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, 2 insertions, 2 deletions

diff --git a/mm/readahead.c b/mm/readahead.c
index 998ad592f408..ba22d7fe0afb 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -90,7 +90,7 @@ int read_cache_pages(struct address_space *mapping, struct list_head *pages,
                 page = list_to_page(pages);
                 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))) {
                         read_cache_pages_invalidate_page(mapping, page);
                         continue;
                 }
@@ -128,7 +128,7 @@ static int read_pages(struct address_space *mapping, struct file *filp,
                 struct page *page = list_to_page(pages);
                 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))) {
                         mapping->a_ops->readpage(filp, page);
                 }
                 page_cache_release(page);