btrfs: use bio_for_each_segment_all in __btrfsic_submit_bio

And remove the bogus check for a NULL return value from kmap, which
can't happen.  While we're at it: I don't think that kmapping up to 256
will work without deadlocks on highmem machines, a better idea would
be to use vm_map_ram to map all of them into a single virtual address
range.  Incidentally that would also simplify the code a lot.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/check-integrity.c b/fs/btrfs/check-integrity.c
index a6f657f..86f681f 100644 (file)
--- a/fs/btrfs/check-integrity.c
+++ b/fs/btrfs/check-integrity.c
@@ -2819,10 +2819,11 @@ static void __btrfsic_submit_bio(struct bio *bio)
         * btrfsic_mount(), this might return NULL */
        dev_state = btrfsic_dev_state_lookup(bio->bi_bdev);
        if (NULL != dev_state &&
-           (bio_op(bio) == REQ_OP_WRITE) && NULL != bio->bi_io_vec) {
+           (bio_op(bio) == REQ_OP_WRITE) && bio_has_data(bio)) {
                unsigned int i;
                u64 dev_bytenr;
                u64 cur_bytenr;
+               struct bio_vec *bvec;
                int bio_is_patched;
                char **mapped_datav;
 
@@ -2840,32 +2841,23 @@ static void __btrfsic_submit_bio(struct bio *bio)
                if (!mapped_datav)
                        goto leave;
                cur_bytenr = dev_bytenr;
-               for (i = 0; i < bio->bi_vcnt; i++) {
-                       BUG_ON(bio->bi_io_vec[i].bv_len != PAGE_SIZE);
-                       mapped_datav[i] = kmap(bio->bi_io_vec[i].bv_page);
-                       if (!mapped_datav[i]) {
-                               while (i > 0) {
-                                       i--;
-                                       kunmap(bio->bi_io_vec[i].bv_page);
-                               }
-                               kfree(mapped_datav);
-                               goto leave;
-                       }
+
+               bio_for_each_segment_all(bvec, bio, i) {
+                       BUG_ON(bvec->bv_len != PAGE_SIZE);
+                       mapped_datav[i] = kmap(bvec->bv_page);
+
                        if (dev_state->state->print_mask &
                            BTRFSIC_PRINT_MASK_SUBMIT_BIO_BH_VERBOSE)
                                pr_info("#%u: bytenr=%llu, len=%u, offset=%u\n",
-                                      i, cur_bytenr, bio->bi_io_vec[i].bv_len,
-                                      bio->bi_io_vec[i].bv_offset);
-                       cur_bytenr += bio->bi_io_vec[i].bv_len;
+                                      i, cur_bytenr, bvec->bv_len, bvec->bv_offset);
+                       cur_bytenr += bvec->bv_len;
                }
                btrfsic_process_written_block(dev_state, dev_bytenr,
                                              mapped_datav, bio->bi_vcnt,
                                              bio, &bio_is_patched,
                                              NULL, bio->bi_opf);
-               while (i > 0) {
-                       i--;
-                       kunmap(bio->bi_io_vec[i].bv_page);
-               }
+               bio_for_each_segment_all(bvec, bio, i)
+                       kunmap(bvec->bv_page);
                kfree(mapped_datav);
        } else if (NULL != dev_state && (bio->bi_opf & REQ_PREFLUSH)) {
                if (dev_state->state->print_mask &