btrfs: remove dead create_space_info calls (dc2d3005) · Commits · 戴 / test

Since commit (btrfs: Separate space_info create/update), we've separated out the creation and updating of the space info structures. That commit was a straightforward refactoring of the two parts of update_space_info, but we can go a step further. Since commits (Btrfs: fix OOPS of empty filesystem after balance) and (Btrfs: Link block groups of different raid types), we know that the space_info structures will be created at mount and there will only ever be, at most, three of them. This patch cleans out the create_space_info calls after __find_space_info returns NULL since __find_space_info *can't* return NULL. The initial cause for reviewing this was the kobject_add calls from create_space_info occuring in sites where fs-reclaim wasn't allowed. Now we are certain they occur only early in the mount process and are safe. Signed-off-by:

Jeff Mahoney <jeffm@suse.com> Reviewed-by:

Nikolay Borisov <nborisov@suse.com> Reviewed-by:

David Sterba <dsterba@suse.com> Signed-off-by:

David Sterba <dsterba@suse.com>

fs/btrfs/ctree.h

+3 −3

Original line number	Diff line number	Diff line
		@@ -954,9 +954,9 @@ struct btrfs_fs_info {
		struct btrfs_fs_devices *fs_devices;

		/*
		* the space_info list is almost entirely read only. It only changes
		* when we add a new raid type to the FS, and that happens
		* very rarely. RCU is used to protect it.
		* The space_info list is effectively read only after initial
		* setup. It is populated at mount time and cleaned up after
		* all block groups are removed. RCU is used to protect it.
		*/
		struct list_head space_info;

fs/btrfs/extent-tree.c

+2 −14

Original line number	Diff line number	Diff line
		@@ -4606,11 +4606,7 @@ static int do_chunk_alloc(struct btrfs_trans_handle *trans,
		return -ENOSPC;

		space_info = __find_space_info(fs_info, flags);
		if (!space_info) {
		ret = create_space_info(fs_info, flags, &space_info);
		if (ret)
		return ret;
		}
		ASSERT(space_info);

		again:
		spin_lock(&space_info->lock);
		@@ -10265,15 +10261,7 @@ int btrfs_make_block_group(struct btrfs_trans_handle *trans,
		* with its ->space_info set.
		*/
		cache->space_info = __find_space_info(fs_info, cache->flags);
		if (!cache->space_info) {
		ret = create_space_info(fs_info, cache->flags,
		&cache->space_info);
		if (ret) {
		btrfs_remove_free_space_cache(cache);
		btrfs_put_block_group(cache);
		return ret;
		}
		}
		ASSERT(cache->space_info);

		ret = btrfs_add_block_group_cache(fs_info, cache);
		if (ret) {

Admin message