xen/blk[front|back]: Enhance discard support with secure erasing support.

Part of the blkdev_issue_discard(xx) operation is that it can also
issue a secure discard operation that will permanantly remove the
sectors in question. We advertise that we can support that via the
'discard-secure' attribute and on the request, if the 'secure' bit
is set, we will attempt to pass in REQ_DISCARD | REQ_SECURE.

CC: Li Dongyang <lidongyang@novell.com>
[v1: Used 'flag' instead of 'secure:1' bit]
[v2: Use 'reserved' uint8_t instead of adding a new value]
[v3: Check for nseg when mapping instead of operation]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 31 insertions, 10 deletions

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 2c2c4be7d9d6..351ddeffd430 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -98,7 +98,8 @@ struct blkfront_info
         unsigned long shadow_free;
         unsigned int feature_flush;
         unsigned int flush_op;
-        unsigned int feature_discard;
+        unsigned int feature_discard:1;
+        unsigned int feature_secdiscard:1;
         unsigned int discard_granularity;
         unsigned int discard_alignment;
         int is_ready;
@@ -305,11 +306,14 @@ static int blkif_queue_request(struct request *req)
                 ring_req->operation = info->flush_op;
         }
 
-        if (unlikely(req->cmd_flags & REQ_DISCARD)) {
+        if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE))) {
                 /* id, sector_number and handle are set above. */
                 ring_req->operation = BLKIF_OP_DISCARD;
-                ring_req->u.discard.nr_segments = 0;
                 ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
+                if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard)
+                        ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
+                else
+                        ring_req->u.discard.flag = 0;
         } else {
                 ring_req->u.rw.nr_segments = blk_rq_map_sg(req->q, req,
                                                            info->sg);
@@ -426,6 +430,8 @@ static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
                 blk_queue_max_discard_sectors(rq, get_capacity(gd));
                 rq->limits.discard_granularity = info->discard_granularity;
                 rq->limits.discard_alignment = info->discard_alignment;
+                if (info->feature_secdiscard)
+                        queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq);
         }
 
         /* Hard sector size and max sectors impersonate the equiv. hardware. */
@@ -707,6 +713,8 @@ static void blkif_free(struct blkfront_info *info, int suspend)
 static void blkif_completion(struct blk_shadow *s)
 {
         int i;
+        /* Do not let BLKIF_OP_DISCARD as nr_segment is in the same place
+         * flag. */
         for (i = 0; i < s->req.u.rw.nr_segments; i++)
                 gnttab_end_foreign_access(s->req.u.rw.seg[i].gref, 0, 0UL);
 }
@@ -738,7 +746,8 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
                 id   = bret->id;
                 req  = info->shadow[id].request;
 
-                blkif_completion(&info->shadow[id]);
+                if (bret->operation != BLKIF_OP_DISCARD)
+                        blkif_completion(&info->shadow[id]);
 
                 add_id_to_freelist(info, id);
 
@@ -751,7 +760,9 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
                                            info->gd->disk_name);
                                 error = -EOPNOTSUPP;
                                 info->feature_discard = 0;
+                                info->feature_secdiscard = 0;
                                 queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
+                                queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq);
                         }
                         __blk_end_request_all(req, error);
                         break;
@@ -1039,13 +1050,15 @@ static int blkif_recover(struct blkfront_info *info)
                 req->u.rw.id = get_id_from_freelist(info);
                 memcpy(&info->shadow[req->u.rw.id], &copy[i], sizeof(copy[i]));
 
+                if (req->operation != BLKIF_OP_DISCARD) {
                 /* Rewrite any grant references invalidated by susp/resume. */
-                for (j = 0; j < req->u.rw.nr_segments; j++)
-                        gnttab_grant_foreign_access_ref(
-                                req->u.rw.seg[j].gref,
-                                info->xbdev->otherend_id,
-                                pfn_to_mfn(info->shadow[req->u.rw.id].frame[j]),
-                                rq_data_dir(info->shadow[req->u.rw.id].request));
+                        for (j = 0; j < req->u.rw.nr_segments; j++)
+                                gnttab_grant_foreign_access_ref(
+                                        req->u.rw.seg[j].gref,
+                                        info->xbdev->otherend_id,
+                                        pfn_to_mfn(info->shadow[req->u.rw.id].frame[j]),
+                                        rq_data_dir(info->shadow[req->u.rw.id].request));
+                }
                 info->shadow[req->u.rw.id].req = *req;
 
                 info->ring.req_prod_pvt++;
@@ -1137,11 +1150,13 @@ static void blkfront_setup_discard(struct blkfront_info *info)
         char *type;
         unsigned int discard_granularity;
         unsigned int discard_alignment;
+        unsigned int discard_secure;
 
         type = xenbus_read(XBT_NIL, info->xbdev->otherend, "type", NULL);
         if (IS_ERR(type))
                 return;
 
+        info->feature_secdiscard = 0;
         if (strncmp(type, "phy", 3) == 0) {
                 err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
                         "discard-granularity", "%u", &discard_granularity,
@@ -1152,6 +1167,12 @@ static void blkfront_setup_discard(struct blkfront_info *info)
                         info->discard_granularity = discard_granularity;
                         info->discard_alignment = discard_alignment;
                 }
+                err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
+                            "discard-secure", "%d", &discard_secure,
+                            NULL);
+                if (!err)
+                        info->feature_secdiscard = discard_secure;
+
         } else if (strncmp(type, "file", 4) == 0)
                 info->feature_discard = 1;