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xen-block: scale sector based quantities correctly 

The Xen blkif protocol requires that sector based quantities should be
interpreted strictly as multiples of 512 bytes. Specifically:

"first_sect and last_sect in blkif_request_segment, as well as
sector_number in blkif_request, are always expressed in 512-byte units."

Commit fcab2b464e "xen: add header and build dataplane/xen-block.c"
incorrectly modified behaviour to use the block device logical_block_size
property as the scale, instead of correctly shifting values by the
hardcoded BDRV_SECTOR_BITS (and hence scaling them to 512 byte units).
This patch undoes that change and restores compliance with the spec.

Furthermore, this patch also restores the original xen_disk behaviour
of advertizing a hardcoded 'sector-size' value of 512 in xenstore and
scaling 'sectors' accordingly. The realize() method is also modified to
fail if logical_block_size is set to anything other than 512.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Message-Id: <20190401121719.27208-1-paul.durrant@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
This commit is contained in:
Paul Durrant 2019-04-01 13:17:19 +01:00 committed by Anthony PERARD
parent 15f084505a
commit 2bcd05cf24
3 changed files with 23 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
hw/block/dataplane/xen-block.c
View File

@ -49,7 +49,6 @@ struct XenBlockDataPlane {
unsigned int *ring_ref;
unsigned int nr_ring_ref;
void *sring;
int64_t file_blk;
int protocol;
blkif_back_rings_t rings;
int more_work;
@ -168,7 +167,7 @@ static int xen_block_parse_request(XenBlockRequest *request)
goto err;
}
request->start = request->req.sector_number * dataplane->file_blk;
request->start = request->req.sector_number * XEN_BLKIF_SECTOR_SIZE;
for (i = 0; i < request->req.nr_segments; i++) {
if (i == BLKIF_MAX_SEGMENTS_PER_REQUEST) {
error_report("error: nr_segments too big");
@ -178,14 +177,14 @@ static int xen_block_parse_request(XenBlockRequest *request)
error_report("error: first > last sector");
goto err;
}
if (request->req.seg[i].last_sect * dataplane->file_blk >=
if (request->req.seg[i].last_sect * XEN_BLKIF_SECTOR_SIZE >=
XC_PAGE_SIZE) {
error_report("error: page crossing");
goto err;
}
len = (request->req.seg[i].last_sect -
request->req.seg[i].first_sect + 1) * dataplane->file_blk;
request->req.seg[i].first_sect + 1) * XEN_BLKIF_SECTOR_SIZE;
request->size += len;
}
if (request->start + request->size > blk_getlength(dataplane->blk)) {
@ -205,7 +204,6 @@ static int xen_block_copy_request(XenBlockRequest *request)
XenDevice *xendev = dataplane->xendev;
XenDeviceGrantCopySegment segs[BLKIF_MAX_SEGMENTS_PER_REQUEST];
int i, count;
int64_t file_blk = dataplane->file_blk;
bool to_domain = (request->req.operation == BLKIF_OP_READ);
void *virt = request->buf;
Error *local_err = NULL;
@ -220,16 +218,17 @@ static int xen_block_copy_request(XenBlockRequest *request)
if (to_domain) {
segs[i].dest.foreign.ref = request->req.seg[i].gref;
segs[i].dest.foreign.offset = request->req.seg[i].first_sect *
file_blk;
XEN_BLKIF_SECTOR_SIZE;
segs[i].source.virt = virt;
} else {
segs[i].source.foreign.ref = request->req.seg[i].gref;
segs[i].source.foreign.offset = request->req.seg[i].first_sect *
file_blk;
XEN_BLKIF_SECTOR_SIZE;
segs[i].dest.virt = virt;
}
segs[i].len = (request->req.seg[i].last_sect -
request->req.seg[i].first_sect + 1) * file_blk;
request->req.seg[i].first_sect + 1) *
XEN_BLKIF_SECTOR_SIZE;
virt += segs[i].len;
}
@ -331,22 +330,22 @@ static bool xen_block_split_discard(XenBlockRequest *request,
XenBlockDataPlane *dataplane = request->dataplane;
int64_t byte_offset;
int byte_chunk;
uint64_t byte_remaining, limit;
uint64_t byte_remaining;
uint64_t sec_start = sector_number;
uint64_t sec_count = nr_sectors;
/* Wrap around, or overflowing byte limit? */
if (sec_start + sec_count < sec_count ||
sec_start + sec_count > INT64_MAX / dataplane->file_blk) {
sec_start + sec_count > INT64_MAX / XEN_BLKIF_SECTOR_SIZE) {
return false;
}
limit = BDRV_REQUEST_MAX_SECTORS * dataplane->file_blk;
byte_offset = sec_start * dataplane->file_blk;
byte_remaining = sec_count * dataplane->file_blk;
byte_offset = sec_start * XEN_BLKIF_SECTOR_SIZE;
byte_remaining = sec_count * XEN_BLKIF_SECTOR_SIZE;
do {
byte_chunk = byte_remaining > limit ? limit : byte_remaining;
byte_chunk = byte_remaining > BDRV_REQUEST_MAX_BYTES ?
BDRV_REQUEST_MAX_BYTES : byte_remaining;
request->aio_inflight++;
blk_aio_pdiscard(dataplane->blk, byte_offset, byte_chunk,
xen_block_complete_aio, request);
@ -632,7 +631,6 @@ XenBlockDataPlane *xen_block_dataplane_create(XenDevice *xendev,
XenBlockDataPlane *dataplane = g_new0(XenBlockDataPlane, 1);
dataplane->xendev = xendev;
dataplane->file_blk = conf->logical_block_size;
dataplane->blk = conf->blk;
QLIST_INIT(&dataplane->inflight);

10
hw/block/xen-block.c
View File

@ -149,7 +149,7 @@ static void xen_block_set_size(XenBlockDevice *blockdev)
const char *type = object_get_typename(OBJECT(blockdev));
XenBlockVdev *vdev = &blockdev->props.vdev;
BlockConf *conf = &blockdev->props.conf;
int64_t sectors = blk_getlength(conf->blk) / conf->logical_block_size;
int64_t sectors = blk_getlength(conf->blk) / XEN_BLKIF_SECTOR_SIZE;
XenDevice *xendev = XEN_DEVICE(blockdev);
trace_xen_block_size(type, vdev->disk, vdev->partition, sectors);
@ -223,6 +223,12 @@ static void xen_block_realize(XenDevice *xendev, Error **errp)
blkconf_blocksizes(conf);
if (conf->logical_block_size != XEN_BLKIF_SECTOR_SIZE) {
error_setg(errp, "logical_block_size != %u not supported",
XEN_BLKIF_SECTOR_SIZE);
return;
}
if (conf->logical_block_size > conf->physical_block_size) {
error_setg(
errp, "logical_block_size > physical_block_size not supported");
@ -253,7 +259,7 @@ static void xen_block_realize(XenDevice *xendev, Error **errp)
blockdev->device_type);
xen_device_backend_printf(xendev, "sector-size", "%u",
conf->logical_block_size);
XEN_BLKIF_SECTOR_SIZE);
xen_block_set_size(blockdev);

2
hw/block/xen_blkif.h
View File

@ -143,4 +143,6 @@ static inline void blkif_get_x86_64_req(blkif_request_t *dst,
}
}
#define XEN_BLKIF_SECTOR_SIZE 512
#endif /* XEN_BLKIF_H */