dm-verity: fix up various workqueue-related comments

Replace obsolete mentions of "tasklets" with "softirq context", and
"workqueue" with "kworker".

This reflects the fact that the implementation of the
"try_verify_in_tasklet" dm-verity option now accesses softirq context
using either the BH workqueue API or inline execution, not the tasklet
API.  The old names conflated the API with the intended execution
context, so they became outdated when the APIs changed.

Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

Author: Eric Biggers

drivers/md/dm-verity-target.c

@@ -254,9 +254,9 @@ static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
 		data = dm_bufio_get(v->bufio, hash_block, &buf);
 		if (IS_ERR_OR_NULL(data)) {
 			/*
-			 * In tasklet and the hash was not in the bufio cache.
-			 * Return early and resume execution from a work-queue
-			 * to read the hash from disk.
+			 * In softirq and the hash was not in the bufio cache.
+			 * Return early and resume execution from a kworker to
+			 * read the hash from disk.
 			 */
 			return -EAGAIN;
 		}
@@ -303,7 +303,7 @@ static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
 		else if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
 			/*
 			 * Error handling code (FEC included) cannot be run in a
-			 * tasklet since it may sleep, so fallback to work-queue.
+			 * softirq since it may sleep, so fallback to a kworker.
 			 */
 			r = -EAGAIN;
 			goto release_ret_r;
@@ -425,8 +425,8 @@ static int verity_handle_data_hash_mismatch(struct dm_verity *v,
 
 	if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
 		/*
-		 * Error handling code (FEC included) cannot be run in the
-		 * BH workqueue, so fallback to a standard workqueue.
+		 * Error handling code (FEC included) cannot be run in a
+		 * softirq since it may sleep, so fallback to a kworker.
 		 */
 		return -EAGAIN;
 	}
@@ -519,8 +519,8 @@ static int verity_verify_io(struct dm_verity_io *io)
 
 	if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
 		/*
-		 * Copy the iterator in case we need to restart
-		 * verification in a work-queue.
+		 * Copy the iterator in case we need to restart verification in
+		 * a kworker.
 		 */
 		iter_copy = io->iter;
 		iter = &iter_copy;
@@ -657,7 +657,7 @@ static void verity_bh_work(struct work_struct *w)
 	io->in_bh = true;
 	err = verity_verify_io(io);
 	if (err == -EAGAIN || err == -ENOMEM) {
-		/* fallback to retrying with work-queue */
+		/* fallback to retrying in a kworker */
 		INIT_WORK(&io->work, verity_work);
 		queue_work(io->v->verify_wq, &io->work);
 		return;
@@ -1644,7 +1644,7 @@ static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	 * reducing wait times when reading from a dm-verity device.
 	 *
 	 * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
-	 * allows verify_wq to preempt softirq since verification in BH workqueue
+	 * allows verify_wq to preempt softirq since verification in softirq
 	 * will fall-back to using it for error handling (or if the bufio cache
 	 * doesn't have required hashes).
 	 */