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/inode.c b/fs/btrfs/inode.c
index c038644..1af1ea8 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1700,6 +1700,7 @@
ordered_extent->len);
BUG_ON(ret);
} else {
+ BUG_ON(root == root->fs_info->tree_root);
ret = insert_reserved_file_extent(trans, inode,
ordered_extent->file_offset,
ordered_extent->start,
@@ -3196,7 +3197,7 @@
BUG_ON(new_size > 0 && min_type != BTRFS_EXTENT_DATA_KEY);
- if (root->ref_cows)
+ if (root->ref_cows || root == root->fs_info->tree_root)
btrfs_drop_extent_cache(inode, new_size & (~mask), (u64)-1, 0);
path = btrfs_alloc_path();
@@ -3344,7 +3345,8 @@
} else {
break;
}
- if (found_extent && root->ref_cows) {
+ if (found_extent && (root->ref_cows ||
+ root == root->fs_info->tree_root)) {
btrfs_set_path_blocking(path);
ret = btrfs_free_extent(trans, root, extent_start,
extent_num_bytes, 0,
@@ -3675,7 +3677,8 @@
int ret;
truncate_inode_pages(&inode->i_data, 0);
- if (inode->i_nlink && btrfs_root_refs(&root->root_item) != 0)
+ if (inode->i_nlink && (btrfs_root_refs(&root->root_item) != 0 ||
+ root == root->fs_info->tree_root))
goto no_delete;
if (is_bad_inode(inode)) {
@@ -3888,7 +3891,14 @@
}
spin_unlock(&root->inode_lock);
- if (empty && btrfs_root_refs(&root->root_item) == 0) {
+ /*
+ * Free space cache has inodes in the tree root, but the tree root has a
+ * root_refs of 0, so this could end up dropping the tree root as a
+ * snapshot, so we need the extra !root->fs_info->tree_root check to
+ * make sure we don't drop it.
+ */
+ if (empty && btrfs_root_refs(&root->root_item) == 0 &&
+ root != root->fs_info->tree_root) {
synchronize_srcu(&root->fs_info->subvol_srcu);
spin_lock(&root->inode_lock);
empty = RB_EMPTY_ROOT(&root->inode_tree);
@@ -4282,14 +4292,24 @@
struct btrfs_root *root = BTRFS_I(inode)->root;
struct btrfs_trans_handle *trans;
int ret = 0;
+ bool nolock = false;
if (BTRFS_I(inode)->dummy_inode)
return 0;
+ smp_mb();
+ nolock = (root->fs_info->closing && root == root->fs_info->tree_root);
+
if (wbc->sync_mode == WB_SYNC_ALL) {
- trans = btrfs_join_transaction(root, 1);
+ if (nolock)
+ trans = btrfs_join_transaction_nolock(root, 1);
+ else
+ trans = btrfs_join_transaction(root, 1);
btrfs_set_trans_block_group(trans, inode);
- ret = btrfs_commit_transaction(trans, root);
+ if (nolock)
+ ret = btrfs_end_transaction_nolock(trans, root);
+ else
+ ret = btrfs_commit_transaction(trans, root);
}
return ret;
}
@@ -6308,6 +6328,21 @@
spin_unlock(&root->fs_info->ordered_extent_lock);
}
+ if (root == root->fs_info->tree_root) {
+ struct btrfs_block_group_cache *block_group;
+
+ block_group = btrfs_lookup_block_group(root->fs_info,
+ BTRFS_I(inode)->block_group);
+ if (block_group && block_group->inode == inode) {
+ spin_lock(&block_group->lock);
+ block_group->inode = NULL;
+ spin_unlock(&block_group->lock);
+ btrfs_put_block_group(block_group);
+ } else if (block_group) {
+ btrfs_put_block_group(block_group);
+ }
+ }
+
spin_lock(&root->orphan_lock);
if (!list_empty(&BTRFS_I(inode)->i_orphan)) {
printk(KERN_INFO "BTRFS: inode %lu still on the orphan list\n",
@@ -6340,7 +6375,8 @@
{
struct btrfs_root *root = BTRFS_I(inode)->root;
- if (btrfs_root_refs(&root->root_item) == 0)
+ if (btrfs_root_refs(&root->root_item) == 0 &&
+ root != root->fs_info->tree_root)
return 1;
else
return generic_drop_inode(inode);
@@ -6757,27 +6793,33 @@
return err;
}
-int btrfs_prealloc_file_range(struct inode *inode, int mode,
- u64 start, u64 num_bytes, u64 min_size,
- loff_t actual_len, u64 *alloc_hint)
+static int __btrfs_prealloc_file_range(struct inode *inode, int mode,
+ u64 start, u64 num_bytes, u64 min_size,
+ loff_t actual_len, u64 *alloc_hint,
+ struct btrfs_trans_handle *trans)
{
- struct btrfs_trans_handle *trans;
struct btrfs_root *root = BTRFS_I(inode)->root;
struct btrfs_key ins;
u64 cur_offset = start;
int ret = 0;
+ bool own_trans = true;
+ if (trans)
+ own_trans = false;
while (num_bytes > 0) {
- trans = btrfs_start_transaction(root, 3);
- if (IS_ERR(trans)) {
- ret = PTR_ERR(trans);
- break;
+ if (own_trans) {
+ trans = btrfs_start_transaction(root, 3);
+ if (IS_ERR(trans)) {
+ ret = PTR_ERR(trans);
+ break;
+ }
}
ret = btrfs_reserve_extent(trans, root, num_bytes, min_size,
0, *alloc_hint, (u64)-1, &ins, 1);
if (ret) {
- btrfs_end_transaction(trans, root);
+ if (own_trans)
+ btrfs_end_transaction(trans, root);
break;
}
@@ -6810,11 +6852,30 @@
ret = btrfs_update_inode(trans, root, inode);
BUG_ON(ret);
- btrfs_end_transaction(trans, root);
+ if (own_trans)
+ btrfs_end_transaction(trans, root);
}
return ret;
}
+int btrfs_prealloc_file_range(struct inode *inode, int mode,
+ u64 start, u64 num_bytes, u64 min_size,
+ loff_t actual_len, u64 *alloc_hint)
+{
+ return __btrfs_prealloc_file_range(inode, mode, start, num_bytes,
+ min_size, actual_len, alloc_hint,
+ NULL);
+}
+
+int btrfs_prealloc_file_range_trans(struct inode *inode,
+ struct btrfs_trans_handle *trans, int mode,
+ u64 start, u64 num_bytes, u64 min_size,
+ loff_t actual_len, u64 *alloc_hint)
+{
+ return __btrfs_prealloc_file_range(inode, mode, start, num_bytes,
+ min_size, actual_len, alloc_hint, trans);
+}
+
static long btrfs_fallocate(struct inode *inode, int mode,
loff_t offset, loff_t len)
{