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Subject[PATCH 1/18] splice: abstract out actor data
Date
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>
---
fs/ocfs2/file.c | 11 ++++-
fs/splice.c | 100 ++++++++++++++++++++++++++++++++-------------
include/linux/pipe_fs_i.h | 10 +++--
3 files changed, 85 insertions(+), 36 deletions(-)

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index ac6c964..eb97b20 100644
--- 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,
+ };
+
+ sd.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 cb21136..6871de6 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -666,31 +666,24 @@ 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;
@@ -702,10 +695,10 @@ 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) {
@@ -717,7 +710,7 @@ ssize_t __splice_from_pipe(struct pipe_inode_info *pipe,
do_wakeup = 1;
}

- if (!sd.total_len)
+ if (!sd->total_len)
break;
}

@@ -730,7 +723,7 @@ 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;
@@ -770,6 +763,13 @@ 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,
+ };
+
+ sd.file = out;

/*
* The actor worker might be calling ->prepare_write and
@@ -778,7 +778,7 @@ 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;
@@ -802,6 +802,11 @@ 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,
+ };
ssize_t ret;
int err;

@@ -809,7 +814,8 @@ 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);
+ sd.file = out;
+ ret = __splice_from_pipe(pipe, &sd, pipe_to_file);
if (ret > 0) {
*ppos += ret;

@@ -948,14 +954,17 @@ 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
@@ -991,7 +1000,13 @@ 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;
@@ -1001,19 +1016,19 @@ 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;

@@ -1058,6 +1073,33 @@ 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,
+ };
+ size_t ret;
+
+ sd.file = out;
+ 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
--- 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
--
1.5.2.1.174.gcd03
-
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