do_splice_to(struct file *in, loff_t *ppos,
+			 struct pipe_inode_info *pipe, size_t len,
+			 unsigned int flags)
 {
-	loff_t pos, isize, left;
+	loff_t isize, left;
 	int ret;
 
 	if (unlikely(!in->f_op || !in->f_op->splice_read))
@@ -761,28 +766,27 @@ static long do_splice_to(struct file *in, struct pipe_inode_info *pipe,
 	if (unlikely(!(in->f_mode & FMODE_READ)))
 		return -EBADF;
 
-	pos = in->f_pos;
-
-	ret = rw_verify_area(READ, in, &pos, len);
+	ret = rw_verify_area(READ, in, ppos, len);
 	if (unlikely(ret < 0))
 		return ret;
 
 	isize = i_size_read(in->f_mapping->host);
-	if (unlikely(in->f_pos >= isize))
+	if (unlikely(*ppos >= isize))
 		return 0;
 	
-	left = isize - in->f_pos;
+	left = isize - *ppos;
 	if (unlikely(left < len))
 		len = left;
 
-	return in->f_op->splice_read(in, pipe, len, flags);
+	return in->f_op->splice_read(in, ppos, pipe, len, flags);
 }
 
-long do_splice_direct(struct file *in, struct file *out, size_t len,
-		      unsigned int flags)
+long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
+		      size_t len, unsigned int flags)
 {
 	struct pipe_inode_info *pipe;
 	long ret, bytes;
+	loff_t out_off;
 	umode_t i_mode;
 	int i;
 
@@ -820,6 +824,7 @@ long do_splice_direct(struct file *in, struct file *out, size_t len,
 	 */
 	ret = 0;
 	bytes = 0;
+	out_off = 0;
 
 	while (len) {
 		size_t read_len, max_read_len;
@@ -829,7 +834,7 @@ long do_splice_direct(struct file *in, struct file *out, size_t len,
 		 */
 		max_read_len = min(len, (size_t)(PIPE_BUFFERS*PAGE_SIZE));
 
-		ret = do_splice_to(in, pipe, max_read_len, flags);
+		ret = do_splice_to(in, ppos, pipe, max_read_len, flags);
 		if (unlikely(ret < 0))
 			goto out_release;
 
@@ -840,7 +845,7 @@ long do_splice_direct(struct file *in, struct file *out, size_t len,
 		 * must not do the output in nonblocking mode as then we
 		 * could get stuck data in the internal pipe:
 		 */
-		ret = do_splice_from(pipe, out, read_len,
+		ret = do_splice_from(pipe, out, &out_off, read_len,
 				     flags & ~SPLICE_F_NONBLOCK);
 		if (unlikely(ret < 0))
 			goto out_release;
@@ -898,6 +903,7 @@ static long do_splice(struct file *in, loff_t __user *off_in,
 		      size_t len, unsigned int flags)
 {
 	struct pipe_inode_info *pipe;
+	loff_t offset, *off;
 
 	pipe = in->f_dentry->d_inode->i_pipe;
 	if (pipe) {
@@ -906,12 +912,13 @@ static long do_splice(struct file *in, loff_t __user *off_in,
 		if (off_out) {
 			if (out->f_op->llseek == no_llseek)
 				return -EINVAL;
-			if (copy_from_user(&out->f_pos, off_out,
-					   sizeof(loff_t)))
+			if (copy_from_user(&offset, off_out, sizeof(loff_t)))
 				return -EFAULT;
-		}
+			off = &offset;
+		} else
+			off = &out->f_pos;
 
-		return do_splice_from(pipe, out, len, flags);
+		return do_splice_from(pipe, out, off, len, flags);
 	}
 
 	pipe = out->f_dentry->d_inode->i_pipe;
@@ -921,11 +928,13 @@ static long do_splice(struct file *in, loff_t __user *off_in,
 		if (off_in) {
 			if (in->f_op->llseek == no_llseek)
 				return -EINVAL;
-			if (copy_from_user(&in->f_pos, off_in, sizeof(loff_t)))
+			if (copy_from_user(&offset, off_in, sizeof(loff_t)))
 				return -EFAULT;
-		}
+			off = &offset;
+		} else
+			off = &in->f_pos;
 
-		return do_splice_to(in, pipe, len, flags);
+		return do_splice_to(in, off, pipe, len, flags);
 	}
 
 	return -EINVAL;
@@ -961,3 +970,182 @@ asmlinkage long sys_splice(int fd_in, loff_t __user *off_in,
 
 	return error;
 }
+
+/*
+ * Link contents of ipipe to opipe.
+ */
+static int link_pipe(struct pipe_inode_info *ipipe,
+		     struct pipe_inode_info *opipe,
+		     size_t len, unsigned int flags)
+{
+	struct pipe_buffer *ibuf, *obuf;
+	int ret = 0, do_wakeup = 0, i;
+
+	/*
+	 * Potential ABBA deadlock, work around it by ordering lock
+	 * grabbing by inode address. Otherwise two different processes
+	 * could deadlock (one doing tee from A -> B, the other from B -> A).
+	 */
+	if (ipipe->inode < opipe->inode) {
+		mutex_lock(&ipipe->inode->i_mutex);
+		mutex_lock(&opipe->inode->i_mutex);
+	} else {
+		mutex_lock(&opipe->inode->i_mutex);
+		mutex_lock(&ipipe->inode->i_mutex);
+	}
+
+	for (i = 0;; i++) {
+		if (!opipe->readers) {
+			send_sig(SIGPIPE, current, 0);
+			if (!ret)
+				ret = -EPIPE;
+			break;
+		}
+		if (ipipe->nrbufs - i) {
+			ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1));
+
+			/*
+			 * If we have room, fill this buffer
+			 */
+			if (opipe->nrbufs < PIPE_BUFFERS) {
+				int nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1);
+
+				/*
+				 * Get a reference to this pipe buffer,
+				 * so we can copy the contents over.
+				 */
+				ibuf->ops->get(ipipe, ibuf);
+
+				obuf = opipe->bufs + nbuf;
+				*obuf = *ibuf;
+
+				if (obuf->len > len)
+					obuf->len = len;
+
+				opipe->nrbufs++;
+				do_wakeup = 1;
+				ret += obuf->len;
+				len -= obuf->len;
+
+				if (!len)
+					break;
+				if (opipe->nrbufs < PIPE_BUFFERS)
+					continue;
+			}
+
+			/*
+			 * We have input available, but no output room.
+			 * If we already copied data, return that.
+			 */
+			if (flags & SPLICE_F_NONBLOCK) {
+				if (!ret)
+					ret = -EAGAIN;
+				break;
+			}
+			if (signal_pending(current)) {
+				if (!ret)
+					ret = -ERESTARTSYS;
+				break;
+			}
+			if (do_wakeup) {
+				smp_mb();
+				if (waitqueue_active(&opipe->wait))
+					wake_up_interruptible(&opipe->wait);
+				kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
+				do_wakeup = 0;
+			}
+
+			opipe->waiting_writers++;
+			pipe_wait(opipe);
+			opipe->waiting_writers--;
+			continue;
+		}
+
+		/*
+		 * No input buffers, do the usual checks for available
+		 * writers and blocking and wait if necessary
+		 */
+		if (!ipipe->writers)
+			break;
+		if (!ipipe->waiting_writers) {
+			if (ret)
+				break;
+		}
+		if (flags & SPLICE_F_NONBLOCK) {
+			if (!ret)
+				ret = -EAGAIN;
+			break;
+		}
+		if (signal_pending(current)) {
+			if (!ret)
+				ret = -ERESTARTSYS;
+			break;
+		}
+
+		if (waitqueue_active(&ipipe->wait))
+			wake_up_interruptible_sync(&ipipe->wait);
+		kill_fasync(&ipipe->fasync_writers, SIGIO, POLL_OUT);
+
+		pipe_wait(ipipe);
+	}
+
+	mutex_unlock(&ipipe->inode->i_mutex);
+	mutex_unlock(&opipe->inode->i_mutex);
+
+	if (do_wakeup) {
+		smp_mb();
+		if (waitqueue_active(&opipe->wait))
+			wake_up_interruptible(&opipe->wait);
+		kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
+	}
+
+	return ret;
+}
+
+/*
+ * This is a tee(1) implementation that works on pipes. It doesn't copy
+ * any data, it simply references the 'in' pages on the 'out' pipe.
+ * The 'flags' used are the SPLICE_F_* variants, currently the only
+ * applicable one is SPLICE_F_NONBLOCK.
+ */
+static long do_tee(struct file *in, struct file *out, size_t len,
+		   unsigned int flags)
+{
+	struct pipe_inode_info *ipipe = in->f_dentry->d_inode->i_pipe;
+	struct pipe_inode_info *opipe = out->f_dentry->d_inode->i_pipe;
+
+	/*
+	 * Link ipipe to the two output pipes, consuming as we go along.
+	 */
+	if (ipipe && opipe)
+		return link_pipe(ipipe, opipe, len, flags);
+
+	return -EINVAL;
+}
+
+asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags)
+{
+	struct file *in;
+	int error, fput_in;
+
+	if (unlikely(!len))
+		return 0;
+
+	error = -EBADF;
+	in = fget_light(fdin, &fput_in);
+	if (in) {
+		if (in->f_mode & FMODE_READ) {
+			int fput_out;
+			struct file *out = fget_light(fdout, &fput_out);
+
+			if (out) {
+				if (out->f_mode & FMODE_WRITE)
+					error = do_tee(in, out, len, flags);
+				fput_light(out, fput_out);
+			}
+		}
+ 		fput_light(in, fput_in);
+ 	}
+
+	return error;
+}