btrfs: unify extent buffer allocation api

Make the extent buffer allocation interface consistent.  Cloned eb will
set a valid fs_info.  For dummy eb, we can drop the length parameter and
set it from fs_info.

The built-in sanity checks may pass a NULL fs_info that's queried for
nodesize, but we know it's 4096.
Signed-off-by: NDavid Sterba <dsterba@suse.cz>

fs/btrfs/ctree.c

@@ -1363,8 +1363,7 @@ tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
 
 	if (tm->op == MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
 		BUG_ON(tm->slot != 0);
-		eb_rewin = alloc_dummy_extent_buffer(eb->start,
-						fs_info->tree_root->nodesize);
+		eb_rewin = alloc_dummy_extent_buffer(fs_info, eb->start);
 		if (!eb_rewin) {
 			btrfs_tree_read_unlock_blocking(eb);
 			free_extent_buffer(eb);
@@ -1444,7 +1443,7 @@ get_old_root(struct btrfs_root *root, u64 time_seq)
 	} else if (old_root) {
 		btrfs_tree_read_unlock(eb_root);
 		free_extent_buffer(eb_root);
-		eb = alloc_dummy_extent_buffer(logical, root->nodesize);
+		eb = alloc_dummy_extent_buffer(root->fs_info, logical);
 	} else {
 		btrfs_set_lock_blocking_rw(eb_root, BTRFS_READ_LOCK);
 		eb = btrfs_clone_extent_buffer(eb_root);

fs/btrfs/extent_io.c

@@ -4643,7 +4643,7 @@ struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src)
 	struct extent_buffer *new;
 	unsigned long num_pages = num_extent_pages(src->start, src->len);
 
-	new = __alloc_extent_buffer(NULL, src->start, src->len);
+	new = __alloc_extent_buffer(src->fs_info, src->start, src->len);
 	if (new == NULL)
 		return NULL;
 
@@ -4666,13 +4666,26 @@ struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src)
 	return new;
 }
 
-struct extent_buffer *alloc_dummy_extent_buffer(u64 start, unsigned long len)
+struct extent_buffer *alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
+						u64 start)
 {
 	struct extent_buffer *eb;
-	unsigned long num_pages = num_extent_pages(0, len);
+	unsigned long len;
+	unsigned long num_pages;
 	unsigned long i;
 
-	eb = __alloc_extent_buffer(NULL, start, len);
+	if (!fs_info) {
+		/*
+		 * Called only from tests that don't always have a fs_info
+		 * available, but we know that nodesize is 4096
+		 */
+		len = 4096;
+	} else {
+		len = fs_info->tree_root->nodesize;
+	}
+	num_pages = num_extent_pages(0, len);
+
+	eb = __alloc_extent_buffer(fs_info, start, len);
 	if (!eb)
 		return NULL;
 
@@ -4770,7 +4783,7 @@ struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info,
 	eb = find_extent_buffer(fs_info, start);
 	if (eb)
 		return eb;
-	eb = alloc_dummy_extent_buffer(start, len);
+	eb = alloc_dummy_extent_buffer(fs_info, start);
 	if (!eb)
 		return NULL;
 	eb->fs_info = fs_info;

fs/btrfs/extent_io.h

@@ -263,7 +263,8 @@ void set_page_extent_mapped(struct page *page);
 
 struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
 					  u64 start, unsigned long len);
-struct extent_buffer *alloc_dummy_extent_buffer(u64 start, unsigned long len);
+struct extent_buffer *alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
+		u64 start);
 struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src);
 struct extent_buffer *find_extent_buffer(struct btrfs_fs_info *fs_info,
 					 u64 start);

fs/btrfs/tests/extent-buffer-tests.c

@@ -53,7 +53,7 @@ static int test_btrfs_split_item(void)
 		return -ENOMEM;
 	}
 
-	path->nodes[0] = eb = alloc_dummy_extent_buffer(0, 4096);
+	path->nodes[0] = eb = alloc_dummy_extent_buffer(NULL, 4096);
 	if (!eb) {
 		test_msg("Could not allocate dummy buffer\n");
 		ret = -ENOMEM;

fs/btrfs/tests/inode-tests.c

@@ -255,7 +255,7 @@ static noinline int test_btrfs_get_extent(void)
 		goto out;
 	}
 
-	root->node = alloc_dummy_extent_buffer(0, 4096);
+	root->node = alloc_dummy_extent_buffer(NULL, 4096);
 	if (!root->node) {
 		test_msg("Couldn't allocate dummy buffer\n");
 		goto out;
@@ -843,7 +843,7 @@ static int test_hole_first(void)
 		goto out;
 	}
 
-	root->node = alloc_dummy_extent_buffer(0, 4096);
+	root->node = alloc_dummy_extent_buffer(NULL, 4096);
 	if (!root->node) {
 		test_msg("Couldn't allocate dummy buffer\n");
 		goto out;

fs/btrfs/tests/qgroup-tests.c

@@ -404,6 +404,16 @@ int btrfs_test_qgroups(void)
 		ret = -ENOMEM;
 		goto out;
 	}
+	/* We are using this root as our extent root */
+	root->fs_info->extent_root = root;
+
+	/*
+	 * Some of the paths we test assume we have a filled out fs_info, so we
+	 * just need to add the root in there so we don't panic.
+	 */
+	root->fs_info->tree_root = root;
+	root->fs_info->quota_root = root;
+	root->fs_info->quota_enabled = 1;
 
 	/*
 	 * Can't use bytenr 0, some things freak out
@@ -448,17 +458,6 @@ int btrfs_test_qgroups(void)
 		goto out;
 	}
 
-	/* We are using this root as our extent root */
-	root->fs_info->extent_root = root;
-
-	/*
-	 * Some of the paths we test assume we have a filled out fs_info, so we
-	 * just need to addt he root in there so we don't panic.
-	 */
-	root->fs_info->tree_root = root;
-	root->fs_info->quota_root = root;
-	root->fs_info->quota_enabled = 1;
-
 	test_msg("Running qgroup tests\n");
 	ret = test_no_shared_qgroup(root);
 	if (ret)