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Date: Wed, 30 Nov 2011 13:15:54 -0500
From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To: linux-kernel@...r.kernel.org, xen-devel@...ts.xensource.com,
Ian.Campbell@...rix.com, lidongyang@...ell.com, JBeulich@...ell.com
Cc: axboe@...nel.dk, Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Subject: [PATCH 2/4] 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@...ell.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@...cle.com>
---
drivers/block/xen-blkback/blkback.c | 18 ++++++++++-----
drivers/block/xen-blkback/common.h | 7 ++++-
drivers/block/xen-blkback/xenbus.c | 12 ++++++++++
drivers/block/xen-blkfront.c | 41 ++++++++++++++++++++++++++--------
include/xen/interface/io/blkif.h | 18 ++++++++++++++-
5 files changed, 77 insertions(+), 19 deletions(-)
diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index d7104ab..9d2261b 100644
--- 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_DISCARD_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;
@@ -643,8 +646,11 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
break;
}
- /* Check that the number of segments is sane. */
- nseg = req->u.rw.nr_segments;
+ if (unlikely(operation == REQ_DISCARD))
+ nseg = 0;
+ else
+ /* Check that the number of segments is sane. */
+ nseg = req->u.rw.nr_segments;
if (unlikely(nseg == 0 && operation != WRITE_FLUSH &&
operation != REQ_DISCARD) ||
@@ -708,7 +714,7 @@ 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 (operation != REQ_DISCARD && xen_blkbk_map(req, pending_req, seg))
+ if (nseg && xen_blkbk_map(req, pending_req, seg))
goto fail_flush;
/*
diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
index dbfe7b3..d0ee7ed 100644
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -69,7 +69,7 @@ struct blkif_x86_32_request_rw {
} __attribute__((__packed__));
struct blkif_x86_32_request_discard {
- uint8_t nr_segments; /* number of segments */
+ uint8_t flag; /* BLKIF_DISCARD_SECURE or zero */
blkif_vdev_t _pad1; /* was "handle" for read/write requests */
uint64_t id; /* private guest value, echoed in resp */
blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
@@ -104,7 +104,7 @@ struct blkif_x86_64_request_rw {
} __attribute__((__packed__));
struct blkif_x86_64_request_discard {
- uint8_t nr_segments; /* number of segments */
+ uint8_t flag; /* BLKIF_DISCARD_SECURE or zero */
blkif_vdev_t _pad1; /* was "handle" for read/write requests */
uint32_t _pad2; /* offsetof(blkif_..,u.discard.id)==8 */
uint64_t id;
@@ -164,6 +164,7 @@ struct xen_vbd {
/* Cached size parameter. */
sector_t size;
bool flush_support;
+ bool discard_secure;
};
struct backend_info;
@@ -261,6 +262,7 @@ static inline void blkif_get_x86_32_req(struct blkif_request *dst,
dst->u.rw.seg[i] = src->u.rw.seg[i];
break;
case BLKIF_OP_DISCARD:
+ dst->u.discard.flag = src->u.discard.flag;
dst->u.discard.sector_number = src->u.discard.sector_number;
dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
break;
@@ -290,6 +292,7 @@ static inline void blkif_get_x86_64_req(struct blkif_request *dst,
dst->u.rw.seg[i] = src->u.rw.seg[i];
break;
case BLKIF_OP_DISCARD:
+ dst->u.discard.flag = src->u.discard.flag;
dst->u.discard.sector_number = src->u.discard.sector_number;
dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
break;
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index f759ad4..187fd2c 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -338,6 +338,9 @@ 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;
@@ -420,6 +423,15 @@ 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 2c2c4be..351ddef 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], ©[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;
diff --git a/include/xen/interface/io/blkif.h b/include/xen/interface/io/blkif.h
index f88e28b..ee338bf 100644
--- a/include/xen/interface/io/blkif.h
+++ b/include/xen/interface/io/blkif.h
@@ -84,6 +84,21 @@ 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
+ * The backend can optionally provide three extra XenBus attributes to
+ * further optimize the discard functionality:
+ * 'discard-aligment' - Devices that support discard functionality may
+ * internally allocate space in units that are bigger than the exported
+ * logical block size. The discard-alignment parameter indicates how many bytes
+ * the beginning of the partition is offset from the internal allocation unit's
+ * natural alignment.
+ * 'discard-granularity' - Devices that support discard functionality may
+ * internally allocate space using units that are bigger than the logical block
+ * size. The discard-granularity parameter indicates the size of the internal
+ * allocation unit in bytes if reported by the device. Otherwise the
+ * discard-granularity will be set to match the device's physical block size.
+ * 'discard-secure' - All copies of the discarded sectors (potentially created
+ * by garbage collection) must also be erased. To use this feature, the flag
+ * BLKIF_DISCARD_SECURE must be set in the blkif_request_trim.
*/
#define BLKIF_OP_DISCARD 5
@@ -111,7 +126,8 @@ struct blkif_request_rw {
} __attribute__((__packed__));
struct blkif_request_discard {
- uint8_t nr_segments; /* number of segments */
+ uint8_t flag; /* BLKIF_DISCARD_SECURE or zero. */
+#define BLKIF_DISCARD_SECURE (1<<0) /* ignored if discard-secure=0 */
blkif_vdev_t _pad1; /* only for read/write requests */
#ifdef CONFIG_X86_64
uint32_t _pad2; /* offsetof(blkif_req..,u.discard.id)==8*/
--
1.7.7.3
--
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