Commit 80ff3856 authored by Yan Zheng's avatar Yan Zheng Committed by Chris Mason
Browse files

Btrfs: update nodatacow code v2 



This patch simplifies the nodatacow checker. If all references
were created after the latest snapshot, then we can avoid COW
safely. This patch also updates run_delalloc_nocow to do more
fine-grained checking.

Signed-off-by: default avatarYan Zheng <zheng.yan@oracle.com>
parent 6643558d

fs/btrfs/ctree.h

+5 −3
Original line number Diff line number Diff line
@@ -454,6 +454,7 @@ struct btrfs_root_item { 
	__le64 bytenr;

	__le64 byte_limit;

	__le64 bytes_used;

	__le64 last_snapshot;

	__le32 flags;

	__le32 refs;

	struct btrfs_disk_key drop_progress;
@@ -1413,6 +1414,8 @@ BTRFS_SETGET_STACK_FUNCS(root_refs, struct btrfs_root_item, refs, 32); 
BTRFS_SETGET_STACK_FUNCS(root_flags, struct btrfs_root_item, flags, 32);

BTRFS_SETGET_STACK_FUNCS(root_used, struct btrfs_root_item, bytes_used, 64);

BTRFS_SETGET_STACK_FUNCS(root_limit, struct btrfs_root_item, byte_limit, 64);

BTRFS_SETGET_STACK_FUNCS(root_last_snapshot, struct btrfs_root_item,

			 last_snapshot, 64);



/* struct btrfs_super_block */

BTRFS_SETGET_STACK_FUNCS(super_bytenr, struct btrfs_super_block, bytenr, 64);
@@ -1564,9 +1567,8 @@ int btrfs_update_pinned_extents(struct btrfs_root *root, 
				u64 bytenr, u64 num, int pin);

int btrfs_drop_leaf_ref(struct btrfs_trans_handle *trans,

			struct btrfs_root *root, struct extent_buffer *leaf);

int btrfs_cross_ref_exists(struct btrfs_trans_handle *trans,

			   struct btrfs_root *root,

			   struct btrfs_key *key, u64 bytenr);

int btrfs_cross_ref_exist(struct btrfs_trans_handle *trans,

			  struct btrfs_root *root, u64 bytenr);

int btrfs_extent_post_op(struct btrfs_trans_handle *trans,

			 struct btrfs_root *root);

int btrfs_copy_pinned(struct btrfs_root *root, struct extent_io_tree *copy);

fs/btrfs/extent-tree.c

+18 −113
Original line number Diff line number Diff line
@@ -848,9 +848,8 @@ int btrfs_lookup_extent_ref(struct btrfs_trans_handle *trans, 
	return 0;

}



static int get_reference_status(struct btrfs_root *root, u64 bytenr,

				u64 parent_gen, u64 ref_objectid,

			        u64 *min_generation, u32 *ref_count)

int btrfs_cross_ref_exist(struct btrfs_trans_handle *trans,

			  struct btrfs_root *root, u64 bytenr)

{

	struct btrfs_root *extent_root = root->fs_info->extent_root;

	struct btrfs_path *path;
@@ -858,8 +857,8 @@ static int get_reference_status(struct btrfs_root *root, u64 bytenr, 
	struct btrfs_extent_ref *ref_item;

	struct btrfs_key key;

	struct btrfs_key found_key;

	u64 root_objectid = root->root_key.objectid;

	u64 ref_generation;

	u64 ref_root;

	u64 last_snapshot;

	u32 nritems;

	int ret;
@@ -872,7 +871,9 @@ static int get_reference_status(struct btrfs_root *root, u64 bytenr, 
	if (ret < 0)

		goto out;

	BUG_ON(ret == 0);

	if (ret < 0 || path->slots[0] == 0)



	ret = -ENOENT;

	if (path->slots[0] == 0)

		goto out;



	path->slots[0]--;
@@ -880,14 +881,10 @@ static int get_reference_status(struct btrfs_root *root, u64 bytenr, 
	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);



	if (found_key.objectid != bytenr ||

	    found_key.type != BTRFS_EXTENT_ITEM_KEY) {

		ret = 1;

	    found_key.type != BTRFS_EXTENT_ITEM_KEY)

		goto out;

	}



	*ref_count = 0;

	*min_generation = (u64)-1;



	last_snapshot = btrfs_root_last_snapshot(&root->root_item);

	while (1) {

		leaf = path->nodes[0];

		nritems = btrfs_header_nritems(leaf);
@@ -910,113 +907,21 @@ static int get_reference_status(struct btrfs_root *root, u64 bytenr, 


		ref_item = btrfs_item_ptr(leaf, path->slots[0],

					  struct btrfs_extent_ref);

		ref_generation = btrfs_ref_generation(leaf, ref_item);

		/*

		 * For (parent_gen > 0 && parent_gen > ref_generation):

		 *

		 * we reach here through the oldest root, therefore

		 * all other reference from same snapshot should have

		 * a larger generation.

		 */

		if ((root_objectid != btrfs_ref_root(leaf, ref_item)) ||

		    (parent_gen > 0 && parent_gen > ref_generation) ||

		    (ref_objectid >= BTRFS_FIRST_FREE_OBJECTID &&

		     ref_objectid != btrfs_ref_objectid(leaf, ref_item))) {

			*ref_count = 2;

			break;

		}



		*ref_count = 1;

		if (*min_generation > ref_generation)

			*min_generation = ref_generation;



		path->slots[0]++;

	}

	ret = 0;

out:

	btrfs_free_path(path);

	return ret;

}



int btrfs_cross_ref_exists(struct btrfs_trans_handle *trans,

			   struct btrfs_root *root,

			   struct btrfs_key *key, u64 bytenr)

{

	struct btrfs_root *old_root;

	struct btrfs_path *path = NULL;

	struct extent_buffer *eb;

	struct btrfs_file_extent_item *item;

	u64 ref_generation;

	u64 min_generation;

	u64 extent_start;

	u32 ref_count;

	int level;

	int ret;



	BUG_ON(trans == NULL);

	BUG_ON(key->type != BTRFS_EXTENT_DATA_KEY);

	ret = get_reference_status(root, bytenr, 0, key->objectid,

				   &min_generation, &ref_count);

	if (ret)

		return ret;



	if (ref_count != 1)

		return 1;



	old_root = root->dirty_root->root;

	ref_generation = old_root->root_key.offset;



	/* all references are created in running transaction */

	if (min_generation > ref_generation) {

		ret = 0;

		goto out;

	}



	path = btrfs_alloc_path();

	if (!path) {

		ret = -ENOMEM;

		goto out;

	}



	path->skip_locking = 1;

	/* if no item found, the extent is referenced by other snapshot */

	ret = btrfs_search_slot(NULL, old_root, key, path, 0, 0);

	if (ret)

		goto out;



	eb = path->nodes[0];

	item = btrfs_item_ptr(eb, path->slots[0],

			      struct btrfs_file_extent_item);

	if (btrfs_file_extent_type(eb, item) != BTRFS_FILE_EXTENT_REG ||

	    btrfs_file_extent_disk_bytenr(eb, item) != bytenr) {

		ref_root = btrfs_ref_root(leaf, ref_item);

		if (ref_root != root->root_key.objectid &&

		    ref_root != BTRFS_TREE_LOG_OBJECTID) {

			ret = 1;

			goto out;

		}



	for (level = BTRFS_MAX_LEVEL - 1; level >= -1; level--) {

		if (level >= 0) {

			eb = path->nodes[level];

			if (!eb)

				continue;

			extent_start = eb->start;

		} else

			extent_start = bytenr;



		ret = get_reference_status(root, extent_start, ref_generation,

					   0, &min_generation, &ref_count);

		if (ret)

			goto out;



		if (ref_count != 1) {

		if (btrfs_ref_generation(leaf, ref_item) <= last_snapshot) {

			ret = 1;

			goto out;

		}

		if (level >= 0)

			ref_generation = btrfs_header_generation(eb);



		path->slots[0]++;

	}

	ret = 0;

out:

	if (path)

	btrfs_free_path(path);

	return ret;

}

fs/btrfs/inode.c

+124 −89
Original line number Diff line number Diff line
@@ -298,6 +298,7 @@ static int cow_file_range(struct inode *inode, struct page *locked_page, 
	unsigned long max_compressed = 128 * 1024;

	unsigned long max_uncompressed = 256 * 1024;

	int i;

	int ordered_type;

	int will_compress;



	trans = btrfs_join_transaction(root, 1);
@@ -491,9 +492,10 @@ static int cow_file_range(struct inode *inode, struct page *locked_page, 
		}



		cur_alloc_size = ins.offset;

		ordered_type = will_compress ? BTRFS_ORDERED_COMPRESSED : 0;

		ret = btrfs_add_ordered_extent(inode, start, ins.objectid,

					       ram_size, cur_alloc_size, 0,

					       will_compress);

					       ram_size, cur_alloc_size,

					       ordered_type);

		BUG_ON(ret);



		if (disk_num_bytes < cur_alloc_size) {
@@ -587,115 +589,148 @@ static int cow_file_range(struct inode *inode, struct page *locked_page, 
static int run_delalloc_nocow(struct inode *inode, struct page *locked_page,

			      u64 start, u64 end, int *page_started)

{

	u64 extent_start;

	u64 extent_end;

	u64 bytenr;

	u64 loops = 0;

	u64 total_fs_bytes;

	struct btrfs_root *root = BTRFS_I(inode)->root;

	struct btrfs_block_group_cache *block_group;

	struct btrfs_trans_handle *trans;

	struct extent_buffer *leaf;

	int found_type;

	struct btrfs_path *path;

	struct btrfs_file_extent_item *item;

	int ret;

	int err = 0;

	struct btrfs_file_extent_item *fi;

	struct btrfs_key found_key;

	u64 cow_start;

	u64 cur_offset;

	u64 extent_end;

	u64 disk_bytenr;

	u64 num_bytes;

	int extent_type;

	int ret;

	int nocow;

	int check_prev = 1;



	total_fs_bytes = btrfs_super_total_bytes(&root->fs_info->super_copy);

	path = btrfs_alloc_path();

	BUG_ON(!path);

	trans = btrfs_join_transaction(root, 1);

	BUG_ON(!trans);

again:

	ret = btrfs_lookup_file_extent(NULL, root, path,

				       inode->i_ino, start, 0);

	if (ret < 0) {

		err = ret;

		goto out;

	}



	if (ret != 0) {

		if (path->slots[0] == 0)

			goto not_found;

	cow_start = (u64)-1;

	cur_offset = start;

	while (1) {

		ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,

					       cur_offset, 0);

		BUG_ON(ret < 0);

		if (ret > 0 && path->slots[0] > 0 && check_prev) {

			leaf = path->nodes[0];

			btrfs_item_key_to_cpu(leaf, &found_key,

					      path->slots[0] - 1);

			if (found_key.objectid == inode->i_ino &&

			    found_key.type == BTRFS_EXTENT_DATA_KEY)

				path->slots[0]--;

		}



		check_prev = 0;

next_slot:

		leaf = path->nodes[0];

	item = btrfs_item_ptr(leaf, path->slots[0],

			      struct btrfs_file_extent_item);

		if (path->slots[0] >= btrfs_header_nritems(leaf)) {

			ret = btrfs_next_leaf(root, path);

			if (ret < 0)

				BUG_ON(1);

			if (ret > 0)

				break;

			leaf = path->nodes[0];

		}



	/* are we inside the extent that was found? */

		nocow = 0;

		disk_bytenr = 0;

		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);

	found_type = btrfs_key_type(&found_key);

	if (found_key.objectid != inode->i_ino ||

	    found_type != BTRFS_EXTENT_DATA_KEY)

		goto not_found;



	found_type = btrfs_file_extent_type(leaf, item);

	extent_start = found_key.offset;

	if (found_type == BTRFS_FILE_EXTENT_REG) {

		u64 extent_num_bytes;



		extent_num_bytes = btrfs_file_extent_num_bytes(leaf, item);

		extent_end = extent_start + extent_num_bytes;

		err = 0;



		if (btrfs_file_extent_compression(leaf, item) ||

		    btrfs_file_extent_encryption(leaf,item) ||

		    btrfs_file_extent_other_encoding(leaf, item))

			goto not_found;



		if (loops && start != extent_start)

			goto not_found;

		if (found_key.objectid > inode->i_ino ||

		    found_key.type > BTRFS_EXTENT_DATA_KEY ||

		    found_key.offset > end)

			break;



		if (start < extent_start || start >= extent_end)

			goto not_found;

		if (found_key.offset > cur_offset) {

			extent_end = found_key.offset;

			goto out_check;

		}



		bytenr = btrfs_file_extent_disk_bytenr(leaf, item);

		if (bytenr == 0)

			goto not_found;

		fi = btrfs_item_ptr(leaf, path->slots[0],

				    struct btrfs_file_extent_item);

		extent_type = btrfs_file_extent_type(leaf, fi);



		if (btrfs_cross_ref_exists(trans, root, &found_key, bytenr))

			goto not_found;

		/*

		 * we may be called by the resizer, make sure we're inside

		 * the limits of the FS

		 */

		if (extent_type == BTRFS_FILE_EXTENT_REG) {

			struct btrfs_block_group_cache *block_group;

			disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);

			extent_end = found_key.offset +

				btrfs_file_extent_num_bytes(leaf, fi);

			if (extent_end <= start) {

				path->slots[0]++;

				goto next_slot;

			}

			if (btrfs_file_extent_compression(leaf, fi) ||

			    btrfs_file_extent_encryption(leaf, fi) ||

			    btrfs_file_extent_other_encoding(leaf, fi))

				goto out_check;

			if (disk_bytenr == 0)

				goto out_check;

			if (btrfs_cross_ref_exist(trans, root, disk_bytenr))

				goto out_check;

			block_group = btrfs_lookup_block_group(root->fs_info,

						       bytenr);

							       disk_bytenr);

			if (!block_group || block_group->ro)

			goto not_found;



		bytenr += btrfs_file_extent_offset(leaf, item);

		extent_num_bytes = min(end + 1, extent_end) - start;

		ret = btrfs_add_ordered_extent(inode, start, bytenr,

						extent_num_bytes,

						extent_num_bytes, 1, 0);

		if (ret) {

			err = ret;

			goto out;

				goto out_check;

			disk_bytenr += btrfs_file_extent_offset(leaf, fi);

			nocow = 1;

		} else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {

			extent_end = found_key.offset +

				btrfs_file_extent_inline_len(leaf, fi);

			extent_end = ALIGN(extent_end, root->sectorsize);

		} else {

			BUG_ON(1);

		}

out_check:

		if (extent_end <= start) {

			path->slots[0]++;

			goto next_slot;

		}

		if (!nocow) {

			if (cow_start == (u64)-1)

				cow_start = cur_offset;

			cur_offset = extent_end;

			if (cur_offset > end)

				break;

			path->slots[0]++;

			goto next_slot;

		}



		btrfs_release_path(root, path);

		start = extent_end;

		if (start <= end) {

			loops++;

			goto again;

		if (cow_start != (u64)-1) {

			ret = cow_file_range(inode, locked_page, cow_start,

					found_key.offset - 1, page_started);

			BUG_ON(ret);

			cow_start = (u64)-1;

		}

	} else {

not_found:

		btrfs_end_transaction(trans, root);

		btrfs_free_path(path);

		return cow_file_range(inode, locked_page, start, end,



		disk_bytenr += cur_offset - found_key.offset;

		num_bytes = min(end + 1, extent_end) - cur_offset;



		ret = btrfs_add_ordered_extent(inode, cur_offset, disk_bytenr,

					       num_bytes, num_bytes,

					       BTRFS_ORDERED_NOCOW);

		cur_offset = extent_end;

		if (cur_offset > end)

			break;

	}

	btrfs_release_path(root, path);



	if (cur_offset <= end && cow_start == (u64)-1)

		cow_start = cur_offset;

	if (cow_start != (u64)-1) {

		ret = cow_file_range(inode, locked_page, cow_start, end,

				     page_started);

		BUG_ON(ret);

	}

out:

	WARN_ON(err);

	btrfs_end_transaction(trans, root);



	ret = btrfs_end_transaction(trans, root);

	BUG_ON(ret);

	btrfs_free_path(path);

	return err;

	return 0;

}



/*

fs/btrfs/ioctl.c

+1 −0
Original line number Diff line number Diff line
@@ -112,6 +112,7 @@ static noinline int create_subvol(struct btrfs_root *root, 
	btrfs_set_root_level(&root_item, 0);

	btrfs_set_root_refs(&root_item, 1);

	btrfs_set_root_used(&root_item, 0);

	btrfs_set_root_last_snapshot(&root_item, 0);



	memset(&root_item.drop_progress, 0, sizeof(root_item.drop_progress));

	root_item.drop_level = 0;

fs/btrfs/ordered-data.c

+3 −6
Original line number Diff line number Diff line
@@ -165,8 +165,7 @@ static inline struct rb_node *tree_search(struct btrfs_ordered_inode_tree *tree, 
 * inserted.

 */

int btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,

			     u64 start, u64 len, u64 disk_len, int nocow,

			     int compressed)

			     u64 start, u64 len, u64 disk_len, int type)

{

	struct btrfs_ordered_inode_tree *tree;

	struct rb_node *node;
@@ -183,10 +182,8 @@ int btrfs_add_ordered_extent(struct inode *inode, u64 file_offset, 
	entry->len = len;

	entry->disk_len = disk_len;

	entry->inode = inode;

	if (nocow)

		set_bit(BTRFS_ORDERED_NOCOW, &entry->flags);

	if (compressed)

		set_bit(BTRFS_ORDERED_COMPRESSED, &entry->flags);

	if (type == BTRFS_ORDERED_NOCOW || type == BTRFS_ORDERED_COMPRESSED)

		set_bit(type, &entry->flags);



	/* one ref for the tree */

	atomic_set(&entry->refs, 1);