On 26.05.2011 08:38, Li Zefan wrote:
> For a filesystem that has lots of files in it, the first time we mount
> it with free ino caching support, it can take quite a long time to
> setup the caching before we can create new files.
>
> Here we fill the cache with [highest_ino, BTRFS_LAST_FREE_OBJECTID]
> before we start the caching thread to search through the extent tree.
This also sound like a very good consumer for the readahead-API.
-Arne
>
> Signed-off-by: Li Zefan <l...@cn.fujitsu.com>
> ---
>
> based on the integration-test branch.
>
> v2: fixed an off-by-one bug
>
> ---
> fs/btrfs/inode-map.c | 28 ++++++++++++++++++++++------
> 1 files changed, 22 insertions(+), 6 deletions(-)
>
> diff --git a/fs/btrfs/inode-map.c b/fs/btrfs/inode-map.c
> index 0009705..3262cd1 100644
> --- a/fs/btrfs/inode-map.c
> +++ b/fs/btrfs/inode-map.c
> @@ -60,12 +60,12 @@ again:
>
> while (1) {
> smp_mb();
> - if (fs_info->closing > 1)
> + if (fs_info->closing)
> goto out;
>
> leaf = path->nodes[0];
> slot = path->slots[0];
> - if (path->slots[0] >= btrfs_header_nritems(leaf)) {
> + if (slot >= btrfs_header_nritems(leaf)) {
> ret = btrfs_next_leaf(root, path);
> if (ret < 0)
> goto out;
> @@ -100,7 +100,7 @@ again:
> if (key.type != BTRFS_INODE_ITEM_KEY)
> goto next;
>
> - if (key.objectid >= BTRFS_LAST_FREE_OBJECTID)
> + if (key.objectid >= root->highest_objectid)
> break;
>
> if (last != (u64)-1 && last + 1 != key.objectid) {
> @@ -114,9 +114,9 @@ next:
> path->slots[0]++;
> }
>
> - if (last < BTRFS_LAST_FREE_OBJECTID - 1) {
> + if (last < root->highest_objectid - 1) {
> __btrfs_add_free_space(ctl, last + 1,
> - BTRFS_LAST_FREE_OBJECTID - last - 1);
> + root->highest_objectid - last - 1);
> }
>
> spin_lock(&root->cache_lock);
> @@ -136,8 +136,10 @@ out:
>
> static void start_caching(struct btrfs_root *root)
> {
> + struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
> struct task_struct *tsk;
> int ret;
> + u64 objectid;
>
> spin_lock(&root->cache_lock);
> if (root->cached != BTRFS_CACHE_NO) {
> @@ -156,6 +158,19 @@ static void start_caching(struct btrfs_root *root)
> return;
> }
>
> + /*
> + * It can be quite time-consuming to fill the cache by searching
> + * through the extent tree, and this can keep ino allocation path
> + * waiting. Therefore at start we quickly find out the highest
> + * inode number and we know we can use inode numbers which fall in
> + * [highest_ino + 1, BTRFS_LAST_FREE_OBJECTID].
> + */
> + ret = btrfs_find_free_objectid(root, &objectid);
> + if (!ret && objectid <= BTRFS_LAST_FREE_OBJECTID) {
> + __btrfs_add_free_space(ctl, objectid,
> + BTRFS_LAST_FREE_OBJECTID - objectid + 1);
> + }
> +
> tsk = kthread_run(caching_kthread, root, "btrfs-ino-cache-%llu\n",
> root->root_key.objectid);
> BUG_ON(IS_ERR(tsk));
> @@ -209,7 +224,8 @@ again:
>
> start_caching(root);
>
> - if (objectid <= root->cache_progress)
> + if (objectid <= root->cache_progress ||
> + objectid > root->highest_objectid)
> __btrfs_add_free_space(ctl, objectid, 1);
> else
> __btrfs_add_free_space(pinned, objectid, 1);
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