diff options
Diffstat (limited to 'fs/splice.c')
| -rw-r--r-- | fs/splice.c | 162 |
1 files changed, 151 insertions, 11 deletions
diff --git a/fs/splice.c b/fs/splice.c index 666953d59a35..e405cf552f5c 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); } |