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提交 06454c24 编写于 作者: P Paul Durrant 提交者： Stefano Stabellini
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xen_disk: remove use of grant map/unmap 

Now that the (native or emulated) xen_be_copy_grant_refs() helper is
always available, the xen_disk code can be significantly simplified by
removing direct use of grant map and unmap operations.
Signed-off-by: NPaul Durrant <paul.durrant@citrix.com>
Acked-by: NAnthony Perard <anthony.perard@citrix.com>
Signed-off-by: NStefano Stabellini <sstabellini@kernel.org>
上级 3fe12b84
隐藏空白更改
内联 并排
Showing with 25 addition and 327 deletion
hw/block/xen_disk.c
浏览文件 @ 06454c24
......@@ -36,27 +36,9 @@
/* ------------------------------------------------------------- */
static int batch_maps = 0;
/* ------------------------------------------------------------- */
#define BLOCK_SIZE 512
#define IOCB_COUNT (BLKIF_MAX_SEGMENTS_PER_REQUEST + 2)
struct PersistentGrant {
void *page;
struct XenBlkDev *blkdev;
};
typedef struct PersistentGrant PersistentGrant;
struct PersistentRegion {
void *addr;
int num;
};
typedef struct PersistentRegion PersistentRegion;
struct ioreq {
blkif_request_t req;
int16_t status;
......@@ -65,14 +47,11 @@ struct ioreq {
off_t start;
QEMUIOVector v;
int presync;
uint8_t mapped;
/* grant mapping */
uint32_t refs[BLKIF_MAX_SEGMENTS_PER_REQUEST];
int prot;
void *page[BLKIF_MAX_SEGMENTS_PER_REQUEST];
void *pages;
int num_unmap;
/* aio status */
int aio_inflight;
......@@ -103,7 +82,6 @@ struct XenBlkDev {
int protocol;
blkif_back_rings_t rings;
int more_work;
int cnt_map;
/* request lists */
QLIST_HEAD(inflight_head, ioreq) inflight;
......@@ -114,13 +92,7 @@ struct XenBlkDev {
int requests_finished;
unsigned int max_requests;
/* Persistent grants extension */
gboolean feature_discard;
gboolean feature_persistent;
GTree *persistent_gnts;
GSList *persistent_regions;
unsigned int persistent_gnt_count;
unsigned int max_grants;
/* qemu block driver */
DriveInfo *dinfo;
......@@ -139,10 +111,8 @@ static void ioreq_reset(struct ioreq *ioreq)
ioreq->status = 0;
ioreq->start = 0;
ioreq->presync = 0;
ioreq->mapped = 0;
memset(ioreq->refs, 0, sizeof(ioreq->refs));
ioreq->prot = 0;
memset(ioreq->page, 0, sizeof(ioreq->page));
ioreq->pages = NULL;
......@@ -156,37 +126,6 @@ static void ioreq_reset(struct ioreq *ioreq)
qemu_iovec_reset(&ioreq->v);
}
static gint int_cmp(gconstpointer a, gconstpointer b, gpointer user_data)
{
uint ua = GPOINTER_TO_UINT(a);
uint ub = GPOINTER_TO_UINT(b);
return (ua > ub) - (ua < ub);
}
static void destroy_grant(gpointer pgnt)
{
PersistentGrant *grant = pgnt;
struct XenBlkDev *blkdev = grant->blkdev;
struct XenDevice *xendev = &blkdev->xendev;
xen_be_unmap_grant_ref(xendev, grant->page);
grant->blkdev->persistent_gnt_count--;
xen_pv_printf(xendev, 3, "unmapped grant %p\n", grant->page);
g_free(grant);
}
static void remove_persistent_region(gpointer data, gpointer dev)
{
PersistentRegion *region = data;
struct XenBlkDev *blkdev = dev;
struct XenDevice *xendev = &blkdev->xendev;
xen_be_unmap_grant_refs(xendev, region->addr, region->num);
xen_pv_printf(xendev, 3, "unmapped grant region %p with %d pages\n",
region->addr, region->num);
g_free(region);
}
static struct ioreq *ioreq_start(struct XenBlkDev *blkdev)
{
struct ioreq *ioreq = NULL;
......@@ -254,7 +193,6 @@ static int ioreq_parse(struct ioreq *ioreq)
ioreq->req.handle, ioreq->req.id, ioreq->req.sector_number);
switch (ioreq->req.operation) {
case BLKIF_OP_READ:
ioreq->prot = PROT_WRITE; /* to memory */
break;
case BLKIF_OP_FLUSH_DISKCACHE:
ioreq->presync = 1;
......@@ -263,7 +201,6 @@ static int ioreq_parse(struct ioreq *ioreq)
}
/* fall through */
case BLKIF_OP_WRITE:
ioreq->prot = PROT_READ; /* from memory */
break;
case BLKIF_OP_DISCARD:
return 0;
......@@ -310,171 +247,6 @@ err:
return -1;
}
static void ioreq_unmap(struct ioreq *ioreq)
{
struct XenBlkDev *blkdev = ioreq->blkdev;
struct XenDevice *xendev = &blkdev->xendev;
int i;
if (ioreq->num_unmap == 0 || ioreq->mapped == 0) {
return;
}
if (batch_maps) {
if (!ioreq->pages) {
return;
}
xen_be_unmap_grant_refs(xendev, ioreq->pages, ioreq->num_unmap);
ioreq->blkdev->cnt_map -= ioreq->num_unmap;
ioreq->pages = NULL;
} else {
for (i = 0; i < ioreq->num_unmap; i++) {
if (!ioreq->page[i]) {
continue;
}
xen_be_unmap_grant_ref(xendev, ioreq->page[i]);
ioreq->blkdev->cnt_map--;
ioreq->page[i] = NULL;
}
}
ioreq->mapped = 0;
}
static int ioreq_map(struct ioreq *ioreq)
{
struct XenBlkDev *blkdev = ioreq->blkdev;
struct XenDevice *xendev = &blkdev->xendev;
uint32_t refs[BLKIF_MAX_SEGMENTS_PER_REQUEST];
void *page[BLKIF_MAX_SEGMENTS_PER_REQUEST];
int i, j, new_maps = 0;
PersistentGrant *grant;
PersistentRegion *region;
/* refs variable will contain the information necessary
* to map the grants that are needed to fulfill this request.
*
* After mapping the needed grants, the page array will contain the
* memory address of each granted page in the order specified in ioreq
* (disregarding if it's a persistent grant or not).
*/
if (ioreq->v.niov == 0 || ioreq->mapped == 1) {
return 0;
}
if (ioreq->blkdev->feature_persistent) {
for (i = 0; i < ioreq->v.niov; i++) {
grant = g_tree_lookup(ioreq->blkdev->persistent_gnts,
GUINT_TO_POINTER(ioreq->refs[i]));
if (grant != NULL) {
page[i] = grant->page;
xen_pv_printf(&ioreq->blkdev->xendev, 3,
"using persistent-grant %" PRIu32 "\n",
ioreq->refs[i]);
} else {
/* Add the grant to the list of grants that
* should be mapped
*/
refs[new_maps] = ioreq->refs[i];
page[i] = NULL;
new_maps++;
}
}
/* Set the protection to RW, since grants may be reused later
* with a different protection than the one needed for this request
*/
ioreq->prot = PROT_WRITE | PROT_READ;
} else {
/* All grants in the request should be mapped */
memcpy(refs, ioreq->refs, sizeof(refs));
memset(page, 0, sizeof(page));
new_maps = ioreq->v.niov;
}
if (batch_maps && new_maps) {
ioreq->pages = xen_be_map_grant_refs(xendev, refs, new_maps,
ioreq->prot);
if (ioreq->pages == NULL) {
xen_pv_printf(&ioreq->blkdev->xendev, 0,
"can't map %d grant refs (%s, %d maps)\n",
new_maps, strerror(errno), ioreq->blkdev->cnt_map);
return -1;
}
for (i = 0, j = 0; i < ioreq->v.niov; i++) {
if (page[i] == NULL) {
page[i] = ioreq->pages + (j++) * XC_PAGE_SIZE;
}
}
ioreq->blkdev->cnt_map += new_maps;
} else if (new_maps) {
for (i = 0; i < new_maps; i++) {
ioreq->page[i] = xen_be_map_grant_ref(xendev, refs[i],
ioreq->prot);
if (ioreq->page[i] == NULL) {
xen_pv_printf(&ioreq->blkdev->xendev, 0,
"can't map grant ref %d (%s, %d maps)\n",
refs[i], strerror(errno), ioreq->blkdev->cnt_map);
ioreq->mapped = 1;
ioreq_unmap(ioreq);
return -1;
}
ioreq->blkdev->cnt_map++;
}
for (i = 0, j = 0; i < ioreq->v.niov; i++) {
if (page[i] == NULL) {
page[i] = ioreq->page[j++];
}
}
}
if (ioreq->blkdev->feature_persistent && new_maps != 0 &&
(!batch_maps || (ioreq->blkdev->persistent_gnt_count + new_maps <=
ioreq->blkdev->max_grants))) {
/*
* If we are using persistent grants and batch mappings only
* add the new maps to the list of persistent grants if the whole
* area can be persistently mapped.
*/
if (batch_maps) {
region = g_malloc0(sizeof(*region));
region->addr = ioreq->pages;
region->num = new_maps;
ioreq->blkdev->persistent_regions = g_slist_append(
ioreq->blkdev->persistent_regions,
region);
}
while ((ioreq->blkdev->persistent_gnt_count < ioreq->blkdev->max_grants)
&& new_maps) {
/* Go through the list of newly mapped grants and add as many
* as possible to the list of persistently mapped grants.
*
* Since we start at the end of ioreq->page(s), we only need
* to decrease new_maps to prevent this granted pages from
* being unmapped in ioreq_unmap.
*/
grant = g_malloc0(sizeof(*grant));
new_maps--;
if (batch_maps) {
grant->page = ioreq->pages + (new_maps) * XC_PAGE_SIZE;
} else {
grant->page = ioreq->page[new_maps];
}
grant->blkdev = ioreq->blkdev;
xen_pv_printf(&ioreq->blkdev->xendev, 3,
"adding grant %" PRIu32 " page: %p\n",
refs[new_maps], grant->page);
g_tree_insert(ioreq->blkdev->persistent_gnts,
GUINT_TO_POINTER(refs[new_maps]),
grant);
ioreq->blkdev->persistent_gnt_count++;
}
assert(!batch_maps || new_maps == 0);
}
for (i = 0; i < ioreq->v.niov; i++) {
ioreq->v.iov[i].iov_base += (uintptr_t)page[i];
}
ioreq->mapped = 1;
ioreq->num_unmap = new_maps;
return 0;
}
static void ioreq_free_copy_buffers(struct ioreq *ioreq)
{
int i;
......@@ -570,32 +342,28 @@ static void qemu_aio_complete(void *opaque, int ret)
goto done;
}
if (xen_feature_grant_copy) {
switch (ioreq->req.operation) {
case BLKIF_OP_READ:
/* in case of failure ioreq->aio_errors is increased */
if (ret == 0) {
ioreq_grant_copy(ioreq);
}
ioreq_free_copy_buffers(ioreq);
break;
case BLKIF_OP_WRITE:
case BLKIF_OP_FLUSH_DISKCACHE:
if (!ioreq->req.nr_segments) {
break;
}
ioreq_free_copy_buffers(ioreq);
break;
default:
switch (ioreq->req.operation) {
case BLKIF_OP_READ:
/* in case of failure ioreq->aio_errors is increased */
if (ret == 0) {
ioreq_grant_copy(ioreq);
}
ioreq_free_copy_buffers(ioreq);
break;
case BLKIF_OP_WRITE:
case BLKIF_OP_FLUSH_DISKCACHE:
if (!ioreq->req.nr_segments) {
break;
}
ioreq_free_copy_buffers(ioreq);
break;
default:
break;
}
ioreq->status = ioreq->aio_errors ? BLKIF_RSP_ERROR : BLKIF_RSP_OKAY;
if (!xen_feature_grant_copy) {
ioreq_unmap(ioreq);
}
ioreq_finish(ioreq);
switch (ioreq->req.operation) {
case BLKIF_OP_WRITE:
case BLKIF_OP_FLUSH_DISKCACHE:
......@@ -655,18 +423,13 @@ static int ioreq_runio_qemu_aio(struct ioreq *ioreq)
{
struct XenBlkDev *blkdev = ioreq->blkdev;
if (xen_feature_grant_copy) {
ioreq_init_copy_buffers(ioreq);
if (ioreq->req.nr_segments && (ioreq->req.operation == BLKIF_OP_WRITE ||
ioreq->req.operation == BLKIF_OP_FLUSH_DISKCACHE) &&
ioreq_grant_copy(ioreq)) {
ioreq_free_copy_buffers(ioreq);
goto err;
}
} else {
if (ioreq->req.nr_segments && ioreq_map(ioreq)) {
goto err;
}
ioreq_init_copy_buffers(ioreq);
if (ioreq->req.nr_segments &&
(ioreq->req.operation == BLKIF_OP_WRITE ||
ioreq->req.operation == BLKIF_OP_FLUSH_DISKCACHE) &&
ioreq_grant_copy(ioreq)) {
ioreq_free_copy_buffers(ioreq);
goto err;
}
ioreq->aio_inflight++;
......@@ -707,9 +470,6 @@ static int ioreq_runio_qemu_aio(struct ioreq *ioreq)
}
default:
/* unknown operation (shouldn't happen -- parse catches this) */
if (!xen_feature_grant_copy) {
ioreq_unmap(ioreq);
}
goto err;
}
......@@ -895,10 +655,6 @@ static void blk_alloc(struct XenDevice *xendev)
blkdev->ctx = iothread_get_aio_context(blkdev->iothread);
blkdev->bh = aio_bh_new(blkdev->ctx, blk_bh, blkdev);
if (xen_mode != XEN_EMULATE) {
batch_maps = 1;
}
}
static void blk_parse_discard(struct XenBlkDev *blkdev)
......@@ -981,15 +737,10 @@ static int blk_init(struct XenDevice *xendev)
blkdev->file_blk = BLOCK_SIZE;
xen_pv_printf(&blkdev->xendev, 3, "grant copy operation %s\n",
xen_feature_grant_copy ? "enabled" : "disabled");
/* fill info
* blk_connect supplies sector-size and sectors
*/
xenstore_write_be_int(&blkdev->xendev, "feature-flush-cache", 1);
xenstore_write_be_int(&blkdev->xendev, "feature-persistent",
!xen_feature_grant_copy);
xenstore_write_be_int(&blkdev->xendev, "info", info);
xenstore_write_be_int(&blkdev->xendev, "max-ring-page-order",
......@@ -1016,19 +767,10 @@ out_error:
return -1;
}
/*
* We need to account for the grant allocations requiring contiguous
* chunks; the worst case number would be
* max_req * max_seg + (max_req - 1) * (max_seg - 1) + 1,
* but in order to keep things simple just use
* 2 * max_req * max_seg.
*/
#define MAX_GRANTS(max_req, max_seg) (2 * (max_req) * (max_seg))
static int blk_connect(struct XenDevice *xendev)
{
struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
int pers, index, qflags;
int index, qflags;
bool readonly = true;
bool writethrough = true;
int order, ring_ref;
......@@ -1150,11 +892,6 @@ static int blk_connect(struct XenDevice *xendev)
&blkdev->xendev.remote_port) == -1) {
return -1;
}
if (xenstore_read_fe_int(&blkdev->xendev, "feature-persistent", &pers)) {
blkdev->feature_persistent = FALSE;
} else {
blkdev->feature_persistent = !!pers;
}
if (!blkdev->xendev.protocol) {
blkdev->protocol = BLKIF_PROTOCOL_NATIVE;
......@@ -1189,11 +926,8 @@ static int blk_connect(struct XenDevice *xendev)
return -1;
}
/* Calculate the maximum number of grants needed by ioreqs */
max_grants = MAX_GRANTS(blkdev->max_requests,
BLKIF_MAX_SEGMENTS_PER_REQUEST);
/* Add on the number needed for the ring pages */
max_grants += blkdev->nr_ring_ref;
max_grants = blkdev->nr_ring_ref;
xen_be_set_max_grant_refs(xendev, max_grants);
......@@ -1204,8 +938,6 @@ static int blk_connect(struct XenDevice *xendev)
return -1;
}
blkdev->cnt_map++;
switch (blkdev->protocol) {
case BLKIF_PROTOCOL_NATIVE:
{
......@@ -1229,19 +961,6 @@ static int blk_connect(struct XenDevice *xendev)
}
}
if (blkdev->feature_persistent) {
/* Init persistent grants */
blkdev->max_grants = blkdev->max_requests *
BLKIF_MAX_SEGMENTS_PER_REQUEST;
blkdev->persistent_gnts = g_tree_new_full((GCompareDataFunc)int_cmp,
NULL, NULL,
batch_maps ?
(GDestroyNotify)g_free :
(GDestroyNotify)destroy_grant);
blkdev->persistent_regions = NULL;
blkdev->persistent_gnt_count = 0;
}
blk_set_aio_context(blkdev->blk, blkdev->ctx);
xen_be_bind_evtchn(&blkdev->xendev);
......@@ -1274,29 +993,8 @@ static void blk_disconnect(struct XenDevice *xendev)
if (blkdev->sring) {
xen_be_unmap_grant_refs(xendev, blkdev->sring,
blkdev->nr_ring_ref);
blkdev->cnt_map--;
blkdev->sring = NULL;
}
/*
* Unmap persistent grants before switching to the closed state
* so the frontend can free them.
*
* In the !batch_maps case g_tree_destroy will take care of unmapping
* the grant, but in the batch_maps case we need to iterate over every
* region in persistent_regions and unmap it.
*/
if (blkdev->feature_persistent) {
g_tree_destroy(blkdev->persistent_gnts);
assert(batch_maps || blkdev->persistent_gnt_count == 0);
if (batch_maps) {
blkdev->persistent_gnt_count = 0;
g_slist_foreach(blkdev->persistent_regions,
(GFunc)remove_persistent_region, blkdev);
g_slist_free(blkdev->persistent_regions);
}
blkdev->feature_persistent = false;
}
}
static int blk_free(struct XenDevice *xendev)
......
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