ocfs2: fix i_mutex locking in ocfs2_splice_to_file()

Rearrange locking of i_mutex on destination and call to
ocfs2_rw_lock() so locks are only held while buffers are copied with
the pipe_to_file() actor, and not while waiting for more data on the
pipe.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

3 files changed, 79 insertions, 22 deletions

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 8672b9536039..c2a87c885b73 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1912,6 +1912,22 @@ out_sems:
         return written ? written : ret;
 }
 
+static int ocfs2_splice_to_file(struct pipe_inode_info *pipe,
+                                struct file *out,
+                                struct splice_desc *sd)
+{
+        int ret;
+
+        ret = ocfs2_prepare_inode_for_write(out->f_path.dentry, &sd->pos,
+                                            sd->total_len, 0, NULL);
+        if (ret < 0) {
+                mlog_errno(ret);
+                return ret;
+        }
+
+        return splice_from_pipe_feed(pipe, sd, pipe_to_file);
+}
+
 static ssize_t ocfs2_file_splice_write(struct pipe_inode_info *pipe,
                                        struct file *out,
                                        loff_t *ppos,
@@ -1919,38 +1935,76 @@ static ssize_t ocfs2_file_splice_write(struct pipe_inode_info *pipe,
                                        unsigned int flags)
 {
         int ret;
-        struct inode *inode = out->f_path.dentry->d_inode;
+        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,
+        };
 
         mlog_entry("(0x%p, 0x%p, %u, '%.*s')\n", out, pipe,
                    (unsigned int)len,
                    out->f_path.dentry->d_name.len,
                    out->f_path.dentry->d_name.name);
 
-        mutex_lock_nested(&inode->i_mutex, I_MUTEX_PARENT);
+        if (pipe->inode)
+                mutex_lock_nested(&pipe->inode->i_mutex, I_MUTEX_PARENT);
 
-        ret = ocfs2_rw_lock(inode, 1);
-        if (ret < 0) {
-                mlog_errno(ret);
-                goto out;
-        }
+        splice_from_pipe_begin(&sd);
+        do {
+                ret = splice_from_pipe_next(pipe, &sd);
+                if (ret <= 0)
+                        break;
 
-        ret = ocfs2_prepare_inode_for_write(out->f_path.dentry, ppos, len, 0,
-                                            NULL);
-        if (ret < 0) {
-                mlog_errno(ret);
-                goto out_unlock;
-        }
+                mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD);
+                ret = ocfs2_rw_lock(inode, 1);
+                if (ret < 0)
+                        mlog_errno(ret);
+                else {
+                        ret = ocfs2_splice_to_file(pipe, out, &sd);
+                        ocfs2_rw_unlock(inode, 1);
+                }
+                mutex_unlock(&inode->i_mutex);
+        } while (ret > 0);
+        splice_from_pipe_end(pipe, &sd);
 
         if (pipe->inode)
-                mutex_lock_nested(&pipe->inode->i_mutex, I_MUTEX_CHILD);
-        ret = generic_file_splice_write_nolock(pipe, out, ppos, len, flags);
-        if (pipe->inode)
                 mutex_unlock(&pipe->inode->i_mutex);
 
-out_unlock:
-        ocfs2_rw_unlock(inode, 1);
-out:
-        mutex_unlock(&inode->i_mutex);
+        if (sd.num_spliced)
+                ret = sd.num_spliced;
+
+        if (ret > 0) {
+                unsigned long nr_pages;
+
+                *ppos += ret;
+                nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+
+                /*
+                 * If file or inode is SYNC and we actually wrote some data,
+                 * sync it.
+                 */
+                if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) {
+                        int err;
+
+                        mutex_lock(&inode->i_mutex);
+                        err = ocfs2_rw_lock(inode, 1);
+                        if (err < 0) {
+                                mlog_errno(err);
+                        } else {
+                                err = generic_osync_inode(inode, mapping,
+                                                  OSYNC_METADATA|OSYNC_DATA);
+                                ocfs2_rw_unlock(inode, 1);
+                        }
+                        mutex_unlock(&inode->i_mutex);
+
+                        if (err)
+                                ret = err;
+                }
+                balance_dirty_pages_ratelimited_nr(mapping, nr_pages);
+        }
 
         mlog_exit(ret);
         return ret;
diff --git a/fs/splice.c b/fs/splice.c
index a1f595b9db40..584b2b7a1dbe 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -555,8 +555,8 @@ 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;
@@ -600,6 +600,7 @@ 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)
 {
diff --git a/include/linux/splice.h b/include/linux/splice.h
index 8fc2a635586e..5f3faa9d15ae 100644
--- a/include/linux/splice.h
+++ b/include/linux/splice.h
@@ -75,6 +75,8 @@ extern int splice_from_pipe_next(struct pipe_inode_info *,
 extern void splice_from_pipe_begin(struct splice_desc *);
 extern void splice_from_pipe_end(struct pipe_inode_info *,
                                  struct splice_desc *);
+extern int pipe_to_file(struct pipe_inode_info *, struct pipe_buffer *,
+                        struct splice_desc *);
 
 extern ssize_t splice_to_pipe(struct pipe_inode_info *,
                               struct splice_pipe_desc *);