[PATCH 8/9] mm: dont set __GFP_WRITE on ramfs/sysfs writes

[Fengguang Wu <fengguang.wu@intel.com>]

[-- Attachment #1: mm-__GFP_WRITE-cap_account_dirty.patch --]
[-- Type: text/plain, Size: 886 bytes --]

Try to avoid page reclaim waits when writing to ramfs/sysfs etc.

Maybe not a big deal...

CC: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
---
 mm/filemap.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- linux.orig/mm/filemap.c	2012-02-28 10:24:12.000000000 +0800
+++ linux/mm/filemap.c	2012-02-28 10:25:55.568321275 +0800
@@ -2340,9 +2340,13 @@ struct page *grab_cache_page_write_begin
 	int status;
 	gfp_t gfp_mask;
 	struct page *page;
-	gfp_t lru_gfp_mask = GFP_KERNEL | __GFP_WRITE;
+	gfp_t lru_gfp_mask = GFP_KERNEL;
 
-	gfp_mask = mapping_gfp_mask(mapping) | __GFP_WRITE;
+	gfp_mask = mapping_gfp_mask(mapping);
+	if (mapping_cap_account_dirty(mapping)) {
+		gfp_mask |= __GFP_WRITE;
+		lru_gfp_mask |= __GFP_WRITE;
+	}
 	if (flags & AOP_FLAG_NOFS) {
 		gfp_mask &= ~__GFP_FS;
 		lru_gfp_mask &= ~__GFP_FS;