Btrfs: add a incompatible format change for smaller metadata extent refs
We currently store the first key of the tree block inside the reference for the
tree block in the extent tree. This takes up quite a bit of space. Make a new
key type for metadata which holds the level as the offset and completely removes
storing the btrfs_tree_block_info inside the extent ref. This reduces the size
from 51 bytes to 33 bytes per extent reference for each tree block. In practice
this results in a 30-35% decrease in the size of our extent tree, which means we
COW less and can keep more of the extent tree in memory which makes our heavy
metadata operations go much faster. This is not an automatic format change, you
must enable it at mkfs time or with btrfstune. This patch deals with having
metadata stored as either the old format or the new format so it is easy to
convert. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 3d55123..7505856 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -442,11 +442,16 @@
block_group->key.offset)
break;
- if (key.type == BTRFS_EXTENT_ITEM_KEY) {
+ if (key.type == BTRFS_EXTENT_ITEM_KEY ||
+ key.type == BTRFS_METADATA_ITEM_KEY) {
total_found += add_new_free_space(block_group,
fs_info, last,
key.objectid);
- last = key.objectid + key.offset;
+ if (key.type == BTRFS_METADATA_ITEM_KEY)
+ last = key.objectid +
+ fs_info->tree_root->leafsize;
+ else
+ last = key.objectid + key.offset;
if (total_found > (1024 * 1024 * 2)) {
total_found = 0;
@@ -718,15 +723,21 @@
key.objectid = start;
key.offset = len;
- btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
+ key.type = BTRFS_EXTENT_ITEM_KEY;
ret = btrfs_search_slot(NULL, root->fs_info->extent_root, &key, path,
0, 0);
+ if (ret > 0) {
+ btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
+ if (key.objectid == start &&
+ key.type == BTRFS_METADATA_ITEM_KEY)
+ ret = 0;
+ }
btrfs_free_path(path);
return ret;
}
/*
- * helper function to lookup reference count and flags of extent.
+ * helper function to lookup reference count and flags of a tree block.
*
* the head node for delayed ref is used to store the sum of all the
* reference count modifications queued up in the rbtree. the head
@@ -736,7 +747,7 @@
*/
int btrfs_lookup_extent_info(struct btrfs_trans_handle *trans,
struct btrfs_root *root, u64 bytenr,
- u64 num_bytes, u64 *refs, u64 *flags)
+ u64 offset, int metadata, u64 *refs, u64 *flags)
{
struct btrfs_delayed_ref_head *head;
struct btrfs_delayed_ref_root *delayed_refs;
@@ -749,13 +760,29 @@
u64 extent_flags;
int ret;
+ /*
+ * If we don't have skinny metadata, don't bother doing anything
+ * different
+ */
+ if (metadata && !btrfs_fs_incompat(root->fs_info, SKINNY_METADATA)) {
+ offset = root->leafsize;
+ metadata = 0;
+ }
+
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
- key.objectid = bytenr;
- key.type = BTRFS_EXTENT_ITEM_KEY;
- key.offset = num_bytes;
+ if (metadata) {
+ key.objectid = bytenr;
+ key.type = BTRFS_METADATA_ITEM_KEY;
+ key.offset = offset;
+ } else {
+ key.objectid = bytenr;
+ key.type = BTRFS_EXTENT_ITEM_KEY;
+ key.offset = offset;
+ }
+
if (!trans) {
path->skip_locking = 1;
path->search_commit_root = 1;
@@ -766,6 +793,13 @@
if (ret < 0)
goto out_free;
+ if (ret > 0 && metadata && key.type == BTRFS_METADATA_ITEM_KEY) {
+ key.type = BTRFS_EXTENT_ITEM_KEY;
+ key.offset = root->leafsize;
+ btrfs_release_path(path);
+ goto again;
+ }
+
if (ret == 0) {
leaf = path->nodes[0];
item_size = btrfs_item_size_nr(leaf, path->slots[0]);
@@ -1453,6 +1487,8 @@
int want;
int ret;
int err = 0;
+ bool skinny_metadata = btrfs_fs_incompat(root->fs_info,
+ SKINNY_METADATA);
key.objectid = bytenr;
key.type = BTRFS_EXTENT_ITEM_KEY;
@@ -1464,11 +1500,46 @@
path->keep_locks = 1;
} else
extra_size = -1;
+
+ /*
+ * Owner is our parent level, so we can just add one to get the level
+ * for the block we are interested in.
+ */
+ if (skinny_metadata && owner < BTRFS_FIRST_FREE_OBJECTID) {
+ key.type = BTRFS_METADATA_ITEM_KEY;
+ key.offset = owner;
+ }
+
+again:
ret = btrfs_search_slot(trans, root, &key, path, extra_size, 1);
if (ret < 0) {
err = ret;
goto out;
}
+
+ /*
+ * We may be a newly converted file system which still has the old fat
+ * extent entries for metadata, so try and see if we have one of those.
+ */
+ if (ret > 0 && skinny_metadata) {
+ skinny_metadata = false;
+ if (path->slots[0]) {
+ path->slots[0]--;
+ btrfs_item_key_to_cpu(path->nodes[0], &key,
+ path->slots[0]);
+ if (key.objectid == bytenr &&
+ key.type == BTRFS_EXTENT_ITEM_KEY &&
+ key.offset == num_bytes)
+ ret = 0;
+ }
+ if (ret) {
+ key.type = BTRFS_EXTENT_ITEM_KEY;
+ key.offset = num_bytes;
+ btrfs_release_path(path);
+ goto again;
+ }
+ }
+
if (ret && !insert) {
err = -ENOENT;
goto out;
@@ -1504,11 +1575,9 @@
ptr = (unsigned long)(ei + 1);
end = (unsigned long)ei + item_size;
- if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
+ if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK && !skinny_metadata) {
ptr += sizeof(struct btrfs_tree_block_info);
BUG_ON(ptr > end);
- } else {
- BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
}
err = -ENOENT;
@@ -1973,10 +2042,8 @@
ref_root = ref->root;
if (node->action == BTRFS_ADD_DELAYED_REF && insert_reserved) {
- if (extent_op) {
- BUG_ON(extent_op->update_key);
+ if (extent_op)
flags |= extent_op->flags_to_set;
- }
ret = alloc_reserved_file_extent(trans, root,
parent, ref_root, flags,
ref->objectid, ref->offset,
@@ -2029,18 +2096,33 @@
u32 item_size;
int ret;
int err = 0;
+ int metadata = (node->type == BTRFS_TREE_BLOCK_REF_KEY ||
+ node->type == BTRFS_SHARED_BLOCK_REF_KEY);
if (trans->aborted)
return 0;
+ if (metadata && !btrfs_fs_incompat(root->fs_info, SKINNY_METADATA))
+ metadata = 0;
+
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
key.objectid = node->bytenr;
- key.type = BTRFS_EXTENT_ITEM_KEY;
- key.offset = node->num_bytes;
+ if (metadata) {
+ struct btrfs_delayed_tree_ref *tree_ref;
+
+ tree_ref = btrfs_delayed_node_to_tree_ref(node);
+ key.type = BTRFS_METADATA_ITEM_KEY;
+ key.offset = tree_ref->level;
+ } else {
+ key.type = BTRFS_EXTENT_ITEM_KEY;
+ key.offset = node->num_bytes;
+ }
+
+again:
path->reada = 1;
path->leave_spinning = 1;
ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key,
@@ -2050,6 +2132,14 @@
goto out;
}
if (ret > 0) {
+ if (metadata) {
+ btrfs_release_path(path);
+ metadata = 0;
+
+ key.offset = node->num_bytes;
+ key.type = BTRFS_EXTENT_ITEM_KEY;
+ goto again;
+ }
err = -EIO;
goto out;
}
@@ -2089,10 +2179,8 @@
struct btrfs_key ins;
u64 parent = 0;
u64 ref_root = 0;
-
- ins.objectid = node->bytenr;
- ins.offset = node->num_bytes;
- ins.type = BTRFS_EXTENT_ITEM_KEY;
+ bool skinny_metadata = btrfs_fs_incompat(root->fs_info,
+ SKINNY_METADATA);
ref = btrfs_delayed_node_to_tree_ref(node);
if (node->type == BTRFS_SHARED_BLOCK_REF_KEY)
@@ -2100,10 +2188,18 @@
else
ref_root = ref->root;
+ ins.objectid = node->bytenr;
+ if (skinny_metadata) {
+ ins.offset = ref->level;
+ ins.type = BTRFS_METADATA_ITEM_KEY;
+ } else {
+ ins.offset = node->num_bytes;
+ ins.type = BTRFS_EXTENT_ITEM_KEY;
+ }
+
BUG_ON(node->ref_mod != 1);
if (node->action == BTRFS_ADD_DELAYED_REF && insert_reserved) {
- BUG_ON(!extent_op || !extent_op->update_flags ||
- !extent_op->update_key);
+ BUG_ON(!extent_op || !extent_op->update_flags);
ret = alloc_reserved_tree_block(trans, root,
parent, ref_root,
extent_op->flags_to_set,
@@ -5312,6 +5408,8 @@
int num_to_del = 1;
u32 item_size;
u64 refs;
+ bool skinny_metadata = btrfs_fs_incompat(root->fs_info,
+ SKINNY_METADATA);
path = btrfs_alloc_path();
if (!path)
@@ -5323,6 +5421,9 @@
is_data = owner_objectid >= BTRFS_FIRST_FREE_OBJECTID;
BUG_ON(!is_data && refs_to_drop != 1);
+ if (is_data)
+ skinny_metadata = 0;
+
ret = lookup_extent_backref(trans, extent_root, path, &iref,
bytenr, num_bytes, parent,
root_objectid, owner_objectid,
@@ -5339,6 +5440,11 @@
found_extent = 1;
break;
}
+ if (key.type == BTRFS_METADATA_ITEM_KEY &&
+ key.offset == owner_objectid) {
+ found_extent = 1;
+ break;
+ }
if (path->slots[0] - extent_slot > 5)
break;
extent_slot--;
@@ -5364,8 +5470,36 @@
key.type = BTRFS_EXTENT_ITEM_KEY;
key.offset = num_bytes;
+ if (!is_data && skinny_metadata) {
+ key.type = BTRFS_METADATA_ITEM_KEY;
+ key.offset = owner_objectid;
+ }
+
ret = btrfs_search_slot(trans, extent_root,
&key, path, -1, 1);
+ if (ret > 0 && skinny_metadata && path->slots[0]) {
+ /*
+ * Couldn't find our skinny metadata item,
+ * see if we have ye olde extent item.
+ */
+ path->slots[0]--;
+ btrfs_item_key_to_cpu(path->nodes[0], &key,
+ path->slots[0]);
+ if (key.objectid == bytenr &&
+ key.type == BTRFS_EXTENT_ITEM_KEY &&
+ key.offset == num_bytes)
+ ret = 0;
+ }
+
+ if (ret > 0 && skinny_metadata) {
+ skinny_metadata = false;
+ key.type = BTRFS_EXTENT_ITEM_KEY;
+ key.offset = num_bytes;
+ btrfs_release_path(path);
+ ret = btrfs_search_slot(trans, extent_root,
+ &key, path, -1, 1);
+ }
+
if (ret) {
printk(KERN_ERR "umm, got %d back from search"
", was looking for %llu\n", ret,
@@ -5435,7 +5569,8 @@
BUG_ON(item_size < sizeof(*ei));
ei = btrfs_item_ptr(leaf, extent_slot,
struct btrfs_extent_item);
- if (owner_objectid < BTRFS_FIRST_FREE_OBJECTID) {
+ if (owner_objectid < BTRFS_FIRST_FREE_OBJECTID &&
+ key.type == BTRFS_EXTENT_ITEM_KEY) {
struct btrfs_tree_block_info *bi;
BUG_ON(item_size < sizeof(*ei) + sizeof(*bi));
bi = (struct btrfs_tree_block_info *)(ei + 1);
@@ -6349,7 +6484,12 @@
struct btrfs_extent_inline_ref *iref;
struct btrfs_path *path;
struct extent_buffer *leaf;
- u32 size = sizeof(*extent_item) + sizeof(*block_info) + sizeof(*iref);
+ u32 size = sizeof(*extent_item) + sizeof(*iref);
+ bool skinny_metadata = btrfs_fs_incompat(root->fs_info,
+ SKINNY_METADATA);
+
+ if (!skinny_metadata)
+ size += sizeof(*block_info);
path = btrfs_alloc_path();
if (!path)
@@ -6370,12 +6510,16 @@
btrfs_set_extent_generation(leaf, extent_item, trans->transid);
btrfs_set_extent_flags(leaf, extent_item,
flags | BTRFS_EXTENT_FLAG_TREE_BLOCK);
- block_info = (struct btrfs_tree_block_info *)(extent_item + 1);
- btrfs_set_tree_block_key(leaf, block_info, key);
- btrfs_set_tree_block_level(leaf, block_info, level);
+ if (skinny_metadata) {
+ iref = (struct btrfs_extent_inline_ref *)(extent_item + 1);
+ } else {
+ block_info = (struct btrfs_tree_block_info *)(extent_item + 1);
+ btrfs_set_tree_block_key(leaf, block_info, key);
+ btrfs_set_tree_block_level(leaf, block_info, level);
+ iref = (struct btrfs_extent_inline_ref *)(block_info + 1);
+ }
- iref = (struct btrfs_extent_inline_ref *)(block_info + 1);
if (parent > 0) {
BUG_ON(!(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
btrfs_set_extent_inline_ref_type(leaf, iref,
@@ -6390,7 +6534,7 @@
btrfs_mark_buffer_dirty(leaf);
btrfs_free_path(path);
- ret = update_block_group(root, ins->objectid, ins->offset, 1);
+ ret = update_block_group(root, ins->objectid, root->leafsize, 1);
if (ret) { /* -ENOENT, logic error */
printk(KERN_ERR "btrfs update block group failed for %llu "
"%llu\n", (unsigned long long)ins->objectid,
@@ -6594,7 +6738,8 @@
struct extent_buffer *buf;
u64 flags = 0;
int ret;
-
+ bool skinny_metadata = btrfs_fs_incompat(root->fs_info,
+ SKINNY_METADATA);
block_rsv = use_block_rsv(trans, root, blocksize);
if (IS_ERR(block_rsv))
@@ -6627,7 +6772,10 @@
else
memset(&extent_op->key, 0, sizeof(extent_op->key));
extent_op->flags_to_set = flags;
- extent_op->update_key = 1;
+ if (skinny_metadata)
+ extent_op->update_key = 0;
+ else
+ extent_op->update_key = 1;
extent_op->update_flags = 1;
extent_op->is_data = 0;
@@ -6704,8 +6852,9 @@
continue;
/* We don't lock the tree block, it's OK to be racy here */
- ret = btrfs_lookup_extent_info(trans, root, bytenr, blocksize,
- &refs, &flags);
+ ret = btrfs_lookup_extent_info(trans, root, bytenr,
+ wc->level - 1, 1, &refs,
+ &flags);
/* We don't care about errors in readahead. */
if (ret < 0)
continue;
@@ -6772,7 +6921,7 @@
(wc->stage == UPDATE_BACKREF && !(wc->flags[level] & flag)))) {
BUG_ON(!path->locks[level]);
ret = btrfs_lookup_extent_info(trans, root,
- eb->start, eb->len,
+ eb->start, level, 1,
&wc->refs[level],
&wc->flags[level]);
BUG_ON(ret == -ENOMEM);
@@ -6870,7 +7019,7 @@
btrfs_tree_lock(next);
btrfs_set_lock_blocking(next);
- ret = btrfs_lookup_extent_info(trans, root, bytenr, blocksize,
+ ret = btrfs_lookup_extent_info(trans, root, bytenr, level - 1, 1,
&wc->refs[level - 1],
&wc->flags[level - 1]);
if (ret < 0) {
@@ -7001,7 +7150,7 @@
path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
ret = btrfs_lookup_extent_info(trans, root,
- eb->start, eb->len,
+ eb->start, level, 1,
&wc->refs[level],
&wc->flags[level]);
if (ret < 0) {
@@ -7211,8 +7360,7 @@
ret = btrfs_lookup_extent_info(trans, root,
path->nodes[level]->start,
- path->nodes[level]->len,
- &wc->refs[level],
+ level, 1, &wc->refs[level],
&wc->flags[level]);
if (ret < 0) {
err = ret;