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-rw-r--r--fs/splice.c162
1 files changed, 151 insertions, 11 deletions
diff --git a/fs/splice.c b/fs/splice.c
index 666953d5..e405cf5 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1112,6 +1112,9 @@ long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
return ret;
}
+static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
+ struct pipe_inode_info *opipe,
+ size_t len, unsigned int flags);
/*
* After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same
* location, so checking ->i_pipe is not enough to verify that this is a
@@ -1132,12 +1135,32 @@ static long do_splice(struct file *in, loff_t __user *off_in,
struct file *out, loff_t __user *off_out,
size_t len, unsigned int flags)
{
- struct pipe_inode_info *pipe;
+ struct pipe_inode_info *ipipe;
+ struct pipe_inode_info *opipe;
loff_t offset, *off;
long ret;
- pipe = pipe_info(in->f_path.dentry->d_inode);
- if (pipe) {
+ ipipe = pipe_info(in->f_path.dentry->d_inode);
+ opipe = pipe_info(out->f_path.dentry->d_inode);
+
+ if (ipipe && opipe) {
+ if (off_in || off_out)
+ return -ESPIPE;
+
+ if (!(in->f_mode & FMODE_READ))
+ return -EBADF;
+
+ if (!(out->f_mode & FMODE_WRITE))
+ return -EBADF;
+
+ /* Splicing to self would be fun, but... */
+ if (ipipe == opipe)
+ return -EINVAL;
+
+ return splice_pipe_to_pipe(ipipe, opipe, len, flags);
+ }
+
+ if (ipipe) {
if (off_in)
return -ESPIPE;
if (off_out) {
@@ -1149,7 +1172,7 @@ static long do_splice(struct file *in, loff_t __user *off_in,
} else
off = &out->f_pos;
- ret = do_splice_from(pipe, out, off, len, flags);
+ ret = do_splice_from(ipipe, out, off, len, flags);
if (off_out && copy_to_user(off_out, off, sizeof(loff_t)))
ret = -EFAULT;
@@ -1157,8 +1180,7 @@ static long do_splice(struct file *in, loff_t __user *off_in,
return ret;
}
- pipe = pipe_info(out->f_path.dentry->d_inode);
- if (pipe) {
+ if (opipe) {
if (off_out)
return -ESPIPE;
if (off_in) {
@@ -1170,7 +1192,7 @@ static long do_splice(struct file *in, loff_t __user *off_in,
} else
off = &in->f_pos;
- ret = do_splice_to(in, off, pipe, len, flags);
+ ret = do_splice_to(in, off, opipe, len, flags);
if (off_in && copy_to_user(off_in, off, sizeof(loff_t)))
ret = -EFAULT;
@@ -1511,7 +1533,7 @@ SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in,
* Make sure there's data to read. Wait for input if we can, otherwise
* return an appropriate error.
*/
-static int link_ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
+static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
{
int ret;
@@ -1549,7 +1571,7 @@ static int link_ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
* Make sure there's writeable room. Wait for room if we can, otherwise
* return an appropriate error.
*/
-static int link_opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
+static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
{
int ret;
@@ -1587,6 +1609,124 @@ static int link_opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
}
/*
+ * Splice contents of ipipe to opipe.
+ */
+static int splice_pipe_to_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, nbuf;
+ bool input_wakeup = false;
+
+
+retry:
+ ret = ipipe_prep(ipipe, flags);
+ if (ret)
+ return ret;
+
+ ret = opipe_prep(opipe, flags);
+ if (ret)
+ return ret;
+
+ /*
+ * Potential ABBA deadlock, work around it by ordering lock
+ * grabbing by pipe info address. Otherwise two different processes
+ * could deadlock (one doing tee from A -> B, the other from B -> A).
+ */
+ pipe_double_lock(ipipe, opipe);
+
+ do {
+ if (!opipe->readers) {
+ send_sig(SIGPIPE, current, 0);
+ if (!ret)
+ ret = -EPIPE;
+ break;
+ }
+
+ if (!ipipe->nrbufs && !ipipe->writers)
+ break;
+
+ /*
+ * Cannot make any progress, because either the input
+ * pipe is empty or the output pipe is full.
+ */
+ if (!ipipe->nrbufs || opipe->nrbufs >= PIPE_BUFFERS) {
+ /* Already processed some buffers, break */
+ if (ret)
+ break;
+
+ if (flags & SPLICE_F_NONBLOCK) {
+ ret = -EAGAIN;
+ break;
+ }
+
+ /*
+ * We raced with another reader/writer and haven't
+ * managed to process any buffers. A zero return
+ * value means EOF, so retry instead.
+ */
+ pipe_unlock(ipipe);
+ pipe_unlock(opipe);
+ goto retry;
+ }
+
+ ibuf = ipipe->bufs + ipipe->curbuf;
+ nbuf = (opipe->curbuf + opipe->nrbufs) % PIPE_BUFFERS;
+ obuf = opipe->bufs + nbuf;
+
+ if (len >= ibuf->len) {
+ /*
+ * Simply move the whole buffer from ipipe to opipe
+ */
+ *obuf = *ibuf;
+ ibuf->ops = NULL;
+ opipe->nrbufs++;
+ ipipe->curbuf = (ipipe->curbuf + 1) % PIPE_BUFFERS;
+ ipipe->nrbufs--;
+ input_wakeup = true;
+ } else {
+ /*
+ * Get a reference to this pipe buffer,
+ * so we can copy the contents over.
+ */
+ ibuf->ops->get(ipipe, ibuf);
+ *obuf = *ibuf;
+
+ /*
+ * Don't inherit the gift flag, we need to
+ * prevent multiple steals of this page.
+ */
+ obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
+
+ obuf->len = len;
+ opipe->nrbufs++;
+ ibuf->offset += obuf->len;
+ ibuf->len -= obuf->len;
+ }
+ ret += obuf->len;
+ len -= obuf->len;
+ } while (len);
+
+ pipe_unlock(ipipe);
+ pipe_unlock(opipe);
+
+ /*
+ * If we put data in the output pipe, wakeup any potential readers.
+ */
+ if (ret > 0) {
+ smp_mb();
+ if (waitqueue_active(&opipe->wait))
+ wake_up_interruptible(&opipe->wait);
+ kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
+ }
+ if (input_wakeup)
+ wakeup_pipe_writers(ipipe);
+
+ return ret;
+}
+
+/*
* Link contents of ipipe to opipe.
*/
static int link_pipe(struct pipe_inode_info *ipipe,
@@ -1690,9 +1830,9 @@ static long do_tee(struct file *in, struct file *out, size_t len,
* Keep going, unless we encounter an error. The ipipe/opipe
* ordering doesn't really matter.
*/
- ret = link_ipipe_prep(ipipe, flags);
+ ret = ipipe_prep(ipipe, flags);
if (!ret) {
- ret = link_opipe_prep(opipe, flags);
+ ret = opipe_prep(opipe, flags);
if (!ret)
ret = link_pipe(ipipe, opipe, len, flags);
}
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