Btrfs: Integrate metadata reservation with start_transaction
Besides simplify the code, this change makes sure all metadata
reservation for normal metadata operations are released after
committing transaction.
Changes since V1:
Add code that check if unlink and rmdir will free space.
Add ENOSPC handling for clone ioctl.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 3367278..657df6e 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -616,6 +616,113 @@
}
/*
+ * helper function to lookup reference count and flags of extent.
+ *
+ * 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
+ * node may also store the extent flags to set. This way you can check
+ * to see what the reference count and extent flags would be if all of
+ * the delayed refs are not processed.
+ */
+int btrfs_lookup_extent_info(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root, u64 bytenr,
+ u64 num_bytes, u64 *refs, u64 *flags)
+{
+ struct btrfs_delayed_ref_head *head;
+ struct btrfs_delayed_ref_root *delayed_refs;
+ struct btrfs_path *path;
+ struct btrfs_extent_item *ei;
+ struct extent_buffer *leaf;
+ struct btrfs_key key;
+ u32 item_size;
+ u64 num_refs;
+ u64 extent_flags;
+ int ret;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ key.objectid = bytenr;
+ key.type = BTRFS_EXTENT_ITEM_KEY;
+ key.offset = num_bytes;
+ if (!trans) {
+ path->skip_locking = 1;
+ path->search_commit_root = 1;
+ }
+again:
+ ret = btrfs_search_slot(trans, root->fs_info->extent_root,
+ &key, path, 0, 0);
+ if (ret < 0)
+ goto out_free;
+
+ if (ret == 0) {
+ leaf = path->nodes[0];
+ item_size = btrfs_item_size_nr(leaf, path->slots[0]);
+ if (item_size >= sizeof(*ei)) {
+ ei = btrfs_item_ptr(leaf, path->slots[0],
+ struct btrfs_extent_item);
+ num_refs = btrfs_extent_refs(leaf, ei);
+ extent_flags = btrfs_extent_flags(leaf, ei);
+ } else {
+#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
+ struct btrfs_extent_item_v0 *ei0;
+ BUG_ON(item_size != sizeof(*ei0));
+ ei0 = btrfs_item_ptr(leaf, path->slots[0],
+ struct btrfs_extent_item_v0);
+ num_refs = btrfs_extent_refs_v0(leaf, ei0);
+ /* FIXME: this isn't correct for data */
+ extent_flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
+#else
+ BUG();
+#endif
+ }
+ BUG_ON(num_refs == 0);
+ } else {
+ num_refs = 0;
+ extent_flags = 0;
+ ret = 0;
+ }
+
+ if (!trans)
+ goto out;
+
+ delayed_refs = &trans->transaction->delayed_refs;
+ spin_lock(&delayed_refs->lock);
+ head = btrfs_find_delayed_ref_head(trans, bytenr);
+ if (head) {
+ if (!mutex_trylock(&head->mutex)) {
+ atomic_inc(&head->node.refs);
+ spin_unlock(&delayed_refs->lock);
+
+ btrfs_release_path(root->fs_info->extent_root, path);
+
+ mutex_lock(&head->mutex);
+ mutex_unlock(&head->mutex);
+ btrfs_put_delayed_ref(&head->node);
+ goto again;
+ }
+ if (head->extent_op && head->extent_op->update_flags)
+ extent_flags |= head->extent_op->flags_to_set;
+ else
+ BUG_ON(num_refs == 0);
+
+ num_refs += head->node.ref_mod;
+ mutex_unlock(&head->mutex);
+ }
+ spin_unlock(&delayed_refs->lock);
+out:
+ WARN_ON(num_refs == 0);
+ if (refs)
+ *refs = num_refs;
+ if (flags)
+ *flags = extent_flags;
+out_free:
+ btrfs_free_path(path);
+ return ret;
+}
+
+/*
* Back reference rules. Back refs have three main goals:
*
* 1) differentiate between all holders of references to an extent so that
@@ -2949,113 +3056,6 @@
}
/*
- * unreserve num_items number of items worth of metadata space. This needs to
- * be paired with btrfs_reserve_metadata_space.
- *
- * NOTE: if you have the option, run this _AFTER_ you do a
- * btrfs_end_transaction, since btrfs_end_transaction will run delayed ref
- * oprations which will result in more used metadata, so we want to make sure we
- * can do that without issue.
- */
-int btrfs_unreserve_metadata_space(struct btrfs_root *root, int num_items)
-{
- struct btrfs_fs_info *info = root->fs_info;
- struct btrfs_space_info *meta_sinfo;
- u64 num_bytes;
- u64 alloc_target;
- bool bug = false;
-
- /* get the space info for where the metadata will live */
- alloc_target = btrfs_get_alloc_profile(root, 0);
- meta_sinfo = __find_space_info(info, alloc_target);
-
- num_bytes = calculate_bytes_needed(root, num_items);
-
- spin_lock(&meta_sinfo->lock);
- if (meta_sinfo->bytes_may_use < num_bytes) {
- bug = true;
- meta_sinfo->bytes_may_use = 0;
- } else {
- meta_sinfo->bytes_may_use -= num_bytes;
- }
- spin_unlock(&meta_sinfo->lock);
-
- BUG_ON(bug);
-
- return 0;
-}
-
-/*
- * Reserve some metadata space for use. We'll calculate the worste case number
- * of bytes that would be needed to modify num_items number of items. If we
- * have space, fantastic, if not, you get -ENOSPC. Please call
- * btrfs_unreserve_metadata_space when you are done for the _SAME_ number of
- * items you reserved, since whatever metadata you needed should have already
- * been allocated.
- *
- * This will commit the transaction to make more space if we don't have enough
- * metadata space. THe only time we don't do this is if we're reserving space
- * inside of a transaction, then we will just return -ENOSPC and it is the
- * callers responsibility to handle it properly.
- */
-int btrfs_reserve_metadata_space(struct btrfs_root *root, int num_items)
-{
- struct btrfs_fs_info *info = root->fs_info;
- struct btrfs_space_info *meta_sinfo;
- u64 num_bytes;
- u64 used;
- u64 alloc_target;
- int retries = 0;
-
- /* get the space info for where the metadata will live */
- alloc_target = btrfs_get_alloc_profile(root, 0);
- meta_sinfo = __find_space_info(info, alloc_target);
-
- num_bytes = calculate_bytes_needed(root, num_items);
-again:
- spin_lock(&meta_sinfo->lock);
-
- if (unlikely(!meta_sinfo->bytes_root))
- meta_sinfo->bytes_root = calculate_bytes_needed(root, 6);
-
- if (!retries)
- meta_sinfo->bytes_may_use += num_bytes;
-
- used = meta_sinfo->bytes_used + meta_sinfo->bytes_reserved +
- meta_sinfo->bytes_pinned + meta_sinfo->bytes_readonly +
- meta_sinfo->bytes_super + meta_sinfo->bytes_root +
- meta_sinfo->bytes_may_use + meta_sinfo->bytes_delalloc;
-
- if (used > meta_sinfo->total_bytes) {
- retries++;
- if (retries == 1) {
- if (maybe_allocate_chunk(NULL, root, meta_sinfo,
- num_bytes))
- goto again;
- retries++;
- } else {
- spin_unlock(&meta_sinfo->lock);
- }
-
- if (retries == 2) {
- shrink_delalloc(NULL, root, meta_sinfo, num_bytes);
- goto again;
- }
- spin_lock(&meta_sinfo->lock);
- meta_sinfo->bytes_may_use -= num_bytes;
- spin_unlock(&meta_sinfo->lock);
-
- dump_space_info(meta_sinfo, 0, 0);
- return -ENOSPC;
- }
-
- check_force_delalloc(meta_sinfo);
- spin_unlock(&meta_sinfo->lock);
-
- return 0;
-}
-
-/*
* This will check the space that the inode allocates from to make sure we have
* enough space for bytes.
*/
@@ -3095,9 +3095,9 @@
spin_unlock(&data_sinfo->lock);
alloc:
alloc_target = btrfs_get_alloc_profile(root, 1);
- trans = btrfs_start_transaction(root, 1);
- if (!trans)
- return -ENOMEM;
+ trans = btrfs_join_transaction(root, 1);
+ if (IS_ERR(trans))
+ return PTR_ERR(trans);
ret = do_chunk_alloc(trans, root->fs_info->extent_root,
bytes + 2 * 1024 * 1024,
@@ -3118,8 +3118,8 @@
if (!committed && !root->fs_info->open_ioctl_trans) {
committed = 1;
trans = btrfs_join_transaction(root, 1);
- if (!trans)
- return -ENOMEM;
+ if (IS_ERR(trans))
+ return PTR_ERR(trans);
ret = btrfs_commit_transaction(trans, root);
if (ret)
return ret;
@@ -3701,6 +3701,59 @@
fs_info->chunk_root->block_rsv = &fs_info->chunk_block_rsv;
}
+static u64 calc_trans_metadata_size(struct btrfs_root *root, int num_items)
+{
+ return (root->leafsize + root->nodesize * (BTRFS_MAX_LEVEL - 1)) *
+ 3 * num_items;
+}
+
+int btrfs_trans_reserve_metadata(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ int num_items, int *retries)
+{
+ u64 num_bytes;
+ int ret;
+
+ if (num_items == 0 || root->fs_info->chunk_root == root)
+ return 0;
+
+ num_bytes = calc_trans_metadata_size(root, num_items);
+ ret = btrfs_block_rsv_add(trans, root, &root->fs_info->trans_block_rsv,
+ num_bytes, retries);
+ if (!ret) {
+ trans->bytes_reserved += num_bytes;
+ trans->block_rsv = &root->fs_info->trans_block_rsv;
+ }
+ return ret;
+}
+
+void btrfs_trans_release_metadata(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root)
+{
+ if (!trans->bytes_reserved)
+ return;
+
+ BUG_ON(trans->block_rsv != &root->fs_info->trans_block_rsv);
+ btrfs_block_rsv_release(root, trans->block_rsv,
+ trans->bytes_reserved);
+ trans->bytes_reserved = 0;
+}
+
+int btrfs_snap_reserve_metadata(struct btrfs_trans_handle *trans,
+ struct btrfs_pending_snapshot *pending)
+{
+ struct btrfs_root *root = pending->root;
+ struct btrfs_block_rsv *src_rsv = get_block_rsv(trans, root);
+ struct btrfs_block_rsv *dst_rsv = &pending->block_rsv;
+ /*
+ * two for root back/forward refs, two for directory entries
+ * and one for root of the snapshot.
+ */
+ u64 num_bytes = calc_trans_metadata_size(root, 5);
+ dst_rsv->space_info = src_rsv->space_info;
+ return block_rsv_migrate_bytes(src_rsv, dst_rsv, num_bytes);
+}
+
static int update_block_group(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
u64 bytenr, u64 num_bytes, int alloc)
@@ -5824,7 +5877,7 @@
wc = kzalloc(sizeof(*wc), GFP_NOFS);
BUG_ON(!wc);
- trans = btrfs_start_transaction(tree_root, 1);
+ trans = btrfs_start_transaction(tree_root, 0);
if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
level = btrfs_header_level(root->node);
@@ -5920,7 +5973,9 @@
BUG_ON(ret);
btrfs_end_transaction(trans, tree_root);
- trans = btrfs_start_transaction(tree_root, 1);
+ trans = btrfs_start_transaction(tree_root, 0);
+ if (IS_ERR(trans))
+ return PTR_ERR(trans);
} else {
unsigned long update;
update = trans->delayed_ref_updates;