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[PATCH 3/5] splice: use splice_from_pipe in generic_file_splice_write

To: Al Viro <viro@xxxxxxxxxxxxxxxxxx>, Jens Axboe <axboe@xxxxxxxxx>, Mark Fasheh <mfasheh@xxxxxxxx>, Joel Becker <jlbec@xxxxxxxxxxxx>
Subject: [PATCH 3/5] splice: use splice_from_pipe in generic_file_splice_write
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Thu, 12 Dec 2013 10:15:02 -0800
Cc: linux-fsdevel@xxxxxxxxxxxxxxx, xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
References: <20131212181459.994196463@xxxxxxxxxxxxxxxxxxxxxx>
User-agent: quilt/0.60-1
Reuse generic_write_sync instead of reimplementing it in the splice
write path both in the generic code and ocfs2.  Only needs a little
bit of refactoring for the actors to provide the desired functionality.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 fs/ocfs2/file.c        |   58 ++++++++++-----------------------------------
 fs/splice.c            |   61 +++++++++++++++++-------------------------------
 include/linux/splice.h |    2 ++
 3 files changed, 36 insertions(+), 85 deletions(-)

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index c68e111..5b1b5f9 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2423,38 +2423,14 @@ out_sems:
        return 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, &sd->pos,
-                                           sd->total_len, 0, NULL, 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,
                                       size_t len,
                                       unsigned int flags)
 {
-       int ret;
-       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,
-       };
-
+       struct inode *inode = out->f_mapping->host;
+       ssize_t ret;
 
        trace_ocfs2_file_splice_write(inode, out, out->f_path.dentry,
                        (unsigned long long)OCFS2_I(inode)->ip_blkno,
@@ -2467,35 +2443,25 @@ static ssize_t ocfs2_file_splice_write(struct 
pipe_inode_info *pipe,
                mlog_errno(ret);
                goto out_unlock_inode;
        }
-       pipe_lock(pipe);
 
-       splice_from_pipe_begin(&sd);
-       do {
-               ret = splice_from_pipe_next(pipe, &sd);
-               if (ret <= 0)
-                       break;
-
-               ret = ocfs2_splice_to_file(pipe, out, &sd);
-       } while (ret > 0);
-       splice_from_pipe_end(pipe, &sd);
+       ret = ocfs2_prepare_inode_for_write(out, ppos, len, 0, NULL, NULL);
+       if (ret < 0) {
+               mlog_errno(ret);
+               goto out_unlock_rw;
+       }
 
-       pipe_unlock(pipe);
+       ret = splice_from_pipe(pipe, out, ppos, len, flags, __pipe_to_file);
 
+out_unlock_rw:
        ocfs2_rw_unlock(inode, 1);
 out_unlock_inode:
        mutex_unlock(&inode->i_mutex);
 
-       if (sd.num_spliced)
-               ret = sd.num_spliced;
-
        if (ret > 0) {
-               int err;
-
-               err = generic_write_sync(out, *ppos, ret);
+               int err = generic_write_sync(out, *ppos, ret);
                if (err)
-                       ret = err;
-               else
-                       *ppos += ret;
+                       return ret;
+               *ppos += ret;
        }
 
        return ret;
diff --git a/fs/splice.c b/fs/splice.c
index 4fb6c1f..108e527 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -727,7 +727,7 @@ 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.
  */
-int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
+int __pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
                 struct splice_desc *sd)
 {
        struct file *file = sd->u.file;
@@ -766,6 +766,22 @@ int pipe_to_file(struct pipe_inode_info *pipe, struct 
pipe_buffer *buf,
 out:
        return ret;
 }
+EXPORT_SYMBOL(__pipe_to_file);
+
+int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
+                struct splice_desc *sd)
+{
+       struct file *file = sd->u.file;
+       int ret;
+
+       ret = file_remove_suid(file);
+       if (ret)
+               return ret;
+       ret = file_update_time(file);
+       if (ret)
+               return ret;
+       return __pipe_to_file(pipe, buf, sd);
+}
 EXPORT_SYMBOL(pipe_to_file);
 
 static void wakeup_pipe_writers(struct pipe_inode_info *pipe)
@@ -995,55 +1011,22 @@ 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,
-       };
+       struct inode *inode = out->f_mapping->host;
        ssize_t ret;
 
        mutex_lock(&inode->i_mutex);
-
-       pipe_lock(pipe);
-
-       splice_from_pipe_begin(&sd);
-       do {
-               ret = splice_from_pipe_next(pipe, &sd);
-               if (ret <= 0)
-                       break;
-
-               ret = file_remove_suid(out);
-               if (!ret) {
-                       ret = file_update_time(out);
-                       if (!ret)
-                               ret = splice_from_pipe_feed(pipe, &sd,
-                                                           pipe_to_file);
-               }
-       } while (ret > 0);
-       splice_from_pipe_end(pipe, &sd);
-
-       pipe_unlock(pipe);
+       ret = splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_file);
        mutex_unlock(&inode->i_mutex);
 
-       if (sd.num_spliced)
-               ret = sd.num_spliced;
-
        if (ret > 0) {
-               int err;
-
-               err = generic_write_sync(out, *ppos, ret);
+               int err = generic_write_sync(out, *ppos, ret);
                if (err)
-                       ret = err;
-               else
-                       *ppos += ret;
+                       return err;
+               *ppos += ret;
        }
 
        return ret;
 }
-
 EXPORT_SYMBOL(generic_file_splice_write);
 
 static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer 
*buf,
diff --git a/include/linux/splice.h b/include/linux/splice.h
index 74575cb..c5aca88 100644
--- a/include/linux/splice.h
+++ b/include/linux/splice.h
@@ -78,6 +78,8 @@ 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 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 *);
-- 
1.7.10.4


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