[PATCH 3/4] mmc_block: Add discard and secure discard support

[Adrian Hunter]

Enable MMC to service discard requests.  In the case of SD
and MMC cards that do not support trim, discards become
erases.  In the case of cards (MMC) that only allow erases
in multiples of erase group size, round to the nearest
completely discarded erase group.

Also implement BLKSECDISCARD using MMC secure erase and
trim operations.

Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
---
 drivers/mmc/card/block.c |  125 +++++++++++++++++++++++++++++++++++++++++++++-
 drivers/mmc/card/queue.c |   16 +++++-
 2 files changed, 138 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index cb9fbc8..f7129b3 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -31,6 +31,7 @@
 #include <linux/mutex.h>
 #include <linux/scatterlist.h>
 #include <linux/string_helpers.h>
+#include <linux/delay.h>
 
 #include <linux/mmc/card.h>
 #include <linux/mmc/host.h>
@@ -138,9 +139,91 @@ mmc_blk_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 	return 0;
 }
 
+static int mmc_blk_check_eod(struct block_device *bdev, unsigned int from,
+			     unsigned int nr)
+{
+	unsigned int maxsector;
+
+	if (!nr)
+		return 0;
+
+	maxsector = bdev->bd_inode->i_size >> 9;
+	if (maxsector && (maxsector < nr || maxsector - nr < from))
+		return 1;
+
+	return 0;
+}
+
+static int mmc_blk_secure_erase(struct mmc_blk_data *md, unsigned int from,
+				unsigned int nr)
+{
+	struct mmc_card *card = md->queue.card;
+	unsigned int arg;
+	int err;
+
+	if (!mmc_can_secure_erase_trim(card))
+		return -EOPNOTSUPP;
+
+	if (mmc_can_trim(card) && !mmc_erase_group_aligned(card, from, nr))
+		arg = MMC_SECURE_TRIM1_ARG;
+	else
+		arg = MMC_SECURE_ERASE_ARG;
+
+	mmc_claim_host(card->host);
+	err = mmc_erase(card, from, nr, arg);
+	if (!err && arg == MMC_SECURE_TRIM1_ARG)
+		err = mmc_erase(card, from, nr, MMC_SECURE_TRIM2_ARG);
+	mmc_release_host(card->host);
+
+	return err;
+}
+
+static int mmc_blk_ioctl_secdiscard(struct block_device *bdev, uint64_t start,
+				 uint64_t len)
+{
+	struct mmc_blk_data *md = bdev->bd_disk->private_data;
+	unsigned int from, nr;
+
+	if ((start & 511) || (len & 511))
+		return -EINVAL;
+
+	start >>= 9;
+	len >>= 9;
+
+	if (start > UINT_MAX || len > UINT_MAX)
+		return -EINVAL;
+
+	from = start;
+	nr = len;
+
+	if (mmc_blk_check_eod(bdev, from, nr))
+		return -EINVAL;
+
+	if (bdev != bdev->bd_contains)
+		from += bdev->bd_part->start_sect;
+
+	return mmc_blk_secure_erase(md, from, nr);
+}
+
+static int mmc_blk_ioctl(struct block_device *bdev, fmode_t mode,
+			 unsigned cmd, unsigned long arg)
+{
+	uint64_t range[2];
+
+	switch (cmd) {
+	case BLKSECDISCARD:
+		if (copy_from_user(range, (void __user *)arg, sizeof(range)))
+			return -EFAULT;
+
+		return mmc_blk_ioctl_secdiscard(bdev, range[0], range[1]);
+	}
+	return -ENOTTY;
+}
+
 static const struct block_device_operations mmc_bdops = {
 	.open			= mmc_blk_open,
 	.release		= mmc_blk_release,
+	.ioctl			= mmc_blk_ioctl,
 	.getgeo			= mmc_blk_getgeo,
 	.owner			= THIS_MODULE,
 };
@@ -242,7 +325,40 @@ static u32 get_card_status(struct mmc_card *card, struct request *req)
 	return cmd.resp[0];
 }
 
-static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
+static int mmc_blk_issue_discard_rq(struct mmc_queue *mq, struct request *req)
+{
+	struct mmc_blk_data *md = mq->data;
+	struct mmc_card *card = md->queue.card;
+	unsigned int from, nr, arg;
+	int err = 0;
+
+	mmc_claim_host(card->host);
+
+	if (!mmc_can_erase(card)) {
+		err = -EOPNOTSUPP;
+		goto out;
+	}
+
+	from = blk_rq_pos(req);
+	nr = blk_rq_sectors(req);
+
+	if (mmc_can_trim(card))
+		arg = MMC_TRIM_ARG;
+	else
+		arg = MMC_ERASE_ARG;
+
+	err = mmc_erase(card, from, nr, arg);
+out:
+	spin_lock_irq(&md->lock);
+	__blk_end_request(req, err, blk_rq_bytes(req));
+	spin_unlock_irq(&md->lock);
+
+	mmc_release_host(card->host);
+
+	return err ? 0 : 1;
+}
+
+static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *req)
 {
 	struct mmc_blk_data *md = mq->data;
 	struct mmc_card *card = md->queue.card;
@@ -470,6 +586,13 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
 	return 0;
 }
 
+static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
+{
+	if (blk_discard_rq(req))
+		return mmc_blk_issue_discard_rq(mq, req);
+	else
+		return mmc_blk_issue_rw_rq(mq, req);
+}
 
 static inline int mmc_blk_readonly(struct mmc_card *card)
 {
diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
index d6ded24..37f648f 100644
--- a/drivers/mmc/card/queue.c
+++ b/drivers/mmc/card/queue.c
@@ -30,9 +30,9 @@
 static int mmc_prep_request(struct request_queue *q, struct request *req)
 {
 	/*
-	 * We only like normal block requests.
+	 * We only like normal block requests and discards.
 	 */
-	if (!blk_fs_request(req)) {
+	if (!blk_fs_request(req) && !blk_discard_rq(req)) {
 		blk_dump_rq_flags(req, "MMC bad request");
 		return BLKPREP_KILL;
 	}
@@ -130,6 +130,18 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card, spinlock_t *lock
 	blk_queue_prep_rq(mq->queue, mmc_prep_request);
 	blk_queue_ordered(mq->queue, QUEUE_ORDERED_DRAIN, NULL);
 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, mq->queue);
+	if (mmc_can_erase(card)) {
+		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mq->queue);
+		mq->queue->limits.max_discard_sectors = UINT_MAX;
+		if (card->erased_byte == 0)
+			mq->queue->limits.discard_zeroes_data = 1;
+		if (!mmc_can_trim(card) && is_power_of_2(card->erase_size)) {
+			mq->queue->limits.discard_granularity =
+							card->erase_size << 9;
+			mq->queue->limits.discard_alignment =
+							card->erase_size << 9;
+		}
+	}
 
 #ifdef CONFIG_MMC_BLOCK_BOUNCE
 	if (host->max_hw_segs == 1) {
-- 
1.6.3.3
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