Commit afe990fb authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: cleanup the reserved space inside loop of btrfs_buffered_write() 



Inside the main loop of btrfs_buffered_write(), if something wrong
happened, there is a out-of-loop cleanup path to release the reserved
space.

This behavior saves some code lines, but makes it much harder to read,
as we need to check release_bytes to make sure when we need to do the
cleanup.

Factor out the cleanup part into a helper, release_reserved_space(), to
do the cleanup inside the main loop, so that we can move @release_bytes
inside the loop.

This will make later refactoring of the main loop much easier.

Reviewed-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: default avatarFilipe Manana <fdmanana@suse.com>
Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 563bd2b7

fs/btrfs/file.c

+28 −17
Original line number Diff line number Diff line
@@ -1076,6 +1076,24 @@ int btrfs_write_check(struct kiocb *iocb, size_t count) 
	return 0;

}



static void release_space(struct btrfs_inode *inode, struct extent_changeset *data_reserved,

			  u64 start, u64 len, bool only_release_metadata)

{

	if (len == 0)

		return;



	if (only_release_metadata) {

		btrfs_check_nocow_unlock(inode);

		btrfs_delalloc_release_metadata(inode, len, true);

	} else {

		const struct btrfs_fs_info *fs_info = inode->root->fs_info;



		btrfs_delalloc_release_space(inode, data_reserved,

					     round_down(start, fs_info->sectorsize),

					     len, true);

	}

}



ssize_t btrfs_buffered_write(struct kiocb *iocb, struct iov_iter *i)

{

	struct file *file = iocb->ki_filp;
@@ -1083,7 +1101,6 @@ ssize_t btrfs_buffered_write(struct kiocb *iocb, struct iov_iter *i) 
	struct inode *inode = file_inode(file);

	struct btrfs_fs_info *fs_info = inode_to_fs_info(inode);

	struct extent_changeset *data_reserved = NULL;

	u64 release_bytes = 0;

	u64 lockstart;

	u64 lockend;

	size_t num_written = 0;
@@ -1092,7 +1109,6 @@ ssize_t btrfs_buffered_write(struct kiocb *iocb, struct iov_iter *i) 
	unsigned int ilock_flags = 0;

	const bool nowait = (iocb->ki_flags & IOCB_NOWAIT);

	unsigned int bdp_flags = (nowait ? BDP_ASYNC : 0);

	bool only_release_metadata = false;



	if (nowait)

		ilock_flags |= BTRFS_ILOCK_TRY;
@@ -1127,7 +1143,9 @@ ssize_t btrfs_buffered_write(struct kiocb *iocb, struct iov_iter *i) 
		size_t dirty_sectors;

		size_t num_sectors;

		struct folio *folio = NULL;

		u64 release_bytes;

		int extents_locked;

		bool only_release_metadata = false;



		/*

		 * Fault pages before locking them in prepare_one_folio()
@@ -1138,7 +1156,6 @@ ssize_t btrfs_buffered_write(struct kiocb *iocb, struct iov_iter *i) 
			break;

		}



		only_release_metadata = false;

		sector_offset = pos & (fs_info->sectorsize - 1);



		extent_changeset_release(data_reserved);
@@ -1193,6 +1210,8 @@ ssize_t btrfs_buffered_write(struct kiocb *iocb, struct iov_iter *i) 
		ret = balance_dirty_pages_ratelimited_flags(inode->i_mapping, bdp_flags);

		if (ret) {

			btrfs_delalloc_release_extents(BTRFS_I(inode), reserve_bytes);

			release_space(BTRFS_I(inode), data_reserved,

				      pos, release_bytes, only_release_metadata);

			break;

		}
@@ -1200,6 +1219,8 @@ ssize_t btrfs_buffered_write(struct kiocb *iocb, struct iov_iter *i) 
		if (ret) {

			btrfs_delalloc_release_extents(BTRFS_I(inode),

						       reserve_bytes);

			release_space(BTRFS_I(inode), data_reserved,

				      pos, release_bytes, only_release_metadata);

			break;

		}
@@ -1212,6 +1233,8 @@ ssize_t btrfs_buffered_write(struct kiocb *iocb, struct iov_iter *i) 


			btrfs_delalloc_release_extents(BTRFS_I(inode),

						       reserve_bytes);

			release_space(BTRFS_I(inode), data_reserved,

				      pos, release_bytes, only_release_metadata);

			ret = extents_locked;

			break;

		}
@@ -1279,10 +1302,11 @@ ssize_t btrfs_buffered_write(struct kiocb *iocb, struct iov_iter *i) 
		btrfs_delalloc_release_extents(BTRFS_I(inode), reserve_bytes);

		if (ret) {

			btrfs_drop_folio(fs_info, folio, pos, copied);

			release_space(BTRFS_I(inode), data_reserved,

				      pos, release_bytes, only_release_metadata);

			break;

		}



		release_bytes = 0;

		if (only_release_metadata)

			btrfs_check_nocow_unlock(BTRFS_I(inode));
@@ -1294,19 +1318,6 @@ ssize_t btrfs_buffered_write(struct kiocb *iocb, struct iov_iter *i) 
		num_written += copied;

	}



	if (release_bytes) {

		if (only_release_metadata) {

			btrfs_check_nocow_unlock(BTRFS_I(inode));

			btrfs_delalloc_release_metadata(BTRFS_I(inode),

					release_bytes, true);

		} else {

			btrfs_delalloc_release_space(BTRFS_I(inode),

					data_reserved,

					round_down(pos, fs_info->sectorsize),

					release_bytes, true);

		}

	}



	extent_changeset_free(data_reserved);

	if (num_written > 0) {

		pagecache_isize_extended(inode, old_isize, iocb->ki_pos);