Commit 5599f393 authored by Haisu Wang's avatar Haisu Wang Committed by David Sterba
Browse files

btrfs: simplify range tracking in cow_file_range() 



Simplify tracking of the range processed by using cur_alloc_size only to
store the reserved part that may fail to the allocated extent. Remove
the ram_size as well since it is always equal to cur_alloc_size in the
context. Advance the start in normal path until extent allocation
succeeds and keep the start unchanged in the error handling path.

Passed the fstest generic/475 test for a hundred times with quota
enabled. And a modified generic/475 test by removing the sleep time
for a hundred times. About one tenth of the tests do enter the error
handling path due to fail to reserve extent.

Suggested-by: default avatarQu Wenruo <wqu@suse.com>
Signed-off-by: default avatarHaisu Wang <haisuwang@tencent.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 7c855e16

fs/btrfs/inode.c

+14 −18
Original line number Diff line number Diff line
@@ -1332,7 +1332,6 @@ static noinline int cow_file_range(struct btrfs_inode *inode, 
	u64 alloc_hint = 0;

	u64 orig_start = start;

	u64 num_bytes;

	unsigned long ram_size;

	u64 cur_alloc_size = 0;

	u64 min_alloc_size;

	u64 blocksize = fs_info->sectorsize;
@@ -1340,7 +1339,6 @@ static noinline int cow_file_range(struct btrfs_inode *inode, 
	struct extent_map *em;

	unsigned clear_bits;

	unsigned long page_ops;

	bool extent_reserved = false;

	int ret = 0;



	if (btrfs_is_free_space_inode(inode)) {
@@ -1394,8 +1392,7 @@ static noinline int cow_file_range(struct btrfs_inode *inode, 
		struct btrfs_ordered_extent *ordered;

		struct btrfs_file_extent file_extent;



		cur_alloc_size = num_bytes;

		ret = btrfs_reserve_extent(root, cur_alloc_size, cur_alloc_size,

		ret = btrfs_reserve_extent(root, num_bytes, num_bytes,

					   min_alloc_size, 0, alloc_hint,

					   &ins, 1, 1);

		if (ret == -EAGAIN) {
@@ -1426,9 +1423,7 @@ static noinline int cow_file_range(struct btrfs_inode *inode, 
		if (ret < 0)

			goto out_unlock;

		cur_alloc_size = ins.offset;

		extent_reserved = true;



		ram_size = ins.offset;

		file_extent.disk_bytenr = ins.objectid;

		file_extent.disk_num_bytes = ins.offset;

		file_extent.num_bytes = ins.offset;
@@ -1436,14 +1431,14 @@ static noinline int cow_file_range(struct btrfs_inode *inode, 
		file_extent.offset = 0;

		file_extent.compression = BTRFS_COMPRESS_NONE;



		lock_extent(&inode->io_tree, start, start + ram_size - 1,

		lock_extent(&inode->io_tree, start, start + cur_alloc_size - 1,

			    &cached);



		em = btrfs_create_io_em(inode, start, &file_extent,

					BTRFS_ORDERED_REGULAR);

		if (IS_ERR(em)) {

			unlock_extent(&inode->io_tree, start,

				      start + ram_size - 1, &cached);

				      start + cur_alloc_size - 1, &cached);

			ret = PTR_ERR(em);

			goto out_reserve;

		}
@@ -1453,7 +1448,7 @@ static noinline int cow_file_range(struct btrfs_inode *inode, 
						     1 << BTRFS_ORDERED_REGULAR);

		if (IS_ERR(ordered)) {

			unlock_extent(&inode->io_tree, start,

				      start + ram_size - 1, &cached);

				      start + cur_alloc_size - 1, &cached);

			ret = PTR_ERR(ordered);

			goto out_drop_extent_cache;

		}
@@ -1474,7 +1469,7 @@ static noinline int cow_file_range(struct btrfs_inode *inode, 
			 */

			if (ret)

				btrfs_drop_extent_map_range(inode, start,

							    start + ram_size - 1,

							    start + cur_alloc_size - 1,

							    false);

		}

		btrfs_put_ordered_extent(ordered);
@@ -1492,7 +1487,7 @@ static noinline int cow_file_range(struct btrfs_inode *inode, 
		page_ops = (keep_locked ? 0 : PAGE_UNLOCK);

		page_ops |= PAGE_SET_ORDERED;



		extent_clear_unlock_delalloc(inode, start, start + ram_size - 1,

		extent_clear_unlock_delalloc(inode, start, start + cur_alloc_size - 1,

					     locked_folio, &cached,

					     EXTENT_LOCKED | EXTENT_DELALLOC,

					     page_ops);
@@ -1502,7 +1497,7 @@ static noinline int cow_file_range(struct btrfs_inode *inode, 
			num_bytes -= cur_alloc_size;

		alloc_hint = ins.objectid + ins.offset;

		start += cur_alloc_size;

		extent_reserved = false;

		cur_alloc_size = 0;



		/*

		 * btrfs_reloc_clone_csums() error, since start is increased
@@ -1518,7 +1513,7 @@ static noinline int cow_file_range(struct btrfs_inode *inode, 
	return ret;



out_drop_extent_cache:

	btrfs_drop_extent_map_range(inode, start, start + ram_size - 1, false);

	btrfs_drop_extent_map_range(inode, start, start + cur_alloc_size - 1, false);

out_reserve:

	btrfs_dec_block_group_reservations(fs_info, ins.objectid);

	btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset, 1);
@@ -1572,13 +1567,12 @@ static noinline int cow_file_range(struct btrfs_inode *inode, 
	 * to decrement again the data space_info's bytes_may_use counter,

	 * therefore we do not pass it the flag EXTENT_CLEAR_DATA_RESV.

	 */

	if (extent_reserved) {

	if (cur_alloc_size) {

		extent_clear_unlock_delalloc(inode, start,

					     start + cur_alloc_size - 1,

					     locked_folio, &cached, clear_bits,

					     page_ops);

		btrfs_qgroup_free_data(inode, NULL, start, cur_alloc_size, NULL);

		start += cur_alloc_size;

	}



	/*
@@ -1587,11 +1581,13 @@ static noinline int cow_file_range(struct btrfs_inode *inode, 
	 * space_info's bytes_may_use counter, reserved in

	 * btrfs_check_data_free_space().

	 */

	if (start < end) {

	if (start + cur_alloc_size < end) {

		clear_bits |= EXTENT_CLEAR_DATA_RESV;

		extent_clear_unlock_delalloc(inode, start, end, locked_folio,

		extent_clear_unlock_delalloc(inode, start + cur_alloc_size,

					     end, locked_folio,

					     &cached, clear_bits, page_ops);

		btrfs_qgroup_free_data(inode, NULL, start, end - start + 1, NULL);

		btrfs_qgroup_free_data(inode, NULL, start + cur_alloc_size,

				       end - start - cur_alloc_size + 1, NULL);

	}

	return ret;

}