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yaml
---
r: 143332
b: refs/heads/master
c: b3c2d2d
h: refs/heads/master
v: v3
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Miklos Szeredi authored and Jens Axboe committed Apr 15, 2009
1 parent 5a77f58 commit 44cf712
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Showing 3 changed files with 154 additions and 75 deletions.
2 changes: 1 addition & 1 deletion [refs]
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Original file line number Diff line number Diff line change
@@ -1,2 +1,2 @@
---
refs/heads/master: 91e463c8f5f7a5b09d3d034c01a88567af60c504
refs/heads/master: b3c2d2ddd63944ef2a1e4a43077b602288107e01
217 changes: 143 additions & 74 deletions trunk/fs/splice.c
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Original file line number Diff line number Diff line change
Expand Up @@ -601,107 +601,176 @@ static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
return ret;
}

static void wakeup_pipe_writers(struct pipe_inode_info *pipe)
{
smp_mb();
if (waitqueue_active(&pipe->wait))
wake_up_interruptible(&pipe->wait);
kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
}

/**
* __splice_from_pipe - splice data from a pipe to given actor
* splice_from_pipe_feed - feed available data from a pipe to a file
* @pipe: pipe to splice from
* @sd: information to @actor
* @actor: handler that splices the data
*
* Description:
* This function does little more than loop over the pipe and call
* @actor to do the actual moving of a single struct pipe_buffer to
* the desired destination. See pipe_to_file, pipe_to_sendpage, or
* pipe_to_user.
* This function loops over the pipe and calls @actor to do the
* actual moving of a single struct pipe_buffer to the desired
* destination. It returns when there's no more buffers left in
* the pipe or if the requested number of bytes (@sd->total_len)
* have been copied. It returns a positive number (one) if the
* pipe needs to be filled with more data, zero if the required
* number of bytes have been copied and -errno on error.
*
* This, together with splice_from_pipe_{begin,end,next}, may be
* used to implement the functionality of __splice_from_pipe() when
* locking is required around copying the pipe buffers to the
* destination.
*/
ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd,
splice_actor *actor)
int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd,
splice_actor *actor)
{
int ret, do_wakeup, err;

ret = 0;
do_wakeup = 0;

for (;;) {
if (pipe->nrbufs) {
struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
const struct pipe_buf_operations *ops = buf->ops;
int ret;

sd->len = buf->len;
if (sd->len > sd->total_len)
sd->len = sd->total_len;
while (pipe->nrbufs) {
struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
const struct pipe_buf_operations *ops = buf->ops;

err = actor(pipe, buf, sd);
if (err <= 0) {
if (!ret && err != -ENODATA)
ret = err;
sd->len = buf->len;
if (sd->len > sd->total_len)
sd->len = sd->total_len;

break;
}
ret = actor(pipe, buf, sd);
if (ret <= 0) {
if (ret == -ENODATA)
ret = 0;
return ret;
}
buf->offset += ret;
buf->len -= ret;

ret += err;
buf->offset += err;
buf->len -= err;
sd->num_spliced += ret;
sd->len -= ret;
sd->pos += ret;
sd->total_len -= ret;

sd->len -= err;
sd->pos += err;
sd->total_len -= err;
if (sd->len)
continue;
if (!buf->len) {
buf->ops = NULL;
ops->release(pipe, buf);
pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1);
pipe->nrbufs--;
if (pipe->inode)
sd->need_wakeup = true;
}

if (!buf->len) {
buf->ops = NULL;
ops->release(pipe, buf);
pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1);
pipe->nrbufs--;
if (pipe->inode)
do_wakeup = 1;
}
if (!sd->total_len)
return 0;
}

if (!sd->total_len)
break;
}
return 1;
}
EXPORT_SYMBOL(splice_from_pipe_feed);

if (pipe->nrbufs)
continue;
/**
* splice_from_pipe_next - wait for some data to splice from
* @pipe: pipe to splice from
* @sd: information about the splice operation
*
* Description:
* This function will wait for some data and return a positive
* value (one) if pipe buffers are available. It will return zero
* or -errno if no more data needs to be spliced.
*/
int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd)
{
while (!pipe->nrbufs) {
if (!pipe->writers)
break;
if (!pipe->waiting_writers) {
if (ret)
break;
}
return 0;

if (sd->flags & SPLICE_F_NONBLOCK) {
if (!ret)
ret = -EAGAIN;
break;
}
if (!pipe->waiting_writers && sd->num_spliced)
return 0;

if (signal_pending(current)) {
if (!ret)
ret = -ERESTARTSYS;
break;
}
if (sd->flags & SPLICE_F_NONBLOCK)
return -EAGAIN;

if (do_wakeup) {
smp_mb();
if (waitqueue_active(&pipe->wait))
wake_up_interruptible_sync(&pipe->wait);
kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
do_wakeup = 0;
if (signal_pending(current))
return -ERESTARTSYS;

if (sd->need_wakeup) {
wakeup_pipe_writers(pipe);
sd->need_wakeup = false;
}

pipe_wait(pipe);
}

if (do_wakeup) {
smp_mb();
if (waitqueue_active(&pipe->wait))
wake_up_interruptible(&pipe->wait);
kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
}
return 1;
}
EXPORT_SYMBOL(splice_from_pipe_next);

return ret;
/**
* splice_from_pipe_begin - start splicing from pipe
* @pipe: pipe to splice from
*
* Description:
* This function should be called before a loop containing
* splice_from_pipe_next() and splice_from_pipe_feed() to
* initialize the necessary fields of @sd.
*/
void splice_from_pipe_begin(struct splice_desc *sd)
{
sd->num_spliced = 0;
sd->need_wakeup = false;
}
EXPORT_SYMBOL(splice_from_pipe_begin);

/**
* splice_from_pipe_end - finish splicing from pipe
* @pipe: pipe to splice from
* @sd: information about the splice operation
*
* Description:
* This function will wake up pipe writers if necessary. It should
* be called after a loop containing splice_from_pipe_next() and
* splice_from_pipe_feed().
*/
void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd)
{
if (sd->need_wakeup)
wakeup_pipe_writers(pipe);
}
EXPORT_SYMBOL(splice_from_pipe_end);

/**
* __splice_from_pipe - splice data from a pipe to given actor
* @pipe: pipe to splice from
* @sd: information to @actor
* @actor: handler that splices the data
*
* Description:
* This function does little more than loop over the pipe and call
* @actor to do the actual moving of a single struct pipe_buffer to
* the desired destination. See pipe_to_file, pipe_to_sendpage, or
* pipe_to_user.
*
*/
ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd,
splice_actor *actor)
{
int ret;

splice_from_pipe_begin(sd);
do {
ret = splice_from_pipe_next(pipe, sd);
if (ret > 0)
ret = splice_from_pipe_feed(pipe, sd, actor);
} while (ret > 0);
splice_from_pipe_end(pipe, sd);

return sd->num_spliced ? sd->num_spliced : ret;
}
EXPORT_SYMBOL(__splice_from_pipe);

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10 changes: 10 additions & 0 deletions trunk/include/linux/splice.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,8 @@ struct splice_desc {
void *data; /* cookie */
} u;
loff_t pos; /* file position */
size_t num_spliced; /* number of bytes already spliced */
bool need_wakeup; /* need to wake up writer */
};

struct partial_page {
Expand Down Expand Up @@ -66,6 +68,14 @@ extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *,
splice_actor *);
extern ssize_t __splice_from_pipe(struct pipe_inode_info *,
struct splice_desc *, splice_actor *);
extern int splice_from_pipe_feed(struct pipe_inode_info *, struct splice_desc *,
splice_actor *);
extern int splice_from_pipe_next(struct pipe_inode_info *,
struct splice_desc *);
extern void splice_from_pipe_begin(struct splice_desc *);
extern void splice_from_pipe_end(struct pipe_inode_info *,
struct splice_desc *);

extern ssize_t splice_to_pipe(struct pipe_inode_info *,
struct splice_pipe_desc *);
extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
Expand Down

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