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https://github.com/schoebel/mars
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mars_if: fix bio semantics
This commit is contained in:
schoebel
Thomas Schoebel-Theuer
parent
847f2a416f
commit
ec42130eb5
93
mars_if.c
93
mars_if.c
@ -220,30 +220,75 @@ void if_timer(unsigned long data)
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*/
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static int if_make_request(struct request_queue *q, struct bio *bio)
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{
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struct if_input *input = q->queuedata;
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struct if_brick *brick = input->brick;
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/* Original flags of the source bio
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*/
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const int rw = bio_data_dir(bio);
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const int sectors = bio_sectors(bio);
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const bool ahead = bio_rw_flagged(bio, BIO_RW_AHEAD) && rw == READ;
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const bool barrier = bio_rw_flagged(bio, BIO_RW_BARRIER);
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const bool syncio = bio_rw_flagged(bio, BIO_RW_SYNCIO);
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const bool unplug = bio_rw_flagged(bio, BIO_RW_UNPLUG);
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const bool meta = bio_rw_flagged(bio, BIO_RW_META);
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const bool discard = bio_rw_flagged(bio, BIO_RW_DISCARD);
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const bool noidle = bio_rw_flagged(bio, BIO_RW_NOIDLE);
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const int prio = bio_prio(bio);
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/* Transform into MARS flags
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*/
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const int ref_prio =
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(prio == IOPRIO_CLASS_RT || (meta | syncio)) ?
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MARS_PRIO_HIGH :
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(prio == IOPRIO_CLASS_IDLE) ?
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MARS_PRIO_LOW :
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MARS_PRIO_NORMAL;
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const bool do_unplug = ALWAYS_UNPLUG | unplug | noidle;
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const bool do_skip_sync = brick->skip_sync && !(barrier | syncio);
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struct bio_wrapper *biow;
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struct if_input *input;
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struct if_brick *brick = NULL;
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struct mref_object *mref = NULL;
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struct if_mref_aspect *mref_a;
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struct bio_vec *bvec;
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int i;
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bool assigned = false;
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const bool unplug = bio_rw_flagged(bio, BIO_RW_UNPLUG) || bio_rw_flagged(bio, BIO_RW_SYNCIO);
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const bool barrier = ((bio->bi_rw & 1) != READ && bio_rw_flagged(bio, BIO_RW_BARRIER));
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loff_t pos = ((loff_t)bio->bi_sector) << 9; // TODO: make dynamic
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int rw = bio_data_dir(bio);
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int total_len = bio->bi_size;
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int error = -ENOSYS;
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MARS_IO("bio %p size = %d rw = %d unplug = %d barrier = %d\n", bio, bio->bi_size, rw, unplug, barrier);
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MARS_IO("bio %p "
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"size = %d "
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"rw = %d "
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"sectors = %d "
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"ahead = %d "
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"barrier = %d "
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"syncio = %d "
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"unplug = %d "
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"meta = %d "
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"discard = %d "
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"noidle = %d "
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"prio = %d "
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"pos = %lldd "
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"total_len = %d\n",
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bio,
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bio->bi_size,
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rw,
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sectors,
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ahead,
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barrier,
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syncio,
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unplug,
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meta,
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discard,
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noidle,
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prio,
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pos,
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total_len);
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might_sleep();
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input = q->queuedata;
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if (unlikely(!input))
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goto err;
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if (unlikely(!bio_sectors(bio))) {
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if (unlikely(!sectors)) {
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_if_unplug(input);
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/* THINK: usually this happens only at write barriers.
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* We have no "barrier" operation in MARS, since
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@ -257,15 +302,18 @@ static int if_make_request(struct request_queue *q, struct bio *bio)
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}
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#ifdef DENY_READA // provisinary -- we should introduce an equivalent of READA also to the MARS infrastructure
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if (bio_rw(bio) == READA) {
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if (ahead) {
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atomic_inc(&input->total_reada_count);
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bio_endio(bio, -EWOULDBLOCK);
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return 0;
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}
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#else
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(void)ahead; // shut up gcc
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#endif
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brick = input->brick;
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CHECK_PTR(brick, err);
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if (unlikely(discard)) { // NYI
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bio_endio(bio, 0);
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return 0;
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}
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biow = brick_mem_alloc(sizeof(struct bio_wrapper));
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CHECK_PTR(biow, err);
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@ -289,14 +337,6 @@ static int if_make_request(struct request_queue *q, struct bio *bio)
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msleep(100);
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}
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#ifdef IO_DEBUGGING
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{
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const unsigned short prio = bio_prio(bio);
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const bool sync = bio_rw_flagged(bio, BIO_RW_SYNCIO);
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MARS_IO("BIO raw_rw = 0x%016lx len = %d prio = %d sync = %d unplug = %d\n", bio->bi_rw, bio->bi_size, prio, sync, unplug);
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}
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#endif
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down(&input->kick_sem);
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bio_for_each_segment(bvec, bio, i) {
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@ -357,7 +397,7 @@ static int if_make_request(struct request_queue *q, struct bio *bio)
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mref = tmp_mref;
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mref_a = tmp_a;
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this_len = bv_len;
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if (barrier) {
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if (!do_skip_sync) {
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mref->ref_skip_sync = false;
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}
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@ -416,6 +456,7 @@ static int if_make_request(struct request_queue *q, struct bio *bio)
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mref->ref_pos = pos;
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mref->ref_len = prefetch_len;
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mref->ref_data = data; // direct IO
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mref->ref_prio = ref_prio;
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mref_a->orig_page = page;
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mref_a->is_kmapped = true;
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@ -445,7 +486,7 @@ static int if_make_request(struct request_queue *q, struct bio *bio)
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mref_a->bio_count = 1;
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assigned = true;
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if (brick->skip_sync && !barrier) {
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if (do_skip_sync) {
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mref->ref_skip_sync = true;
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}
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@ -495,7 +536,7 @@ err:
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}
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}
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if (ALWAYS_UNPLUG || unplug ||
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if (do_unplug ||
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(brick && brick->max_plugged > 0 && atomic_read(&input->plugged_count) > brick->max_plugged)) {
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_if_unplug(input);
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}
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