Btrfs: Support reading/writing on disk free ino cache
This is similar to block group caching.
We dedicate a special inode in fs tree to save free ino cache.
At the very first time we create/delete a file after mount, the free ino
cache will be loaded from disk into memory. When the fs tree is commited,
the cache will be written back to disk.
To keep compatibility, we check the root generation against the generation
of the special inode when loading the cache, so the loading will fail
if the btrfs filesystem was mounted in an older kernel before.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index fcbdcef..7d8b6b6 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -209,7 +209,8 @@
return ret;
}
- return btrfs_update_inode(trans, root, inode);
+ ret = btrfs_update_inode(trans, root, inode);
+ return ret;
}
static int readahead_cache(struct inode *inode)
@@ -525,6 +526,7 @@
spin_lock(&block_group->lock);
block_group->disk_cache_state = BTRFS_DC_CLEAR;
spin_unlock(&block_group->lock);
+ ret = 0;
printk(KERN_ERR "btrfs: failed to load free space cache "
"for block group %llu\n", block_group->key.objectid);
@@ -893,6 +895,7 @@
spin_lock(&block_group->lock);
block_group->disk_cache_state = BTRFS_DC_ERROR;
spin_unlock(&block_group->lock);
+ ret = 0;
printk(KERN_ERR "btrfs: failed to write free space cace "
"for block group %llu\n", block_group->key.objectid);
@@ -2458,3 +2461,95 @@
return ino;
}
+
+struct inode *lookup_free_ino_inode(struct btrfs_root *root,
+ struct btrfs_path *path)
+{
+ struct inode *inode = NULL;
+
+ spin_lock(&root->cache_lock);
+ if (root->cache_inode)
+ inode = igrab(root->cache_inode);
+ spin_unlock(&root->cache_lock);
+ if (inode)
+ return inode;
+
+ inode = __lookup_free_space_inode(root, path, 0);
+ if (IS_ERR(inode))
+ return inode;
+
+ spin_lock(&root->cache_lock);
+ if (!root->fs_info->closing)
+ root->cache_inode = igrab(inode);
+ spin_unlock(&root->cache_lock);
+
+ return inode;
+}
+
+int create_free_ino_inode(struct btrfs_root *root,
+ struct btrfs_trans_handle *trans,
+ struct btrfs_path *path)
+{
+ return __create_free_space_inode(root, trans, path,
+ BTRFS_FREE_INO_OBJECTID, 0);
+}
+
+int load_free_ino_cache(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
+{
+ struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
+ struct btrfs_path *path;
+ struct inode *inode;
+ int ret = 0;
+ u64 root_gen = btrfs_root_generation(&root->root_item);
+
+ /*
+ * If we're unmounting then just return, since this does a search on the
+ * normal root and not the commit root and we could deadlock.
+ */
+ smp_mb();
+ if (fs_info->closing)
+ return 0;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return 0;
+
+ inode = lookup_free_ino_inode(root, path);
+ if (IS_ERR(inode))
+ goto out;
+
+ if (root_gen != BTRFS_I(inode)->generation)
+ goto out_put;
+
+ ret = __load_free_space_cache(root, inode, ctl, path, 0);
+
+ if (ret < 0)
+ printk(KERN_ERR "btrfs: failed to load free ino cache for "
+ "root %llu\n", root->root_key.objectid);
+out_put:
+ iput(inode);
+out:
+ btrfs_free_path(path);
+ return ret;
+}
+
+int btrfs_write_out_ino_cache(struct btrfs_root *root,
+ struct btrfs_trans_handle *trans,
+ struct btrfs_path *path)
+{
+ struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
+ struct inode *inode;
+ int ret;
+
+ inode = lookup_free_ino_inode(root, path);
+ if (IS_ERR(inode))
+ return 0;
+
+ ret = __btrfs_write_out_cache(root, inode, ctl, NULL, trans, path, 0);
+ if (ret < 0)
+ printk(KERN_ERR "btrfs: failed to write free ino cache "
+ "for root %llu\n", root->root_key.objectid);
+
+ iput(inode);
+ return ret;
+}