1 files changed, 318 insertions, 20 deletions

diff --git a/fs/splice.c b/fs/splice.c
index 666953d59a3..73766d24f97 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -507,9 +507,131 @@ ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
 
         return ret;
 }
-
 EXPORT_SYMBOL(generic_file_splice_read);
 
+static const struct pipe_buf_operations default_pipe_buf_ops = {
+        .can_merge = 0,
+        .map = generic_pipe_buf_map,
+        .unmap = generic_pipe_buf_unmap,
+        .confirm = generic_pipe_buf_confirm,
+        .release = generic_pipe_buf_release,
+        .steal = generic_pipe_buf_steal,
+        .get = generic_pipe_buf_get,
+};
+
+static ssize_t kernel_readv(struct file *file, const struct iovec *vec,
+                            unsigned long vlen, loff_t offset)
+{
+        mm_segment_t old_fs;
+        loff_t pos = offset;
+        ssize_t res;
+
+        old_fs = get_fs();
+        set_fs(get_ds());
+        /* The cast to a user pointer is valid due to the set_fs() */
+        res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos);
+        set_fs(old_fs);
+
+        return res;
+}
+
+static ssize_t kernel_write(struct file *file, const char *buf, size_t count,
+                            loff_t pos)
+{
+        mm_segment_t old_fs;
+        ssize_t res;
+
+        old_fs = get_fs();
+        set_fs(get_ds());
+        /* The cast to a user pointer is valid due to the set_fs() */
+        res = vfs_write(file, (const char __user *)buf, count, &pos);
+        set_fs(old_fs);
+
+        return res;
+}
+
+ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
+                                 struct pipe_inode_info *pipe, size_t len,
+                                 unsigned int flags)
+{
+        unsigned int nr_pages;
+        unsigned int nr_freed;
+        size_t offset;
+        struct page *pages[PIPE_BUFFERS];
+        struct partial_page partial[PIPE_BUFFERS];
+        struct iovec vec[PIPE_BUFFERS];
+        pgoff_t index;
+        ssize_t res;
+        size_t this_len;
+        int error;
+        int i;
+        struct splice_pipe_desc spd = {
+                .pages = pages,
+                .partial = partial,
+                .flags = flags,
+                .ops = &default_pipe_buf_ops,
+                .spd_release = spd_release_page,
+        };
+
+        index = *ppos >> PAGE_CACHE_SHIFT;
+        offset = *ppos & ~PAGE_CACHE_MASK;
+        nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+
+        for (i = 0; i < nr_pages && i < PIPE_BUFFERS && len; i++) {
+                struct page *page;
+
+                page = alloc_page(GFP_USER);
+                error = -ENOMEM;
+                if (!page)
+                        goto err;
+
+                this_len = min_t(size_t, len, PAGE_CACHE_SIZE - offset);
+                vec[i].iov_base = (void __user *) page_address(page);
+                vec[i].iov_len = this_len;
+                pages[i] = page;
+                spd.nr_pages++;
+                len -= this_len;
+                offset = 0;
+        }
+
+        res = kernel_readv(in, vec, spd.nr_pages, *ppos);
+        if (res < 0) {
+                error = res;
+                goto err;
+        }
+
+        error = 0;
+        if (!res)
+                goto err;
+
+        nr_freed = 0;
+        for (i = 0; i < spd.nr_pages; i++) {
+                this_len = min_t(size_t, vec[i].iov_len, res);
+                partial[i].offset = 0;
+                partial[i].len = this_len;
+                if (!this_len) {
+                        __free_page(pages[i]);
+                        pages[i] = NULL;
+                        nr_freed++;
+                }
+                res -= this_len;
+        }
+        spd.nr_pages -= nr_freed;
+
+        res = splice_to_pipe(pipe, &spd);
+        if (res > 0)
+                *ppos += res;
+
+        return res;
+
+err:
+        for (i = 0; i < spd.nr_pages; i++)
+                __free_page(pages[i]);
+
+        return error;
+}
+EXPORT_SYMBOL(default_file_splice_read);
+
 /*
  * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
  * using sendpage(). Return the number of bytes sent.
@@ -881,6 +1003,36 @@ generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
 
 EXPORT_SYMBOL(generic_file_splice_write);
 
+static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
+                          struct splice_desc *sd)
+{
+        int ret;
+        void *data;
+
+        ret = buf->ops->confirm(pipe, buf);
+        if (ret)
+                return ret;
+
+        data = buf->ops->map(pipe, buf, 0);
+        ret = kernel_write(sd->u.file, data + buf->offset, sd->len, sd->pos);
+        buf->ops->unmap(pipe, buf, data);
+
+        return ret;
+}
+
+static ssize_t default_file_splice_write(struct pipe_inode_info *pipe,
+                                         struct file *out, loff_t *ppos,
+                                         size_t len, unsigned int flags)
+{
+        ssize_t ret;
+
+        ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf);
+        if (ret > 0)
+                *ppos += ret;
+
+        return ret;
+}
+
 /**
  * generic_splice_sendpage - splice data from a pipe to a socket
  * @pipe:       pipe to splice from
@@ -908,11 +1060,10 @@ EXPORT_SYMBOL(generic_splice_sendpage);
 static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
                            loff_t *ppos, size_t len, unsigned int flags)
 {
+        ssize_t (*splice_write)(struct pipe_inode_info *, struct file *,
+                                loff_t *, size_t, unsigned int);
         int ret;
 
-        if (unlikely(!out->f_op || !out->f_op->splice_write))
-                return -EINVAL;
-
         if (unlikely(!(out->f_mode & FMODE_WRITE)))
                 return -EBADF;
 
@@ -923,7 +1074,11 @@ static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
         if (unlikely(ret < 0))
                 return ret;
 
-        return out->f_op->splice_write(pipe, out, ppos, len, flags);
+        splice_write = out->f_op->splice_write;
+        if (!splice_write)
+                splice_write = default_file_splice_write;
+
+        return splice_write(pipe, out, ppos, len, flags);
 }
 
 /*
@@ -933,11 +1088,10 @@ static long do_splice_to(struct file *in, loff_t *ppos,
                          struct pipe_inode_info *pipe, size_t len,
                          unsigned int flags)
 {
+        ssize_t (*splice_read)(struct file *, loff_t *,
+                               struct pipe_inode_info *, size_t, unsigned int);
         int ret;
 
-        if (unlikely(!in->f_op || !in->f_op->splice_read))
-                return -EINVAL;
-
         if (unlikely(!(in->f_mode & FMODE_READ)))
                 return -EBADF;
 
@@ -945,7 +1099,11 @@ static long do_splice_to(struct file *in, loff_t *ppos,
         if (unlikely(ret < 0))
                 return ret;
 
-        return in->f_op->splice_read(in, ppos, pipe, len, flags);
+        splice_read = in->f_op->splice_read;
+        if (!splice_read)
+                splice_read = default_file_splice_read;
+
+        return splice_read(in, ppos, pipe, len, flags);
 }
 
 /**
@@ -1112,6 +1270,9 @@ 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 +1293,32 @@ 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 +1330,7 @@ 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 +1338,7 @@ 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 +1350,7 @@ 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 +1691,7 @@ 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 +1729,7 @@ 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 +1767,124 @@ 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 +1988,9 @@ 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);
                 }