[PATCH V4 4/5] block: Add secure discard

[Adrian Hunter <adrian.hunter@nokia.com>]

>From 1cdd5b576bfafcd53857ed4d37830446e96e8206 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 4/5] 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>
---
 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 3c37894..7931081 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1513,7 +1513,10 @@ 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 f26051f..24a146d 100644
--- a/block/compat_ioctl.c
+++ b/block/compat_ioctl.c
@@ -753,6 +753,7 @@ 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 6f3db6f..afcfe48 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)
@@ -226,7 +229,8 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
 		unlock_kernel();
 		return 0;
 
-	case BLKDISCARD: {
+	case BLKDISCARD:
+	case BLKSECDISCARD: {
 		uint64_t range[2];
 
 		if (!(mode & FMODE_WRITE))
@@ -235,7 +239,8 @@ 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 4d379c8..147e631 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -176,6 +176,7 @@ enum rq_flag_bits {
 	__REQ_INTEGRITY,	/* integrity metadata has been remapped */
 	__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 */
 };
 
@@ -215,6 +216,7 @@ enum rq_flag_bits {
 #define REQ_INTEGRITY		(1 << __REQ_INTEGRITY)
 #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 204fbe2..da643f4 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -404,6 +404,7 @@ 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) |		\
@@ -539,6 +540,8 @@ 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| \
@@ -931,10 +934,12 @@ 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 dc9d185..2f5df1f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -176,6 +176,7 @@ 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
@@ -318,6 +319,7 @@ 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 3b4a695..a711b47 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -667,6 +667,9 @@ 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,
@@ -1773,6 +1776,8 @@ 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';
 }
@@ -1785,6 +1790,9 @@ 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