| Message ID | 20180320192526.4629-1-jeffm@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 20.03.2018 21:25, jeffm@suse.com wrote: > From: Jeff Mahoney <jeffm@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 <jeffm@suse.com> So when I did this cleanup I really wasn't sure under what conditions space_info was allocated apart from mount time. I'm glad you were able to prove it's not really done at any other time. Reviewed-by: Nikolay Borisov <nborisov@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) { > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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) {