block: drop virtual merging accounting
Mikulas Patocka [Fri, 15 Aug 2008 08:15:19 +0000 (10:15 +0200)]
Remove virtual merge accounting.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

block/blk-merge.c
fs/bio.c
include/linux/bio.h

index 6cf8f0c..2c2a2ee 100644 (file)
@@ -66,7 +66,7 @@ void blk_recalc_rq_segments(struct request *rq)
                 */
                high = page_to_pfn(bv->bv_page) > q->bounce_pfn;
                if (high || highprv)
-                       goto new_hw_segment;
+                       goto new_segment;
                if (cluster) {
                        if (seg_size + bv->bv_len > q->max_segment_size)
                                goto new_segment;
@@ -74,8 +74,6 @@ void blk_recalc_rq_segments(struct request *rq)
                                goto new_segment;
                        if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv))
                                goto new_segment;
-                       if (BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len))
-                               goto new_hw_segment;
 
                        seg_size += bv->bv_len;
                        hw_seg_size += bv->bv_len;
@@ -83,17 +81,11 @@ void blk_recalc_rq_segments(struct request *rq)
                        continue;
                }
 new_segment:
-               if (BIOVEC_VIRT_MERGEABLE(bvprv, bv) &&
-                   !BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len))
-                       hw_seg_size += bv->bv_len;
-               else {
-new_hw_segment:
-                       if (nr_hw_segs == 1 &&
-                           hw_seg_size > rq->bio->bi_hw_front_size)
-                               rq->bio->bi_hw_front_size = hw_seg_size;
-                       hw_seg_size = BIOVEC_VIRT_START_SIZE(bv) + bv->bv_len;
-                       nr_hw_segs++;
-               }
+               if (nr_hw_segs == 1 &&
+                   hw_seg_size > rq->bio->bi_hw_front_size)
+                       rq->bio->bi_hw_front_size = hw_seg_size;
+               hw_seg_size = bv->bv_len;
+               nr_hw_segs++;
 
                nr_phys_segs++;
                bvprv = bv;
@@ -150,23 +142,6 @@ static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio,
        return 0;
 }
 
-static int blk_hw_contig_segment(struct request_queue *q, struct bio *bio,
-                                struct bio *nxt)
-{
-       if (!bio_flagged(bio, BIO_SEG_VALID))
-               blk_recount_segments(q, bio);
-       if (!bio_flagged(nxt, BIO_SEG_VALID))
-               blk_recount_segments(q, nxt);
-       if (bio_has_data(bio) &&
-           (!BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)) ||
-            BIOVEC_VIRT_OVERSIZE(bio->bi_hw_back_size + nxt->bi_hw_front_size)))
-               return 0;
-       if (bio->bi_hw_back_size + nxt->bi_hw_front_size > q->max_segment_size)
-               return 0;
-
-       return 1;
-}
-
 /*
  * map a request to scatterlist, return number of sg entries setup. Caller
  * must make sure sg can hold rq->nr_phys_segments entries
@@ -304,7 +279,6 @@ int ll_back_merge_fn(struct request_queue *q, struct request *req,
                     struct bio *bio)
 {
        unsigned short max_sectors;
-       int len;
 
        if (unlikely(blk_pc_request(req)))
                max_sectors = q->max_hw_sectors;
@@ -321,20 +295,6 @@ int ll_back_merge_fn(struct request_queue *q, struct request *req,
                blk_recount_segments(q, req->biotail);
        if (!bio_flagged(bio, BIO_SEG_VALID))
                blk_recount_segments(q, bio);
-       len = req->biotail->bi_hw_back_size + bio->bi_hw_front_size;
-       if (!bio_has_data(bio) || 
-           (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio))
-            && !BIOVEC_VIRT_OVERSIZE(len))) {
-               int mergeable =  ll_new_mergeable(q, req, bio);
-
-               if (mergeable) {
-                       if (req->nr_hw_segments == 1)
-                               req->bio->bi_hw_front_size = len;
-                       if (bio->bi_hw_segments == 1)
-                               bio->bi_hw_back_size = len;
-               }
-               return mergeable;
-       }
 
        return ll_new_hw_segment(q, req, bio);
 }
@@ -343,7 +303,6 @@ int ll_front_merge_fn(struct request_queue *q, struct request *req,
                      struct bio *bio)
 {
        unsigned short max_sectors;
-       int len;
 
        if (unlikely(blk_pc_request(req)))
                max_sectors = q->max_hw_sectors;
@@ -357,24 +316,10 @@ int ll_front_merge_fn(struct request_queue *q, struct request *req,
                        q->last_merge = NULL;
                return 0;
        }
-       len = bio->bi_hw_back_size + req->bio->bi_hw_front_size;
        if (!bio_flagged(bio, BIO_SEG_VALID))
                blk_recount_segments(q, bio);
        if (!bio_flagged(req->bio, BIO_SEG_VALID))
                blk_recount_segments(q, req->bio);
-       if (!bio_has_data(bio) || 
-           (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(req->bio)) &&
-            !BIOVEC_VIRT_OVERSIZE(len))) {
-               int mergeable =  ll_new_mergeable(q, req, bio);
-
-               if (mergeable) {
-                       if (bio->bi_hw_segments == 1)
-                               bio->bi_hw_front_size = len;
-                       if (req->nr_hw_segments == 1)
-                               req->biotail->bi_hw_back_size = len;
-               }
-               return mergeable;
-       }
 
        return ll_new_hw_segment(q, req, bio);
 }
@@ -406,18 +351,6 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
                return 0;
 
        total_hw_segments = req->nr_hw_segments + next->nr_hw_segments;
-       if (blk_hw_contig_segment(q, req->biotail, next->bio)) {
-               int len = req->biotail->bi_hw_back_size +
-                               next->bio->bi_hw_front_size;
-               /*
-                * propagate the combined length to the end of the requests
-                */
-               if (req->nr_hw_segments == 1)
-                       req->bio->bi_hw_front_size = len;
-               if (next->nr_hw_segments == 1)
-                       next->biotail->bi_hw_back_size = len;
-               total_hw_segments--;
-       }
 
        if (total_hw_segments > q->max_hw_segments)
                return 0;
index 3cba7ae..4ac7c59 100644 (file)
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -350,8 +350,7 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
         */
 
        while (bio->bi_phys_segments >= q->max_phys_segments
-              || bio->bi_hw_segments >= q->max_hw_segments
-              || BIOVEC_VIRT_OVERSIZE(bio->bi_size)) {
+              || bio->bi_hw_segments >= q->max_hw_segments) {
 
                if (retried_segments)
                        return 0;
@@ -395,8 +394,7 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
        }
 
        /* If we may be able to merge these biovecs, force a recount */
-       if (bio->bi_vcnt && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec) ||
-           BIOVEC_VIRT_MERGEABLE(bvec-1, bvec)))
+       if (bio->bi_vcnt && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec)))
                bio->bi_flags &= ~(1 << BIO_SEG_VALID);
 
        bio->bi_vcnt++;
index 33c3947..894d16c 100644 (file)
 
 #ifdef CONFIG_BLOCK
 
-/* Platforms may set this to teach the BIO layer about IOMMU hardware. */
 #include <asm/io.h>
 
-#if defined(BIO_VMERGE_MAX_SIZE) && defined(BIO_VMERGE_BOUNDARY)
-#define BIOVEC_VIRT_START_SIZE(x) (bvec_to_phys(x) & (BIO_VMERGE_BOUNDARY - 1))
-#define BIOVEC_VIRT_OVERSIZE(x)        ((x) > BIO_VMERGE_MAX_SIZE)
-#else
-#define BIOVEC_VIRT_START_SIZE(x)      0
-#define BIOVEC_VIRT_OVERSIZE(x)                0
-#endif
-
-#ifndef BIO_VMERGE_BOUNDARY
-#define BIO_VMERGE_BOUNDARY    0
-#endif
-
 #define BIO_DEBUG
 
 #ifdef BIO_DEBUG
@@ -240,8 +227,6 @@ static inline void *bio_data(struct bio *bio)
        ((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
 #endif
 
-#define BIOVEC_VIRT_MERGEABLE(vec1, vec2)      \
-       ((((bvec_to_phys((vec1)) + (vec1)->bv_len) | bvec_to_phys((vec2))) & (BIO_VMERGE_BOUNDARY - 1)) == 0)
 #define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
        (((addr1) | (mask)) == (((addr2) - 1) | (mask)))
 #define BIOVEC_SEG_BOUNDARY(q, b1, b2) \