From 4d730c35200c4b9a0ce31c9b95cb1a2030ad2139 Mon Sep 17 00:00:00 2001
From: Shaohua Li <shaohua.li@intel.com>
Date: Mon, 9 Aug 2010 17:19:06 -0700
Subject: [PATCH] --- yaml --- r: 207231 b: refs/heads/master c:
 ff36b801624d02a876bb7deded6ab860ea3503f2 h: refs/heads/master i:   207229:
 f74ba0bb7d1a7230b1285a3b2c3c80cf4be8f595   207227:
 ea76ec19e7d6369b34b5f6adf10183399b78141d   207223:
 f56ed7325192cb6da6a3339a19ad14b21e18720c   207215:
 f2a7a3f99bb7b34e15307d69bfe2b720823c8132   207199:
 b8e849a3885753eb501d242d18a6644156991207   207167:
 627dc00dc8f25a04c10b99fb1ec40e2daca7ce9c   207103:
 016038080b2bd131dce11acc1a25239d1e261b7c v: v3

---
 [refs]           |  2 +-
 trunk/mm/shmem.c | 70 +++++++++++++++++++++++++++++++++---------------
 2 files changed, 50 insertions(+), 22 deletions(-)

diff --git a/[refs] b/[refs]
index c71090b20fd1..766d6e9b0f5e 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 7e496299d4d2ad8083effed6c5a18313a919edc6
+refs/heads/master: ff36b801624d02a876bb7deded6ab860ea3503f2
diff --git a/trunk/mm/shmem.c b/trunk/mm/shmem.c
index 0618fdad406c..566f9a481e64 100644
--- a/trunk/mm/shmem.c
+++ b/trunk/mm/shmem.c
@@ -1222,6 +1222,7 @@ static int shmem_getpage(struct inode *inode, unsigned long idx,
 	struct shmem_sb_info *sbinfo;
 	struct page *filepage = *pagep;
 	struct page *swappage;
+	struct page *prealloc_page = NULL;
 	swp_entry_t *entry;
 	swp_entry_t swap;
 	gfp_t gfp;
@@ -1246,7 +1247,6 @@ static int shmem_getpage(struct inode *inode, unsigned long idx,
 		filepage = find_lock_page(mapping, idx);
 	if (filepage && PageUptodate(filepage))
 		goto done;
-	error = 0;
 	gfp = mapping_gfp_mask(mapping);
 	if (!filepage) {
 		/*
@@ -1257,7 +1257,19 @@ static int shmem_getpage(struct inode *inode, unsigned long idx,
 		if (error)
 			goto failed;
 		radix_tree_preload_end();
+		if (sgp != SGP_READ && !prealloc_page) {
+			/* We don't care if this fails */
+			prealloc_page = shmem_alloc_page(gfp, info, idx);
+			if (prealloc_page) {
+				if (mem_cgroup_cache_charge(prealloc_page,
+						current->mm, GFP_KERNEL)) {
+					page_cache_release(prealloc_page);
+					prealloc_page = NULL;
+				}
+			}
+		}
 	}
+	error = 0;
 
 	spin_lock(&info->lock);
 	shmem_recalc_inode(inode);
@@ -1405,28 +1417,38 @@ static int shmem_getpage(struct inode *inode, unsigned long idx,
 		if (!filepage) {
 			int ret;
 
-			spin_unlock(&info->lock);
-			filepage = shmem_alloc_page(gfp, info, idx);
-			if (!filepage) {
-				shmem_unacct_blocks(info->flags, 1);
-				shmem_free_blocks(inode, 1);
-				error = -ENOMEM;
-				goto failed;
-			}
-			SetPageSwapBacked(filepage);
+			if (!prealloc_page) {
+				spin_unlock(&info->lock);
+				filepage = shmem_alloc_page(gfp, info, idx);
+				if (!filepage) {
+					shmem_unacct_blocks(info->flags, 1);
+					shmem_free_blocks(inode, 1);
+					error = -ENOMEM;
+					goto failed;
+				}
+				SetPageSwapBacked(filepage);
 
-			/* Precharge page while we can wait, compensate after */
-			error = mem_cgroup_cache_charge(filepage, current->mm,
-					GFP_KERNEL);
-			if (error) {
-				page_cache_release(filepage);
-				shmem_unacct_blocks(info->flags, 1);
-				shmem_free_blocks(inode, 1);
-				filepage = NULL;
-				goto failed;
+				/*
+				 * Precharge page while we can wait, compensate
+				 * after
+				 */
+				error = mem_cgroup_cache_charge(filepage,
+					current->mm, GFP_KERNEL);
+				if (error) {
+					page_cache_release(filepage);
+					shmem_unacct_blocks(info->flags, 1);
+					shmem_free_blocks(inode, 1);
+					filepage = NULL;
+					goto failed;
+				}
+
+				spin_lock(&info->lock);
+			} else {
+				filepage = prealloc_page;
+				prealloc_page = NULL;
+				SetPageSwapBacked(filepage);
 			}
 
-			spin_lock(&info->lock);
 			entry = shmem_swp_alloc(info, idx, sgp);
 			if (IS_ERR(entry))
 				error = PTR_ERR(entry);
@@ -1467,13 +1489,19 @@ static int shmem_getpage(struct inode *inode, unsigned long idx,
 	}
 done:
 	*pagep = filepage;
-	return 0;
+	error = 0;
+	goto out;
 
 failed:
 	if (*pagep != filepage) {
 		unlock_page(filepage);
 		page_cache_release(filepage);
 	}
+out:
+	if (prealloc_page) {
+		mem_cgroup_uncharge_cache_page(prealloc_page);
+		page_cache_release(prealloc_page);
+	}
 	return error;
 }