Merge tag 'dm-3.10-changes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm

Pull device-mapper updates from Alasdair Kergon:
 "Allow devices that hold metadata for the device-mapper thin
  provisioning target to be extended easily; allow WRITE SAME on
  multipath devices; an assortment of little fixes and clean-ups."

* tag 'dm-3.10-changes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm: (21 commits)
  dm cache: set config value
  dm cache: move config fns
  dm thin: generate event when metadata threshold passed
  dm persistent metadata: add space map threshold callback
  dm persistent data: add threshold callback to space map
  dm thin: detect metadata device resizing
  dm persistent data: support space map resizing
  dm thin: open dev read only when possible
  dm thin: refactor data dev resize
  dm cache: replace memcpy with struct assignment
  dm cache: fix typos in comments
  dm cache policy: fix description of lookup fn
  dm: document iterate_devices
  dm persistent data: fix error message typos
  dm cache: tune migration throttling
  dm mpath: enable WRITE SAME support
  dm table: fix write same support
  dm bufio: avoid a possible __vmalloc deadlock
  dm snapshot: fix error return code in snapshot_ctr
  dm cache: fix error return code in cache_create
  ...

1 files changed, 23 insertions, 1 deletions

diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index c6083132c4b8..0387e05cdb98 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -319,6 +319,9 @@ static void __cache_size_refresh(void)
 static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask,
 			       enum data_mode *data_mode)
 {
+	unsigned noio_flag;
+	void *ptr;
+
 	if (c->block_size <= DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT) {
 		*data_mode = DATA_MODE_SLAB;
 		return kmem_cache_alloc(DM_BUFIO_CACHE(c), gfp_mask);
@@ -332,7 +335,26 @@ static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask,
 	}
 
 	*data_mode = DATA_MODE_VMALLOC;
-	return __vmalloc(c->block_size, gfp_mask, PAGE_KERNEL);
+
+	/*
+	 * __vmalloc allocates the data pages and auxiliary structures with
+	 * gfp_flags that were specified, but pagetables are always allocated
+	 * with GFP_KERNEL, no matter what was specified as gfp_mask.
+	 *
+	 * Consequently, we must set per-process flag PF_MEMALLOC_NOIO so that
+	 * all allocations done by this process (including pagetables) are done
+	 * as if GFP_NOIO was specified.
+	 */
+
+	if (gfp_mask & __GFP_NORETRY)
+		noio_flag = memalloc_noio_save();
+
+	ptr = __vmalloc(c->block_size, gfp_mask, PAGE_KERNEL);
+
+	if (gfp_mask & __GFP_NORETRY)
+		memalloc_noio_restore(noio_flag);
+
+	return ptr;
 }
 
 /*