[PATCH] pass b_size to ->get_block()

Pass amount of disk needs to be mapped to get_block().  This way one can
modify the fs ->get_block() functions to map multiple blocks at the same time.

[akpm@osdl.org: performance tweak]
[akpm@osdl.org: remove unneeded assignments]
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 11 insertions, 1 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index e7a1461f4387..a507b58550f1 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1738,6 +1738,7 @@ static int __block_write_full_page(struct inode *inode, struct page *page,
         sector_t block;
         sector_t last_block;
         struct buffer_head *bh, *head;
+        const unsigned blocksize = 1 << inode->i_blkbits;
         int nr_underway = 0;
 
         BUG_ON(!PageLocked(page));
@@ -1745,7 +1746,7 @@ static int __block_write_full_page(struct inode *inode, struct page *page,
         last_block = (i_size_read(inode) - 1) >> inode->i_blkbits;
 
         if (!page_has_buffers(page)) {
-                create_empty_buffers(page, 1 << inode->i_blkbits,
+                create_empty_buffers(page, blocksize,
                                         (1 << BH_Dirty)|(1 << BH_Uptodate));
         }
 
@@ -1780,6 +1781,7 @@ 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)) {
+                        WARN_ON(bh->b_size != blocksize);
                         err = get_block(inode, block, bh, 1);
                         if (err)
                                 goto recover;
@@ -1933,6 +1935,7 @@ static int __block_prepare_write(struct inode *inode, struct page *page,
                 if (buffer_new(bh))
                         clear_buffer_new(bh);
                 if (!buffer_mapped(bh)) {
+                        WARN_ON(bh->b_size != blocksize);
                         err = get_block(inode, block, bh, 1);
                         if (err)
                                 break;
@@ -2088,6 +2091,7 @@ int block_read_full_page(struct page *page, get_block_t *get_block)
 
                         fully_mapped = 0;
                         if (iblock < lblock) {
+                                WARN_ON(bh->b_size != blocksize);
                                 err = get_block(inode, iblock, bh, 0);
                                 if (err)
                                         SetPageError(page);
@@ -2409,6 +2413,7 @@ int nobh_prepare_write(struct page *page, unsigned from, unsigned to,
                 create = 1;
                 if (block_start >= to)
                         create = 0;
+                map_bh.b_size = blocksize;
                 ret = get_block(inode, block_in_file + block_in_page,
                                         &map_bh, create);
                 if (ret)
@@ -2669,6 +2674,7 @@ int block_truncate_page(struct address_space *mapping,
 
         err = 0;
         if (!buffer_mapped(bh)) {
+                WARN_ON(bh->b_size != blocksize);
                 err = get_block(inode, iblock, bh, 0);
                 if (err)
                         goto unlock;
@@ -2755,6 +2761,7 @@ sector_t generic_block_bmap(struct address_space *mapping, sector_t block,
         struct inode *inode = mapping->host;
         tmp.b_state = 0;
         tmp.b_blocknr = 0;
+        tmp.b_size = 1 << inode->i_blkbits;
         get_block(inode, block, &tmp, 0);
         return tmp.b_blocknr;
 }
diff --git a/fs/mpage.c b/fs/mpage.c
index e431cb3878d6..7903b740cc11 100644
--- a/fs/mpage.c
+++ b/fs/mpage.c
@@ -192,6 +192,7 @@ do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
                                 page_block++, block_in_file++) {
                 bh.b_state = 0;
                 if (block_in_file < last_block) {
+                        bh.b_size = blocksize;
                         if (get_block(inode, block_in_file, &bh, 0))
                                 goto confused;
                 }
@@ -472,6 +473,7 @@ __mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block,
         for (page_block = 0; page_block < blocks_per_page; ) {
 
                 map_bh.b_state = 0;
+                map_bh.b_size = 1 << blkbits;
                 if (get_block(inode, block_in_file, &map_bh, 1))
                         goto confused;
                 if (buffer_new(&map_bh))
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index 464f068f8b16..fb7e9b7ccbe3 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -280,6 +280,7 @@ map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
         set_buffer_mapped(bh);
         bh->b_bdev = sb->s_bdev;
         bh->b_blocknr = block;
+        bh->b_size = sb->s_blocksize;
 }
 
 /*