From d2311e69857815ae2f728b48e6730f833a617092 Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Wed, 23 Jan 2019 15:15:14 +0800 Subject: [PATCH] btrfs: relocation: Delay reloc tree deletion after merge_reloc_roots Relocation code will drop btrfs_root::reloc_root as soon as merge_reloc_root() finishes. However later qgroup code will need to access btrfs_root::reloc_root after merge_reloc_root() for delayed subtree rescan. So alter the timming of resetting btrfs_root:::reloc_root, make it happens after transaction commit. With this patch, we will introduce a new btrfs_root::state, BTRFS_ROOT_DEAD_RELOC_TREE, to info part of btrfs_root::reloc_tree user that although btrfs_root::reloc_tree is still non-NULL, but still it's not used any more. The lifespan of btrfs_root::reloc tree will become: Old behavior | New ------------------------------------------------------------------------ btrfs_init_reloc_root() --- | btrfs_init_reloc_root() --- set reloc_root | | set reloc_root | | | | | | | merge_reloc_root() | | merge_reloc_root() | |- btrfs_update_reloc_root() --- | |- btrfs_update_reloc_root() -+- clear btrfs_root::reloc_root | set ROOT_DEAD_RELOC_TREE | | record root into dirty | | roots rbtree | | | | reloc_block_group() Or | | btrfs_recover_relocation() | | | After transaction commit | | |- clean_dirty_subvols() --- | clear btrfs_root::reloc_root During ROOT_DEAD_RELOC_TREE set lifespan, the only user of btrfs_root::reloc_tree should be qgroup. Since reloc root needs a longer life-span, this patch will also delay btrfs_drop_snapshot() call. Now btrfs_drop_snapshot() is called in clean_dirty_subvols(). This patch will increase the size of btrfs_root by 16 bytes. Signed-off-by: Qu Wenruo Signed-off-by: David Sterba --- fs/btrfs/ctree.h | 15 ++++++++ fs/btrfs/disk-io.c | 1 + fs/btrfs/relocation.c | 85 ++++++++++++++++++++++++++++++++++--------- 3 files changed, 84 insertions(+), 17 deletions(-) diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index fecc64d8e285..dd0ccc6403b0 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -1199,6 +1199,13 @@ enum { BTRFS_ROOT_MULTI_LOG_TASKS, BTRFS_ROOT_DIRTY, BTRFS_ROOT_DELETING, + + /* + * Reloc tree is orphan, only kept here for qgroup delayed subtree scan + * + * Set for the subvolume tree owning the reloc tree. + */ + BTRFS_ROOT_DEAD_RELOC_TREE, }; /* @@ -1311,6 +1318,14 @@ struct btrfs_root { struct list_head ordered_root; u64 nr_ordered_extents; + /* + * Not empty if this subvolume root has gone through tree block swap + * (relocation) + * + * Will be used by reloc_control::dirty_subvol_roots. + */ + struct list_head reloc_dirty_list; + /* * Number of currently running SEND ioctls to prevent * manipulation with the read-only status via SUBVOL_SETFLAGS diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index de4b7ed02da1..9e24fdb57453 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1176,6 +1176,7 @@ static void __setup_root(struct btrfs_root *root, struct btrfs_fs_info *fs_info, INIT_LIST_HEAD(&root->delalloc_root); INIT_LIST_HEAD(&root->ordered_extents); INIT_LIST_HEAD(&root->ordered_root); + INIT_LIST_HEAD(&root->reloc_dirty_list); INIT_LIST_HEAD(&root->logged_list[0]); INIT_LIST_HEAD(&root->logged_list[1]); spin_lock_init(&root->inode_lock); diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index de802ba35a34..b915f3e157bd 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -162,6 +162,8 @@ struct reloc_control { struct mapping_tree reloc_root_tree; /* list of reloc trees */ struct list_head reloc_roots; + /* list of subvolume trees that get relocated */ + struct list_head dirty_subvol_roots; /* size of metadata reservation for merging reloc trees */ u64 merging_rsv_size; /* size of relocated tree nodes */ @@ -1467,15 +1469,17 @@ int btrfs_update_reloc_root(struct btrfs_trans_handle *trans, struct btrfs_root_item *root_item; int ret; - if (!root->reloc_root) + if (test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state) || + !root->reloc_root) goto out; reloc_root = root->reloc_root; root_item = &reloc_root->root_item; + /* root->reloc_root will stay until current relocation finished */ if (fs_info->reloc_ctl->merge_reloc_tree && btrfs_root_refs(root_item) == 0) { - root->reloc_root = NULL; + set_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state); __del_reloc_root(reloc_root); } @@ -2120,6 +2124,58 @@ static int find_next_key(struct btrfs_path *path, int level, return 1; } +/* + * Insert current subvolume into reloc_control::dirty_subvol_roots + */ +static void insert_dirty_subvol(struct btrfs_trans_handle *trans, + struct reloc_control *rc, + struct btrfs_root *root) +{ + struct btrfs_root *reloc_root = root->reloc_root; + struct btrfs_root_item *reloc_root_item; + + /* @root must be a subvolume tree root with a valid reloc tree */ + ASSERT(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID); + ASSERT(reloc_root); + + reloc_root_item = &reloc_root->root_item; + memset(&reloc_root_item->drop_progress, 0, + sizeof(reloc_root_item->drop_progress)); + reloc_root_item->drop_level = 0; + btrfs_set_root_refs(reloc_root_item, 0); + btrfs_update_reloc_root(trans, root); + + if (list_empty(&root->reloc_dirty_list)) { + btrfs_grab_fs_root(root); + list_add_tail(&root->reloc_dirty_list, &rc->dirty_subvol_roots); + } +} + +static int clean_dirty_subvols(struct reloc_control *rc) +{ + struct btrfs_root *root; + struct btrfs_root *next; + int ret = 0; + + list_for_each_entry_safe(root, next, &rc->dirty_subvol_roots, + reloc_dirty_list) { + struct btrfs_root *reloc_root = root->reloc_root; + + clear_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state); + list_del_init(&root->reloc_dirty_list); + root->reloc_root = NULL; + if (reloc_root) { + int ret2; + + ret2 = btrfs_drop_snapshot(reloc_root, NULL, 0, 1); + if (ret2 < 0 && !ret) + ret = ret2; + } + btrfs_put_fs_root(root); + } + return ret; +} + /* * merge the relocated tree blocks in reloc tree with corresponding * fs tree. @@ -2258,13 +2314,8 @@ static noinline_for_stack int merge_reloc_root(struct reloc_control *rc, out: btrfs_free_path(path); - if (err == 0) { - memset(&root_item->drop_progress, 0, - sizeof(root_item->drop_progress)); - root_item->drop_level = 0; - btrfs_set_root_refs(root_item, 0); - btrfs_update_reloc_root(trans, root); - } + if (err == 0) + insert_dirty_subvol(trans, rc, root); if (trans) btrfs_end_transaction_throttle(trans); @@ -2409,14 +2460,6 @@ again: } else { list_del_init(&reloc_root->root_list); } - - ret = btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0, 1); - if (ret < 0) { - if (list_empty(&reloc_root->root_list)) - list_add_tail(&reloc_root->root_list, - &reloc_roots); - goto out; - } } if (found) { @@ -4078,6 +4121,9 @@ restart: goto out_free; } btrfs_commit_transaction(trans); + ret = clean_dirty_subvols(rc); + if (ret < 0 && !err) + err = ret; out_free: btrfs_free_block_rsv(fs_info, rc->block_rsv); btrfs_free_path(path); @@ -4172,6 +4218,7 @@ static struct reloc_control *alloc_reloc_control(void) return NULL; INIT_LIST_HEAD(&rc->reloc_roots); + INIT_LIST_HEAD(&rc->dirty_subvol_roots); backref_cache_init(&rc->backref_cache); mapping_tree_init(&rc->reloc_root_tree); extent_io_tree_init(&rc->processed_blocks, NULL); @@ -4467,6 +4514,10 @@ int btrfs_recover_relocation(struct btrfs_root *root) goto out_free; } err = btrfs_commit_transaction(trans); + + ret = clean_dirty_subvols(rc); + if (ret < 0 && !err) + err = ret; out_free: kfree(rc); out: -- 2.30.2