btrfs: pass an inode to btrfs_add_extent_mapping()

Instead of passing fs_info and extent map tree arguments to
btrfs_add_extent_mapping(), we can pass an inode instead, as extent maps
are always inserted in the extent map tree of an inode, and the fs_info
can be extracted from the inode (inode->root->fs_info). The only exception
is in the self tests where we allocate an extent map tree and then use it
to insert/update/remove extent maps. However the tests can be changed to
use a test inode and then use the inode's extent map tree.

So change btrfs_add_extent_mapping() to have an inode as an argument
instead of a fs_info and an extent map tree. This reduces the number of
parameters and will also be needed for an upcoming change.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
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/extent_map.c

@@ -546,10 +546,9 @@ static noinline int merge_extent_mapping(struct extent_map_tree *em_tree,
 }
 
 /*
- * Add extent mapping into em_tree.
+ * Add extent mapping into an inode's extent map tree.
  *
- * @fs_info:  the filesystem
- * @em_tree:  extent tree into which we want to insert the extent mapping
+ * @inode:    target inode
  * @em_in:    extent we are inserting
  * @start:    start of the logical range btrfs_get_extent() is requesting
  * @len:      length of the logical range btrfs_get_extent() is requesting
@@ -557,8 +556,8 @@ static noinline int merge_extent_mapping(struct extent_map_tree *em_tree,
  * Note that @em_in's range may be different from [start, start+len),
  * but they must be overlapped.
  *
- * Insert @em_in into @em_tree. In case there is an overlapping range, handle
- * the -EEXIST by either:
+ * Insert @em_in into the inode's extent map tree. In case there is an
+ * overlapping range, handle the -EEXIST by either:
  * a) Returning the existing extent in @em_in if @start is within the
  *    existing em.
  * b) Merge the existing extent with @em_in passed in.
@@ -566,12 +565,13 @@ static noinline int merge_extent_mapping(struct extent_map_tree *em_tree,
  * Return 0 on success, otherwise -EEXIST.
  *
  */
-int btrfs_add_extent_mapping(struct btrfs_fs_info *fs_info,
-			     struct extent_map_tree *em_tree,
+int btrfs_add_extent_mapping(struct btrfs_inode *inode,
 			     struct extent_map **em_in, u64 start, u64 len)
 {
 	int ret;
 	struct extent_map *em = *em_in;
+	struct extent_map_tree *em_tree = &inode->extent_tree;
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
 
 	/*
 	 * Tree-checker should have rejected any inline extent with non-zero

fs/btrfs/extent_map.h

@@ -132,8 +132,7 @@ int unpin_extent_cache(struct btrfs_inode *inode, u64 start, u64 len, u64 gen);
 void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em);
 struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
 					 u64 start, u64 len);
-int btrfs_add_extent_mapping(struct btrfs_fs_info *fs_info,
-			     struct extent_map_tree *em_tree,
+int btrfs_add_extent_mapping(struct btrfs_inode *inode,
 			     struct extent_map **em_in, u64 start, u64 len);
 void btrfs_drop_extent_map_range(struct btrfs_inode *inode,
 				 u64 start, u64 end,

fs/btrfs/inode.c

@@ -6972,7 +6972,7 @@ struct extent_map *btrfs_get_extent(struct btrfs_inode *inode,
 	}
 
 	write_lock(&em_tree->lock);
-	ret = btrfs_add_extent_mapping(fs_info, em_tree, &em, start, len);
+	ret = btrfs_add_extent_mapping(inode, &em, start, len);
 	write_unlock(&em_tree->lock);
 out:
 	btrfs_free_path(path);