Merge branch 'for-linus' of git://git.kernel.dk/linux-block

Pull block bits from Jens Axboe:
 "As vacation is coming up, thought I'd better get rid of my pending
  changes in my for-linus branch for this iteration.  It contains:

   - Two patches for mtip32xx.  Killing a non-compliant sysfs interface
     and moving it to debugfs, where it belongs.

   - A few patches from Asias.  Two legit bug fixes, and one killing an
     interface that is no longer in use.

   - A patch from Jan, making the annoying partition ioctl warning a bit
     less annoying, by restricting it to !CAP_SYS_RAWIO only.

   - Three bug fixes for drbd from Lars Ellenberg.

   - A fix for an old regression for umem, it hasn't really worked since
     the plugging scheme was changed in 3.0.

   - A few fixes from Tejun.

   - A splice fix from Eric Dumazet, fixing an issue with pipe
     resizing."

* 'for-linus' of git://git.kernel.dk/linux-block:
  scsi: Silence unnecessary warnings about ioctl to partition
  block: Drop dead function blk_abort_queue()
  block: Mitigate lock unbalance caused by lock switching
  block: Avoid missed wakeup in request waitqueue
  umem: fix up unplugging
  splice: fix racy pipe->buffers uses
  drbd: fix null pointer dereference with on-congestion policy when diskless
  drbd: fix list corruption by failing but already aborted reads
  drbd: fix access of unallocated pages and kernel panic
  xen/blkfront: Add WARN to deal with misbehaving backends.
  blkcg: drop local variable @q from blkg_destroy()
  mtip32xx: Create debugfs entries for troubleshooting
  mtip32xx: Remove 'registers' and 'flags' from sysfs
  blkcg: fix blkg_alloc() failure path
  block: blkcg_policy_cfq shouldn't be used if !CONFIG_CFQ_GROUP_IOSCHED
  block: fix return value on cfq_init() failure
  mtip32xx: Remove version.h header file inclusion
  xen/blkback: Copy id field when doing BLKIF_DISCARD.

1 files changed, 20 insertions, 15 deletions

diff --git a/fs/splice.c b/fs/splice.c
index c9f1318..7bf08fa 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -273,13 +273,16 @@ void spd_release_page(struct splice_pipe_desc *spd, unsigned int 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)
+int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd)
 {
-	if (pipe->buffers <= PIPE_DEF_BUFFERS)
+	unsigned int buffers = ACCESS_ONCE(pipe->buffers);
+
+	spd->nr_pages_max = buffers;
+	if (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);
+	spd->pages = kmalloc(buffers * sizeof(struct page *), GFP_KERNEL);
+	spd->partial = kmalloc(buffers * sizeof(struct partial_page), GFP_KERNEL);
 
 	if (spd->pages && spd->partial)
 		return 0;
@@ -289,10 +292,9 @@ int splice_grow_spd(struct pipe_inode_info *pipe, struct splice_pipe_desc *spd)
 	return -ENOMEM;
 }
 
-void splice_shrink_spd(struct pipe_inode_info *pipe,
-		       struct splice_pipe_desc *spd)
+void splice_shrink_spd(struct splice_pipe_desc *spd)
 {
-	if (pipe->buffers <= PIPE_DEF_BUFFERS)
+	if (spd->nr_pages_max <= PIPE_DEF_BUFFERS)
 		return;
 
 	kfree(spd->pages);
@@ -315,6 +317,7 @@ __generic_file_splice_read(struct file *in, loff_t *ppos,
 	struct splice_pipe_desc spd = {
 		.pages = pages,
 		.partial = partial,
+		.nr_pages_max = PIPE_DEF_BUFFERS,
 		.flags = flags,
 		.ops = &page_cache_pipe_buf_ops,
 		.spd_release = spd_release_page,
@@ -326,7 +329,7 @@ __generic_file_splice_read(struct file *in, loff_t *ppos,
 	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, pipe->buffers);
+	nr_pages = min(req_pages, spd.nr_pages_max);
 
 	/*
 	 * Lookup the (hopefully) full range of pages we need.
@@ -497,7 +500,7 @@ fill_it:
 	if (spd.nr_pages)
 		error = splice_to_pipe(pipe, &spd);
 
-	splice_shrink_spd(pipe, &spd);
+	splice_shrink_spd(&spd);
 	return error;
 }
 
@@ -598,6 +601,7 @@ ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
 	struct splice_pipe_desc spd = {
 		.pages = pages,
 		.partial = partial,
+		.nr_pages_max = PIPE_DEF_BUFFERS,
 		.flags = flags,
 		.ops = &default_pipe_buf_ops,
 		.spd_release = spd_release_page,
@@ -608,8 +612,8 @@ ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
 
 	res = -ENOMEM;
 	vec = __vec;
-	if (pipe->buffers > PIPE_DEF_BUFFERS) {
-		vec = kmalloc(pipe->buffers * sizeof(struct iovec), GFP_KERNEL);
+	if (spd.nr_pages_max > PIPE_DEF_BUFFERS) {
+		vec = kmalloc(spd.nr_pages_max * sizeof(struct iovec), GFP_KERNEL);
 		if (!vec)
 			goto shrink_ret;
 	}
@@ -617,7 +621,7 @@ ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
 	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 < spd.nr_pages_max && len; i++) {
 		struct page *page;
 
 		page = alloc_page(GFP_USER);
@@ -665,7 +669,7 @@ ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
 shrink_ret:
 	if (vec != __vec)
 		kfree(vec);
-	splice_shrink_spd(pipe, &spd);
+	splice_shrink_spd(&spd);
 	return res;
 
 err:
@@ -1614,6 +1618,7 @@ static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov,
 	struct splice_pipe_desc spd = {
 		.pages = pages,
 		.partial = partial,
+		.nr_pages_max = PIPE_DEF_BUFFERS,
 		.flags = flags,
 		.ops = &user_page_pipe_buf_ops,
 		.spd_release = spd_release_page,
@@ -1629,13 +1634,13 @@ static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov,
 
 	spd.nr_pages = get_iovec_page_array(iov, nr_segs, spd.pages,
 					    spd.partial, false,
-					    pipe->buffers);
+					    spd.nr_pages_max);
 	if (spd.nr_pages <= 0)
 		ret = spd.nr_pages;
 	else
 		ret = splice_to_pipe(pipe, &spd);
 
-	splice_shrink_spd(pipe, &spd);
+	splice_shrink_spd(&spd);
 	return ret;
 }