Btrfs: optimize how we account for space in truncate
Currently we're starting and stopping a transaction for no real reason, so kill
that and just reserve enough space as if we can truncate all in one transaction.
Also use btrfs_block_rsv_check() for our reserve to minimize the amount of space
we may have to allocate for our slack space. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index fe3891e..4d057c0 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -6482,6 +6482,7 @@
struct btrfs_trans_handle *trans;
unsigned long nr;
u64 mask = root->sectorsize - 1;
+ u64 min_size = btrfs_calc_trans_metadata_size(root, 2);
ret = btrfs_truncate_page(inode->i_mapping, inode->i_size);
if (ret)
@@ -6530,17 +6531,21 @@
if (!rsv)
return -ENOMEM;
- trans = btrfs_start_transaction(root, 4);
+ /*
+ * 2 for the truncate slack space
+ * 1 for the orphan item we're going to add
+ * 1 for the orphan item deletion
+ * 1 for updating the inode.
+ */
+ trans = btrfs_start_transaction(root, 5);
if (IS_ERR(trans)) {
err = PTR_ERR(trans);
goto out;
}
- /*
- * Reserve space for the truncate process. Truncate should be adding
- * space, but if there are snapshots it may end up using space.
- */
- ret = btrfs_truncate_reserve_metadata(trans, root, rsv);
+ /* Migrate the slack space for the truncate to our reserve */
+ ret = btrfs_block_rsv_migrate(&root->fs_info->trans_block_rsv, rsv,
+ min_size);
BUG_ON(ret);
ret = btrfs_orphan_add(trans, inode);
@@ -6549,21 +6554,6 @@
goto out;
}
- nr = trans->blocks_used;
- btrfs_end_transaction(trans, root);
- btrfs_btree_balance_dirty(root, nr);
-
- /*
- * Ok so we've already migrated our bytes over for the truncate, so here
- * just reserve the one slot we need for updating the inode.
- */
- trans = btrfs_start_transaction(root, 1);
- if (IS_ERR(trans)) {
- err = PTR_ERR(trans);
- goto out;
- }
- trans->block_rsv = rsv;
-
/*
* setattr is responsible for setting the ordered_data_close flag,
* but that is only tested during the last file release. That
@@ -6585,20 +6575,30 @@
btrfs_add_ordered_operation(trans, root, inode);
while (1) {
+ ret = btrfs_block_rsv_check(trans, root, rsv, min_size, 0);
+ if (ret) {
+ /*
+ * This can only happen with the original transaction we
+ * started above, every other time we shouldn't have a
+ * transaction started yet.
+ */
+ if (ret == -EAGAIN)
+ goto end_trans;
+ err = ret;
+ break;
+ }
+
if (!trans) {
- trans = btrfs_start_transaction(root, 3);
+ /* Just need the 1 for updating the inode */
+ trans = btrfs_start_transaction(root, 1);
if (IS_ERR(trans)) {
err = PTR_ERR(trans);
goto out;
}
-
- ret = btrfs_truncate_reserve_metadata(trans, root,
- rsv);
- BUG_ON(ret);
-
- trans->block_rsv = rsv;
}
+ trans->block_rsv = rsv;
+
ret = btrfs_truncate_inode_items(trans, root, inode,
inode->i_size,
BTRFS_EXTENT_DATA_KEY);
@@ -6613,7 +6613,7 @@
err = ret;
break;
}
-
+end_trans:
nr = trans->blocks_used;
btrfs_end_transaction(trans, root);
trans = NULL;