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-rw-r--r--fs/splice.c272
1 files changed, 230 insertions, 42 deletions
diff --git a/fs/splice.c b/fs/splice.c
index e50a460..8d57e89 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -125,12 +125,19 @@ static void page_cache_pipe_buf_unmap(struct pipe_inode_info *info,
kunmap(buf->page);
}
+static void page_cache_pipe_buf_get(struct pipe_inode_info *info,
+ struct pipe_buffer *buf)
+{
+ page_cache_get(buf->page);
+}
+
static struct pipe_buf_operations page_cache_pipe_buf_ops = {
.can_merge = 0,
.map = page_cache_pipe_buf_map,
.unmap = page_cache_pipe_buf_unmap,
.release = page_cache_pipe_buf_release,
.steal = page_cache_pipe_buf_steal,
+ .get = page_cache_pipe_buf_get,
};
/*
@@ -231,8 +238,9 @@ static ssize_t move_to_pipe(struct pipe_inode_info *pipe, struct page **pages,
}
static int
-__generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe,
- size_t len, unsigned int flags)
+__generic_file_splice_read(struct file *in, loff_t *ppos,
+ struct pipe_inode_info *pipe, size_t len,
+ unsigned int flags)
{
struct address_space *mapping = in->f_mapping;
unsigned int offset, nr_pages;
@@ -241,8 +249,8 @@ __generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe,
pgoff_t index;
int i, error;
- index = in->f_pos >> PAGE_CACHE_SHIFT;
- offset = in->f_pos & ~PAGE_CACHE_MASK;
+ index = *ppos >> PAGE_CACHE_SHIFT;
+ offset = *ppos & ~PAGE_CACHE_MASK;
nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
if (nr_pages > PIPE_BUFFERS)
@@ -348,8 +356,9 @@ fill_it:
*
* Will read pages from given file and fill them into a pipe.
*/
-ssize_t generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe,
- size_t len, unsigned int flags)
+ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
+ struct pipe_inode_info *pipe, size_t len,
+ unsigned int flags)
{
ssize_t spliced;
int ret;
@@ -358,12 +367,12 @@ ssize_t generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe,
spliced = 0;
while (len) {
- ret = __generic_file_splice_read(in, pipe, len, flags);
+ ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
if (ret <= 0)
break;
- in->f_pos += ret;
+ *ppos += ret;
len -= ret;
spliced += ret;
@@ -561,7 +570,7 @@ typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
* to the wanted destination. See pipe_to_file/pipe_to_sendpage above.
*/
static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out,
- size_t len, unsigned int flags,
+ loff_t *ppos, size_t len, unsigned int flags,
splice_actor *actor)
{
int ret, do_wakeup, err;
@@ -573,7 +582,7 @@ static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out,
sd.total_len = len;
sd.flags = flags;
sd.file = out;
- sd.pos = out->f_pos;
+ sd.pos = *ppos;
if (pipe->inode)
mutex_lock(&pipe->inode->i_mutex);
@@ -656,9 +665,7 @@ static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out,
kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
}
- out->f_pos = sd.pos;
return ret;
-
}
/**
@@ -674,12 +681,12 @@ static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out,
*/
ssize_t
generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
- size_t len, unsigned int flags)
+ loff_t *ppos, size_t len, unsigned int flags)
{
struct address_space *mapping = out->f_mapping;
ssize_t ret;
- ret = move_from_pipe(pipe, out, len, flags, pipe_to_file);
+ ret = move_from_pipe(pipe, out, ppos, len, flags, pipe_to_file);
/*
* If file or inode is SYNC and we actually wrote some data, sync it.
@@ -715,9 +722,9 @@ EXPORT_SYMBOL(generic_file_splice_write);
*
*/
ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
- size_t len, unsigned int flags)
+ loff_t *ppos, size_t len, unsigned int flags)
{
- return move_from_pipe(pipe, out, len, flags, pipe_to_sendpage);
+ return move_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
}
EXPORT_SYMBOL(generic_splice_sendpage);
@@ -726,9 +733,8 @@ EXPORT_SYMBOL(generic_splice_sendpage);
* Attempt to initiate a splice from pipe to file.
*/
static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
- size_t len, unsigned int flags)
+ loff_t *ppos, size_t len, unsigned int flags)
{
- loff_t pos;
int ret;
if (unlikely(!out->f_op || !out->f_op->splice_write))
@@ -737,22 +743,21 @@ static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
if (unlikely(!(out->f_mode & FMODE_WRITE)))
return -EBADF;
- pos = out->f_pos;
-
- ret = rw_verify_area(WRITE, out, &pos, len);
+ ret = rw_verify_area(WRITE, out, ppos, len);
if (unlikely(ret < 0))
return ret;
- return out->f_op->splice_write(pipe, out, len, flags);
+ return out->f_op->splice_write(pipe, out, ppos, len, flags);
}
/*
* Attempt to initiate a splice from a file to a pipe.
*/
-static long do_splice_to(struct file *in, struct pipe_inode_info *pipe,
- size_t len, unsigned int flags)
+static long do_splice_to(struct file *in, loff_t *ppos,
+ struct pipe_inode_info *pipe, size_t len,
+ unsigned int flags)
{
- loff_t pos, isize, left;
+ loff_t isize, left;
int ret;
if (unlikely(!in->f_op || !in->f_op->splice_read))
@@ -761,28 +766,27 @@ static long do_splice_to(struct file *in, struct pipe_inode_info *pipe,
if (unlikely(!(in->f_mode & FMODE_READ)))
return -EBADF;
- pos = in->f_pos;
-
- ret = rw_verify_area(READ, in, &pos, len);
+ ret = rw_verify_area(READ, in, ppos, len);
if (unlikely(ret < 0))
return ret;
isize = i_size_read(in->f_mapping->host);
- if (unlikely(in->f_pos >= isize))
+ if (unlikely(*ppos >= isize))
return 0;
- left = isize - in->f_pos;
+ left = isize - *ppos;
if (unlikely(left < len))
len = left;
- return in->f_op->splice_read(in, pipe, len, flags);
+ return in->f_op->splice_read(in, ppos, pipe, len, flags);
}
-long do_splice_direct(struct file *in, struct file *out, size_t len,
- unsigned int flags)
+long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
+ size_t len, unsigned int flags)
{
struct pipe_inode_info *pipe;
long ret, bytes;
+ loff_t out_off;
umode_t i_mode;
int i;
@@ -820,6 +824,7 @@ long do_splice_direct(struct file *in, struct file *out, size_t len,
*/
ret = 0;
bytes = 0;
+ out_off = 0;
while (len) {
size_t read_len, max_read_len;
@@ -829,7 +834,7 @@ long do_splice_direct(struct file *in, struct file *out, size_t len,
*/
max_read_len = min(len, (size_t)(PIPE_BUFFERS*PAGE_SIZE));
- ret = do_splice_to(in, pipe, max_read_len, flags);
+ ret = do_splice_to(in, ppos, pipe, max_read_len, flags);
if (unlikely(ret < 0))
goto out_release;
@@ -840,7 +845,7 @@ long do_splice_direct(struct file *in, struct file *out, size_t len,
* 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, read_len,
+ ret = do_splice_from(pipe, out, &out_off, read_len,
flags & ~SPLICE_F_NONBLOCK);
if (unlikely(ret < 0))
goto out_release;
@@ -898,6 +903,7 @@ static long do_splice(struct file *in, loff_t __user *off_in,
size_t len, unsigned int flags)
{
struct pipe_inode_info *pipe;
+ loff_t offset, *off;
pipe = in->f_dentry->d_inode->i_pipe;
if (pipe) {
@@ -906,12 +912,13 @@ static long do_splice(struct file *in, loff_t __user *off_in,
if (off_out) {
if (out->f_op->llseek == no_llseek)
return -EINVAL;
- if (copy_from_user(&out->f_pos, off_out,
- sizeof(loff_t)))
+ if (copy_from_user(&offset, off_out, sizeof(loff_t)))
return -EFAULT;
- }
+ off = &offset;
+ } else
+ off = &out->f_pos;
- return do_splice_from(pipe, out, len, flags);
+ return do_splice_from(pipe, out, off, len, flags);
}
pipe = out->f_dentry->d_inode->i_pipe;
@@ -921,11 +928,13 @@ static long do_splice(struct file *in, loff_t __user *off_in,
if (off_in) {
if (in->f_op->llseek == no_llseek)
return -EINVAL;
- if (copy_from_user(&in->f_pos, off_in, sizeof(loff_t)))
+ if (copy_from_user(&offset, off_in, sizeof(loff_t)))
return -EFAULT;
- }
+ off = &offset;
+ } else
+ off = &in->f_pos;
- return do_splice_to(in, pipe, len, flags);
+ return do_splice_to(in, off, pipe, len, flags);
}
return -EINVAL;
@@ -961,3 +970,182 @@ asmlinkage long sys_splice(int fd_in, loff_t __user *off_in,
return error;
}
+
+/*
+ * Link contents of ipipe to opipe.
+ */
+static int link_pipe(struct pipe_inode_info *ipipe,
+ struct pipe_inode_info *opipe,
+ size_t len, unsigned int flags)
+{
+ struct pipe_buffer *ibuf, *obuf;
+ int ret = 0, do_wakeup = 0, i;
+
+ /*
+ * Potential ABBA deadlock, work around it by ordering lock
+ * grabbing by inode address. Otherwise two different processes
+ * could deadlock (one doing tee from A -> B, the other from B -> A).
+ */
+ if (ipipe->inode < opipe->inode) {
+ mutex_lock(&ipipe->inode->i_mutex);
+ mutex_lock(&opipe->inode->i_mutex);
+ } else {
+ mutex_lock(&opipe->inode->i_mutex);
+ mutex_lock(&ipipe->inode->i_mutex);
+ }
+
+ for (i = 0;; i++) {
+ if (!opipe->readers) {
+ send_sig(SIGPIPE, current, 0);
+ if (!ret)
+ ret = -EPIPE;
+ break;
+ }
+ if (ipipe->nrbufs - i) {
+ ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1));
+
+ /*
+ * If we have room, fill this buffer
+ */
+ if (opipe->nrbufs < PIPE_BUFFERS) {
+ int nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1);
+
+ /*
+ * Get a reference to this pipe buffer,
+ * so we can copy the contents over.
+ */
+ ibuf->ops->get(ipipe, ibuf);
+
+ obuf = opipe->bufs + nbuf;
+ *obuf = *ibuf;
+
+ if (obuf->len > len)
+ obuf->len = len;
+
+ opipe->nrbufs++;
+ do_wakeup = 1;
+ ret += obuf->len;
+ len -= obuf->len;
+
+ if (!len)
+ break;
+ if (opipe->nrbufs < PIPE_BUFFERS)
+ continue;
+ }
+
+ /*
+ * We have input available, but no output room.
+ * If we already copied data, return that.
+ */
+ if (flags & SPLICE_F_NONBLOCK) {
+ if (!ret)
+ ret = -EAGAIN;
+ break;
+ }
+ if (signal_pending(current)) {
+ if (!ret)
+ ret = -ERESTARTSYS;
+ break;
+ }
+ if (do_wakeup) {
+ smp_mb();
+ if (waitqueue_active(&opipe->wait))
+ wake_up_interruptible(&opipe->wait);
+ kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
+ do_wakeup = 0;
+ }
+
+ opipe->waiting_writers++;
+ pipe_wait(opipe);
+ opipe->waiting_writers--;
+ continue;
+ }
+
+ /*
+ * No input buffers, do the usual checks for available
+ * writers and blocking and wait if necessary
+ */
+ if (!ipipe->writers)
+ break;
+ if (!ipipe->waiting_writers) {
+ if (ret)
+ break;
+ }
+ if (flags & SPLICE_F_NONBLOCK) {
+ if (!ret)
+ ret = -EAGAIN;
+ break;
+ }
+ if (signal_pending(current)) {
+ if (!ret)
+ ret = -ERESTARTSYS;
+ break;
+ }
+
+ if (waitqueue_active(&ipipe->wait))
+ wake_up_interruptible_sync(&ipipe->wait);
+ kill_fasync(&ipipe->fasync_writers, SIGIO, POLL_OUT);
+
+ pipe_wait(ipipe);
+ }
+
+ mutex_unlock(&ipipe->inode->i_mutex);
+ mutex_unlock(&opipe->inode->i_mutex);
+
+ if (do_wakeup) {
+ smp_mb();
+ if (waitqueue_active(&opipe->wait))
+ wake_up_interruptible(&opipe->wait);
+ kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
+ }
+
+ return ret;
+}
+
+/*
+ * This is a tee(1) implementation that works on pipes. It doesn't copy
+ * any data, it simply references the 'in' pages on the 'out' pipe.
+ * The 'flags' used are the SPLICE_F_* variants, currently the only
+ * applicable one is SPLICE_F_NONBLOCK.
+ */
+static long do_tee(struct file *in, struct file *out, size_t len,
+ unsigned int flags)
+{
+ struct pipe_inode_info *ipipe = in->f_dentry->d_inode->i_pipe;
+ struct pipe_inode_info *opipe = out->f_dentry->d_inode->i_pipe;
+
+ /*
+ * Link ipipe to the two output pipes, consuming as we go along.
+ */
+ if (ipipe && opipe)
+ return link_pipe(ipipe, opipe, len, flags);
+
+ return -EINVAL;
+}
+
+asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags)
+{
+ struct file *in;
+ int error, fput_in;
+
+ if (unlikely(!len))
+ return 0;
+
+ error = -EBADF;
+ in = fget_light(fdin, &fput_in);
+ if (in) {
+ if (in->f_mode & FMODE_READ) {
+ int fput_out;
+ struct file *out = fget_light(fdout, &fput_out);
+
+ if (out) {
+ if (out->f_mode & FMODE_WRITE)
+ error = do_tee(in, out, len, flags);
+ fput_light(out, fput_out);
+ }
+ }
+ fput_light(in, fput_in);
+ }
+
+ return error;
+}