Btrfs: introduce the delayed inode ref deletion for the single link inode

The inode reference item is close to inode item, so we insert it simultaneously
with the inode item insertion when we create a file/directory.. In fact, we also
can handle the inode reference deletion by the same way. So we made this patch to
introduce the delayed inode reference deletion for the single link inode(At most
case, the file doesn't has hard link, so we don't take the hard link into account).

This function is based on the delayed inode mechanism. After applying this patch,
we can reduce the time of the file/directory deletion by ~10%.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 53 insertions, 2 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 06bcf5b53cb0..9eaa1c8ed385 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3309,6 +3309,7 @@ static void btrfs_read_locked_inode(struct inode *inode)
         struct btrfs_timespec *tspec;
         struct btrfs_root *root = BTRFS_I(inode)->root;
         struct btrfs_key location;
+        unsigned long ptr;
         int maybe_acls;
         u32 rdev;
         int ret;
@@ -3332,7 +3333,7 @@ static void btrfs_read_locked_inode(struct inode *inode)
         leaf = path->nodes[0];
 
         if (filled)
-                goto cache_acl;
+                goto cache_index;
 
         inode_item = btrfs_item_ptr(leaf, path->slots[0],
                                     struct btrfs_inode_item);
@@ -3375,6 +3376,30 @@ static void btrfs_read_locked_inode(struct inode *inode)
 
         BTRFS_I(inode)->index_cnt = (u64)-1;
         BTRFS_I(inode)->flags = btrfs_inode_flags(leaf, inode_item);
+
+cache_index:
+        path->slots[0]++;
+        if (inode->i_nlink != 1 ||
+            path->slots[0] >= btrfs_header_nritems(leaf))
+                goto cache_acl;
+
+        btrfs_item_key_to_cpu(leaf, &location, path->slots[0]);
+        if (location.objectid != btrfs_ino(inode))
+                goto cache_acl;
+
+        ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
+        if (location.type == BTRFS_INODE_REF_KEY) {
+                struct btrfs_inode_ref *ref;
+
+                ref = (struct btrfs_inode_ref *)ptr;
+                BTRFS_I(inode)->dir_index = btrfs_inode_ref_index(leaf, ref);
+        } else if (location.type == BTRFS_INODE_EXTREF_KEY) {
+                struct btrfs_inode_extref *extref;
+
+                extref = (struct btrfs_inode_extref *)ptr;
+                BTRFS_I(inode)->dir_index = btrfs_inode_extref_index(leaf,
+                                                                     extref);
+        }
 cache_acl:
         /*
          * try to precache a NULL acl entry for files that don't have
@@ -3587,6 +3612,24 @@ static int __btrfs_unlink_inode(struct btrfs_trans_handle *trans,
                 goto err;
         btrfs_release_path(path);
 
+        /*
+         * If we don't have dir index, we have to get it by looking up
+         * the inode ref, since we get the inode ref, remove it directly,
+         * it is unnecessary to do delayed deletion.
+         *
+         * But if we have dir index, needn't search inode ref to get it.
+         * Since the inode ref is close to the inode item, it is better
+         * that we delay to delete it, and just do this deletion when
+         * we update the inode item.
+         */
+        if (BTRFS_I(inode)->dir_index) {
+                ret = btrfs_delayed_delete_inode_ref(inode);
+                if (!ret) {
+                        index = BTRFS_I(inode)->dir_index;
+                        goto skip_backref;
+                }
+        }
+
         ret = btrfs_del_inode_ref(trans, root, name, name_len, ino,
                                   dir_ino, &index);
         if (ret) {
@@ -3596,7 +3639,7 @@ static int __btrfs_unlink_inode(struct btrfs_trans_handle *trans,
                 btrfs_abort_transaction(trans, root, ret);
                 goto err;
         }
-
+skip_backref:
         ret = btrfs_delete_delayed_dir_index(trans, root, dir, index);
         if (ret) {
                 btrfs_abort_transaction(trans, root, ret);
@@ -5465,6 +5508,7 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
          * number
          */
         BTRFS_I(inode)->index_cnt = 2;
+        BTRFS_I(inode)->dir_index = *index;
         BTRFS_I(inode)->root = root;
         BTRFS_I(inode)->generation = trans->transid;
         inode->i_generation = BTRFS_I(inode)->generation;
@@ -5809,6 +5853,8 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
                 goto fail;
         }
 
+        /* There are several dir indexes for this inode, clear the cache. */
+        BTRFS_I(inode)->dir_index = 0ULL;
         inc_nlink(inode);
         inode_inc_iversion(inode);
         inode->i_ctime = CURRENT_TIME;
@@ -7861,6 +7907,7 @@ struct inode *btrfs_alloc_inode(struct super_block *sb)
         ei->flags = 0;
         ei->csum_bytes = 0;
         ei->index_cnt = (u64)-1;
+        ei->dir_index = 0;
         ei->last_unlink_trans = 0;
         ei->last_log_commit = 0;
 
@@ -8148,6 +8195,7 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry,
         if (ret)
                 goto out_fail;
 
+        BTRFS_I(old_inode)->dir_index = 0ULL;
         if (unlikely(old_ino == BTRFS_FIRST_FREE_OBJECTID)) {
                 /* force full log commit if subvolume involved. */
                 root->fs_info->last_trans_log_full_commit = trans->transid;
@@ -8236,6 +8284,9 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry,
                 goto out_fail;
         }
 
+        if (old_inode->i_nlink == 1)
+                BTRFS_I(old_inode)->dir_index = index;
+
         if (old_ino != BTRFS_FIRST_FREE_OBJECTID) {
                 struct dentry *parent = new_dentry->d_parent;
                 btrfs_log_new_name(trans, old_inode, old_dir, parent);