mm, fs: introduce mapping_gfp_constraint()

There are many places which use mapping_gfp_mask to restrict a more
generic gfp mask which would be used for allocations which are not
directly related to the page cache but they are performed in the same
context.

Let's introduce a helper function which makes the restriction explicit and
easier to track.  This patch doesn't introduce any functional changes.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c
index 560af0437704..1061611ae14d 100644
--- a/fs/ext4/readpage.c
+++ b/fs/ext4/readpage.c
@@ -166,7 +166,7 @@ int ext4_mpage_readpages(struct address_space *mapping,
                         page = list_entry(pages->prev, struct page, lru);
                         list_del(&page->lru);
                         if (add_to_page_cache_lru(page, mapping, page->index,
-                                        GFP_KERNEL & mapping_gfp_mask(mapping)))
+                                  mapping_gfp_constraint(mapping, GFP_KERNEL)))
                                 goto next_page;
                 }