From: Jeff Mahoney <je...@suse.com>
Since commit 2be12ef79 (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
c59021f84 (Btrfs: fix OOPS of empty filesystem after balance) and
b742bb82f (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 <je...@suse.com>
---
fs/btrfs/ctree.h | 6 +++---
fs/btrfs/extent-tree.c | 16 ++--------------
2 files changed, 5 insertions(+), 17 deletions(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index da308774b8a4..ffbb05aa66fa 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -952,9 +952,9 @@ 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;
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 2d5e963fae88..0e9a21230217 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4603,11 +4603,7 @@ 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);
@@ -10255,15 +10251,7 @@ 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) {
--
2.15.1
--
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