Commit 2464b693 authored by Coly Li's avatar Coly Li Committed by Jens Axboe
Browse files

bcache: add code comments for journal_read_bucket() 



This patch adds more code comments in journal_read_bucket(), this is an
effort to make the code to be more understandable.

Signed-off-by: default avatarColy Li <colyli@suse.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 7e865eba

drivers/md/bcache/journal.c

+24 −0
Original line number Diff line number Diff line
@@ -100,6 +100,20 @@ reread: left = ca->sb.bucket_size - offset; 


			blocks = set_blocks(j, block_bytes(ca->set));



			/*

			 * Nodes in 'list' are in linear increasing order of

			 * i->j.seq, the node on head has the smallest (oldest)

			 * journal seq, the node on tail has the biggest

			 * (latest) journal seq.

			 */



			/*

			 * Check from the oldest jset for last_seq. If

			 * i->j.seq < j->last_seq, it means the oldest jset

			 * in list is expired and useless, remove it from

			 * this list. Otherwise, j is a condidate jset for

			 * further following checks.

			 */

			while (!list_empty(list)) {

				i = list_first_entry(list,

					struct journal_replay, list);
@@ -109,13 +123,22 @@ reread: left = ca->sb.bucket_size - offset; 
				kfree(i);

			}



			/* iterate list in reverse order (from latest jset) */

			list_for_each_entry_reverse(i, list, list) {

				if (j->seq == i->j.seq)

					goto next_set;



				/*

				 * if j->seq is less than any i->j.last_seq

				 * in list, j is an expired and useless jset.

				 */

				if (j->seq < i->j.last_seq)

					goto next_set;



				/*

				 * 'where' points to first jset in list which

				 * is elder then j.

				 */

				if (j->seq > i->j.seq) {

					where = &i->list;

					goto add;
@@ -129,6 +152,7 @@ reread: left = ca->sb.bucket_size - offset; 
			if (!i)

				return -ENOMEM;

			memcpy(&i->j, j, bytes);

			/* Add to the location after 'where' points to */

			list_add(&i->list, where);

			ret = 1;