fs/buffer.c: call __block_write_begin() if we have page

If we have the appropriate page already, call __block_write_begin()
directly instead of releasing and regrabbing it inside of
block_write_begin().

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 4 insertions, 5 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index 74566c6f67b1..d895d9fd5b71 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2458,11 +2458,10 @@ int nobh_write_begin(struct address_space *mapping,
         *fsdata = NULL;
 
         if (page_has_buffers(page)) {
-                unlock_page(page);
-                page_cache_release(page);
-                *pagep = NULL;
-                return block_write_begin(mapping, pos, len, flags, pagep,
-                                         get_block);
+                ret = __block_write_begin(page, pos, len, get_block);
+                if (unlikely(ret))
+                        goto out_release;
+                return ret;
         }
 
         if (PageMappedToDisk(page))