From c622ae6085d0c6ad834213bbf1477eb311359078 Mon Sep 17 00:00:00 2001 From: liubo Date: Sat, 26 Mar 2011 08:01:12 -0400 Subject: [PATCH] btrfs: make inode ref log recovery faster When we recover from crash via write-ahead log tree and process the inode refs, for each btrfs_inode_ref item, we will 1) check if we already have a perfect match in fs/file tree, if we have, then we're done. 2) search the corresponding back reference in fs/file tree, and check all the names in this back reference to see if they are also in the log to avoid conflict corners. 3) recover the logged inode refs to fs/file tree. In current btrfs, however, - for 2)'s check, once is enough, since the checked back reference will remain unchanged after processing all the inode refs belonged to the key. - it has no need to do another 1) between 2) and 3). I've made a small test to show how it improves, $dd if=/dev/zero of=foobar bs=4K count=1 $sync $make 100 hard links continuously, like ln foobar link_i $fsync foobar $echo b > /proc/sysrq-trigger after reboot $time mount DEV PATH without patch: real 0m0.285s user 0m0.001s sys 0m0.009s with patch: real 0m0.123s user 0m0.000s sys 0m0.010s Changelog v1->v2: - fix double free - pointed by David Sterba Changelog v2->v3: - adjust free order Signed-off-by: Liu Bo Signed-off-by: Chris Mason --- fs/btrfs/tree-log.c | 35 +++++++++++------------------------ 1 file changed, 11 insertions(+), 24 deletions(-) diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index f9425e33e358..c50271ad3157 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -799,12 +799,12 @@ static noinline int add_inode_ref(struct btrfs_trans_handle *trans, struct inode *dir; int ret; struct btrfs_inode_ref *ref; - struct btrfs_dir_item *di; struct inode *inode; char *name; int namelen; unsigned long ref_ptr; unsigned long ref_end; + int search_done = 0; /* * it is possible that we didn't log all the parent directories @@ -845,7 +845,10 @@ again: * existing back reference, and we don't want to create * dangling pointers in the directory. */ -conflict_again: + + if (search_done) + goto insert; + ret = btrfs_search_slot(NULL, root, key, path, 0, 0); if (ret == 0) { char *victim_name; @@ -886,37 +889,21 @@ conflict_again: ret = btrfs_unlink_inode(trans, root, dir, inode, victim_name, victim_name_len); - kfree(victim_name); - btrfs_release_path(root, path); - goto conflict_again; } kfree(victim_name); ptr = (unsigned long)(victim_ref + 1) + victim_name_len; } BUG_ON(ret); - } - btrfs_release_path(root, path); - - /* look for a conflicting sequence number */ - di = btrfs_lookup_dir_index_item(trans, root, path, dir->i_ino, - btrfs_inode_ref_index(eb, ref), - name, namelen, 0); - if (di && !IS_ERR(di)) { - ret = drop_one_dir_item(trans, root, path, dir, di); - BUG_ON(ret); - } - btrfs_release_path(root, path); - - /* look for a conflicting name */ - di = btrfs_lookup_dir_item(trans, root, path, dir->i_ino, - name, namelen, 0); - if (di && !IS_ERR(di)) { - ret = drop_one_dir_item(trans, root, path, dir, di); - BUG_ON(ret); + /* + * NOTE: we have searched root tree and checked the + * coresponding ref, it does not need to check again. + */ + search_done = 1; } btrfs_release_path(root, path); +insert: /* insert our name */ ret = btrfs_add_link(trans, dir, inode, name, namelen, 0, btrfs_inode_ref_index(eb, ref)); -- 2.30.2