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Refactor xbd_queue_cb, extracting the code which converts bus_dma segments

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into blkif segments, and moving it into a new function.  This will be used
by upcoming support for indirect-segment blkif requests.

This commit should not result in any functional changes.
This commit is contained in:
Colin Percival 2015-06-20 00:02:03 +00:00
parent 99b858f537
commit d0ecc14d49
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=284618
1 changed files with 49 additions and 44 deletions
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93
sys/dev/xen/blkfront/blkfront.c
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@ -155,18 +155,57 @@ xbd_free_command(struct xbd_command *cm)
xbd_thaw(cm->cm_sc, XBDF_CM_SHORTAGE);
}
static void
mksegarray(bus_dma_segment_t *segs, int nsegs,
grant_ref_t * gref_head, int otherend_id, int readonly,
grant_ref_t * sg_ref, blkif_request_segment_t * sg)
{
struct blkif_request_segment *last_block_sg = sg + nsegs;
vm_paddr_t buffer_ma;
uint64_t fsect, lsect;
int ref;
while (sg < last_block_sg) {
buffer_ma = segs->ds_addr;
fsect = (buffer_ma & PAGE_MASK) >> XBD_SECTOR_SHFT;
lsect = fsect + (segs->ds_len >> XBD_SECTOR_SHFT) - 1;
KASSERT(lsect <= 7, ("XEN disk driver data cannot "
"cross a page boundary"));
/* install a grant reference. */
ref = gnttab_claim_grant_reference(gref_head);
/*
* GNTTAB_LIST_END == 0xffffffff, but it is private
* to gnttab.c.
*/
KASSERT(ref != ~0, ("grant_reference failed"));
gnttab_grant_foreign_access_ref(
ref,
otherend_id,
buffer_ma >> PAGE_SHIFT,
readonly);
*sg_ref = ref;
*sg = (struct blkif_request_segment) {
.gref = ref,
.first_sect = fsect,
.last_sect = lsect
};
sg++;
sg_ref++;
segs++;
}
}
static void
xbd_queue_cb(void *arg, bus_dma_segment_t *segs, int nsegs, int error)
{
struct xbd_softc *sc;
struct xbd_command *cm;
blkif_request_t *ring_req;
struct blkif_request_segment *sg;
struct blkif_request_segment *last_block_sg;
grant_ref_t *sg_ref;
vm_paddr_t buffer_ma;
uint64_t fsect, lsect;
int ref;
int op;
cm = arg;
@ -191,44 +230,10 @@ xbd_queue_cb(void *arg, bus_dma_segment_t *segs, int nsegs, int error)
ring_req->handle = (blkif_vdev_t)(uintptr_t)sc->xbd_disk;
ring_req->nr_segments = nsegs;
cm->cm_nseg = nsegs;
sg = ring_req->seg;
last_block_sg = sg + nsegs;
sg_ref = cm->cm_sg_refs;
while (sg < last_block_sg) {
buffer_ma = segs->ds_addr;
fsect = (buffer_ma & PAGE_MASK) >> XBD_SECTOR_SHFT;
lsect = fsect + (segs->ds_len >> XBD_SECTOR_SHFT) - 1;
KASSERT(lsect <= 7, ("XEN disk driver data cannot "
"cross a page boundary"));
/* install a grant reference. */
ref = gnttab_claim_grant_reference(&cm->cm_gref_head);
/*
* GNTTAB_LIST_END == 0xffffffff, but it is private
* to gnttab.c.
*/
KASSERT(ref != ~0, ("grant_reference failed"));
gnttab_grant_foreign_access_ref(
ref,
xenbus_get_otherend_id(sc->xbd_dev),
buffer_ma >> PAGE_SHIFT,
ring_req->operation == BLKIF_OP_WRITE);
*sg_ref = ref;
*sg = (struct blkif_request_segment) {
.gref = ref,
.first_sect = fsect,
.last_sect = lsect
};
sg++;
sg_ref++;
segs++;
}
mksegarray(segs, nsegs, &cm->cm_gref_head,
xenbus_get_otherend_id(sc->xbd_dev),
cm->cm_operation == BLKIF_OP_WRITE,
cm->cm_sg_refs, ring_req->seg);
if (cm->cm_operation == BLKIF_OP_READ)
op = BUS_DMASYNC_PREREAD;