btrfs: remove no longer used EXTENT_MAP_DELALLOC block start value

After commit ac3c0d36 ("btrfs: make fiemap more efficient and accurate
reporting extent sharedness") we no longer need to create special extent
maps during fiemap that have a block start with the EXTENT_MAP_DELALLOC
value. So this block start value for extent maps is no longer used since
then, therefore remove it.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/defrag.c

@@ -996,9 +996,8 @@ static int defrag_collect_targets(struct btrfs_inode *inode,
 		    em->len <= inode->root->fs_info->max_inline)
 			goto next;
 
-		/* Skip hole/delalloc/preallocated extents */
+		/* Skip holes and preallocated extents. */
 		if (em->block_start == EXTENT_MAP_HOLE ||
-		    em->block_start == EXTENT_MAP_DELALLOC ||
 		    test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
 			goto next;
 

fs/btrfs/extent_map.c

@@ -212,9 +212,6 @@ static int mergable_maps(struct extent_map *prev, struct extent_map *next)
 	if (!list_empty(&prev->list) || !list_empty(&next->list))
 		return 0;
 
-	ASSERT(next->block_start != EXTENT_MAP_DELALLOC &&
-	       prev->block_start != EXTENT_MAP_DELALLOC);
-
 	if (extent_map_end(prev) == next->start &&
 	    prev->flags == next->flags &&
 	    ((next->block_start == EXTENT_MAP_HOLE &&

fs/btrfs/extent_map.h

@@ -9,8 +9,6 @@
 #define EXTENT_MAP_LAST_BYTE ((u64)-4)
 #define EXTENT_MAP_HOLE ((u64)-3)
 #define EXTENT_MAP_INLINE ((u64)-2)
-/* used only during fiemap calls */
-#define EXTENT_MAP_DELALLOC ((u64)-1)
 
 /* bits for the extent_map::flags field */
 enum {

include/trace/events/btrfs.h

@@ -265,8 +265,7 @@ DEFINE_EVENT(btrfs__inode, btrfs_inode_evict,
 	__print_symbolic_u64(type,					\
 		{ EXTENT_MAP_LAST_BYTE, "LAST_BYTE" 	},		\
 		{ EXTENT_MAP_HOLE, 	"HOLE" 		},		\
-		{ EXTENT_MAP_INLINE, 	"INLINE" 	},		\
-		{ EXTENT_MAP_DELALLOC,	"DELALLOC" 	})
+		{ EXTENT_MAP_INLINE,	"INLINE"	})
 
 #define show_map_type(type)			\
 	type, (type >= EXTENT_MAP_LAST_BYTE) ? "-" :  __show_map_type(type)