fs/block_dev.c: add bdev_read_page() and bdev_write_page()
A block device driver may choose to provide a rw_page operation. These
will be called when the filesystem is attempting to do page sized I/O to
page cache pages (ie not for direct I/O). This does preclude I/Os that
are larger than page size, so this may only be a performance gain for
some devices.
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Tested-by: Dheeraj Reddy <dheeraj.reddy@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/mpage.c b/fs/mpage.c
index 10da0da..5f9ed62 100644
--- a/fs/mpage.c
+++ b/fs/mpage.c
@@ -269,6 +269,11 @@
alloc_new:
if (bio == NULL) {
+ if (first_hole == blocks_per_page) {
+ if (!bdev_read_page(bdev, blocks[0] << (blkbits - 9),
+ page))
+ goto out;
+ }
bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
min_t(int, nr_pages, bio_get_nr_vecs(bdev)),
GFP_KERNEL);
@@ -587,6 +592,13 @@
alloc_new:
if (bio == NULL) {
+ if (first_unmapped == blocks_per_page) {
+ if (!bdev_write_page(bdev, blocks[0] << (blkbits - 9),
+ page, wbc)) {
+ clean_buffers(page, first_unmapped);
+ goto out;
+ }
+ }
bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
bio_get_nr_vecs(bdev), GFP_NOFS|__GFP_HIGH);
if (bio == NULL)