splice: abstract out actor data

For direct splicing (or private splicing), the output may not be a file.
So abstract out the handling into a specified actor function and put
the data in the splice_desc structure earlier, so we can build on top
of that.

This is the first step in better splice handling for drivers, and also
for implementing vmsplice _to_ user memory.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index ac6c964..93565c0 100644 (file)
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1636,9 +1636,14 @@ static ssize_t __ocfs2_file_splice_write(struct pipe_inode_info *pipe,
        int ret, err;
        struct address_space *mapping = out->f_mapping;
        struct inode *inode = mapping->host;
-
-       ret = __splice_from_pipe(pipe, out, ppos, len, flags,
-                                ocfs2_splice_write_actor);
+       struct splice_desc sd = {
+               .total_len = len,
+               .flags = flags,
+               .pos = *ppos,
+               .file = out,
+       };
+
+       ret = __splice_from_pipe(pipe, &sd, ocfs2_splice_write_actor);
        if (ret > 0) {
                *ppos += ret;
 

diff --git a/fs/splice.c b/fs/splice.c
index e7d7080..68f6328 100644 (file)
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -668,31 +668,24 @@ out_ret:
  * 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)
+ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd,
+                          splice_actor *actor)
 {
        int ret, do_wakeup, err;
-       struct splice_desc sd;
 
        ret = 0;
        do_wakeup = 0;
 
-       sd.total_len = len;
-       sd.flags = flags;
-       sd.file = out;
-       sd.pos = *ppos;
-
        for (;;) {
                if (pipe->nrbufs) {
                        struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
                        const struct pipe_buf_operations *ops = buf->ops;
 
-                       sd.len = buf->len;
-                       if (sd.len > sd.total_len)
-                               sd.len = sd.total_len;
+                       sd->len = buf->len;
+                       if (sd->len > sd->total_len)
+                               sd->len = sd->total_len;
 
-                       err = actor(pipe, buf, &sd);
+                       err = actor(pipe, buf, sd);
                        if (err <= 0) {
                                if (!ret && err != -ENODATA)
                                        ret = err;
@@ -704,10 +697,10 @@ ssize_t __splice_from_pipe(struct pipe_inode_info *pipe,
                        buf->offset += err;
                        buf->len -= err;
 
-                       sd.len -= err;
-                       sd.pos += err;
-                       sd.total_len -= err;
-                       if (sd.len)
+                       sd->len -= err;
+                       sd->pos += err;
+                       sd->total_len -= err;
+                       if (sd->len)
                                continue;
 
                        if (!buf->len) {
@@ -719,7 +712,7 @@ ssize_t __splice_from_pipe(struct pipe_inode_info *pipe,
                                        do_wakeup = 1;
                        }
 
-                       if (!sd.total_len)
+                       if (!sd->total_len)
                                break;
                }
 
@@ -732,7 +725,7 @@ ssize_t __splice_from_pipe(struct pipe_inode_info *pipe,
                                break;
                }
 
-               if (flags & SPLICE_F_NONBLOCK) {
+               if (sd->flags & SPLICE_F_NONBLOCK) {
                        if (!ret)
                                ret = -EAGAIN;
                        break;
@@ -772,6 +765,12 @@ ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
 {
        ssize_t ret;
        struct inode *inode = out->f_mapping->host;
+       struct splice_desc sd = {
+               .total_len = len,
+               .flags = flags,
+               .pos = *ppos,
+               .file = out,
+       };
 
        /*
         * The actor worker might be calling ->prepare_write and
@@ -780,7 +779,7 @@ ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
         * 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);
+       ret = __splice_from_pipe(pipe, &sd, actor);
        inode_double_unlock(inode, pipe->inode);
 
        return ret;
@@ -804,6 +803,12 @@ generic_file_splice_write_nolock(struct pipe_inode_info *pipe, struct file *out,
 {
        struct address_space *mapping = out->f_mapping;
        struct inode *inode = mapping->host;
+       struct splice_desc sd = {
+               .total_len = len,
+               .flags = flags,
+               .pos = *ppos,
+               .file = out,
+       };
        ssize_t ret;
        int err;
 
@@ -811,7 +816,7 @@ generic_file_splice_write_nolock(struct pipe_inode_info *pipe, struct file *out,
        if (unlikely(err))
                return err;
 
-       ret = __splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_file);
+       ret = __splice_from_pipe(pipe, &sd, pipe_to_file);
        if (ret > 0) {
                unsigned long nr_pages;
 
@@ -956,14 +961,17 @@ static long do_splice_to(struct file *in, loff_t *ppos,
        return in->f_op->splice_read(in, ppos, pipe, len, flags);
 }
 
-long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
-                     size_t len, unsigned int flags)
+/*
+ * Splices from an input file to an actor, using a 'direct' pipe.
+ */
+ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
+                              splice_direct_actor *actor)
 {
        struct pipe_inode_info *pipe;
        long ret, bytes;
-       loff_t out_off;
        umode_t i_mode;
-       int i;
+       size_t len;
+       int i, flags;
 
        /*
         * We require the input being a regular file, as we don't want to
@@ -999,7 +1007,13 @@ long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
         */
        ret = 0;
        bytes = 0;
-       out_off = 0;
+       len = sd->total_len;
+       flags = sd->flags;
+
+       /*
+        * Don't block on output, we have to drain the direct pipe.
+        */
+       sd->flags &= ~SPLICE_F_NONBLOCK;
 
        while (len) {
                size_t read_len, max_read_len;
@@ -1009,19 +1023,19 @@ long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
                 */
                max_read_len = min(len, (size_t)(PIPE_BUFFERS*PAGE_SIZE));
 
-               ret = do_splice_to(in, ppos, pipe, max_read_len, flags);
+               ret = do_splice_to(in, &sd->pos, pipe, max_read_len, flags);
                if (unlikely(ret < 0))
                        goto out_release;
 
                read_len = ret;
+               sd->total_len = read_len;
 
                /*
                 * NOTE: nonblocking mode only applies to the input. We
                 * 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, &out_off, read_len,
-                                    flags & ~SPLICE_F_NONBLOCK);
+               ret = actor(pipe, sd);
                if (unlikely(ret < 0))
                        goto out_release;
 
@@ -1066,6 +1080,33 @@ out_release:
                return bytes;
 
        return ret;
+
+}
+EXPORT_SYMBOL(splice_direct_to_actor);
+
+static int direct_splice_actor(struct pipe_inode_info *pipe,
+                              struct splice_desc *sd)
+{
+       struct file *file = sd->file;
+
+       return do_splice_from(pipe, file, &sd->pos, sd->total_len, sd->flags);
+}
+
+long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
+                     size_t len, unsigned int flags)
+{
+       struct splice_desc sd = {
+               .len            = len,
+               .total_len      = len,
+               .flags          = flags,
+               .pos            = *ppos,
+               .file           = out,
+       };
+       size_t ret;
+
+       ret = splice_direct_to_actor(in, &sd, direct_splice_actor);
+       *ppos = sd.pos;
+       return ret;
 }
 
 /*

diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index c8884f9..883ba9b 100644 (file)
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -94,13 +94,15 @@ struct splice_desc {
 
 typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
                           struct splice_desc *);
+typedef int (splice_direct_actor)(struct pipe_inode_info *,
+                                 struct splice_desc *);
 
 extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *,
                                loff_t *, size_t, unsigned int,
                                splice_actor *);
-
-extern ssize_t __splice_from_pipe(struct pipe_inode_info *, struct file *,
-                                 loff_t *, size_t, unsigned int,
-                                 splice_actor *);
+extern ssize_t __splice_from_pipe(struct pipe_inode_info *,
+                                 struct splice_desc *, splice_actor *);
+extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
+                                     splice_direct_actor *);
 
 #endif