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Merge branch 'stable/for-jens-3.8' of git://git.kernel.org/pub/scm/li…
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…nux/kernel/git/konrad/xen into for-3.8/drivers
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Jens Axboe committed Nov 12, 2012
2 parents f1d6a32 + cb5bd4d commit 8d0ff39
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Showing 4 changed files with 478 additions and 55 deletions.
295 changes: 270 additions & 25 deletions drivers/block/xen-blkback/blkback.c
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,7 @@
#include <linux/list.h>
#include <linux/delay.h>
#include <linux/freezer.h>
#include <linux/bitmap.h>

#include <xen/events.h>
#include <xen/page.h>
Expand Down Expand Up @@ -79,6 +80,7 @@ struct pending_req {
unsigned short operation;
int status;
struct list_head free_list;
DECLARE_BITMAP(unmap_seg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
};

#define BLKBACK_INVALID_HANDLE (~0)
Expand All @@ -98,6 +100,36 @@ struct xen_blkbk {

static struct xen_blkbk *blkbk;

/*
* Maximum number of grant pages that can be mapped in blkback.
* BLKIF_MAX_SEGMENTS_PER_REQUEST * RING_SIZE is the maximum number of
* pages that blkback will persistently map.
* Currently, this is:
* RING_SIZE = 32 (for all known ring types)
* BLKIF_MAX_SEGMENTS_PER_REQUEST = 11
* sizeof(struct persistent_gnt) = 48
* So the maximum memory used to store the grants is:
* 32 * 11 * 48 = 16896 bytes
*/
static inline unsigned int max_mapped_grant_pages(enum blkif_protocol protocol)
{
switch (protocol) {
case BLKIF_PROTOCOL_NATIVE:
return __CONST_RING_SIZE(blkif, PAGE_SIZE) *
BLKIF_MAX_SEGMENTS_PER_REQUEST;
case BLKIF_PROTOCOL_X86_32:
return __CONST_RING_SIZE(blkif_x86_32, PAGE_SIZE) *
BLKIF_MAX_SEGMENTS_PER_REQUEST;
case BLKIF_PROTOCOL_X86_64:
return __CONST_RING_SIZE(blkif_x86_64, PAGE_SIZE) *
BLKIF_MAX_SEGMENTS_PER_REQUEST;
default:
BUG();
}
return 0;
}


/*
* Little helpful macro to figure out the index and virtual address of the
* pending_pages[..]. For each 'pending_req' we have have up to
Expand Down Expand Up @@ -129,6 +161,57 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
static void make_response(struct xen_blkif *blkif, u64 id,
unsigned short op, int st);

#define foreach_grant(pos, rbtree, node) \
for ((pos) = container_of(rb_first((rbtree)), typeof(*(pos)), node); \
&(pos)->node != NULL; \
(pos) = container_of(rb_next(&(pos)->node), typeof(*(pos)), node))


static void add_persistent_gnt(struct rb_root *root,
struct persistent_gnt *persistent_gnt)
{
struct rb_node **new = &(root->rb_node), *parent = NULL;
struct persistent_gnt *this;

/* Figure out where to put new node */
while (*new) {
this = container_of(*new, struct persistent_gnt, node);

parent = *new;
if (persistent_gnt->gnt < this->gnt)
new = &((*new)->rb_left);
else if (persistent_gnt->gnt > this->gnt)
new = &((*new)->rb_right);
else {
pr_alert(DRV_PFX " trying to add a gref that's already in the tree\n");
BUG();
}
}

/* Add new node and rebalance tree. */
rb_link_node(&(persistent_gnt->node), parent, new);
rb_insert_color(&(persistent_gnt->node), root);
}

static struct persistent_gnt *get_persistent_gnt(struct rb_root *root,
grant_ref_t gref)
{
struct persistent_gnt *data;
struct rb_node *node = root->rb_node;

while (node) {
data = container_of(node, struct persistent_gnt, node);

if (gref < data->gnt)
node = node->rb_left;
else if (gref > data->gnt)
node = node->rb_right;
else
return data;
}
return NULL;
}

/*
* Retrieve from the 'pending_reqs' a free pending_req structure to be used.
*/
Expand Down Expand Up @@ -275,6 +358,11 @@ int xen_blkif_schedule(void *arg)
{
struct xen_blkif *blkif = arg;
struct xen_vbd *vbd = &blkif->vbd;
struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
struct persistent_gnt *persistent_gnt;
int ret = 0;
int segs_to_unmap = 0;

xen_blkif_get(blkif);

Expand Down Expand Up @@ -302,6 +390,36 @@ int xen_blkif_schedule(void *arg)
print_stats(blkif);
}

/* Free all persistent grant pages */
if (!RB_EMPTY_ROOT(&blkif->persistent_gnts)) {
foreach_grant(persistent_gnt, &blkif->persistent_gnts, node) {
BUG_ON(persistent_gnt->handle ==
BLKBACK_INVALID_HANDLE);
gnttab_set_unmap_op(&unmap[segs_to_unmap],
(unsigned long) pfn_to_kaddr(page_to_pfn(
persistent_gnt->page)),
GNTMAP_host_map,
persistent_gnt->handle);

pages[segs_to_unmap] = persistent_gnt->page;
rb_erase(&persistent_gnt->node,
&blkif->persistent_gnts);
kfree(persistent_gnt);
blkif->persistent_gnt_c--;

if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST ||
!rb_next(&persistent_gnt->node)) {
ret = gnttab_unmap_refs(unmap, NULL, pages,
segs_to_unmap);
BUG_ON(ret);
segs_to_unmap = 0;
}
}
}

BUG_ON(blkif->persistent_gnt_c != 0);
BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts));

if (log_stats)
print_stats(blkif);

Expand All @@ -328,6 +446,8 @@ static void xen_blkbk_unmap(struct pending_req *req)
int ret;

for (i = 0; i < req->nr_pages; i++) {
if (!test_bit(i, req->unmap_seg))
continue;
handle = pending_handle(req, i);
if (handle == BLKBACK_INVALID_HANDLE)
continue;
Expand All @@ -344,12 +464,26 @@ static void xen_blkbk_unmap(struct pending_req *req)

static int xen_blkbk_map(struct blkif_request *req,
struct pending_req *pending_req,
struct seg_buf seg[])
struct seg_buf seg[],
struct page *pages[])
{
struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST];
int i;
struct persistent_gnt *persistent_gnts[BLKIF_MAX_SEGMENTS_PER_REQUEST];
struct page *pages_to_gnt[BLKIF_MAX_SEGMENTS_PER_REQUEST];
struct persistent_gnt *persistent_gnt = NULL;
struct xen_blkif *blkif = pending_req->blkif;
phys_addr_t addr = 0;
int i, j;
bool new_map;
int nseg = req->u.rw.nr_segments;
int segs_to_map = 0;
int ret = 0;
int use_persistent_gnts;

use_persistent_gnts = (blkif->vbd.feature_gnt_persistent);

BUG_ON(blkif->persistent_gnt_c >
max_mapped_grant_pages(pending_req->blkif->blk_protocol));

/*
* Fill out preq.nr_sects with proper amount of sectors, and setup
Expand All @@ -359,36 +493,146 @@ static int xen_blkbk_map(struct blkif_request *req,
for (i = 0; i < nseg; i++) {
uint32_t flags;

flags = GNTMAP_host_map;
if (pending_req->operation != BLKIF_OP_READ)
flags |= GNTMAP_readonly;
gnttab_set_map_op(&map[i], vaddr(pending_req, i), flags,
req->u.rw.seg[i].gref,
pending_req->blkif->domid);
if (use_persistent_gnts)
persistent_gnt = get_persistent_gnt(
&blkif->persistent_gnts,
req->u.rw.seg[i].gref);

if (persistent_gnt) {
/*
* We are using persistent grants and
* the grant is already mapped
*/
new_map = false;
} else if (use_persistent_gnts &&
blkif->persistent_gnt_c <
max_mapped_grant_pages(blkif->blk_protocol)) {
/*
* We are using persistent grants, the grant is
* not mapped but we have room for it
*/
new_map = true;
persistent_gnt = kmalloc(
sizeof(struct persistent_gnt),
GFP_KERNEL);
if (!persistent_gnt)
return -ENOMEM;
persistent_gnt->page = alloc_page(GFP_KERNEL);
if (!persistent_gnt->page) {
kfree(persistent_gnt);
return -ENOMEM;
}
persistent_gnt->gnt = req->u.rw.seg[i].gref;
persistent_gnt->handle = BLKBACK_INVALID_HANDLE;

pages_to_gnt[segs_to_map] =
persistent_gnt->page;
addr = (unsigned long) pfn_to_kaddr(
page_to_pfn(persistent_gnt->page));

add_persistent_gnt(&blkif->persistent_gnts,
persistent_gnt);
blkif->persistent_gnt_c++;
pr_debug(DRV_PFX " grant %u added to the tree of persistent grants, using %u/%u\n",
persistent_gnt->gnt, blkif->persistent_gnt_c,
max_mapped_grant_pages(blkif->blk_protocol));
} else {
/*
* We are either using persistent grants and
* hit the maximum limit of grants mapped,
* or we are not using persistent grants.
*/
if (use_persistent_gnts &&
!blkif->vbd.overflow_max_grants) {
blkif->vbd.overflow_max_grants = 1;
pr_alert(DRV_PFX " domain %u, device %#x is using maximum number of persistent grants\n",
blkif->domid, blkif->vbd.handle);
}
new_map = true;
pages[i] = blkbk->pending_page(pending_req, i);
addr = vaddr(pending_req, i);
pages_to_gnt[segs_to_map] =
blkbk->pending_page(pending_req, i);
}

if (persistent_gnt) {
pages[i] = persistent_gnt->page;
persistent_gnts[i] = persistent_gnt;
} else {
persistent_gnts[i] = NULL;
}

if (new_map) {
flags = GNTMAP_host_map;
if (!persistent_gnt &&
(pending_req->operation != BLKIF_OP_READ))
flags |= GNTMAP_readonly;
gnttab_set_map_op(&map[segs_to_map++], addr,
flags, req->u.rw.seg[i].gref,
blkif->domid);
}
}

ret = gnttab_map_refs(map, NULL, &blkbk->pending_page(pending_req, 0), nseg);
BUG_ON(ret);
if (segs_to_map) {
ret = gnttab_map_refs(map, NULL, pages_to_gnt, segs_to_map);
BUG_ON(ret);
}

/*
* Now swizzle the MFN in our domain with the MFN from the other domain
* so that when we access vaddr(pending_req,i) it has the contents of
* the page from the other domain.
*/
for (i = 0; i < nseg; i++) {
if (unlikely(map[i].status != 0)) {
pr_debug(DRV_PFX "invalid buffer -- could not remap it\n");
map[i].handle = BLKBACK_INVALID_HANDLE;
ret |= 1;
bitmap_zero(pending_req->unmap_seg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
for (i = 0, j = 0; i < nseg; i++) {
if (!persistent_gnts[i] ||
persistent_gnts[i]->handle == BLKBACK_INVALID_HANDLE) {
/* This is a newly mapped grant */
BUG_ON(j >= segs_to_map);
if (unlikely(map[j].status != 0)) {
pr_debug(DRV_PFX "invalid buffer -- could not remap it\n");
map[j].handle = BLKBACK_INVALID_HANDLE;
ret |= 1;
if (persistent_gnts[i]) {
rb_erase(&persistent_gnts[i]->node,
&blkif->persistent_gnts);
blkif->persistent_gnt_c--;
kfree(persistent_gnts[i]);
persistent_gnts[i] = NULL;
}
}
}
if (persistent_gnts[i]) {
if (persistent_gnts[i]->handle ==
BLKBACK_INVALID_HANDLE) {
/*
* If this is a new persistent grant
* save the handler
*/
persistent_gnts[i]->handle = map[j].handle;
persistent_gnts[i]->dev_bus_addr =
map[j++].dev_bus_addr;
}
pending_handle(pending_req, i) =
persistent_gnts[i]->handle;

if (ret)
continue;

seg[i].buf = persistent_gnts[i]->dev_bus_addr |
(req->u.rw.seg[i].first_sect << 9);
} else {
pending_handle(pending_req, i) = map[j].handle;
bitmap_set(pending_req->unmap_seg, i, 1);

if (ret) {
j++;
continue;
}

seg[i].buf = map[j++].dev_bus_addr |
(req->u.rw.seg[i].first_sect << 9);
}

pending_handle(pending_req, i) = map[i].handle;

if (ret)
continue;

seg[i].buf = map[i].dev_bus_addr |
(req->u.rw.seg[i].first_sect << 9);
}
return ret;
}
Expand Down Expand Up @@ -591,6 +835,7 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
int operation;
struct blk_plug plug;
bool drain = false;
struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];

switch (req->operation) {
case BLKIF_OP_READ:
Expand Down Expand Up @@ -677,7 +922,7 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
* the hypercall to unmap the grants - that is all done in
* xen_blkbk_unmap.
*/
if (xen_blkbk_map(req, pending_req, seg))
if (xen_blkbk_map(req, pending_req, seg, pages))
goto fail_flush;

/*
Expand All @@ -689,7 +934,7 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
for (i = 0; i < nseg; i++) {
while ((bio == NULL) ||
(bio_add_page(bio,
blkbk->pending_page(pending_req, i),
pages[i],
seg[i].nsec << 9,
seg[i].buf & ~PAGE_MASK) == 0)) {

Expand Down
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