1 files changed, 186 insertions, 185 deletions

diff --git a/fs/splice.c b/fs/splice.c
index c18aa7e03e2b..5384a90665d0 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -182,8 +182,7 @@ ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
         do_wakeup = 0;
         page_nr = 0;
 
-        if (pipe->inode)
-                mutex_lock(&pipe->inode->i_mutex);
+        pipe_lock(pipe);
 
         for (;;) {
                 if (!pipe->readers) {
@@ -245,15 +244,13 @@ ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
                 pipe->waiting_writers--;
         }
 
-        if (pipe->inode) {
-                mutex_unlock(&pipe->inode->i_mutex);
+        pipe_unlock(pipe);
 
-                if (do_wakeup) {
-                        smp_mb();
-                        if (waitqueue_active(&pipe->wait))
-                                wake_up_interruptible(&pipe->wait);
-                        kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
-                }
+        if (do_wakeup) {
+                smp_mb();
+                if (waitqueue_active(&pipe->wait))
+                        wake_up_interruptible(&pipe->wait);
+                kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
         }
 
         while (page_nr < spd_pages)
@@ -555,8 +552,8 @@ static int pipe_to_sendpage(struct pipe_inode_info *pipe,
  * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create
  * a new page in the output file page cache and fill/dirty that.
  */
-static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
-                        struct splice_desc *sd)
+int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
+                 struct splice_desc *sd)
 {
         struct file *file = sd->u.file;
         struct address_space *mapping = file->f_mapping;
@@ -600,108 +597,178 @@ static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
 out:
         return ret;
 }
+EXPORT_SYMBOL(pipe_to_file);
+
+static void wakeup_pipe_writers(struct pipe_inode_info *pipe)
+{
+        smp_mb();
+        if (waitqueue_active(&pipe->wait))
+                wake_up_interruptible(&pipe->wait);
+        kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
+}
 
 /**
- * __splice_from_pipe - splice data from a pipe to given actor
+ * splice_from_pipe_feed - feed available data from a pipe to a file
  * @pipe:       pipe to splice from
  * @sd:         information to @actor
  * @actor:      handler that splices the data
  *
  * Description:
- *    This function does little more than loop over the pipe and call
- *    @actor to do the actual moving of a single struct pipe_buffer to
- *    the desired destination. See pipe_to_file, pipe_to_sendpage, or
- *    pipe_to_user.
+
+ *    This function loops over the pipe and calls @actor to do the
+ *    actual moving of a single struct pipe_buffer to the desired
+ *    destination.  It returns when there's no more buffers left in
+ *    the pipe or if the requested number of bytes (@sd->total_len)
+ *    have been copied.  It returns a positive number (one) if the
+ *    pipe needs to be filled with more data, zero if the required
+ *    number of bytes have been copied and -errno on error.
  *
+ *    This, together with splice_from_pipe_{begin,end,next}, may be
+ *    used to implement the functionality of __splice_from_pipe() when
+ *    locking is required around copying the pipe buffers to the
+ *    destination.
  */
-ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd,
-                           splice_actor *actor)
+int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd,
+                          splice_actor *actor)
 {
-        int ret, do_wakeup, err;
-
-        ret = 0;
-        do_wakeup = 0;
-
-        for (;;) {
-                if (pipe->nrbufs) {
-                        struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
-                        const struct pipe_buf_operations *ops = buf->ops;
+        int ret;
 
-                        sd->len = buf->len;
-                        if (sd->len > sd->total_len)
-                                sd->len = sd->total_len;
+        while (pipe->nrbufs) {
+                struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
+                const struct pipe_buf_operations *ops = buf->ops;
 
-                        err = actor(pipe, buf, sd);
-                        if (err <= 0) {
-                                if (!ret && err != -ENODATA)
-                                        ret = err;
+                sd->len = buf->len;
+                if (sd->len > sd->total_len)
+                        sd->len = sd->total_len;
 
-                                break;
-                        }
+                ret = actor(pipe, buf, sd);
+                if (ret <= 0) {
+                        if (ret == -ENODATA)
+                                ret = 0;
+                        return ret;
+                }
+                buf->offset += ret;
+                buf->len -= ret;
 
-                        ret += err;
-                        buf->offset += err;
-                        buf->len -= err;
+                sd->num_spliced += ret;
+                sd->len -= ret;
+                sd->pos += ret;
+                sd->total_len -= ret;
 
-                        sd->len -= err;
-                        sd->pos += err;
-                        sd->total_len -= err;
-                        if (sd->len)
-                                continue;
+                if (!buf->len) {
+                        buf->ops = NULL;
+                        ops->release(pipe, buf);
+                        pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1);
+                        pipe->nrbufs--;
+                        if (pipe->inode)
+                                sd->need_wakeup = true;
+                }
 
-                        if (!buf->len) {
-                                buf->ops = NULL;
-                                ops->release(pipe, buf);
-                                pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1);
-                                pipe->nrbufs--;
-                                if (pipe->inode)
-                                        do_wakeup = 1;
-                        }
+                if (!sd->total_len)
+                        return 0;
+        }
 
-                        if (!sd->total_len)
-                                break;
-                }
+        return 1;
+}
+EXPORT_SYMBOL(splice_from_pipe_feed);
 
-                if (pipe->nrbufs)
-                        continue;
+/**
+ * splice_from_pipe_next - wait for some data to splice from
+ * @pipe:       pipe to splice from
+ * @sd:         information about the splice operation
+ *
+ * Description:
+ *    This function will wait for some data and return a positive
+ *    value (one) if pipe buffers are available.  It will return zero
+ *    or -errno if no more data needs to be spliced.
+ */
+int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd)
+{
+        while (!pipe->nrbufs) {
                 if (!pipe->writers)
-                        break;
-                if (!pipe->waiting_writers) {
-                        if (ret)
-                                break;
-                }
+                        return 0;
 
-                if (sd->flags & SPLICE_F_NONBLOCK) {
-                        if (!ret)
-                                ret = -EAGAIN;
-                        break;
-                }
+                if (!pipe->waiting_writers && sd->num_spliced)
+                        return 0;
 
-                if (signal_pending(current)) {
-                        if (!ret)
-                                ret = -ERESTARTSYS;
-                        break;
-                }
+                if (sd->flags & SPLICE_F_NONBLOCK)
+                        return -EAGAIN;
 
-                if (do_wakeup) {
-                        smp_mb();
-                        if (waitqueue_active(&pipe->wait))
-                                wake_up_interruptible_sync(&pipe->wait);
-                        kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
-                        do_wakeup = 0;
+                if (signal_pending(current))
+                        return -ERESTARTSYS;
+
+                if (sd->need_wakeup) {
+                        wakeup_pipe_writers(pipe);
+                        sd->need_wakeup = false;
                 }
 
                 pipe_wait(pipe);
         }
 
-        if (do_wakeup) {
-                smp_mb();
-                if (waitqueue_active(&pipe->wait))
-                        wake_up_interruptible(&pipe->wait);
-                kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
-        }
+        return 1;
+}
+EXPORT_SYMBOL(splice_from_pipe_next);
 
-        return ret;
+/**
+ * splice_from_pipe_begin - start splicing from pipe
+ * @pipe:       pipe to splice from
+ *
+ * Description:
+ *    This function should be called before a loop containing
+ *    splice_from_pipe_next() and splice_from_pipe_feed() to
+ *    initialize the necessary fields of @sd.
+ */
+void splice_from_pipe_begin(struct splice_desc *sd)
+{
+        sd->num_spliced = 0;
+        sd->need_wakeup = false;
+}
+EXPORT_SYMBOL(splice_from_pipe_begin);
+
+/**
+ * splice_from_pipe_end - finish splicing from pipe
+ * @pipe:       pipe to splice from
+ * @sd:         information about the splice operation
+ *
+ * Description:
+ *    This function will wake up pipe writers if necessary.  It should
+ *    be called after a loop containing splice_from_pipe_next() and
+ *    splice_from_pipe_feed().
+ */
+void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd)
+{
+        if (sd->need_wakeup)
+                wakeup_pipe_writers(pipe);
+}
+EXPORT_SYMBOL(splice_from_pipe_end);
+
+/**
+ * __splice_from_pipe - splice data from a pipe to given actor
+ * @pipe:       pipe to splice from
+ * @sd:         information to @actor
+ * @actor:      handler that splices the data
+ *
+ * Description:
+ *    This function does little more than loop over the pipe and call
+ *    @actor to do the actual moving of a single struct pipe_buffer to
+ *    the desired destination. See pipe_to_file, pipe_to_sendpage, or
+ *    pipe_to_user.
+ *
+ */
+ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd,
+                           splice_actor *actor)
+{
+        int ret;
+
+        splice_from_pipe_begin(sd);
+        do {
+                ret = splice_from_pipe_next(pipe, sd);
+                if (ret > 0)
+                        ret = splice_from_pipe_feed(pipe, sd, actor);
+        } while (ret > 0);
+        splice_from_pipe_end(pipe, sd);
+
+        return sd->num_spliced ? sd->num_spliced : ret;
 }
 EXPORT_SYMBOL(__splice_from_pipe);
 
@@ -715,7 +782,7 @@ EXPORT_SYMBOL(__splice_from_pipe);
  * @actor:      handler that splices the data
  *
  * Description:
- *    See __splice_from_pipe. This function locks the input and output inodes,
+ *    See __splice_from_pipe. This function locks the pipe inode,
  *    otherwise it's identical to __splice_from_pipe().
  *
  */
@@ -724,7 +791,6 @@ ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
                          splice_actor *actor)
 {
         ssize_t ret;
-        struct inode *inode = out->f_mapping->host;
         struct splice_desc sd = {
                 .total_len = len,
                 .flags = flags,
@@ -732,30 +798,15 @@ ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
                 .u.file = out,
         };
 
-        /*
-         * The actor worker might be calling ->write_begin and
-         * ->write_end. Most of the time, these expect i_mutex to
-         * be held. Since this may result in an ABBA deadlock with
-         * pipe->inode, we have to order lock acquiry here.
-         *
-         * Outer lock must be inode->i_mutex, as pipe_wait() will
-         * release and reacquire pipe->inode->i_mutex, AND inode must
-         * never be a pipe.
-         */
-        WARN_ON(S_ISFIFO(inode->i_mode));
-        mutex_lock_nested(&inode->i_mutex, I_MUTEX_PARENT);
-        if (pipe->inode)
-                mutex_lock_nested(&pipe->inode->i_mutex, I_MUTEX_CHILD);
+        pipe_lock(pipe);
         ret = __splice_from_pipe(pipe, &sd, actor);
-        if (pipe->inode)
-                mutex_unlock(&pipe->inode->i_mutex);
-        mutex_unlock(&inode->i_mutex);
+        pipe_unlock(pipe);
 
         return ret;
 }
 
 /**
- * generic_file_splice_write_nolock - generic_file_splice_write without mutexes
+ * generic_file_splice_write - splice data from a pipe to a file
  * @pipe:       pipe info
  * @out:        file to write to
  * @ppos:       position in @out
@@ -764,13 +815,12 @@ ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
  *
  * Description:
  *    Will either move or copy pages (determined by @flags options) from
- *    the given pipe inode to the given file. The caller is responsible
- *    for acquiring i_mutex on both inodes.
+ *    the given pipe inode to the given file.
  *
  */
 ssize_t
-generic_file_splice_write_nolock(struct pipe_inode_info *pipe, struct file *out,
-                                 loff_t *ppos, size_t len, unsigned int flags)
+generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
+                          loff_t *ppos, size_t len, unsigned int flags)
 {
         struct address_space *mapping = out->f_mapping;
         struct inode *inode = mapping->host;
@@ -781,76 +831,28 @@ generic_file_splice_write_nolock(struct pipe_inode_info *pipe, struct file *out,
                 .u.file = out,
         };
         ssize_t ret;
-        int err;
-
-        err = file_remove_suid(out);
-        if (unlikely(err))
-                return err;
-
-        ret = __splice_from_pipe(pipe, &sd, pipe_to_file);
-        if (ret > 0) {
-                unsigned long nr_pages;
 
-                *ppos += ret;
-                nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+        pipe_lock(pipe);
 
-                /*
-                 * If file or inode is SYNC and we actually wrote some data,
-                 * sync it.
-                 */
-                if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) {
-                        err = generic_osync_inode(inode, mapping,
-                                                  OSYNC_METADATA|OSYNC_DATA);
-
-                        if (err)
-                                ret = err;
-                }
-                balance_dirty_pages_ratelimited_nr(mapping, nr_pages);
-        }
+        splice_from_pipe_begin(&sd);
+        do {
+                ret = splice_from_pipe_next(pipe, &sd);
+                if (ret <= 0)
+                        break;
 
-        return ret;
-}
+                mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD);
+                ret = file_remove_suid(out);
+                if (!ret)
+                        ret = splice_from_pipe_feed(pipe, &sd, pipe_to_file);
+                mutex_unlock(&inode->i_mutex);
+        } while (ret > 0);
+        splice_from_pipe_end(pipe, &sd);
 
-EXPORT_SYMBOL(generic_file_splice_write_nolock);
+        pipe_unlock(pipe);
 
-/**
- * generic_file_splice_write - splice data from a pipe to a file
- * @pipe:       pipe info
- * @out:        file to write to
- * @ppos:       position in @out
- * @len:        number of bytes to splice
- * @flags:      splice modifier flags
- *
- * Description:
- *    Will either move or copy pages (determined by @flags options) from
- *    the given pipe inode to the given file.
- *
- */
-ssize_t
-generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
-                          loff_t *ppos, size_t len, unsigned int flags)
-{
-        struct address_space *mapping = out->f_mapping;
-        struct inode *inode = mapping->host;
-        struct splice_desc sd = {
-                .total_len = len,
-                .flags = flags,
-                .pos = *ppos,
-                .u.file = out,
-        };
-        ssize_t ret;
+        if (sd.num_spliced)
+                ret = sd.num_spliced;
 
-        WARN_ON(S_ISFIFO(inode->i_mode));
-        mutex_lock_nested(&inode->i_mutex, I_MUTEX_PARENT);
-        ret = file_remove_suid(out);
-        if (likely(!ret)) {
-                if (pipe->inode)
-                        mutex_lock_nested(&pipe->inode->i_mutex, I_MUTEX_CHILD);
-                ret = __splice_from_pipe(pipe, &sd, pipe_to_file);
-                if (pipe->inode)
-                        mutex_unlock(&pipe->inode->i_mutex);
-        }
-        mutex_unlock(&inode->i_mutex);
         if (ret > 0) {
                 unsigned long nr_pages;
 
@@ -1339,8 +1341,7 @@ static long vmsplice_to_user(struct file *file, const struct iovec __user *iov,
         if (!pipe)
                 return -EBADF;
 
-        if (pipe->inode)
-                mutex_lock(&pipe->inode->i_mutex);
+        pipe_lock(pipe);
 
         error = ret = 0;
         while (nr_segs) {
@@ -1395,8 +1396,7 @@ static long vmsplice_to_user(struct file *file, const struct iovec __user *iov,
                 iov++;
         }
 
-        if (pipe->inode)
-                mutex_unlock(&pipe->inode->i_mutex);
+        pipe_unlock(pipe);
 
         if (!ret)
                 ret = error;
@@ -1524,7 +1524,7 @@ static int link_ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
                 return 0;
 
         ret = 0;
-        mutex_lock(&pipe->inode->i_mutex);
+        pipe_lock(pipe);
 
         while (!pipe->nrbufs) {
                 if (signal_pending(current)) {
@@ -1542,7 +1542,7 @@ static int link_ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
                 pipe_wait(pipe);
         }
 
-        mutex_unlock(&pipe->inode->i_mutex);
+        pipe_unlock(pipe);
         return ret;
 }
 
@@ -1562,7 +1562,7 @@ static int link_opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
                 return 0;
 
         ret = 0;
-        mutex_lock(&pipe->inode->i_mutex);
+        pipe_lock(pipe);
 
         while (pipe->nrbufs >= PIPE_BUFFERS) {
                 if (!pipe->readers) {
@@ -1583,7 +1583,7 @@ static int link_opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
                 pipe->waiting_writers--;
         }
 
-        mutex_unlock(&pipe->inode->i_mutex);
+        pipe_unlock(pipe);
         return ret;
 }
 
@@ -1599,10 +1599,10 @@ static int link_pipe(struct pipe_inode_info *ipipe,
 
         /*
          * Potential ABBA deadlock, work around it by ordering lock
-         * grabbing by inode address. Otherwise two different processes
+         * grabbing by pipe info address. Otherwise two different processes
          * could deadlock (one doing tee from A -> B, the other from B -> A).
          */
-        inode_double_lock(ipipe->inode, opipe->inode);
+        pipe_double_lock(ipipe, opipe);
 
         do {
                 if (!opipe->readers) {
@@ -1653,7 +1653,8 @@ static int link_pipe(struct pipe_inode_info *ipipe,
         if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK))
                 ret = -EAGAIN;
 
-        inode_double_unlock(ipipe->inode, opipe->inode);
+        pipe_unlock(ipipe);
+        pipe_unlock(opipe);
 
         /*
          * If we put data in the output pipe, wakeup any potential readers.