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]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index ca23dff7d5d1368da2b90365b32bc65f16d9e44a..5ccb648ff864719779526e5eb72c9ed4a3484506 100644 (file)
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -422,13 +422,16 @@ static void xen_blk_discard(struct xen_blkif *blkif, struct blkif_request *req)
        int status = BLKIF_RSP_OKAY;
        struct block_device *bdev = blkif->vbd.bdev;
 
-       if (blkif->blk_backend_type == BLKIF_BACKEND_PHY)
+       if (blkif->blk_backend_type == BLKIF_BACKEND_PHY) {
+               unsigned long secure = (blkif->vbd.discard_secure &&
+                       (req->u.discard.flag & BLKIF_OP_DISCARD_FLAG_SECURE)) ?
+                       BLKDEV_DISCARD_SECURE : 0;
                /* just forward the discard request */
                err = blkdev_issue_discard(bdev,
                                req->u.discard.sector_number,
                                req->u.discard.nr_sectors,
-                               GFP_KERNEL, 0);
-       else if (blkif->blk_backend_type == BLKIF_BACKEND_FILE) {
+                               GFP_KERNEL, secure);
+       } else if (blkif->blk_backend_type == BLKIF_BACKEND_FILE) {
                /* punch a hole in the backing file */
                struct loop_device *lo = bdev->bd_disk->private_data;
                struct file *file = lo->lo_backing_file;

diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
index e638457d9de44d3305011207b333cf85cacb2757..43b72a78a326d5208af33c76dfe003f444ea9028 100644 (file)
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -72,6 +72,7 @@ struct blkif_x86_32_request_rw {
 struct blkif_x86_32_request_discard {
        blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
        uint64_t nr_sectors;
+       uint32_t flag;
 };
 
 struct blkif_x86_32_request {
@@ -101,6 +102,7 @@ struct blkif_x86_64_request_rw {
 struct blkif_x86_64_request_discard {
        blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
        uint64_t nr_sectors;
+       uint32_t flag;
 };
 
 struct blkif_x86_64_request {
@@ -157,6 +159,7 @@ struct xen_vbd {
        /* Cached size parameter. */
        sector_t                size;
        bool                    flush_support;
+       bool                    discard_secure;
 };
 
 struct backend_info;
@@ -259,6 +262,7 @@ static inline void blkif_get_x86_32_req(struct blkif_request *dst,
        case BLKIF_OP_DISCARD:
                dst->u.discard.sector_number = src->u.discard.sector_number;
                dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
+               dst->u.discard.flag = src->u.discard.flag;
                break;
        default:
                break;
@@ -288,6 +292,7 @@ static inline void blkif_get_x86_64_req(struct blkif_request *dst,
        case BLKIF_OP_DISCARD:
                dst->u.discard.sector_number = src->u.discard.sector_number;
                dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
+               dst->u.discard.flag = src->u.discard.flag;
                break;
        default:
                break;

diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index a6d43030b1078e027e4c0ccb41cea7070518e428..0c0ce3975daeb9ccbf1fc25e591b417b6973bc91 100644 (file)
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -378,6 +378,9 @@ static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle,
        if (q && q->flush_flags)
                vbd->flush_support = true;
 
+       if (q && blk_queue_secdiscard(q))
+               vbd->discard_secure = true;
+
        DPRINTK("Successful creation of handle=%04x (dom=%u)\n",
                handle, blkif->domid);
        return 0;
@@ -460,6 +463,15 @@ int xen_blkbk_discard(struct xenbus_transaction xbt, struct backend_info *be)
                                state = 1;
                                blkif->blk_backend_type = BLKIF_BACKEND_PHY;
                        }
+                       /* Optional. */
+                       err = xenbus_printf(xbt, dev->nodename,
+                               "discard-secure", "%d",
+                               blkif->vbd.discard_secure);
+                       if (err) {
+                               xenbus_dev_fatal(dev, err,
+                                       "writting discard-secure");
+                               goto kfree;
+                       }
                }
        } else {
                err = PTR_ERR(type);

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 7b2ec5908413da7b989044828879afa173613b87..807b7b6d6fa38be26ebe0ae47be80c0dc9d7f31f 100644 (file)
--- 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 +306,13 @@ 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->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_OP_DISCARD_FLAG_SECURE;
        } else {
                ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg);
                BUG_ON(ring_req->nr_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
@@ -424,6 +427,8 @@ 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. */
@@ -749,7 +754,9 @@ 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;
@@ -1135,11 +1142,13 @@ 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,
@@ -1150,6 +1159,12 @@ 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;
 

diff --git a/include/xen/interface/io/blkif.h b/include/xen/interface/io/blkif.h
index 9324488f23f0b2eaab58e50f7cdda0b6d4b152ef..13d040e0537c8f7755f9bcafe0aa5db5e53979dc 100644 (file)
--- a/include/xen/interface/io/blkif.h
+++ b/include/xen/interface/io/blkif.h
@@ -84,6 +84,10 @@ typedef uint64_t blkif_sector_t;
  *     e07154r6-Data_Set_Management_Proposal_for_ATA-ACS2.doc
  * http://www.seagate.com/staticfiles/support/disc/manuals/
  *     Interface%20manuals/100293068c.pdf
+ * We also provide three extra XenBus options to the discard operation:
+ * 'discard-granularity' - Max amount of sectors that can be discarded.
+ * 'discard-alignment' - 4K, 128K, etc aligment on sectors to erased.
+ * 'discard-secure' - whether the discard can also securely erase data.
  */
 #define BLKIF_OP_DISCARD           5
 
@@ -107,6 +111,8 @@ struct blkif_request_rw {
 struct blkif_request_discard {
        blkif_sector_t sector_number;
        uint64_t nr_sectors;
+#define BLKIF_OP_DISCARD_FLAG_SECURE   (1<<1) /* ignored if discard-secure=0 */
+       uint32_t flag;
 };
 
 struct blkif_request {