On 13.05.20 г. 9:16 ч., Qu Wenruo wrote:
> SHAREABLE flag is set for subvolumes because users can create snapshot
> for subvolumes, thus sharing tree blocks of them.
>
> But users can't access data reloc tree as it's only an internal tree for
> data relocation, thus it doesn't need the full path replacement treat at
> all.
>
> This patch will make data reloc tree just a non-shareable tree, and add
> btrfs_fs_info::dreloc_root for data reloc tree, so relocation code can
> grab it from fs_info directly.
>
> This would slightly improve tree relocation, as now data reloc tree
> can go through regular COW routine to get relocated, without bothering
> the complex tree reloc tree routine.
>
> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
> ---
> fs/btrfs/ctree.h | 1 +
> fs/btrfs/disk-io.c | 14 +++++++++++++-
> fs/btrfs/inode.c | 7 ++++---
> fs/btrfs/relocation.c | 18 ++++--------------
> 4 files changed, 22 insertions(+), 18 deletions(-)
>
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 65c09aea4cb9..a9690f438a15 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -582,6 +582,7 @@ struct btrfs_fs_info {
> struct btrfs_root *quota_root;
> struct btrfs_root *uuid_root;
> struct btrfs_root *free_space_root;
> + struct btrfs_root *dreloc_root;
Rename this to data_reloc_root or simply reloc_root, dreloc is rather
cryptic.
>
> /* the log root tree is a directory of all the other log roots */
> struct btrfs_root *log_root_tree;
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 4dd3206c1ace..7355ebc648c5 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -1419,7 +1419,8 @@ static int btrfs_init_fs_root(struct btrfs_root *root)
> if (ret)
> goto fail;
>
> - if (root->root_key.objectid != BTRFS_TREE_LOG_OBJECTID) {
> + if (root->root_key.objectid != BTRFS_TREE_LOG_OBJECTID &&
> + root->root_key.objectid != BTRFS_DATA_RELOC_TREE_OBJECTID) {
> set_bit(BTRFS_ROOT_SHAREABLE, &root->state);
> btrfs_check_and_init_root_item(&root->root_item);
> }
> @@ -1525,6 +1526,7 @@ void btrfs_free_fs_info(struct btrfs_fs_info *fs_info)
> btrfs_put_root(fs_info->uuid_root);
> btrfs_put_root(fs_info->free_space_root);
> btrfs_put_root(fs_info->fs_root);
> + btrfs_put_root(fs_info->dreloc_root);
> btrfs_check_leaked_roots(fs_info);
> btrfs_extent_buffer_leak_debug_check(fs_info);
> kfree(fs_info->super_copy);
> @@ -1981,6 +1983,7 @@ static void free_root_pointers(struct btrfs_fs_info *info, bool free_chunk_root)
> free_root_extent_buffers(info->quota_root);
> free_root_extent_buffers(info->uuid_root);
> free_root_extent_buffers(info->fs_root);
> + free_root_extent_buffers(info->dreloc_root);
> if (free_chunk_root)
> free_root_extent_buffers(info->chunk_root);
> free_root_extent_buffers(info->free_space_root);
> @@ -2287,6 +2290,15 @@ static int btrfs_read_roots(struct btrfs_fs_info *fs_info)
> set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state);
> fs_info->csum_root = root;
>
> + location.objectid = BTRFS_DATA_RELOC_TREE_OBJECTID;
> + root = btrfs_get_fs_root(fs_info, &location, true);
> + if (IS_ERR(root)) {
> + ret = PTR_ERR(root);
> + goto out;
> + }
> + set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state);
> + fs_info->dreloc_root = root;
> +
> location.objectid = BTRFS_QUOTA_TREE_OBJECTID;
> root = btrfs_read_tree_root(tree_root, &location);
> if (!IS_ERR(root)) {
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 13bbb6b0d495..6b7ba20eee52 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -4133,7 +4133,7 @@ int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
> * inode.
> */
> if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state) ||
> - root == fs_info->tree_root)
> + root == fs_info->tree_root || root == fs_info->dreloc_root)
> btrfs_drop_extent_cache(BTRFS_I(inode), ALIGN(new_size,
> fs_info->sectorsize),
> (u64)-1, 0);
> @@ -4338,7 +4338,8 @@ int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
>
> if (found_extent &&
> (test_bit(BTRFS_ROOT_SHAREABLE, &root->state) ||
> - root == fs_info->tree_root)) {
> + root == fs_info->tree_root ||
> + root == fs_info->dreloc_root)) {
> struct btrfs_ref ref = { 0 };
>
> bytes_deleted += extent_num_bytes;
> @@ -5046,7 +5047,7 @@ void btrfs_evict_inode(struct inode *inode)
> btrfs_end_transaction(trans);
> }
>
> - if (!(root == fs_info->tree_root ||
> + if (!(root == fs_info->tree_root || root == fs_info->dreloc_root ||
> root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID))
> btrfs_return_ino(root, btrfs_ino(BTRFS_I(inode)));
>
> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
> index 437b782c57e6..cb45ae92f15d 100644
> --- a/fs/btrfs/relocation.c
> +++ b/fs/btrfs/relocation.c
> @@ -1087,7 +1087,8 @@ int replace_file_extents(struct btrfs_trans_handle *trans,
> * if we are modifying block in fs tree, wait for readpage
> * to complete and drop the extent cache
> */
> - if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
> + if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
> + root->root_key.objectid != BTRFS_DATA_RELOC_TREE_OBJECTID) {
> if (first) {
> inode = find_next_inode(root, key.objectid);
> first = 0;
> @@ -3470,15 +3471,11 @@ struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
> {
> struct inode *inode = NULL;
> struct btrfs_trans_handle *trans;
> - struct btrfs_root *root;
> + struct btrfs_root *root = fs_info->dreloc_root;
So why haven't you added code in btrfs_get_fs_root to quickly return a
refcounted root and instead reference it without incrementing the refcount?
> struct btrfs_key key;
> u64 objectid;
> int err = 0;
>
> - root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
> - if (IS_ERR(root))
> - return ERR_CAST(root);
> -
> trans = btrfs_start_transaction(root, 6);
> if (IS_ERR(trans)) {
> btrfs_put_root(root);
> @@ -3501,7 +3498,6 @@ struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
>
> err = btrfs_orphan_add(trans, BTRFS_I(inode));
> out:
> - btrfs_put_root(root);
> btrfs_end_transaction(trans);
> btrfs_btree_balance_dirty(fs_info);
> if (err) {
> @@ -3870,13 +3866,7 @@ int btrfs_recover_relocation(struct btrfs_root *root)
>
> if (err == 0) {
> /* cleanup orphan inode in data relocation tree */
> - fs_root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
> - if (IS_ERR(fs_root)) {
> - err = PTR_ERR(fs_root);
> - } else {
> - err = btrfs_orphan_cleanup(fs_root);
> - btrfs_put_root(fs_root);
> - }
> + err = btrfs_orphan_cleanup(fs_info->dreloc_root);
> }
> return err;
> }
>
