Btrfs: create special free space cache inode
In order to save free space cache, we need an inode to hold the data, and we
need a special item to point at the right inode for the right block group. So
first, create a special item that will point to the right inode, and the number
of extent entries we will have and the number of bitmaps we will have. We
truncate and pre-allocate space everytime to make sure it's uptodate.
This feature will be turned on as soon as you mount with -o space_cache, however
it is safe to boot into old kernels, they will just generate the cache the old
fashion way. When you boot back into a newer kernel we will notice that we
modified and not the cache and automatically discard the cache.
Signed-off-by: Josef Bacik <josef@redhat.com>
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 32d0940..aab40fb 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2688,6 +2688,109 @@
return cache;
}
+static int cache_save_setup(struct btrfs_block_group_cache *block_group,
+ struct btrfs_trans_handle *trans,
+ struct btrfs_path *path)
+{
+ struct btrfs_root *root = block_group->fs_info->tree_root;
+ struct inode *inode = NULL;
+ u64 alloc_hint = 0;
+ int num_pages = 0;
+ int retries = 0;
+ int ret = 0;
+
+ /*
+ * If this block group is smaller than 100 megs don't bother caching the
+ * block group.
+ */
+ if (block_group->key.offset < (100 * 1024 * 1024)) {
+ spin_lock(&block_group->lock);
+ block_group->disk_cache_state = BTRFS_DC_WRITTEN;
+ spin_unlock(&block_group->lock);
+ return 0;
+ }
+
+again:
+ inode = lookup_free_space_inode(root, block_group, path);
+ if (IS_ERR(inode) && PTR_ERR(inode) != -ENOENT) {
+ ret = PTR_ERR(inode);
+ btrfs_release_path(root, path);
+ goto out;
+ }
+
+ if (IS_ERR(inode)) {
+ BUG_ON(retries);
+ retries++;
+
+ if (block_group->ro)
+ goto out_free;
+
+ ret = create_free_space_inode(root, trans, block_group, path);
+ if (ret)
+ goto out_free;
+ goto again;
+ }
+
+ /*
+ * We want to set the generation to 0, that way if anything goes wrong
+ * from here on out we know not to trust this cache when we load up next
+ * time.
+ */
+ BTRFS_I(inode)->generation = 0;
+ ret = btrfs_update_inode(trans, root, inode);
+ WARN_ON(ret);
+
+ if (i_size_read(inode) > 0) {
+ ret = btrfs_truncate_free_space_cache(root, trans, path,
+ inode);
+ if (ret)
+ goto out_put;
+ }
+
+ spin_lock(&block_group->lock);
+ if (block_group->cached != BTRFS_CACHE_FINISHED) {
+ spin_unlock(&block_group->lock);
+ goto out_put;
+ }
+ spin_unlock(&block_group->lock);
+
+ num_pages = (int)div64_u64(block_group->key.offset, 1024 * 1024 * 1024);
+ if (!num_pages)
+ num_pages = 1;
+
+ /*
+ * Just to make absolutely sure we have enough space, we're going to
+ * preallocate 12 pages worth of space for each block group. In
+ * practice we ought to use at most 8, but we need extra space so we can
+ * add our header and have a terminator between the extents and the
+ * bitmaps.
+ */
+ num_pages *= 16;
+ num_pages *= PAGE_CACHE_SIZE;
+
+ ret = btrfs_check_data_free_space(inode, num_pages);
+ if (ret)
+ goto out_put;
+
+ ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, num_pages,
+ num_pages, num_pages,
+ &alloc_hint);
+ btrfs_free_reserved_data_space(inode, num_pages);
+out_put:
+ iput(inode);
+out_free:
+ btrfs_release_path(root, path);
+out:
+ spin_lock(&block_group->lock);
+ if (ret)
+ block_group->disk_cache_state = BTRFS_DC_ERROR;
+ else
+ block_group->disk_cache_state = BTRFS_DC_SETUP;
+ spin_unlock(&block_group->lock);
+
+ return ret;
+}
+
int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
@@ -2700,6 +2803,25 @@
if (!path)
return -ENOMEM;
+again:
+ while (1) {
+ cache = btrfs_lookup_first_block_group(root->fs_info, last);
+ while (cache) {
+ if (cache->disk_cache_state == BTRFS_DC_CLEAR)
+ break;
+ cache = next_block_group(root, cache);
+ }
+ if (!cache) {
+ if (last == 0)
+ break;
+ last = 0;
+ continue;
+ }
+ err = cache_save_setup(cache, trans, path);
+ last = cache->key.objectid + cache->key.offset;
+ btrfs_put_block_group(cache);
+ }
+
while (1) {
if (last == 0) {
err = btrfs_run_delayed_refs(trans, root,
@@ -2709,6 +2831,11 @@
cache = btrfs_lookup_first_block_group(root->fs_info, last);
while (cache) {
+ if (cache->disk_cache_state == BTRFS_DC_CLEAR) {
+ btrfs_put_block_group(cache);
+ goto again;
+ }
+
if (cache->dirty)
break;
cache = next_block_group(root, cache);
@@ -2883,11 +3010,16 @@
struct btrfs_space_info *data_sinfo;
struct btrfs_root *root = BTRFS_I(inode)->root;
u64 used;
- int ret = 0, committed = 0;
+ int ret = 0, committed = 0, alloc_chunk = 1;
/* make sure bytes are sectorsize aligned */
bytes = (bytes + root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
+ if (root == root->fs_info->tree_root) {
+ alloc_chunk = 0;
+ committed = 1;
+ }
+
data_sinfo = BTRFS_I(inode)->space_info;
if (!data_sinfo)
goto alloc;
@@ -2906,7 +3038,7 @@
* if we don't have enough free bytes in this space then we need
* to alloc a new chunk.
*/
- if (!data_sinfo->full) {
+ if (!data_sinfo->full && alloc_chunk) {
u64 alloc_target;
data_sinfo->force_alloc = 1;
@@ -3777,12 +3909,12 @@
struct btrfs_root *root,
u64 bytenr, u64 num_bytes, int alloc)
{
- struct btrfs_block_group_cache *cache;
+ struct btrfs_block_group_cache *cache = NULL;
struct btrfs_fs_info *info = root->fs_info;
- int factor;
u64 total = num_bytes;
u64 old_val;
u64 byte_in_group;
+ int factor;
/* block accounting for super block */
spin_lock(&info->delalloc_lock);
@@ -3804,11 +3936,17 @@
factor = 2;
else
factor = 1;
+
byte_in_group = bytenr - cache->key.objectid;
WARN_ON(byte_in_group > cache->key.offset);
spin_lock(&cache->space_info->lock);
spin_lock(&cache->lock);
+
+ if (btrfs_super_cache_generation(&info->super_copy) != 0 &&
+ cache->disk_cache_state < BTRFS_DC_CLEAR)
+ cache->disk_cache_state = BTRFS_DC_CLEAR;
+
cache->dirty = 1;
old_val = btrfs_block_group_used(&cache->item);
num_bytes = min(total, cache->key.offset - byte_in_group);
@@ -7814,6 +7952,40 @@
return ret;
}
+void btrfs_put_block_group_cache(struct btrfs_fs_info *info)
+{
+ struct btrfs_block_group_cache *block_group;
+ u64 last = 0;
+
+ while (1) {
+ struct inode *inode;
+
+ block_group = btrfs_lookup_first_block_group(info, last);
+ while (block_group) {
+ spin_lock(&block_group->lock);
+ if (block_group->iref)
+ break;
+ spin_unlock(&block_group->lock);
+ block_group = next_block_group(info->tree_root,
+ block_group);
+ }
+ if (!block_group) {
+ if (last == 0)
+ break;
+ last = 0;
+ continue;
+ }
+
+ inode = block_group->inode;
+ block_group->iref = 0;
+ block_group->inode = NULL;
+ spin_unlock(&block_group->lock);
+ iput(inode);
+ last = block_group->key.objectid + block_group->key.offset;
+ btrfs_put_block_group(block_group);
+ }
+}
+
int btrfs_free_block_groups(struct btrfs_fs_info *info)
{
struct btrfs_block_group_cache *block_group;
@@ -7897,6 +8069,8 @@
struct btrfs_key key;
struct btrfs_key found_key;
struct extent_buffer *leaf;
+ int need_clear = 0;
+ u64 cache_gen;
root = info->extent_root;
key.objectid = 0;
@@ -7906,6 +8080,11 @@
if (!path)
return -ENOMEM;
+ cache_gen = btrfs_super_cache_generation(&root->fs_info->super_copy);
+ if (cache_gen != 0 &&
+ btrfs_super_generation(&root->fs_info->super_copy) != cache_gen)
+ need_clear = 1;
+
while (1) {
ret = find_first_block_group(root, path, &key);
if (ret > 0)
@@ -7928,6 +8107,9 @@
INIT_LIST_HEAD(&cache->list);
INIT_LIST_HEAD(&cache->cluster_list);
+ if (need_clear)
+ cache->disk_cache_state = BTRFS_DC_CLEAR;
+
/*
* we only want to have 32k of ram per block group for keeping
* track of free space, and if we pass 1/2 of that we want to
@@ -8032,6 +8214,7 @@
cache->key.offset = size;
cache->key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
cache->sectorsize = root->sectorsize;
+ cache->fs_info = root->fs_info;
/*
* we only want to have 32k of ram per block group for keeping track
@@ -8088,7 +8271,9 @@
struct btrfs_path *path;
struct btrfs_block_group_cache *block_group;
struct btrfs_free_cluster *cluster;
+ struct btrfs_root *tree_root = root->fs_info->tree_root;
struct btrfs_key key;
+ struct inode *inode;
int ret;
root = root->fs_info->extent_root;
@@ -8097,8 +8282,6 @@
BUG_ON(!block_group);
BUG_ON(!block_group->ro);
- memcpy(&key, &block_group->key, sizeof(key));
-
/* make sure this block group isn't part of an allocation cluster */
cluster = &root->fs_info->data_alloc_cluster;
spin_lock(&cluster->refill_lock);
@@ -8117,6 +8300,40 @@
path = btrfs_alloc_path();
BUG_ON(!path);
+ inode = lookup_free_space_inode(root, block_group, path);
+ if (!IS_ERR(inode)) {
+ btrfs_orphan_add(trans, inode);
+ clear_nlink(inode);
+ /* One for the block groups ref */
+ spin_lock(&block_group->lock);
+ if (block_group->iref) {
+ block_group->iref = 0;
+ block_group->inode = NULL;
+ spin_unlock(&block_group->lock);
+ iput(inode);
+ } else {
+ spin_unlock(&block_group->lock);
+ }
+ /* One for our lookup ref */
+ iput(inode);
+ }
+
+ key.objectid = BTRFS_FREE_SPACE_OBJECTID;
+ key.offset = block_group->key.objectid;
+ key.type = 0;
+
+ ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
+ if (ret < 0)
+ goto out;
+ if (ret > 0)
+ btrfs_release_path(tree_root, path);
+ if (ret == 0) {
+ ret = btrfs_del_item(trans, tree_root, path);
+ if (ret)
+ goto out;
+ btrfs_release_path(tree_root, path);
+ }
+
spin_lock(&root->fs_info->block_group_cache_lock);
rb_erase(&block_group->cache_node,
&root->fs_info->block_group_cache_tree);
@@ -8140,6 +8357,8 @@
block_group->space_info->bytes_readonly -= block_group->key.offset;
spin_unlock(&block_group->space_info->lock);
+ memcpy(&key, &block_group->key, sizeof(key));
+
btrfs_clear_space_info_full(root->fs_info);
btrfs_put_block_group(block_group);
