btrfs: don't commit transaction for every subvol create
Recently a Meta-internal workload encountered subvolume creation taking up to 2s each, significantly slower than directory creation. As they were hoping to be able to use subvolumes instead of directories, and were looking to create hundreds, this was a significant issue. After Josef investigated, it turned out to be due to the transaction commit currently performed at the end of subvolume creation. This change improves the workload by not doing transaction commit for every subvolume creation, and merely requiring a transaction commit on fsync. In the worst case, of doing a subvolume create and fsync in a loop, this should require an equal amount of time to the current scheme; and in the best case, the internal workload creating hundreds of subvolumes before fsyncing is greatly improved. While it would be nice to be able to use the log tree and use the normal fsync path, log tree replay can't deal with new subvolume inodes presently. It's possible that there's some reason that the transaction commit is necessary for correctness during subvolume creation; however, git logs indicate that the commit dates back to the beginning of subvolume creation, and there are no notes on why it would be necessary. Reviewed-by: Qu Wenruo <wqu@suse.com> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: Neal Gompa <neal@gompa.dev> Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
parent
f469c8bd90
commit
1b53e51a4a
@ -649,6 +649,8 @@ static noinline int create_subvol(struct mnt_idmap *idmap,
|
||||
}
|
||||
trans->block_rsv = &block_rsv;
|
||||
trans->bytes_reserved = block_rsv.size;
|
||||
/* Tree log can't currently deal with an inode which is a new root. */
|
||||
btrfs_set_log_full_commit(trans);
|
||||
|
||||
ret = btrfs_qgroup_inherit(trans, 0, objectid, inherit);
|
||||
if (ret)
|
||||
@ -757,10 +759,7 @@ out:
|
||||
trans->bytes_reserved = 0;
|
||||
btrfs_subvolume_release_metadata(root, &block_rsv);
|
||||
|
||||
if (ret)
|
||||
btrfs_end_transaction(trans);
|
||||
else
|
||||
ret = btrfs_commit_transaction(trans);
|
||||
btrfs_end_transaction(trans);
|
||||
out_new_inode_args:
|
||||
btrfs_new_inode_args_destroy(&new_inode_args);
|
||||
out_inode:
|
||||
|
Loading…
Reference in New Issue
Block a user