dm verity: only copy bvec_iter in verity_verify_io if in_tasklet

Avoid extra bvec_iter copy unless it is needed to allow retrying
verification, that failed from a tasklet, from a workqueue.

Signed-off-by: Mike Snitzer <snitzer@kernel.org>

diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c
index 5a4ee32..a56e254 100644 (file)
--- a/drivers/md/dm-verity-target.c
+++ b/drivers/md/dm-verity-target.c
@@ -501,15 +501,22 @@ static int verity_verify_io(struct dm_verity_io *io)
 #if defined(CONFIG_DM_VERITY_FEC)
        struct bvec_iter start;
 #endif
-       /*
-        * Copy the iterator in case we need to restart verification in a
-        * work-queue.
-        */
-       struct bvec_iter iter_copy = io->iter;
+       struct bvec_iter iter_copy;
+       struct bvec_iter *iter;
        struct crypto_wait wait;
        struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
        unsigned int b;
 
+       if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
+               /*
+                * Copy the iterator in case we need to restart
+                * verification in a work-queue.
+                */
+               iter_copy = io->iter;
+               iter = &iter_copy;
+       } else
+               iter = &io->iter;
+
        for (b = 0; b < io->n_blocks; b++) {
                int r;
                sector_t cur_block = io->block + b;
@@ -517,7 +524,7 @@ static int verity_verify_io(struct dm_verity_io *io)
 
                if (v->validated_blocks &&
                    likely(test_bit(cur_block, v->validated_blocks))) {
-                       verity_bv_skip_block(v, io, &iter_copy);
+                       verity_bv_skip_block(v, io, iter);
                        continue;
                }
 
@@ -532,7 +539,7 @@ static int verity_verify_io(struct dm_verity_io *io)
                         * If we expect a zero block, don't validate, just
                         * return zeros.
                         */
-                       r = verity_for_bv_block(v, io, &iter_copy,
+                       r = verity_for_bv_block(v, io, iter,
                                                verity_bv_zero);
                        if (unlikely(r < 0))
                                return r;
@@ -546,9 +553,9 @@ static int verity_verify_io(struct dm_verity_io *io)
 
 #if defined(CONFIG_DM_VERITY_FEC)
                if (verity_fec_is_enabled(v))
-                       start = iter_copy;
+                       start = *iter;
 #endif
-               r = verity_for_io_block(v, io, &iter_copy, &wait);
+               r = verity_for_io_block(v, io, iter, &wait);
                if (unlikely(r < 0))
                        return r;