9 files changed, 292 insertions, 108 deletions

diff --git a/fs/fcntl.c b/fs/fcntl.c
index 452d02f9075e..bcba960328fa 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -14,6 +14,7 @@
 #include <linux/dnotify.h>
 #include <linux/slab.h>
 #include <linux/module.h>
+#include <linux/pipe_fs_i.h>
 #include <linux/security.h>
 #include <linux/ptrace.h>
 #include <linux/signal.h>
@@ -412,6 +413,10 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
         case F_NOTIFY:
                 err = fcntl_dirnotify(fd, filp, arg);
                 break;
+        case F_SETPIPE_SZ:
+        case F_GETPIPE_SZ:
+                err = pipe_fcntl(filp, cmd, arg);
+                break;
         default:
                 break;
         }
diff --git a/fs/pipe.c b/fs/pipe.c
index 37ba29ff3158..054b8a6a2c7a 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -11,6 +11,7 @@
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/fs.h>
+#include <linux/log2.h>
 #include <linux/mount.h>
 #include <linux/pipe_fs_i.h>
 #include <linux/uio.h>
@@ -390,7 +391,7 @@ redo:
                         if (!buf->len) {
                                 buf->ops = NULL;
                                 ops->release(pipe, buf);
-                                curbuf = (curbuf + 1) & (PIPE_BUFFERS-1);
+                                curbuf = (curbuf + 1) & (pipe->buffers - 1);
                                 pipe->curbuf = curbuf;
                                 pipe->nrbufs = --bufs;
                                 do_wakeup = 1;
@@ -472,7 +473,7 @@ pipe_write(struct kiocb *iocb, const struct iovec *_iov,
         chars = total_len & (PAGE_SIZE-1); /* size of the last buffer */
         if (pipe->nrbufs && chars != 0) {
                 int lastbuf = (pipe->curbuf + pipe->nrbufs - 1) &
-                                                        (PIPE_BUFFERS-1);
+                                                        (pipe->buffers - 1);
                 struct pipe_buffer *buf = pipe->bufs + lastbuf;
                 const struct pipe_buf_operations *ops = buf->ops;
                 int offset = buf->offset + buf->len;
@@ -518,8 +519,8 @@ redo1:
                         break;
                 }
                 bufs = pipe->nrbufs;
-                if (bufs < PIPE_BUFFERS) {
-                        int newbuf = (pipe->curbuf + bufs) & (PIPE_BUFFERS-1);
+                if (bufs < pipe->buffers) {
+                        int newbuf = (pipe->curbuf + bufs) & (pipe->buffers-1);
                         struct pipe_buffer *buf = pipe->bufs + newbuf;
                         struct page *page = pipe->tmp_page;
                         char *src;
@@ -580,7 +581,7 @@ redo2:
                         if (!total_len)
                                 break;
                 }
-                if (bufs < PIPE_BUFFERS)
+                if (bufs < pipe->buffers)
                         continue;
                 if (filp->f_flags & O_NONBLOCK) {
                         if (!ret)
@@ -640,7 +641,7 @@ static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
                         nrbufs = pipe->nrbufs;
                         while (--nrbufs >= 0) {
                                 count += pipe->bufs[buf].len;
-                                buf = (buf+1) & (PIPE_BUFFERS-1);
+                                buf = (buf+1) & (pipe->buffers - 1);
                         }
                         mutex_unlock(&inode->i_mutex);
 
@@ -671,7 +672,7 @@ pipe_poll(struct file *filp, poll_table *wait)
         }
 
         if (filp->f_mode & FMODE_WRITE) {
-                mask |= (nrbufs < PIPE_BUFFERS) ? POLLOUT | POLLWRNORM : 0;
+                mask |= (nrbufs < pipe->buffers) ? POLLOUT | POLLWRNORM : 0;
                 /*
                  * Most Unices do not set POLLERR for FIFOs but on Linux they
                  * behave exactly like pipes for poll().
@@ -877,25 +878,32 @@ struct pipe_inode_info * alloc_pipe_info(struct inode *inode)
 
         pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL);
         if (pipe) {
-                init_waitqueue_head(&pipe->wait);
-                pipe->r_counter = pipe->w_counter = 1;
-                pipe->inode = inode;
+                pipe->bufs = kzalloc(sizeof(struct pipe_buffer) * PIPE_DEF_BUFFERS, GFP_KERNEL);
+                if (pipe->bufs) {
+                        init_waitqueue_head(&pipe->wait);
+                        pipe->r_counter = pipe->w_counter = 1;
+                        pipe->inode = inode;
+                        pipe->buffers = PIPE_DEF_BUFFERS;
+                        return pipe;
+                }
+                kfree(pipe);
         }
 
-        return pipe;
+        return NULL;
 }
 
 void __free_pipe_info(struct pipe_inode_info *pipe)
 {
         int i;
 
-        for (i = 0; i < PIPE_BUFFERS; i++) {
+        for (i = 0; i < pipe->buffers; i++) {
                 struct pipe_buffer *buf = pipe->bufs + i;
                 if (buf->ops)
                         buf->ops->release(pipe, buf);
         }
         if (pipe->tmp_page)
                 __free_page(pipe->tmp_page);
+        kfree(pipe->bufs);
         kfree(pipe);
 }
 
@@ -1094,6 +1102,81 @@ SYSCALL_DEFINE1(pipe, int __user *, fildes)
 }
 
 /*
+ * Allocate a new array of pipe buffers and copy the info over. Returns the
+ * pipe size if successful, or return -ERROR on error.
+ */
+static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg)
+{
+        struct pipe_buffer *bufs;
+
+        /*
+         * Must be a power-of-2 currently
+         */
+        if (!is_power_of_2(arg))
+                return -EINVAL;
+
+        /*
+         * We can shrink the pipe, if arg >= pipe->nrbufs. Since we don't
+         * expect a lot of shrink+grow operations, just free and allocate
+         * again like we would do for growing. If the pipe currently
+         * contains more buffers than arg, then return busy.
+         */
+        if (arg < pipe->nrbufs)
+                return -EBUSY;
+
+        bufs = kcalloc(arg, sizeof(struct pipe_buffer), GFP_KERNEL);
+        if (unlikely(!bufs))
+                return -ENOMEM;
+
+        /*
+         * The pipe array wraps around, so just start the new one at zero
+         * and adjust the indexes.
+         */
+        if (pipe->nrbufs) {
+                const unsigned int tail = pipe->nrbufs & (pipe->buffers - 1);
+                const unsigned int head = pipe->nrbufs - tail;
+
+                if (head)
+                        memcpy(bufs, pipe->bufs + pipe->curbuf, head * sizeof(struct pipe_buffer));
+                if (tail)
+                        memcpy(bufs + head, pipe->bufs + pipe->curbuf, tail * sizeof(struct pipe_buffer));
+        }
+
+        pipe->curbuf = 0;
+        kfree(pipe->bufs);
+        pipe->bufs = bufs;
+        pipe->buffers = arg;
+        return arg;
+}
+
+long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+        struct pipe_inode_info *pipe;
+        long ret;
+
+        pipe = file->f_path.dentry->d_inode->i_pipe;
+        if (!pipe)
+                return -EBADF;
+
+        mutex_lock(&pipe->inode->i_mutex);
+
+        switch (cmd) {
+        case F_SETPIPE_SZ:
+                ret = pipe_set_size(pipe, arg);
+                break;
+        case F_GETPIPE_SZ:
+                ret = pipe->buffers;
+                break;
+        default:
+                ret = -EINVAL;
+                break;
+        }
+
+        mutex_unlock(&pipe->inode->i_mutex);
+        return ret;
+}
+
+/*
  * pipefs should _never_ be mounted by userland - too much of security hassle,
  * no real gain from having the whole whorehouse mounted. So we don't need
  * any operations on the root directory. However, we need a non-trivial
diff --git a/fs/splice.c b/fs/splice.c
index 9313b6124a2e..ac22b00d86c3 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -193,8 +193,8 @@ ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
                         break;
                 }
 
-                if (pipe->nrbufs < PIPE_BUFFERS) {
-                        int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1);
+                if (pipe->nrbufs < pipe->buffers) {
+                        int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
                         struct pipe_buffer *buf = pipe->bufs + newbuf;
 
                         buf->page = spd->pages[page_nr];
@@ -214,7 +214,7 @@ ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
 
                         if (!--spd->nr_pages)
                                 break;
-                        if (pipe->nrbufs < PIPE_BUFFERS)
+                        if (pipe->nrbufs < pipe->buffers)
                                 continue;
 
                         break;
@@ -265,6 +265,36 @@ static void spd_release_page(struct splice_pipe_desc *spd, unsigned int i)
         page_cache_release(spd->pages[i]);
 }
 
+/*
+ * Check if we need to grow the arrays holding pages and partial page
+ * descriptions.
+ */
+int splice_grow_spd(struct pipe_inode_info *pipe, struct splice_pipe_desc *spd)
+{
+        if (pipe->buffers <= PIPE_DEF_BUFFERS)
+                return 0;
+
+        spd->pages = kmalloc(pipe->buffers * sizeof(struct page *), GFP_KERNEL);
+        spd->partial = kmalloc(pipe->buffers * sizeof(struct partial_page), GFP_KERNEL);
+
+        if (spd->pages && spd->partial)
+                return 0;
+
+        kfree(spd->pages);
+        kfree(spd->partial);
+        return -ENOMEM;
+}
+
+void splice_shrink_spd(struct pipe_inode_info *pipe,
+                       struct splice_pipe_desc *spd)
+{
+        if (pipe->buffers <= PIPE_DEF_BUFFERS)
+                return;
+
+        kfree(spd->pages);
+        kfree(spd->partial);
+}
+
 static int
 __generic_file_splice_read(struct file *in, loff_t *ppos,
                            struct pipe_inode_info *pipe, size_t len,
@@ -272,8 +302,8 @@ __generic_file_splice_read(struct file *in, loff_t *ppos,
 {
         struct address_space *mapping = in->f_mapping;
         unsigned int loff, nr_pages, req_pages;
-        struct page *pages[PIPE_BUFFERS];
-        struct partial_page partial[PIPE_BUFFERS];
+        struct page *pages[PIPE_DEF_BUFFERS];
+        struct partial_page partial[PIPE_DEF_BUFFERS];
         struct page *page;
         pgoff_t index, end_index;
         loff_t isize;
@@ -286,15 +316,18 @@ __generic_file_splice_read(struct file *in, loff_t *ppos,
                 .spd_release = spd_release_page,
         };
 
+        if (splice_grow_spd(pipe, &spd))
+                return -ENOMEM;
+
         index = *ppos >> PAGE_CACHE_SHIFT;
         loff = *ppos & ~PAGE_CACHE_MASK;
         req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
-        nr_pages = min(req_pages, (unsigned)PIPE_BUFFERS);
+        nr_pages = min(req_pages, pipe->buffers);
 
         /*
          * Lookup the (hopefully) full range of pages we need.
          */
-        spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, pages);
+        spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, spd.pages);
         index += spd.nr_pages;
 
         /*
@@ -335,7 +368,7 @@ __generic_file_splice_read(struct file *in, loff_t *ppos,
                         unlock_page(page);
                 }
 
-                pages[spd.nr_pages++] = page;
+                spd.pages[spd.nr_pages++] = page;
                 index++;
         }
 
@@ -356,7 +389,7 @@ __generic_file_splice_read(struct file *in, loff_t *ppos,
                  * this_len is the max we'll use from this page
                  */
                 this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
-                page = pages[page_nr];
+                page = spd.pages[page_nr];
 
                 if (PageReadahead(page))
                         page_cache_async_readahead(mapping, &in->f_ra, in,
@@ -393,8 +426,8 @@ __generic_file_splice_read(struct file *in, loff_t *ppos,
                                         error = -ENOMEM;
                                         break;
                                 }
-                                page_cache_release(pages[page_nr]);
-                                pages[page_nr] = page;
+                                page_cache_release(spd.pages[page_nr]);
+                                spd.pages[page_nr] = page;
                         }
                         /*
                          * page was already under io and is now done, great
@@ -451,8 +484,8 @@ fill_it:
                         len = this_len;
                 }
 
-                partial[page_nr].offset = loff;
-                partial[page_nr].len = this_len;
+                spd.partial[page_nr].offset = loff;
+                spd.partial[page_nr].len = this_len;
                 len -= this_len;
                 loff = 0;
                 spd.nr_pages++;
@@ -464,12 +497,13 @@ fill_it:
          * we got, 'nr_pages' is how many pages are in the map.
          */
         while (page_nr < nr_pages)
-                page_cache_release(pages[page_nr++]);
+                page_cache_release(spd.pages[page_nr++]);
         in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
 
         if (spd.nr_pages)
-                return splice_to_pipe(pipe, &spd);
+                error = splice_to_pipe(pipe, &spd);
 
+        splice_shrink_spd(pipe, &spd);
         return error;
 }
 
@@ -560,9 +594,9 @@ ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
         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];
+        struct page *pages[PIPE_DEF_BUFFERS];
+        struct partial_page partial[PIPE_DEF_BUFFERS];
+        struct iovec *vec, __vec[PIPE_DEF_BUFFERS];
         pgoff_t index;
         ssize_t res;
         size_t this_len;
@@ -576,11 +610,22 @@ ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
                 .spd_release = spd_release_page,
         };
 
+        if (splice_grow_spd(pipe, &spd))
+                return -ENOMEM;
+
+        res = -ENOMEM;
+        vec = __vec;
+        if (pipe->buffers > PIPE_DEF_BUFFERS) {
+                vec = kmalloc(pipe->buffers * sizeof(struct iovec), GFP_KERNEL);
+                if (!vec)
+                        goto shrink_ret;
+        }
+
         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++) {
+        for (i = 0; i < nr_pages && i < pipe->buffers && len; i++) {
                 struct page *page;
 
                 page = alloc_page(GFP_USER);
@@ -591,7 +636,7 @@ ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
                 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.pages[i] = page;
                 spd.nr_pages++;
                 len -= this_len;
                 offset = 0;
@@ -610,11 +655,11 @@ ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
         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;
+                spd.partial[i].offset = 0;
+                spd.partial[i].len = this_len;
                 if (!this_len) {
-                        __free_page(pages[i]);
-                        pages[i] = NULL;
+                        __free_page(spd.pages[i]);
+                        spd.pages[i] = NULL;
                         nr_freed++;
                 }
                 res -= this_len;
@@ -625,13 +670,18 @@ ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
         if (res > 0)
                 *ppos += res;
 
+shrink_ret:
+        if (vec != __vec)
+                kfree(vec);
+        splice_shrink_spd(pipe, &spd);
         return res;
 
 err:
         for (i = 0; i < spd.nr_pages; i++)
-                __free_page(pages[i]);
+                __free_page(spd.pages[i]);
 
-        return error;
+        res = error;
+        goto shrink_ret;
 }
 EXPORT_SYMBOL(default_file_splice_read);
 
@@ -784,7 +834,7 @@ int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd,
                 if (!buf->len) {
                         buf->ops = NULL;
                         ops->release(pipe, buf);
-                        pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1);
+                        pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
                         pipe->nrbufs--;
                         if (pipe->inode)
                                 sd->need_wakeup = true;
@@ -1211,7 +1261,7 @@ out_release:
          * If we did an incomplete transfer we must release
          * the pipe buffers in question:
          */
-        for (i = 0; i < PIPE_BUFFERS; i++) {
+        for (i = 0; i < pipe->buffers; i++) {
                 struct pipe_buffer *buf = pipe->bufs + i;
 
                 if (buf->ops) {
@@ -1371,7 +1421,8 @@ static long do_splice(struct file *in, loff_t __user *off_in,
  */
 static int get_iovec_page_array(const struct iovec __user *iov,
                                 unsigned int nr_vecs, struct page **pages,
-                                struct partial_page *partial, int aligned)
+                                struct partial_page *partial, int aligned,
+                                unsigned int pipe_buffers)
 {
         int buffers = 0, error = 0;
 
@@ -1414,8 +1465,8 @@ static int get_iovec_page_array(const struct iovec __user *iov,
                         break;
 
                 npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
-                if (npages > PIPE_BUFFERS - buffers)
-                        npages = PIPE_BUFFERS - buffers;
+                if (npages > pipe_buffers - buffers)
+                        npages = pipe_buffers - buffers;
 
                 error = get_user_pages_fast((unsigned long)base, npages,
                                         0, &pages[buffers]);
@@ -1450,7 +1501,7 @@ static int get_iovec_page_array(const struct iovec __user *iov,
                  * or if we mapped the max number of pages that we have
                  * room for.
                  */
-                if (error < npages || buffers == PIPE_BUFFERS)
+                if (error < npages || buffers == pipe_buffers)
                         break;
 
                 nr_vecs--;
@@ -1593,8 +1644,8 @@ static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov,
                              unsigned long nr_segs, unsigned int flags)
 {
         struct pipe_inode_info *pipe;
-        struct page *pages[PIPE_BUFFERS];
-        struct partial_page partial[PIPE_BUFFERS];
+        struct page *pages[PIPE_DEF_BUFFERS];
+        struct partial_page partial[PIPE_DEF_BUFFERS];
         struct splice_pipe_desc spd = {
                 .pages = pages,
                 .partial = partial,
@@ -1602,17 +1653,25 @@ static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov,
                 .ops = &user_page_pipe_buf_ops,
                 .spd_release = spd_release_page,
         };
+        long ret;
 
         pipe = pipe_info(file->f_path.dentry->d_inode);
         if (!pipe)
                 return -EBADF;
 
-        spd.nr_pages = get_iovec_page_array(iov, nr_segs, pages, partial,
-                                            flags & SPLICE_F_GIFT);
+        if (splice_grow_spd(pipe, &spd))
+                return -ENOMEM;
+
+        spd.nr_pages = get_iovec_page_array(iov, nr_segs, spd.pages,
+                                            spd.partial, flags & SPLICE_F_GIFT,
+                                            pipe->buffers);
         if (spd.nr_pages <= 0)
-                return spd.nr_pages;
+                ret = spd.nr_pages;
+        else
+                ret = splice_to_pipe(pipe, &spd);
 
-        return splice_to_pipe(pipe, &spd);
+        splice_shrink_spd(pipe, &spd);
+        return ret;
 }
 
 /*
@@ -1738,13 +1797,13 @@ static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
          * Check ->nrbufs without the inode lock first. This function
          * is speculative anyways, so missing one is ok.
          */
-        if (pipe->nrbufs < PIPE_BUFFERS)
+        if (pipe->nrbufs < pipe->buffers)
                 return 0;
 
         ret = 0;
         pipe_lock(pipe);
 
-        while (pipe->nrbufs >= PIPE_BUFFERS) {
+        while (pipe->nrbufs >= pipe->buffers) {
                 if (!pipe->readers) {
                         send_sig(SIGPIPE, current, 0);
                         ret = -EPIPE;
@@ -1810,7 +1869,7 @@ retry:
                  * Cannot make any progress, because either the input
                  * pipe is empty or the output pipe is full.
                  */
-                if (!ipipe->nrbufs || opipe->nrbufs >= PIPE_BUFFERS) {
+                if (!ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) {
                         /* Already processed some buffers, break */
                         if (ret)
                                 break;
@@ -1831,7 +1890,7 @@ retry:
                 }
 
                 ibuf = ipipe->bufs + ipipe->curbuf;
-                nbuf = (opipe->curbuf + opipe->nrbufs) % PIPE_BUFFERS;
+                nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1);
                 obuf = opipe->bufs + nbuf;
 
                 if (len >= ibuf->len) {
@@ -1841,7 +1900,7 @@ retry:
                         *obuf = *ibuf;
                         ibuf->ops = NULL;
                         opipe->nrbufs++;
-                        ipipe->curbuf = (ipipe->curbuf + 1) % PIPE_BUFFERS;
+                        ipipe->curbuf = (ipipe->curbuf + 1) & (ipipe->buffers - 1);
                         ipipe->nrbufs--;
                         input_wakeup = true;
                 } else {
@@ -1914,11 +1973,11 @@ static int link_pipe(struct pipe_inode_info *ipipe,
                  * If we have iterated all input buffers or ran out of
                  * output room, break.
                  */
-                if (i >= ipipe->nrbufs || opipe->nrbufs >= PIPE_BUFFERS)
+                if (i >= ipipe->nrbufs || opipe->nrbufs >= opipe->buffers)
                         break;
 
-                ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1));
-                nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1);
+                ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (ipipe->buffers-1));
+                nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1);
 
                 /*
                  * Get a reference to this pipe buffer,
diff --git a/include/linux/fcntl.h b/include/linux/fcntl.h
index 86037400a6e3..afc00af3229b 100644
--- a/include/linux/fcntl.h
+++ b/include/linux/fcntl.h
@@ -22,6 +22,12 @@
 #define F_NOTIFY        (F_LINUX_SPECIFIC_BASE+2)
 
 /*
+ * Set and get of pipe page size array
+ */
+#define F_SETPIPE_SZ    (F_LINUX_SPECIFIC_BASE + 7)
+#define F_GETPIPE_SZ    (F_LINUX_SPECIFIC_BASE + 8)
+
+/*
  * Types of directory notifications that may be requested.
  */
 #define DN_ACCESS       0x00000001      /* File accessed */
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index b43a9e039059..65f4282fcbaf 100644
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -3,7 +3,7 @@
 
 #define PIPEFS_MAGIC 0x50495045
 
-#define PIPE_BUFFERS (16)
+#define PIPE_DEF_BUFFERS        16
 
 #define PIPE_BUF_FLAG_LRU       0x01    /* page is on the LRU */
 #define PIPE_BUF_FLAG_ATOMIC    0x02    /* was atomically mapped */
@@ -44,17 +44,17 @@ struct pipe_buffer {
  **/
 struct pipe_inode_info {
         wait_queue_head_t wait;
-        unsigned int nrbufs, curbuf;
-        struct page *tmp_page;
+        unsigned int nrbufs, curbuf, buffers;
         unsigned int readers;
         unsigned int writers;
         unsigned int waiting_writers;
         unsigned int r_counter;
         unsigned int w_counter;
+        struct page *tmp_page;
         struct fasync_struct *fasync_readers;
         struct fasync_struct *fasync_writers;
         struct inode *inode;
-        struct pipe_buffer bufs[PIPE_BUFFERS];
+        struct pipe_buffer *bufs;
 };
 
 /*
@@ -154,4 +154,7 @@ int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *);
 int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *);
 void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *);
 
+/* for F_SETPIPE_SZ and F_GETPIPE_SZ */
+long pipe_fcntl(struct file *, unsigned int, unsigned long arg);
+
 #endif
diff --git a/include/linux/splice.h b/include/linux/splice.h
index 18e7c7c0cae6..997c3b4c212b 100644
--- a/include/linux/splice.h
+++ b/include/linux/splice.h
@@ -82,4 +82,11 @@ extern ssize_t splice_to_pipe(struct pipe_inode_info *,
 extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
                                       splice_direct_actor *);
 
+/*
+ * for dynamic pipe sizing
+ */
+extern int splice_grow_spd(struct pipe_inode_info *, struct splice_pipe_desc *);
+extern void splice_shrink_spd(struct pipe_inode_info *,
+                                struct splice_pipe_desc *);
+
 #endif
diff --git a/kernel/relay.c b/kernel/relay.c
index 3d97f2821611..4268287148c1 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -1231,8 +1231,8 @@ static ssize_t subbuf_splice_actor(struct file *in,
         size_t read_subbuf = read_start / subbuf_size;
         size_t padding = rbuf->padding[read_subbuf];
         size_t nonpad_end = read_subbuf * subbuf_size + subbuf_size - padding;
-        struct page *pages[PIPE_BUFFERS];
-        struct partial_page partial[PIPE_BUFFERS];
+        struct page *pages[PIPE_DEF_BUFFERS];
+        struct partial_page partial[PIPE_DEF_BUFFERS];
         struct splice_pipe_desc spd = {
                 .pages = pages,
                 .nr_pages = 0,
@@ -1245,6 +1245,8 @@ static ssize_t subbuf_splice_actor(struct file *in,
 
         if (rbuf->subbufs_produced == rbuf->subbufs_consumed)
                 return 0;
+        if (splice_grow_spd(pipe, &spd))
+                return -ENOMEM;
 
         /*
          * Adjust read len, if longer than what is available
@@ -1255,7 +1257,7 @@ static ssize_t subbuf_splice_actor(struct file *in,
         subbuf_pages = rbuf->chan->alloc_size >> PAGE_SHIFT;
         pidx = (read_start / PAGE_SIZE) % subbuf_pages;
         poff = read_start & ~PAGE_MASK;
-        nr_pages = min_t(unsigned int, subbuf_pages, PIPE_BUFFERS);
+        nr_pages = min_t(unsigned int, subbuf_pages, pipe->buffers);
 
         for (total_len = 0; spd.nr_pages < nr_pages; spd.nr_pages++) {
                 unsigned int this_len, this_end, private;
@@ -1289,16 +1291,19 @@ static ssize_t subbuf_splice_actor(struct file *in,
                 }
         }
 
+        ret = 0;
         if (!spd.nr_pages)
-                return 0;
+                goto out;
 
         ret = *nonpad_ret = splice_to_pipe(pipe, &spd);
         if (ret < 0 || ret < total_len)
-                return ret;
+                goto out;
 
         if (read_start + ret == nonpad_end)
                 ret += padding;
 
+out:
+        splice_shrink_spd(pipe, &spd);
         return ret;
 }
 
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 44f916a04065..7b155a0e6f31 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3269,12 +3269,12 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
                                         size_t len,
                                         unsigned int flags)
 {
-        struct page *pages[PIPE_BUFFERS];
-        struct partial_page partial[PIPE_BUFFERS];
+        struct page *pages_def[PIPE_DEF_BUFFERS];
+        struct partial_page partial_def[PIPE_DEF_BUFFERS];
         struct trace_iterator *iter = filp->private_data;
         struct splice_pipe_desc spd = {
-                .pages          = pages,
-                .partial        = partial,
+                .pages          = pages_def,
+                .partial        = partial_def,
                 .nr_pages       = 0, /* This gets updated below. */
                 .flags          = flags,
                 .ops            = &tracing_pipe_buf_ops,
@@ -3285,6 +3285,9 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
         size_t rem;
         unsigned int i;
 
+        if (splice_grow_spd(pipe, &spd))
+                return -ENOMEM;
+
         /* copy the tracer to avoid using a global lock all around */
         mutex_lock(&trace_types_lock);
         if (unlikely(old_tracer != current_trace && current_trace)) {
@@ -3315,23 +3318,23 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
         trace_access_lock(iter->cpu_file);
 
         /* Fill as many pages as possible. */
-        for (i = 0, rem = len; i < PIPE_BUFFERS && rem; i++) {
-                pages[i] = alloc_page(GFP_KERNEL);
-                if (!pages[i])
+        for (i = 0, rem = len; i < pipe->buffers && rem; i++) {
+                spd.pages[i] = alloc_page(GFP_KERNEL);
+                if (!spd.pages[i])
                         break;
 
                 rem = tracing_fill_pipe_page(rem, iter);
 
                 /* Copy the data into the page, so we can start over. */
                 ret = trace_seq_to_buffer(&iter->seq,
-                                          page_address(pages[i]),
+                                          page_address(spd.pages[i]),
                                           iter->seq.len);
                 if (ret < 0) {
-                        __free_page(pages[i]);
+                        __free_page(spd.pages[i]);
                         break;
                 }
-                partial[i].offset = 0;
-                partial[i].len = iter->seq.len;
+                spd.partial[i].offset = 0;
+                spd.partial[i].len = iter->seq.len;
 
                 trace_seq_init(&iter->seq);
         }
@@ -3342,12 +3345,14 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
 
         spd.nr_pages = i;
 
-        return splice_to_pipe(pipe, &spd);
+        ret = splice_to_pipe(pipe, &spd);
+out:
+        splice_shrink_spd(pipe, &spd);
+        return ret;
 
 out_err:
         mutex_unlock(&iter->mutex);
-
-        return ret;
+        goto out;
 }
 
 static ssize_t
@@ -3746,11 +3751,11 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
                             unsigned int flags)
 {
         struct ftrace_buffer_info *info = file->private_data;
-        struct partial_page partial[PIPE_BUFFERS];
-        struct page *pages[PIPE_BUFFERS];
+        struct partial_page partial_def[PIPE_DEF_BUFFERS];
+        struct page *pages_def[PIPE_DEF_BUFFERS];
         struct splice_pipe_desc spd = {
-                .pages          = pages,
-                .partial        = partial,
+                .pages          = pages_def,
+                .partial        = partial_def,
                 .flags          = flags,
                 .ops            = &buffer_pipe_buf_ops,
                 .spd_release    = buffer_spd_release,
@@ -3759,22 +3764,28 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
         int entries, size, i;
         size_t ret;
 
+        if (splice_grow_spd(pipe, &spd))
+                return -ENOMEM;
+
         if (*ppos & (PAGE_SIZE - 1)) {
                 WARN_ONCE(1, "Ftrace: previous read must page-align\n");
-                return -EINVAL;
+                ret = -EINVAL;
+                goto out;
         }
 
         if (len & (PAGE_SIZE - 1)) {
                 WARN_ONCE(1, "Ftrace: splice_read should page-align\n");
-                if (len < PAGE_SIZE)
-                        return -EINVAL;
+                if (len < PAGE_SIZE) {
+                        ret = -EINVAL;
+                        goto out;
+                }
                 len &= PAGE_MASK;
         }
 
         trace_access_lock(info->cpu);
         entries = ring_buffer_entries_cpu(info->tr->buffer, info->cpu);
 
-        for (i = 0; i < PIPE_BUFFERS && len && entries; i++, len -= PAGE_SIZE) {
+        for (i = 0; i < pipe->buffers && len && entries; i++, len -= PAGE_SIZE) {
                 struct page *page;
                 int r;
 
@@ -3829,11 +3840,12 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
                 else
                         ret = 0;
                 /* TODO: block */
-                return ret;
+                goto out;
         }
 
         ret = splice_to_pipe(pipe, &spd);
-
+        splice_shrink_spd(pipe, &spd);
+out:
         return ret;
 }
 
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 93c4e060c91e..931981774b1a 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1417,12 +1417,13 @@ new_page:
 /*
  * Fill page/offset/length into spd, if it can hold more pages.
  */
-static inline int spd_fill_page(struct splice_pipe_desc *spd, struct page *page,
+static inline int spd_fill_page(struct splice_pipe_desc *spd,
+                                struct pipe_inode_info *pipe, struct page *page,
                                 unsigned int *len, unsigned int offset,
                                 struct sk_buff *skb, int linear,
                                 struct sock *sk)
 {
-        if (unlikely(spd->nr_pages == PIPE_BUFFERS))
+        if (unlikely(spd->nr_pages == pipe->buffers))
                 return 1;
 
         if (linear) {
@@ -1458,7 +1459,8 @@ static inline int __splice_segment(struct page *page, unsigned int poff,
                                    unsigned int plen, unsigned int *off,
                                    unsigned int *len, struct sk_buff *skb,
                                    struct splice_pipe_desc *spd, int linear,
-                                   struct sock *sk)
+                                   struct sock *sk,
+                                   struct pipe_inode_info *pipe)
 {
         if (!*len)
                 return 1;
@@ -1481,7 +1483,7 @@ static inline int __splice_segment(struct page *page, unsigned int poff,
                 /* the linear region may spread across several pages  */
                 flen = min_t(unsigned int, flen, PAGE_SIZE - poff);
 
-                if (spd_fill_page(spd, page, &flen, poff, skb, linear, sk))
+                if (spd_fill_page(spd, pipe, page, &flen, poff, skb, linear, sk))
                         return 1;
 
                 __segment_seek(&page, &poff, &plen, flen);
@@ -1496,9 +1498,9 @@ static inline int __splice_segment(struct page *page, unsigned int poff,
  * Map linear and fragment data from the skb to spd. It reports failure if the
  * pipe is full or if we already spliced the requested length.
  */
-static int __skb_splice_bits(struct sk_buff *skb, unsigned int *offset,
-                             unsigned int *len, struct splice_pipe_desc *spd,
-                             struct sock *sk)
+static int __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
+                             unsigned int *offset, unsigned int *len,
+                             struct splice_pipe_desc *spd, struct sock *sk)
 {
         int seg;
 
@@ -1508,7 +1510,7 @@ static int __skb_splice_bits(struct sk_buff *skb, unsigned int *offset,
         if (__splice_segment(virt_to_page(skb->data),
                              (unsigned long) skb->data & (PAGE_SIZE - 1),
                              skb_headlen(skb),
-                             offset, len, skb, spd, 1, sk))
+                             offset, len, skb, spd, 1, sk, pipe))
                 return 1;
 
         /*
@@ -1518,7 +1520,7 @@ static int __skb_splice_bits(struct sk_buff *skb, unsigned int *offset,
                 const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];
 
                 if (__splice_segment(f->page, f->page_offset, f->size,
-                                     offset, len, skb, spd, 0, sk))
+                                     offset, len, skb, spd, 0, sk, pipe))
                         return 1;
         }
 
@@ -1535,8 +1537,8 @@ int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
                     struct pipe_inode_info *pipe, unsigned int tlen,
                     unsigned int flags)
 {
-        struct partial_page partial[PIPE_BUFFERS];
-        struct page *pages[PIPE_BUFFERS];
+        struct partial_page partial[PIPE_DEF_BUFFERS];
+        struct page *pages[PIPE_DEF_BUFFERS];
         struct splice_pipe_desc spd = {
                 .pages = pages,
                 .partial = partial,
@@ -1546,12 +1548,16 @@ int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
         };
         struct sk_buff *frag_iter;
         struct sock *sk = skb->sk;
+        int ret = 0;
+
+        if (splice_grow_spd(pipe, &spd))
+                return -ENOMEM;
 
         /*
          * __skb_splice_bits() only fails if the output has no room left,
          * so no point in going over the frag_list for the error case.
          */
-        if (__skb_splice_bits(skb, &offset, &tlen, &spd, sk))
+        if (__skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk))
                 goto done;
         else if (!tlen)
                 goto done;
@@ -1562,14 +1568,12 @@ int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
         skb_walk_frags(skb, frag_iter) {
                 if (!tlen)
                         break;
-                if (__skb_splice_bits(frag_iter, &offset, &tlen, &spd, sk))
+                if (__skb_splice_bits(frag_iter, pipe, &offset, &tlen, &spd, sk))
                         break;
         }
 
 done:
         if (spd.nr_pages) {
-                int ret;
-
                 /*
                  * Drop the socket lock, otherwise we have reverse
                  * locking dependencies between sk_lock and i_mutex
@@ -1582,10 +1586,10 @@ done:
                 release_sock(sk);
                 ret = splice_to_pipe(pipe, &spd);
                 lock_sock(sk);
-                return ret;
         }
 
-        return 0;
+        splice_shrink_spd(pipe, &spd);
+        return ret;
 }
 
 /**