[PATCH] Introduce generic_file_splice_write_nolock()
This allows file systems to manage their own i_mutex locking while
still re-using the generic_file_splice_write() logic.
OCFS2 in particular wants this so that it can order cluster locks within
i_mutex.
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fs/splice.c b/fs/splice.c
index c1072b6..68e20e6 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -707,13 +707,12 @@
* key here is the 'actor' worker passed in that actually moves the data
* to the wanted destination. See pipe_to_file/pipe_to_sendpage above.
*/
-ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
- loff_t *ppos, size_t len, unsigned int flags,
- splice_actor *actor)
+static ssize_t __splice_from_pipe(struct pipe_inode_info *pipe,
+ struct file *out, loff_t *ppos, size_t len,
+ unsigned int flags, splice_actor *actor)
{
int ret, do_wakeup, err;
struct splice_desc sd;
- struct inode *inode = out->f_mapping->host;
ret = 0;
do_wakeup = 0;
@@ -723,14 +722,6 @@
sd.file = out;
sd.pos = *ppos;
- /*
- * The actor worker might be calling ->prepare_write and
- * ->commit_write. 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.
- */
- inode_double_lock(inode, pipe->inode);
-
for (;;) {
if (pipe->nrbufs) {
struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
@@ -803,8 +794,6 @@
pipe_wait(pipe);
}
- inode_double_unlock(inode, pipe->inode);
-
if (do_wakeup) {
smp_mb();
if (waitqueue_active(&pipe->wait))
@@ -815,6 +804,69 @@
return ret;
}
+ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
+ loff_t *ppos, size_t len, unsigned int flags,
+ splice_actor *actor)
+{
+ ssize_t ret;
+ struct inode *inode = out->f_mapping->host;
+
+ /*
+ * The actor worker might be calling ->prepare_write and
+ * ->commit_write. 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.
+ */
+ inode_double_lock(inode, pipe->inode);
+ ret = __splice_from_pipe(pipe, out, ppos, len, flags, actor);
+ inode_double_unlock(inode, pipe->inode);
+
+ return ret;
+}
+
+/**
+ * generic_file_splice_write_nolock - generic_file_splice_write without mutexes
+ * @pipe: pipe info
+ * @out: file to write to
+ * @len: number of bytes to splice
+ * @flags: splice modifier flags
+ *
+ * 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.
+ *
+ */
+ssize_t
+generic_file_splice_write_nolock(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;
+ ssize_t ret;
+ int err;
+
+ ret = __splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_file);
+ if (ret > 0) {
+ *ppos += ret;
+
+ /*
+ * 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;
+ }
+ }
+
+ return ret;
+}
+
+EXPORT_SYMBOL(generic_file_splice_write_nolock);
+
/**
* generic_file_splice_write - splice data from a pipe to a file
* @pipe: pipe info