block: add a bi_error field to struct bio
Currently we have two different ways to signal an I/O error on a BIO:
(1) by clearing the BIO_UPTODATE flag
(2) by returning a Linux errno value to the bi_end_io callback
The first one has the drawback of only communicating a single possible
error (-EIO), and the second one has the drawback of not beeing persistent
when bios are queued up, and are not passed along from child to parent
bio in the ever more popular chaining scenario. Having both mechanisms
available has the additional drawback of utterly confusing driver authors
and introducing bugs where various I/O submitters only deal with one of
them, and the others have to add boilerplate code to deal with both kinds
of error returns.
So add a new bi_error field to store an errno value directly in struct
bio and remove the existing mechanisms to clean all this up.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index 4c20c22..a7a259e 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -977,7 +977,7 @@
}
}
-static void pkt_end_io_read(struct bio *bio, int err)
+static void pkt_end_io_read(struct bio *bio)
{
struct packet_data *pkt = bio->bi_private;
struct pktcdvd_device *pd = pkt->pd;
@@ -985,9 +985,9 @@
pkt_dbg(2, pd, "bio=%p sec0=%llx sec=%llx err=%d\n",
bio, (unsigned long long)pkt->sector,
- (unsigned long long)bio->bi_iter.bi_sector, err);
+ (unsigned long long)bio->bi_iter.bi_sector, bio->bi_error);
- if (err)
+ if (bio->bi_error)
atomic_inc(&pkt->io_errors);
if (atomic_dec_and_test(&pkt->io_wait)) {
atomic_inc(&pkt->run_sm);
@@ -996,13 +996,13 @@
pkt_bio_finished(pd);
}
-static void pkt_end_io_packet_write(struct bio *bio, int err)
+static void pkt_end_io_packet_write(struct bio *bio)
{
struct packet_data *pkt = bio->bi_private;
struct pktcdvd_device *pd = pkt->pd;
BUG_ON(!pd);
- pkt_dbg(2, pd, "id=%d, err=%d\n", pkt->id, err);
+ pkt_dbg(2, pd, "id=%d, err=%d\n", pkt->id, bio->bi_error);
pd->stats.pkt_ended++;
@@ -1340,22 +1340,22 @@
pkt_queue_bio(pd, pkt->w_bio);
}
-static void pkt_finish_packet(struct packet_data *pkt, int uptodate)
+static void pkt_finish_packet(struct packet_data *pkt, int error)
{
struct bio *bio;
- if (!uptodate)
+ if (error)
pkt->cache_valid = 0;
/* Finish all bios corresponding to this packet */
- while ((bio = bio_list_pop(&pkt->orig_bios)))
- bio_endio(bio, uptodate ? 0 : -EIO);
+ while ((bio = bio_list_pop(&pkt->orig_bios))) {
+ bio->bi_error = error;
+ bio_endio(bio);
+ }
}
static void pkt_run_state_machine(struct pktcdvd_device *pd, struct packet_data *pkt)
{
- int uptodate;
-
pkt_dbg(2, pd, "pkt %d\n", pkt->id);
for (;;) {
@@ -1384,7 +1384,7 @@
if (atomic_read(&pkt->io_wait) > 0)
return;
- if (test_bit(BIO_UPTODATE, &pkt->w_bio->bi_flags)) {
+ if (!pkt->w_bio->bi_error) {
pkt_set_state(pkt, PACKET_FINISHED_STATE);
} else {
pkt_set_state(pkt, PACKET_RECOVERY_STATE);
@@ -1401,8 +1401,7 @@
break;
case PACKET_FINISHED_STATE:
- uptodate = test_bit(BIO_UPTODATE, &pkt->w_bio->bi_flags);
- pkt_finish_packet(pkt, uptodate);
+ pkt_finish_packet(pkt, pkt->w_bio->bi_error);
return;
default:
@@ -2332,13 +2331,14 @@
}
-static void pkt_end_io_read_cloned(struct bio *bio, int err)
+static void pkt_end_io_read_cloned(struct bio *bio)
{
struct packet_stacked_data *psd = bio->bi_private;
struct pktcdvd_device *pd = psd->pd;
+ psd->bio->bi_error = bio->bi_error;
bio_put(bio);
- bio_endio(psd->bio, err);
+ bio_endio(psd->bio);
mempool_free(psd, psd_pool);
pkt_bio_finished(pd);
}