[PATCH 4.4 49/92] mm: filemap: remove redundant code in do_read_cache_page

From: Greg Kroah-Hartman
Date: Thu May 24 2018 - 07:02:01 EST


4.4-stable review patch. If anyone has any objections, please let me know.

------------------

From: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>

commit 32b635298ff4e991d8d8f64dc23782b02eec29c3 upstream.

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

Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
mm/filemap.c | 43 ++++++++++++-------------------------------
1 file changed, 12 insertions(+), 31 deletions(-)

--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2215,7 +2215,7 @@ static struct page *wait_on_page_read(st
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,
@@ -2237,31 +2237,19 @@ repeat:
/* 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;

@@ -2269,21 +2257,14 @@ retry:
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;