affs_do_readpage_ofs(): just use kmap_atomic() around memcpy()

It forgets kunmap() on a failure exit, but there's really no point keeping
the page kmapped at all - after all, what we are doing is a bunch of memcpy()
into the parts of page, so kmap_atomic()/kunmap_atomic() just around those
memcpy() is enough.

Spotted-by: Insu Yun <wuninsu@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/affs/file.c b/fs/affs/file.c
index 0548c53..22fc7c8 100644 (file)
--- a/fs/affs/file.c
+++ b/fs/affs/file.c
@@ -511,8 +511,6 @@ affs_do_readpage_ofs(struct page *page, unsigned to)
        pr_debug("%s(%lu, %ld, 0, %d)\n", __func__, inode->i_ino,
                 page->index, to);
        BUG_ON(to > PAGE_CACHE_SIZE);
-       kmap(page);
-       data = page_address(page);
        bsize = AFFS_SB(sb)->s_data_blksize;
        tmp = page->index << PAGE_CACHE_SHIFT;
        bidx = tmp / bsize;
@@ -524,14 +522,15 @@ affs_do_readpage_ofs(struct page *page, unsigned to)
                        return PTR_ERR(bh);
                tmp = min(bsize - boff, to - pos);
                BUG_ON(pos + tmp > to || tmp > bsize);
+               data = kmap_atomic(page);
                memcpy(data + pos, AFFS_DATA(bh) + boff, tmp);
+               kunmap_atomic(data);
                affs_brelse(bh);
                bidx++;
                pos += tmp;
                boff = 0;
        }
        flush_dcache_page(page);
-       kunmap(page);
        return 0;
 }