btrfs: move btrfs_drop_extent_cache() to extent_map.c

The function btrfs_drop_extent_cache() doesn't really belong at file.c
because what it does is drop a range of extent maps for a file range.
It directly allocates and manipulates extent maps, by dropping,
splitting and replacing them in an extent map tree, so it should be
located at extent_map.c, where all manipulations of an extent map tree
and its extent maps are supposed to be done.

So move it out of file.c and into extent_map.c. Additionally do the
following changes:

1) Rename it into btrfs_drop_extent_map_range(), as this makes it more
   clear about what it does. The term "cache" is a bit confusing as it's
   not widely used, "extent maps" or "extent mapping" is much more common;

2) Change its 'skip_pinned' argument from int to bool;

3) Turn several of its local variables from int to bool, since they are
   used as booleans;

4) Move the declaration of some variables out of the function's main
   scope and into the scopes where they are used;

5) Remove pointless assignment of false to 'modified' early in the while
   loop, as later that variable is set and it's not used before that
   second assignment;

6) Remove checks for NULL before calling free_extent_map().

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index d2fa32ffe304..17f4a9bbee7f 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -63,6 +63,8 @@ struct extent_map_tree {
 	rwlock_t lock;
 };
 
+struct btrfs_inode;
+
 static inline int extent_map_in_tree(const struct extent_map *em)
 {
 	return !RB_EMPTY_NODE(&em->rb_node);
@@ -104,5 +106,8 @@ struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
 int btrfs_add_extent_mapping(struct btrfs_fs_info *fs_info,
 			     struct extent_map_tree *em_tree,
 			     struct extent_map **em_in, u64 start, u64 len);
+void btrfs_drop_extent_map_range(struct btrfs_inode *inode,
+				 u64 start, u64 end,
+				 bool skip_pinned);
 
 #endif