Author: cperciva
Date: Mon Sep 14 19:35:33 2015
New Revision: 287801
URL: https://svnweb.freebsd.org/changeset/base/287801
Log:
MFC r284618, r284663, r284664, r284670, r284723
Reorganization of blkfront code and updates to comments. No functional
changes.
Modified:
stable/10/sys/dev/xen/blkfront/blkfront.c
stable/10/sys/dev/xen/blkfront/block.h
stable/10/sys/xen/interface/io/blkif.h
Modified: stable/10/sys/dev/xen/blkfront/blkfront.c
==============================================================================
--- stable/10/sys/dev/xen/blkfront/blkfront.c Mon Sep 14 19:32:04 2015
(r287800)
+++ stable/10/sys/dev/xen/blkfront/blkfront.c Mon Sep 14 19:35:33 2015
(r287801)
@@ -156,45 +156,14 @@ xbd_free_command(struct xbd_command *cm)
}
static void
-xbd_queue_cb(void *arg, bus_dma_segment_t *segs, int nsegs, int error)
+xbd_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 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;
+ struct blkif_request_segment *last_block_sg = sg + nsegs;
vm_paddr_t buffer_ma;
uint64_t fsect, lsect;
int ref;
- int op;
-
- cm = arg;
- sc = cm->cm_sc;
-
- if (error) {
- cm->cm_bp->bio_error = EIO;
- biodone(cm->cm_bp);
- xbd_free_command(cm);
- return;
- }
-
- KASSERT(nsegs <= BLKIF_MAX_SEGMENTS_PER_REQUEST,
- ("Too many segments in a blkfront I/O"));
-
- /* Fill out a communications ring structure. */
- ring_req = RING_GET_REQUEST(&sc->xbd_ring, sc->xbd_ring.req_prod_pvt);
- sc->xbd_ring.req_prod_pvt++;
- ring_req->id = cm->cm_id;
- ring_req->operation = cm->cm_operation;
- ring_req->sector_number = cm->cm_sector_number;
- 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;
@@ -205,7 +174,7 @@ xbd_queue_cb(void *arg, bus_dma_segment_
"cross a page boundary"));
/* install a grant reference. */
- ref = gnttab_claim_grant_reference(&cm->cm_gref_head);
+ ref = gnttab_claim_grant_reference(gref_head);
/*
* GNTTAB_LIST_END == 0xffffffff, but it is private
@@ -215,9 +184,9 @@ xbd_queue_cb(void *arg, bus_dma_segment_
gnttab_grant_foreign_access_ref(
ref,
- xenbus_get_otherend_id(sc->xbd_dev),
+ otherend_id,
buffer_ma >> PAGE_SHIFT,
- ring_req->operation == BLKIF_OP_WRITE);
+ readonly);
*sg_ref = ref;
*sg = (struct blkif_request_segment) {
@@ -229,6 +198,42 @@ xbd_queue_cb(void *arg, bus_dma_segment_
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;
+ int op;
+
+ cm = arg;
+ sc = cm->cm_sc;
+
+ if (error) {
+ cm->cm_bp->bio_error = EIO;
+ biodone(cm->cm_bp);
+ xbd_free_command(cm);
+ return;
+ }
+
+ KASSERT(nsegs <= BLKIF_MAX_SEGMENTS_PER_REQUEST,
+ ("Too many segments in a blkfront I/O"));
+
+ /* Fill out a communications ring structure. */
+ ring_req = RING_GET_REQUEST(&sc->xbd_ring, sc->xbd_ring.req_prod_pvt);
+ sc->xbd_ring.req_prod_pvt++;
+ ring_req->id = cm->cm_id;
+ ring_req->operation = cm->cm_operation;
+ ring_req->sector_number = cm->cm_sector_number;
+ ring_req->handle = (blkif_vdev_t)(uintptr_t)sc->xbd_disk;
+ ring_req->nr_segments = nsegs;
+ cm->cm_nseg = nsegs;
+ xbd_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;
@@ -1034,7 +1039,6 @@ xbd_initialize(struct xbd_softc *sc)
const char *node_path;
uint32_t max_ring_page_order;
int error;
- int i;
if (xenbus_get_state(sc->xbd_dev) != XenbusStateInitialising) {
/* Initialization has already been performed. */
@@ -1105,53 +1109,6 @@ xbd_initialize(struct xbd_softc *sc)
sc->xbd_max_requests = XBD_MAX_REQUESTS;
}
- /* Allocate datastructures based on negotiated values. */
- error = bus_dma_tag_create(
- bus_get_dma_tag(sc->xbd_dev), /* parent */
- 512, PAGE_SIZE, /* algnmnt, boundary */
- BUS_SPACE_MAXADDR, /* lowaddr */
- BUS_SPACE_MAXADDR, /* highaddr */
- NULL, NULL, /* filter, filterarg */
- sc->xbd_max_request_size,
- sc->xbd_max_request_segments,
- PAGE_SIZE, /* maxsegsize */
- BUS_DMA_ALLOCNOW, /* flags */
- busdma_lock_mutex, /* lockfunc */
- &sc->xbd_io_lock, /* lockarg */
- &sc->xbd_io_dmat);
- if (error != 0) {
- xenbus_dev_fatal(sc->xbd_dev, error,
- "Cannot allocate parent DMA tag\n");
- return;
- }
-
- /* Per-transaction data allocation. */
- sc->xbd_shadow = malloc(sizeof(*sc->xbd_shadow) * sc->xbd_max_requests,
- M_XENBLOCKFRONT, M_NOWAIT|M_ZERO);
- if (sc->xbd_shadow == NULL) {
- bus_dma_tag_destroy(sc->xbd_io_dmat);
- xenbus_dev_fatal(sc->xbd_dev, ENOMEM,
- "Cannot allocate request structures\n");
- return;
- }
-
- for (i = 0; i < sc->xbd_max_requests; i++) {
- struct xbd_command *cm;
-
- cm = &sc->xbd_shadow[i];
- cm->cm_sg_refs = malloc(
- sizeof(grant_ref_t) * sc->xbd_max_request_segments,
- M_XENBLOCKFRONT, M_NOWAIT);
- if (cm->cm_sg_refs == NULL)
- break;
- cm->cm_id = i;
- cm->cm_flags = XBDCF_INITIALIZER;
- cm->cm_sc = sc;
- if (bus_dmamap_create(sc->xbd_io_dmat, 0, &cm->cm_map) != 0)
- break;
- xbd_free_command(cm);
- }
-
if (xbd_alloc_ring(sc) != 0)
return;
@@ -1210,6 +1167,7 @@ xbd_connect(struct xbd_softc *sc)
unsigned long sectors, sector_size;
unsigned int binfo;
int err, feature_barrier, feature_flush;
+ int i;
if (sc->xbd_state == XBD_STATE_CONNECTED ||
sc->xbd_state == XBD_STATE_SUSPENDED)
@@ -1240,6 +1198,53 @@ xbd_connect(struct xbd_softc *sc)
if (err == 0 && feature_flush != 0)
sc->xbd_flags |= XBDF_FLUSH;
+ /* Allocate datastructures based on negotiated values. */
+ err = bus_dma_tag_create(
+ bus_get_dma_tag(sc->xbd_dev), /* parent */
+ 512, PAGE_SIZE, /* algnmnt, boundary */
+ BUS_SPACE_MAXADDR, /* lowaddr */
+ BUS_SPACE_MAXADDR, /* highaddr */
+ NULL, NULL, /* filter, filterarg */
+ sc->xbd_max_request_size,
+ sc->xbd_max_request_segments,
+ PAGE_SIZE, /* maxsegsize */
+ BUS_DMA_ALLOCNOW, /* flags */
+ busdma_lock_mutex, /* lockfunc */
+ &sc->xbd_io_lock, /* lockarg */
+ &sc->xbd_io_dmat);
+ if (err != 0) {
+ xenbus_dev_fatal(sc->xbd_dev, err,
+ "Cannot allocate parent DMA tag\n");
+ return;
+ }
+
+ /* Per-transaction data allocation. */
+ sc->xbd_shadow = malloc(sizeof(*sc->xbd_shadow) * sc->xbd_max_requests,
+ M_XENBLOCKFRONT, M_NOWAIT|M_ZERO);
+ if (sc->xbd_shadow == NULL) {
+ bus_dma_tag_destroy(sc->xbd_io_dmat);
+ xenbus_dev_fatal(sc->xbd_dev, ENOMEM,
+ "Cannot allocate request structures\n");
+ return;
+ }
+
+ for (i = 0; i < sc->xbd_max_requests; i++) {
+ struct xbd_command *cm;
+
+ cm = &sc->xbd_shadow[i];
+ cm->cm_sg_refs = malloc(
+ sizeof(grant_ref_t) * sc->xbd_max_request_segments,
+ M_XENBLOCKFRONT, M_NOWAIT);
+ if (cm->cm_sg_refs == NULL)
+ break;
+ cm->cm_id = i;
+ cm->cm_flags = XBDCF_INITIALIZER;
+ cm->cm_sc = sc;
+ if (bus_dmamap_create(sc->xbd_io_dmat, 0, &cm->cm_map) != 0)
+ break;
+ xbd_free_command(cm);
+ }
+
if (sc->xbd_disk == NULL) {
device_printf(dev, "%juMB <%s> at %s",
(uintmax_t) sectors / (1048576 / sector_size),
Modified: stable/10/sys/dev/xen/blkfront/block.h
==============================================================================
--- stable/10/sys/dev/xen/blkfront/block.h Mon Sep 14 19:32:04 2015
(r287800)
+++ stable/10/sys/dev/xen/blkfront/block.h Mon Sep 14 19:35:33 2015
(r287801)
@@ -68,9 +68,8 @@
#define XBD_MAX_RING_PAGES 32
/**
- * The maximum number of outstanding requests blocks (request headers plus
- * additional segment blocks) we will allow in a negotiated block-front/back
- * communication channel.
+ * The maximum number of outstanding requests we will allow in a negotiated
+ * block-front/back communication channel.
*/
#define XBD_MAX_REQUESTS \
__CONST_RING_SIZE(blkif, PAGE_SIZE * XBD_MAX_RING_PAGES)
@@ -82,15 +81,6 @@
#define XBD_MAX_REQUEST_SIZE
\
MIN(MAXPHYS, XBD_SEGS_TO_SIZE(BLKIF_MAX_SEGMENTS_PER_REQUEST))
-/**
- * The maximum number of segments (within a request header and accompanying
- * segment blocks) per request we will allow in a negotiated block-front/back
- * communication channel.
- */
-#define XBD_MAX_SEGMENTS_PER_REQUEST
\
- (MIN(BLKIF_MAX_SEGMENTS_PER_REQUEST, \
- XBD_SIZE_TO_SEGS(XBD_MAX_REQUEST_SIZE)))
-
typedef enum {
XBDCF_Q_MASK = 0xFF,
/* This command has contributed to xbd_qfrozen_cnt. */
Modified: stable/10/sys/xen/interface/io/blkif.h
==============================================================================
--- stable/10/sys/xen/interface/io/blkif.h Mon Sep 14 19:32:04 2015
(r287800)
+++ stable/10/sys/xen/interface/io/blkif.h Mon Sep 14 19:35:33 2015
(r287801)
@@ -145,32 +145,6 @@
* The maximum supported size of the request ring buffer in units of
* machine pages. The value must be a power of 2.
*
- * max-requests <uint32_t>
- * Default Value: BLKIF_MAX_RING_REQUESTS(PAGE_SIZE)
- * Maximum Value: BLKIF_MAX_RING_REQUESTS(PAGE_SIZE * max-ring-pages)
- *
- * The maximum number of concurrent, logical requests supported by
- * the backend.
- *
- * Note: A logical request may span multiple ring entries.
- *
- * max-request-segments
- * Values: <uint8_t>
- * Default Value: BLKIF_MAX_SEGMENTS_PER_HEADER_BLOCK
- * Maximum Value: BLKIF_MAX_SEGMENTS_PER_REQUEST
- *
- * The maximum value of blkif_request.nr_segments supported by
- * the backend.
- *
- * max-request-size
- * Values: <uint32_t>
- * Default Value: BLKIF_MAX_SEGMENTS_PER_HEADER_BLOCK * PAGE_SIZE
- * Maximum Value: BLKIF_MAX_SEGMENTS_PER_REQUEST * PAGE_SIZE
- *
- * The maximum amount of data, in bytes, that can be referenced by a
- * request type that accesses frontend memory (currently BLKIF_OP_READ,
- * BLKIF_OP_WRITE, or BLKIF_OP_WRITE_BARRIER).
- *
*------------------------- Backend Device Properties -------------------------
*
* discard-alignment
@@ -269,33 +243,6 @@
* The size of the frontend allocated request ring buffer in units of
* machine pages. The value must be a power of 2.
*
- * max-requests
- * Values: <uint32_t>
- * Default Value: BLKIF_MAX_RING_REQUESTS(PAGE_SIZE)
- * Maximum Value: BLKIF_MAX_RING_REQUESTS(PAGE_SIZE * max-ring-pages)
- *
- * The maximum number of concurrent, logical requests that will be
- * issued by the frontend.
- *
- * Note: A logical request may span multiple ring entries.
- *
- * max-request-segments
- * Values: <uint8_t>
- * Default Value: BLKIF_MAX_SEGMENTS_PER_HEADER_BLOCK
- * Maximum Value: MIN(255, backend/max-request-segments)
- *
- * The maximum value the frontend will set in the
- * blkif_request.nr_segments field.
- *
- * max-request-size
- * Values: <uint32_t>
- * Default Value: BLKIF_MAX_SEGMENTS_PER_HEADER_BLOCK * PAGE_SIZE
- * Maximum Value: max-request-segments * PAGE_SIZE
- *
- * The maximum amount of data, in bytes, that can be referenced by
- * a request type that accesses frontend memory (currently BLKIF_OP_READ,
- * BLKIF_OP_WRITE, or BLKIF_OP_WRITE_BARRIER).
- *
*------------------------- Virtual Device Properties -------------------------
*
* device-type
@@ -457,7 +404,9 @@
#define BLKIF_OP_DISCARD 5
/*
- * Maximum scatter/gather segments per request (header + segment blocks).
+ * Maximum scatter/gather segments per request.
+ * This is carefully chosen so that sizeof(blkif_ring_t) <= PAGE_SIZE.
+ * NB. This could be 12 if the ring indexes weren't stored in the same page.
*/
#define BLKIF_MAX_SEGMENTS_PER_REQUEST 11
@@ -478,21 +427,6 @@ typedef struct blkif_request_segment blk
/*
* Starting ring element for any I/O request.
- *
- * One or more segment blocks can be inserted into the request ring
- * just after a blkif_request_t, allowing requests to operate on
- * up to BLKIF_MAX_SEGMENTS_PER_REQUEST.
- *
- * BLKIF_SEGS_TO_BLOCKS() can be used on blkif_requst.nr_segments
- * to determine the number of contiguous ring entries associated
- * with this request.
- *
- * Note: Due to the way Xen request rings operate, the producer and
- * consumer indices of the ring must be incremented by the
- * BLKIF_SEGS_TO_BLOCKS() value of the associated request.
- * (e.g. a response to a 3 ring entry request must also consume
- * 3 entries in the ring, even though only the first ring entry
- * in the response has any data.)
*/
struct blkif_request {
uint8_t operation; /* BLKIF_OP_??? */
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