Btrfs: Add mount option to turn off data cow
A number of workloads do not require copy on write data or checksumming. mount -o nodatasum to disable checksums and -o nodatacow to disable both copy on write and checksumming. In nodatacow mode, copy on write is still performed when a given extent is under snapshot. Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason
Родитель
b6cda9bcb4
Коммит
be20aa9dba
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@ -70,7 +70,58 @@ void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p)
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memset(p, 0, sizeof(*p));
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}
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static int __btrfs_cow_block(struct btrfs_trans_handle *trans,
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int btrfs_copy_root(struct btrfs_trans_handle *trans,
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struct btrfs_root *root,
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struct extent_buffer *buf,
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struct extent_buffer **cow_ret, u64 new_root_objectid)
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{
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struct extent_buffer *cow;
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u32 nritems;
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int ret = 0;
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int level;
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struct btrfs_key first_key;
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struct btrfs_root new_root;
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memcpy(&new_root, root, sizeof(new_root));
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new_root.root_key.objectid = new_root_objectid;
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WARN_ON(root->ref_cows && trans->transid !=
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root->fs_info->running_transaction->transid);
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WARN_ON(root->ref_cows && trans->transid != root->last_trans);
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level = btrfs_header_level(buf);
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nritems = btrfs_header_nritems(buf);
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if (nritems) {
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if (level == 0)
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btrfs_item_key_to_cpu(buf, &first_key, 0);
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else
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btrfs_node_key_to_cpu(buf, &first_key, 0);
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} else {
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first_key.objectid = 0;
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}
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cow = __btrfs_alloc_free_block(trans, &new_root, buf->len,
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new_root_objectid,
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trans->transid, first_key.objectid,
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level, buf->start, 0);
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if (IS_ERR(cow))
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return PTR_ERR(cow);
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copy_extent_buffer(cow, buf, 0, 0, cow->len);
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btrfs_set_header_bytenr(cow, cow->start);
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btrfs_set_header_generation(cow, trans->transid);
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btrfs_set_header_owner(cow, new_root_objectid);
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WARN_ON(btrfs_header_generation(buf) > trans->transid);
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ret = btrfs_inc_ref(trans, &new_root, buf);
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if (ret)
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return ret;
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btrfs_mark_buffer_dirty(cow);
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*cow_ret = cow;
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return 0;
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}
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int __btrfs_cow_block(struct btrfs_trans_handle *trans,
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struct btrfs_root *root,
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struct extent_buffer *buf,
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struct extent_buffer *parent, int parent_slot,
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@ -431,6 +431,7 @@ struct btrfs_root {
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#define BTRFS_STRING_ITEM_KEY 253
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#define BTRFS_MOUNT_NODATASUM 0x1
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#define BTRFS_MOUNT_NODATACOW 0x2
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#define btrfs_clear_opt(o, opt) ((o) &= ~BTRFS_MOUNT_##opt)
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#define btrfs_set_opt(o, opt) ((o) |= BTRFS_MOUNT_##opt)
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@ -915,6 +916,9 @@ static inline u32 btrfs_level_size(struct btrfs_root *root, int level) {
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btrfs_item_offset_nr(leaf, slot)))
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/* extent-tree.c */
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u32 btrfs_count_snapshots_in_path(struct btrfs_root *root,
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struct btrfs_path *count_path,
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u64 first_extent);
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int btrfs_extent_post_op(struct btrfs_trans_handle *trans,
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struct btrfs_root *root);
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int btrfs_copy_pinned(struct btrfs_root *root, struct extent_map_tree *copy);
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@ -974,6 +978,10 @@ int btrfs_cow_block(struct btrfs_trans_handle *trans,
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struct btrfs_root *root, struct extent_buffer *buf,
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struct extent_buffer *parent, int parent_slot,
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struct extent_buffer **cow_ret);
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int btrfs_copy_root(struct btrfs_trans_handle *trans,
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struct btrfs_root *root,
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struct extent_buffer *buf,
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struct extent_buffer **cow_ret, u64 new_root_objectid);
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int btrfs_extend_item(struct btrfs_trans_handle *trans, struct btrfs_root
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*root, struct btrfs_path *path, u32 data_size);
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int btrfs_truncate_item(struct btrfs_trans_handle *trans,
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@ -679,6 +679,104 @@ out:
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return 0;
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}
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u32 btrfs_count_snapshots_in_path(struct btrfs_root *root,
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struct btrfs_path *count_path,
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u64 first_extent)
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{
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struct btrfs_root *extent_root = root->fs_info->extent_root;
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struct btrfs_path *path;
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u64 bytenr;
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u64 found_objectid;
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u64 root_objectid = 0;
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u32 total_count = 0;
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u32 cur_count;
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u32 refs;
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u32 nritems;
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int ret;
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struct btrfs_key key;
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struct btrfs_key found_key;
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struct extent_buffer *l;
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struct btrfs_extent_item *item;
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struct btrfs_extent_ref *ref_item;
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int level = -1;
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path = btrfs_alloc_path();
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again:
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if (level == -1)
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bytenr = first_extent;
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else
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bytenr = count_path->nodes[level]->start;
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cur_count = 0;
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key.objectid = bytenr;
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key.offset = 0;
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btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
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ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
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if (ret < 0)
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goto out;
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BUG_ON(ret == 0);
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l = path->nodes[0];
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btrfs_item_key_to_cpu(l, &found_key, path->slots[0]);
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if (found_key.objectid != bytenr ||
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found_key.type != BTRFS_EXTENT_ITEM_KEY) {
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goto out;
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}
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item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
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refs = btrfs_extent_refs(l, item);
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while (1) {
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nritems = btrfs_header_nritems(l);
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if (path->slots[0] >= nritems) {
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ret = btrfs_next_leaf(extent_root, path);
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if (ret == 0)
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continue;
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break;
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}
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btrfs_item_key_to_cpu(l, &found_key, path->slots[0]);
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if (found_key.objectid != bytenr)
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break;
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if (found_key.type != BTRFS_EXTENT_REF_KEY) {
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path->slots[0]++;
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continue;
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}
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cur_count++;
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ref_item = btrfs_item_ptr(l, path->slots[0],
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struct btrfs_extent_ref);
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found_objectid = btrfs_ref_root(l, ref_item);
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if (found_objectid != root_objectid)
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total_count++;
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if (total_count > 1)
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goto out;
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if (root_objectid == 0)
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root_objectid = found_objectid;
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path->slots[0]++;
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}
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if (cur_count == 0) {
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total_count = 0;
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goto out;
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}
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if (total_count > 1)
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goto out;
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if (level >= 0 && root->node == count_path->nodes[level])
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goto out;
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level++;
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btrfs_release_path(root, path);
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goto again;
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out:
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btrfs_free_path(path);
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return total_count;
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}
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int btrfs_inc_root_ref(struct btrfs_trans_handle *trans,
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struct btrfs_root *root, u64 owner_objectid)
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{
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@ -1127,9 +1225,6 @@ static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
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if (!path)
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return -ENOMEM;
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if (ref_generation && owner_objectid == 0 && root_objectid == 3) {
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//printk("drop backref root %Lu gen %Lu byte %Lu\n", root_objectid, ref_generation, bytenr );
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}
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ret = lookup_extent_backref(trans, extent_root, path,
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bytenr, root_objectid,
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ref_generation,
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122
fs/btrfs/inode.c
122
fs/btrfs/inode.c
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@ -72,21 +72,22 @@ static unsigned char btrfs_type_by_mode[S_IFMT >> S_SHIFT] = {
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[S_IFLNK >> S_SHIFT] = BTRFS_FT_SYMLINK,
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};
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static int run_delalloc_range(struct inode *inode, u64 start, u64 end)
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static int cow_file_range(struct inode *inode, u64 start, u64 end)
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{
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struct btrfs_root *root = BTRFS_I(inode)->root;
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struct btrfs_trans_handle *trans;
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struct btrfs_key ins;
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u64 alloc_hint = 0;
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u64 num_bytes;
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int ret;
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u64 blocksize = root->sectorsize;
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struct btrfs_key ins;
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int ret;
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mutex_lock(&root->fs_info->fs_mutex);
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trans = btrfs_start_transaction(root, 1);
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btrfs_set_trans_block_group(trans, inode);
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BUG_ON(!trans);
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btrfs_set_trans_block_group(trans, inode);
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num_bytes = (end - start + blocksize) & ~(blocksize - 1);
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num_bytes = max(blocksize, num_bytes);
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ret = btrfs_drop_extents(trans, root, inode,
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start, start + num_bytes, start, &alloc_hint);
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@ -106,6 +107,101 @@ static int run_delalloc_range(struct inode *inode, u64 start, u64 end)
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ins.offset);
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out:
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btrfs_end_transaction(trans, root);
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return ret;
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}
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static int run_delalloc_nocow(struct inode *inode, u64 start, u64 end)
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{
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u64 extent_start;
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u64 extent_end;
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u64 bytenr;
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u64 cow_end;
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struct btrfs_root *root = BTRFS_I(inode)->root;
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struct extent_buffer *leaf;
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int found_type;
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struct btrfs_path *path;
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struct btrfs_file_extent_item *item;
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int ret;
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int err;
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struct btrfs_key found_key;
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path = btrfs_alloc_path();
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BUG_ON(!path);
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again:
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ret = btrfs_lookup_file_extent(NULL, root, path,
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inode->i_ino, start, 0);
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if (ret < 0) {
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btrfs_free_path(path);
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return ret;
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}
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cow_end = end;
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if (ret != 0) {
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if (path->slots[0] == 0)
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goto not_found;
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path->slots[0]--;
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}
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leaf = path->nodes[0];
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item = btrfs_item_ptr(leaf, path->slots[0],
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struct btrfs_file_extent_item);
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/* are we inside the extent that was found? */
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btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
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found_type = btrfs_key_type(&found_key);
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if (found_key.objectid != inode->i_ino ||
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found_type != BTRFS_EXTENT_DATA_KEY) {
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goto not_found;
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}
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found_type = btrfs_file_extent_type(leaf, item);
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extent_start = found_key.offset;
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if (found_type == BTRFS_FILE_EXTENT_REG) {
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extent_end = extent_start +
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btrfs_file_extent_num_bytes(leaf, item);
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err = 0;
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if (start < extent_start || start >= extent_end)
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goto not_found;
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cow_end = min(end, extent_end - 1);
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bytenr = btrfs_file_extent_disk_bytenr(leaf, item);
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if (bytenr == 0)
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goto not_found;
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bytenr += btrfs_file_extent_offset(leaf, item);
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if (btrfs_count_snapshots_in_path(root, path, bytenr) != 1) {
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goto not_found;
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}
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start = extent_end;
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} else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
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goto not_found;
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}
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loop:
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if (start > end) {
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btrfs_free_path(path);
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return 0;
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}
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btrfs_release_path(root, path);
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goto again;
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not_found:
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cow_file_range(inode, start, cow_end);
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start = cow_end + 1;
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goto loop;
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}
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static int run_delalloc_range(struct inode *inode, u64 start, u64 end)
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{
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struct btrfs_root *root = BTRFS_I(inode)->root;
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int ret;
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mutex_lock(&root->fs_info->fs_mutex);
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if (btrfs_test_opt(root, NODATACOW))
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ret = run_delalloc_nocow(inode, start, end);
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else
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ret = cow_file_range(inode, start, end);
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mutex_unlock(&root->fs_info->fs_mutex);
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return ret;
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}
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@ -1907,9 +2003,6 @@ int btrfs_commit_write(struct file *file, struct page *page,
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btrfs_cow_one_page(inode, page, PAGE_CACHE_SIZE);
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set_page_extent_mapped(page);
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set_page_dirty(page);
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if (pos > inode->i_size) {
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i_size_write(inode, pos);
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mark_inode_dirty(inode);
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@ -2078,13 +2171,18 @@ static int create_snapshot(struct btrfs_root *root, char *name, int namelen)
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key.objectid = objectid;
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key.offset = 1;
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btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
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extent_buffer_get(root->node);
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btrfs_cow_block(trans, root, root->node, NULL, 0, &tmp);
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free_extent_buffer(tmp);
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btrfs_set_root_bytenr(&new_root_item, root->node->start);
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btrfs_set_root_level(&new_root_item, btrfs_header_level(root->node));
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btrfs_copy_root(trans, root, root->node, &tmp, objectid);
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btrfs_set_root_bytenr(&new_root_item, tmp->start);
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btrfs_set_root_level(&new_root_item, btrfs_header_level(tmp));
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ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
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&new_root_item);
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free_extent_buffer(tmp);
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if (ret)
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goto fail;
|
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|
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@ -2106,10 +2204,6 @@ static int create_snapshot(struct btrfs_root *root, char *name, int namelen)
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|
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if (ret)
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goto fail;
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ret = btrfs_inc_root_ref(trans, root, objectid);
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if (ret)
|
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goto fail;
|
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fail:
|
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nr = trans->blocks_used;
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err = btrfs_commit_transaction(trans, root);
|
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|
|
|
|||
|
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@ -61,12 +61,13 @@ static void btrfs_put_super (struct super_block * sb)
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}
|
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|
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enum {
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Opt_subvol, Opt_nodatasum, Opt_err,
|
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Opt_subvol, Opt_nodatasum, Opt_nodatacow, Opt_err,
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};
|
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|
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static match_table_t tokens = {
|
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{Opt_subvol, "subvol=%s"},
|
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{Opt_nodatasum, "nodatasum"},
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{Opt_nodatacow, "nodatacow"},
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{Opt_err, NULL}
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};
|
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|
||||
|
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@ -78,12 +79,20 @@ static int parse_options (char * options,
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struct btrfs_fs_info *info = NULL;
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substring_t args[MAX_OPT_ARGS];
|
||||
|
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if (root)
|
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info = root->fs_info;
|
||||
|
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if (!options)
|
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return 1;
|
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|
||||
/*
|
||||
* strsep changes the string, duplicate it because parse_options
|
||||
* gets called twice
|
||||
*/
|
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options = kstrdup(options, GFP_NOFS);
|
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if (!options)
|
||||
return -ENOMEM;
|
||||
|
||||
if (root)
|
||||
info = root->fs_info;
|
||||
|
||||
while ((p = strsep (&options, ",")) != NULL) {
|
||||
int token;
|
||||
if (!*p)
|
||||
|
|
@ -92,17 +101,28 @@ static int parse_options (char * options,
|
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token = match_token(p, tokens, args);
|
||||
switch (token) {
|
||||
case Opt_subvol:
|
||||
if (subvol_name)
|
||||
if (subvol_name) {
|
||||
*subvol_name = match_strdup(&args[0]);
|
||||
}
|
||||
break;
|
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case Opt_nodatasum:
|
||||
if (root)
|
||||
if (info) {
|
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printk("btrfs: setting nodatacsum\n");
|
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btrfs_set_opt(info->mount_opt, NODATASUM);
|
||||
}
|
||||
break;
|
||||
case Opt_nodatacow:
|
||||
if (info) {
|
||||
printk("btrfs: setting nodatacow\n");
|
||||
btrfs_set_opt(info->mount_opt, NODATACOW);
|
||||
btrfs_set_opt(info->mount_opt, NODATASUM);
|
||||
}
|
||||
break;
|
||||
default:
|
||||
return 0;
|
||||
break;
|
||||
}
|
||||
}
|
||||
kfree(options);
|
||||
return 1;
|
||||
}
|
||||
|
||||
|
|
|
|||
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Ссылка в новой задаче