f2fs: add a case of no need to read a page in write begin

If the range we write cover the whole valid data in the last page,
we do not need to read it.

Signed-off-by: Yunlei He <heyunlei@huawei.com>
[Jaegeuk Kim: nullify the remaining area (fix: xfstests/f2fs/001)]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 9ac262564fa6b5934b8ec4987425ea3205bba1cf..2c5df1dc14798948558032f0e73bc25895379015 100644 (file)
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1715,6 +1715,11 @@ repeat:
        if (len == PAGE_SIZE || PageUptodate(page))
                return 0;
 
+       if (!(pos & (PAGE_SIZE - 1)) && (pos + len) >= i_size_read(inode)) {
+               zero_user_segment(page, len, PAGE_SIZE);
+               return 0;
+       }
+
        if (blkaddr == NEW_ADDR) {
                zero_user_segment(page, 0, PAGE_SIZE);
                SetPageUptodate(page);
@@ -1768,7 +1773,7 @@ static int f2fs_write_end(struct file *file,
         * let generic_perform_write() try to copy data again through copied=0.
         */
        if (!PageUptodate(page)) {
-               if (unlikely(copied != PAGE_SIZE))
+               if (unlikely(copied != len))
                        copied = 0;
                else
                        SetPageUptodate(page);