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Subject[PATCH] block: Add secure discard
From 9ba7750fb96d9994e8715b14d8091c37b832b3e6 Mon Sep 17 00:00:00 2001
From: Adrian Hunter <adrian.hunter@nokia.com>
Date: Wed, 23 Jun 2010 15:41:38 +0300
Subject: [PATCH] block: Add secure discard

Secure discard is the same as discard except that all copies
of the discarded sectors (perhaps created by garbage collection)
must also be erased.

Signed-off-by: Adrian Hunter <adrian.hunter@nokia.com>
---



Here is "[PATCH V4 4/5] block: Add secure discard" applied to
git://git.kernel.dk/linux-2.6-block.git for-next.

If Jens takes this patch (originally 4th of 5), Andrew takes patches 1 to 3,
and patch 5 waits for this one to propagate, then there will be no dependency
problem.






block/blk-core.c | 5 ++++-
block/blk-lib.c | 6 ++++++
block/compat_ioctl.c | 1 +
block/elevator.c | 6 ++++++
block/ioctl.c | 15 ++++++++++-----
include/linux/bio.h | 2 ++
include/linux/blkdev.h | 7 ++++++-
include/linux/fs.h | 2 ++
kernel/trace/blktrace.c | 8 ++++++++
9 files changed, 45 insertions(+), 7 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 5ab3ac2..529aa57 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1514,7 +1514,10 @@ static inline void __generic_make_request(struct bio *bio)
if (bio_check_eod(bio, nr_sectors))
goto end_io;

- if ((bio->bi_rw & REQ_DISCARD) && !blk_queue_discard(q)) {
+ if ((bio->bi_rw & REQ_DISCARD) &&
+ (!blk_queue_discard(q) ||
+ ((bio->bi_rw & REQ_SECURE) &&
+ !blk_queue_secdiscard(q)))) {
err = -EOPNOTSUPP;
goto end_io;
}
diff --git a/block/blk-lib.c b/block/blk-lib.c
index e16185b..ba8c0f9 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -50,6 +50,12 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
if (!blk_queue_discard(q))
return -EOPNOTSUPP;

+ if (flags & BLKDEV_IFL_SECURE) {
+ if (!blk_queue_secdiscard(q))
+ return -EOPNOTSUPP;
+ type |= DISCARD_SECURE;
+ }
+
while (nr_sects && !ret) {
unsigned int max_discard_sectors =
min(q->limits.max_discard_sectors, UINT_MAX >> 9);
diff --git a/block/compat_ioctl.c b/block/compat_ioctl.c
index d530856..119f07b 100644
--- a/block/compat_ioctl.c
+++ b/block/compat_ioctl.c
@@ -703,6 +703,7 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
case BLKFLSBUF:
case BLKROSET:
case BLKDISCARD:
+ case BLKSECDISCARD:
/*
* the ones below are implemented in blkdev_locked_ioctl,
* but we call blkdev_ioctl, which gets the lock for us
diff --git a/block/elevator.c b/block/elevator.c
index 816a7c8..ec585c9 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -83,6 +83,12 @@ int elv_rq_merge_ok(struct request *rq, struct bio *bio)
return 0;

/*
+ * Don't merge discard requests and secure discard requests
+ */
+ if ((bio->bi_rw & REQ_SECURE) != (rq->bio->bi_rw & REQ_SECURE))
+ return 0;
+
+ /*
* different data direction or already started, don't merge
*/
if (bio_data_dir(bio) != rq_data_dir(rq))
diff --git a/block/ioctl.c b/block/ioctl.c
index 09fd7f1..d8052f0 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -114,8 +114,10 @@ static int blkdev_reread_part(struct block_device *bdev)
}

static int blk_ioctl_discard(struct block_device *bdev, uint64_t start,
- uint64_t len)
+ uint64_t len, int secure)
{
+ unsigned long flags = BLKDEV_IFL_WAIT;
+
if (start & 511)
return -EINVAL;
if (len & 511)
@@ -125,8 +127,9 @@ static int blk_ioctl_discard(struct block_device *bdev, uint64_t start,

if (start + len > (bdev->bd_inode->i_size >> 9))
return -EINVAL;
- return blkdev_issue_discard(bdev, start, len, GFP_KERNEL,
- BLKDEV_IFL_WAIT);
+ if (secure)
+ flags |= BLKDEV_IFL_SECURE;
+ return blkdev_issue_discard(bdev, start, len, GFP_KERNEL, flags);
}

static int put_ushort(unsigned long arg, unsigned short val)
@@ -213,7 +216,8 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
set_device_ro(bdev, n);
return 0;

- case BLKDISCARD: {
+ case BLKDISCARD:
+ case BLKSECDISCARD: {
uint64_t range[2];

if (!(mode & FMODE_WRITE))
@@ -222,7 +226,8 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
if (copy_from_user(range, (void __user *)arg, sizeof(range)))
return -EFAULT;

- return blk_ioctl_discard(bdev, range[0], range[1]);
+ return blk_ioctl_discard(bdev, range[0], range[1],
+ cmd == BLKSECDISCARD);
}

case HDIO_GETGEO: {
diff --git a/include/linux/bio.h b/include/linux/bio.h
index f655b54..5cb73bb 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -177,6 +177,7 @@ enum rq_flag_bits {
__REQ_FLUSH, /* request for cache flush */
__REQ_IO_STAT, /* account I/O stat */
__REQ_MIXED_MERGE, /* merge of different types, fail separately */
+ __REQ_SECURE, /* secure discard (used with __REQ_DISCARD) */
__REQ_NR_BITS, /* stops here */
};

@@ -217,6 +218,7 @@ enum rq_flag_bits {
#define REQ_FLUSH (1 << __REQ_FLUSH)
#define REQ_IO_STAT (1 << __REQ_IO_STAT)
#define REQ_MIXED_MERGE (1 << __REQ_MIXED_MERGE)
+#define REQ_SECURE (1 << __REQ_SECURE)

/*
* upper 16 bits of bi_rw define the io priority of this bio
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index a8b05fc..cd2dc1f 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -389,6 +389,7 @@ struct request_queue
#define QUEUE_FLAG_DISCARD 16 /* supports DISCARD */
#define QUEUE_FLAG_NOXMERGES 17 /* No extended merges */
#define QUEUE_FLAG_ADD_RANDOM 18 /* Contributes to random pool */
+#define QUEUE_FLAG_SECDISCARD 19 /* supports SECDISCARD */

#define QUEUE_FLAG_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \
(1 << QUEUE_FLAG_CLUSTER) | \
@@ -524,6 +525,8 @@ enum {
#define blk_queue_stackable(q) \
test_bit(QUEUE_FLAG_STACKABLE, &(q)->queue_flags)
#define blk_queue_discard(q) test_bit(QUEUE_FLAG_DISCARD, &(q)->queue_flags)
+#define blk_queue_secdiscard(q) (blk_queue_discard(q) && \
+ test_bit(QUEUE_FLAG_SECDISCARD, &(q)->queue_flags))

#define blk_noretry_request(rq) \
((rq)->cmd_flags & (REQ_FAILFAST_DEV|REQ_FAILFAST_TRANSPORT| \
@@ -918,10 +921,12 @@ static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt,
}
enum{
BLKDEV_WAIT, /* wait for completion */
- BLKDEV_BARRIER, /*issue request with barrier */
+ BLKDEV_BARRIER, /* issue request with barrier */
+ BLKDEV_SECURE, /* secure discard */
};
#define BLKDEV_IFL_WAIT (1 << BLKDEV_WAIT)
#define BLKDEV_IFL_BARRIER (1 << BLKDEV_BARRIER)
+#define BLKDEV_IFL_SECURE (1 << BLKDEV_SECURE)
extern int blkdev_issue_flush(struct block_device *, gfp_t, sector_t *,
unsigned long);
extern int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
diff --git a/include/linux/fs.h b/include/linux/fs.h
index c5c9294..90ac60c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -169,6 +169,7 @@ struct inodes_stat_t {
*/
#define DISCARD_NOBARRIER (WRITE | REQ_DISCARD)
#define DISCARD_BARRIER (WRITE | REQ_DISCARD | REQ_HARDBARRIER)
+#define DISCARD_SECURE (DISCARD_NOBARRIER | REQ_SECURE)

#define SEL_IN 1
#define SEL_OUT 2
@@ -311,6 +312,7 @@ struct inodes_stat_t {
#define BLKALIGNOFF _IO(0x12,122)
#define BLKPBSZGET _IO(0x12,123)
#define BLKDISCARDZEROES _IO(0x12,124)
+#define BLKSECDISCARD _IO(0x12,125)

#define BMAP_IOCTL 1 /* obsolete - kept for compatibility */
#define FIBMAP _IO(0x00,1) /* bmap access */
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 82499a5..959f8d6 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -710,6 +710,9 @@ static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
if (rq->cmd_flags & REQ_DISCARD)
rw |= REQ_DISCARD;

+ if (rq->cmd_flags & REQ_SECURE)
+ rw |= REQ_SECURE;
+
if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
what |= BLK_TC_ACT(BLK_TC_PC);
__blk_add_trace(bt, 0, blk_rq_bytes(rq), rw,
@@ -1816,6 +1819,8 @@ void blk_fill_rwbs(char *rwbs, u32 rw, int bytes)
rwbs[i++] = 'S';
if (rw & REQ_META)
rwbs[i++] = 'M';
+ if (rw & REQ_SECURE)
+ rwbs[i++] = 'E';

rwbs[i] = '\0';
}
@@ -1828,6 +1833,9 @@ void blk_fill_rwbs_rq(char *rwbs, struct request *rq)
if (rq->cmd_flags & REQ_DISCARD)
rw |= REQ_DISCARD;

+ if (rq->cmd_flags & REQ_SECURE)
+ rw |= REQ_SECURE;
+
bytes = blk_rq_bytes(rq);

blk_fill_rwbs(rwbs, rw, bytes);
--
1.6.3.3

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