vfs: add hooks for ext4's delayed allocation support

Export mpage_bio_submit() and __mpage_writepage() for the benefit of
ext4's delayed allocation support.   Also change __block_write_full_page
so that if buffers that have the BH_Delay flag set it will call
get_block() to get the physical block allocated, just as in the
!BH_Mapped case.

Signed-off-by: Alex Tomas <alex@clusterfs.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 5 insertions, 2 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index f4b033237a02..5fa1512cd9a2 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1691,11 +1691,13 @@ static int __block_write_full_page(struct inode *inode, struct page *page,
                          */
                         clear_buffer_dirty(bh);
                         set_buffer_uptodate(bh);
-                } else if (!buffer_mapped(bh) && buffer_dirty(bh)) {
+                } else if ((!buffer_mapped(bh) || buffer_delay(bh)) &&
+                           buffer_dirty(bh)) {
                         WARN_ON(bh->b_size != blocksize);
                         err = get_block(inode, block, bh, 1);
                         if (err)
                                 goto recover;
+                        clear_buffer_delay(bh);
                         if (buffer_new(bh)) {
                                 /* blockdev mappings never come here */
                                 clear_buffer_new(bh);
@@ -1774,7 +1776,8 @@ recover:
         bh = head;
         /* Recovery: lock and submit the mapped buffers */
         do {
-                if (buffer_mapped(bh) && buffer_dirty(bh)) {
+                if (buffer_mapped(bh) && buffer_dirty(bh) &&
+                    !buffer_delay(bh)) {
                         lock_buffer(bh);
                         mark_buffer_async_write(bh);
                 } else {