Btrfs: [PATCH] extent_map: provide generic bmap

generic_bmap is completely trivial, while the extent to bh mapping in
btrfs is rather complex.  So provide a extent_bmap instead that takes
a get_extent callback and can be used by filesystem using the extent_map
code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 2 insertions, 21 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 1ace6d11e097..39c1fe178f47 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1567,28 +1567,9 @@ out:
         return em;
 }
 
-static int btrfs_get_block_bmap(struct inode *inode, sector_t iblock,
-                           struct buffer_head *result, int create)
+static sector_t btrfs_bmap(struct address_space *mapping, sector_t iblock)
 {
-        struct btrfs_root *root = BTRFS_I(inode)->root;
-        u64 start = iblock << inode->i_blkbits;
-        u64 end = start + root->blocksize -1;
-        struct extent_map *em;
-
-        em = btrfs_get_extent(inode, NULL, 0, start, end, 0);
-        if (em && !IS_ERR(em) && em->block_start != EXTENT_MAP_INLINE &&
-            em->block_start != 0) {
-                u64 offset;
-                offset = start - em->start;
-                start = (em->block_start + offset) >> inode->i_blkbits;
-                btrfs_map_bh_to_logical(root, result, start);
-        }
-        return 0;
-}
-
-static sector_t btrfs_bmap(struct address_space *as, sector_t block)
-{
-        return generic_block_bmap(as, block, btrfs_get_block_bmap);
+        return extent_bmap(mapping, iblock, btrfs_get_extent);
 }
 
 static int btrfs_prepare_write(struct file *file, struct page *page,