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>
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 3021564..ff2b1dd 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -1816,3 +1816,22 @@
}
EXPORT_SYMBOL(try_release_extent_mapping);
+sector_t extent_bmap(struct address_space *mapping, sector_t iblock,
+ get_extent_t *get_extent)
+{
+ struct inode *inode = mapping->host;
+ u64 start = iblock << inode->i_blkbits;
+ u64 end = start + (1 << inode->i_blkbits) - 1;
+ struct extent_map *em;
+
+ em = get_extent(inode, NULL, 0, start, end, 0);
+ if (!em || IS_ERR(em))
+ return 0;
+
+ // XXX(hch): block 0 is valid in some cases, e.g. XFS RT device
+ if (em->block_start == EXTENT_MAP_INLINE ||
+ em->block_start == 0)
+ return 0;
+
+ return (em->block_start + start - em->start) >> inode->i_blkbits;
+}