linux-kernel - [PATCH 1/2] mm: filemap: Remove redundant code in do_read_cache

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Date:	Tue, 26 Jan 2016 14:09:29 +0000
From:	Mel Gorman <mgorman@...hsingularity.net>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Hugh Dickins <hughd@...gle.com>, Jan Kara <jack@...e.cz>,
	Linux-FSDevel <linux-fsdevel@...r.kernel.org>,
	Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Mel Gorman <mgorman@...hsingularity.net>
Subject: [PATCH 1/2] mm: filemap: Remove redundant code in do_read_cache_page

do_read_cache_page and __read_cache_page duplicates page filler code
when filling the page for the first time. This patch simply removes the
duplicate logic.

Signed-off-by: Mel Gorman <mgorman@...hsingularity.net>
Reviewed-by: Jan Kara <jack@...e.cz>
---
 mm/filemap.c | 43 ++++++++++++-------------------------------
 1 file changed, 12 insertions(+), 31 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index bc943867d68c..aa38593d0cd5 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2283,7 +2283,7 @@ static struct page *wait_on_page_read(struct page *page)
 	return page;
 }
 
-static struct page *__read_cache_page(struct address_space *mapping,
+static struct page *do_read_cache_page(struct address_space *mapping,
 				pgoff_t index,
 				int (*filler)(void *, struct page *),
 				void *data,
@@ -2305,31 +2305,19 @@ static struct page *__read_cache_page(struct address_space *mapping,
 			/* Presumably ENOMEM for radix tree node */
 			return ERR_PTR(err);
 		}
+
+filler:
 		err = filler(data, page);
 		if (err < 0) {
 			page_cache_release(page);
-			page = ERR_PTR(err);
-		} else {
-			page = wait_on_page_read(page);
+			return ERR_PTR(err);
 		}
-	}
-	return page;
-}
-
-static struct page *do_read_cache_page(struct address_space *mapping,
-				pgoff_t index,
-				int (*filler)(void *, struct page *),
-				void *data,
-				gfp_t gfp)
-
-{
-	struct page *page;
-	int err;
 
-retry:
-	page = __read_cache_page(mapping, index, filler, data, gfp);
-	if (IS_ERR(page))
-		return page;
+		page = wait_on_page_read(page);
+		if (IS_ERR(page))
+			return page;
+		goto out;
+	}
 	if (PageUptodate(page))
 		goto out;
 
@@ -2337,21 +2325,14 @@ static struct page *do_read_cache_page(struct address_space *mapping,
 	if (!page->mapping) {
 		unlock_page(page);
 		page_cache_release(page);
-		goto retry;
+		goto repeat;
 	}
 	if (PageUptodate(page)) {
 		unlock_page(page);
 		goto out;
 	}
-	err = filler(data, page);
-	if (err < 0) {
-		page_cache_release(page);
-		return ERR_PTR(err);
-	} else {
-		page = wait_on_page_read(page);
-		if (IS_ERR(page))
-			return page;
-	}
+	goto filler;
+
 out:
 	mark_page_accessed(page);
 	return page;
-- 
2.6.4