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-rw-r--r--block/blk-core.c34
1 files changed, 15 insertions, 19 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index d1a9a0a64f95..9fe174dc74d1 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1490,9 +1490,9 @@ end_io:
1490/* 1490/*
1491 * We only want one ->make_request_fn to be active at a time, 1491 * We only want one ->make_request_fn to be active at a time,
1492 * else stack usage with stacked devices could be a problem. 1492 * else stack usage with stacked devices could be a problem.
1493 * So use current->bio_{list,tail} to keep a list of requests 1493 * So use current->bio_list to keep a list of requests
1494 * submited by a make_request_fn function. 1494 * submited by a make_request_fn function.
1495 * current->bio_tail is also used as a flag to say if 1495 * current->bio_list is also used as a flag to say if
1496 * generic_make_request is currently active in this task or not. 1496 * generic_make_request is currently active in this task or not.
1497 * If it is NULL, then no make_request is active. If it is non-NULL, 1497 * If it is NULL, then no make_request is active. If it is non-NULL,
1498 * then a make_request is active, and new requests should be added 1498 * then a make_request is active, and new requests should be added
@@ -1500,11 +1500,11 @@ end_io:
1500 */ 1500 */
1501void generic_make_request(struct bio *bio) 1501void generic_make_request(struct bio *bio)
1502{ 1502{
1503 if (current->bio_tail) { 1503 struct bio_list bio_list_on_stack;
1504
1505 if (current->bio_list) {
1504 /* make_request is active */ 1506 /* make_request is active */
1505 *(current->bio_tail) = bio; 1507 bio_list_add(current->bio_list, bio);
1506 bio->bi_next = NULL;
1507 current->bio_tail = &bio->bi_next;
1508 return; 1508 return;
1509 } 1509 }
1510 /* following loop may be a bit non-obvious, and so deserves some 1510 /* following loop may be a bit non-obvious, and so deserves some
@@ -1512,30 +1512,27 @@ void generic_make_request(struct bio *bio)
1512 * Before entering the loop, bio->bi_next is NULL (as all callers 1512 * Before entering the loop, bio->bi_next is NULL (as all callers
1513 * ensure that) so we have a list with a single bio. 1513 * ensure that) so we have a list with a single bio.
1514 * We pretend that we have just taken it off a longer list, so 1514 * We pretend that we have just taken it off a longer list, so
1515 * we assign bio_list to the next (which is NULL) and bio_tail 1515 * we assign bio_list to a pointer to the bio_list_on_stack,
1516 * to &bio_list, thus initialising the bio_list of new bios to be 1516 * thus initialising the bio_list of new bios to be
1517 * added. __generic_make_request may indeed add some more bios 1517 * added. __generic_make_request may indeed add some more bios
1518 * through a recursive call to generic_make_request. If it 1518 * through a recursive call to generic_make_request. If it
1519 * did, we find a non-NULL value in bio_list and re-enter the loop 1519 * did, we find a non-NULL value in bio_list and re-enter the loop
1520 * from the top. In this case we really did just take the bio 1520 * from the top. In this case we really did just take the bio
1521 * of the top of the list (no pretending) and so fixup bio_list and 1521 * of the top of the list (no pretending) and so remove it from
1522 * bio_tail or bi_next, and call into __generic_make_request again. 1522 * bio_list, and call into __generic_make_request again.
1523 * 1523 *
1524 * The loop was structured like this to make only one call to 1524 * The loop was structured like this to make only one call to
1525 * __generic_make_request (which is important as it is large and 1525 * __generic_make_request (which is important as it is large and
1526 * inlined) and to keep the structure simple. 1526 * inlined) and to keep the structure simple.
1527 */ 1527 */
1528 BUG_ON(bio->bi_next); 1528 BUG_ON(bio->bi_next);
1529 bio_list_init(&bio_list_on_stack);
1530 current->bio_list = &bio_list_on_stack;
1529 do { 1531 do {
1530 current->bio_list = bio->bi_next;
1531 if (bio->bi_next == NULL)
1532 current->bio_tail = &current->bio_list;
1533 else
1534 bio->bi_next = NULL;
1535 __generic_make_request(bio); 1532 __generic_make_request(bio);
1536 bio = current->bio_list; 1533 bio = bio_list_pop(current->bio_list);
1537 } while (bio); 1534 } while (bio);
1538 current->bio_tail = NULL; /* deactivate */ 1535 current->bio_list = NULL; /* deactivate */
1539} 1536}
1540EXPORT_SYMBOL(generic_make_request); 1537EXPORT_SYMBOL(generic_make_request);
1541 1538
@@ -1617,8 +1614,7 @@ int blk_rq_check_limits(struct request_queue *q, struct request *rq)
1617 * limitation. 1614 * limitation.
1618 */ 1615 */
1619 blk_recalc_rq_segments(rq); 1616 blk_recalc_rq_segments(rq);
1620 if (rq->nr_phys_segments > queue_max_phys_segments(q) || 1617 if (rq->nr_phys_segments > queue_max_segments(q)) {
1621 rq->nr_phys_segments > queue_max_hw_segments(q)) {
1622 printk(KERN_ERR "%s: over max segments limit.\n", __func__); 1618 printk(KERN_ERR "%s: over max segments limit.\n", __func__);
1623 return -EIO; 1619 return -EIO;
1624 } 1620 }