1 files changed, 345 insertions, 0 deletions
diff --git a/block/blk-lib.c b/block/blk-lib.c
new file mode 100644
index 0000000000..e59c3069e8
--- /dev/null
+++ b/block/blk-lib.c
@@ -0,0 +1,345 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Functions related to generic helpers functions
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/scatterlist.h>
+
+#include "blk.h"
+
+static sector_t bio_discard_limit(struct block_device *bdev, sector_t sector)
+{
+	unsigned int discard_granularity = bdev_discard_granularity(bdev);
+	sector_t granularity_aligned_sector;
+
+	if (bdev_is_partition(bdev))
+		sector += bdev->bd_start_sect;
+
+	granularity_aligned_sector =
+		round_up(sector, discard_granularity >> SECTOR_SHIFT);
+
+	/*
+	 * Make sure subsequent bios start aligned to the discard granularity if
+	 * it needs to be split.
+	 */
+	if (granularity_aligned_sector != sector)
+		return granularity_aligned_sector - sector;
+
+	/*
+	 * Align the bio size to the discard granularity to make splitting the bio
+	 * at discard granularity boundaries easier in the driver if needed.
+	 */
+	return round_down(UINT_MAX, discard_granularity) >> SECTOR_SHIFT;
+}
+
+int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
+		sector_t nr_sects, gfp_t gfp_mask, struct bio **biop)
+{
+	struct bio *bio = *biop;
+	sector_t bs_mask;
+
+	if (bdev_read_only(bdev))
+		return -EPERM;
+	if (!bdev_max_discard_sectors(bdev))
+		return -EOPNOTSUPP;
+
+	/* In case the discard granularity isn't set by buggy device driver */
+	if (WARN_ON_ONCE(!bdev_discard_granularity(bdev))) {
+		pr_err_ratelimited("%pg: Error: discard_granularity is 0.\n",
+				   bdev);
+		return -EOPNOTSUPP;
+	}
+
+	bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
+	if ((sector | nr_sects) & bs_mask)
+		return -EINVAL;
+
+	if (!nr_sects)
+		return -EINVAL;
+
+	while (nr_sects) {
+		sector_t req_sects =
+			min(nr_sects, bio_discard_limit(bdev, sector));
+
+		bio = blk_next_bio(bio, bdev, 0, REQ_OP_DISCARD, gfp_mask);
+		bio->bi_iter.bi_sector = sector;
+		bio->bi_iter.bi_size = req_sects << 9;
+		sector += req_sects;
+		nr_sects -= req_sects;
+
+		/*
+		 * We can loop for a long time in here, if someone does
+		 * full device discards (like mkfs). Be nice and allow
+		 * us to schedule out to avoid softlocking if preempt
+		 * is disabled.
+		 */
+		cond_resched();
+	}
+
+	*biop = bio;
+	return 0;
+}
+EXPORT_SYMBOL(__blkdev_issue_discard);
+
+/**
+ * blkdev_issue_discard - queue a discard
+ * @bdev:	blockdev to issue discard for
+ * @sector:	start sector
+ * @nr_sects:	number of sectors to discard
+ * @gfp_mask:	memory allocation flags (for bio_alloc)
+ *
+ * Description:
+ *    Issue a discard request for the sectors in question.
+ */
+int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
+		sector_t nr_sects, gfp_t gfp_mask)
+{
+	struct bio *bio = NULL;
+	struct blk_plug plug;
+	int ret;
+
+	blk_start_plug(&plug);
+	ret = __blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, &bio);
+	if (!ret && bio) {
+		ret = submit_bio_wait(bio);
+		if (ret == -EOPNOTSUPP)
+			ret = 0;
+		bio_put(bio);
+	}
+	blk_finish_plug(&plug);
+
+	return ret;
+}
+EXPORT_SYMBOL(blkdev_issue_discard);
+
+static int __blkdev_issue_write_zeroes(struct block_device *bdev,
+		sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
+		struct bio **biop, unsigned flags)
+{
+	struct bio *bio = *biop;
+	unsigned int max_write_zeroes_sectors;
+
+	if (bdev_read_only(bdev))
+		return -EPERM;
+
+	/* Ensure that max_write_zeroes_sectors doesn't overflow bi_size */
+	max_write_zeroes_sectors = bdev_write_zeroes_sectors(bdev);
+
+	if (max_write_zeroes_sectors == 0)
+		return -EOPNOTSUPP;
+
+	while (nr_sects) {
+		bio = blk_next_bio(bio, bdev, 0, REQ_OP_WRITE_ZEROES, gfp_mask);
+		bio->bi_iter.bi_sector = sector;
+		if (flags & BLKDEV_ZERO_NOUNMAP)
+			bio->bi_opf |= REQ_NOUNMAP;
+
+		if (nr_sects > max_write_zeroes_sectors) {
+			bio->bi_iter.bi_size = max_write_zeroes_sectors << 9;
+			nr_sects -= max_write_zeroes_sectors;
+			sector += max_write_zeroes_sectors;
+		} else {
+			bio->bi_iter.bi_size = nr_sects << 9;
+			nr_sects = 0;
+		}
+		cond_resched();
+	}
+
+	*biop = bio;
+	return 0;
+}
+
+/*
+ * Convert a number of 512B sectors to a number of pages.
+ * The result is limited to a number of pages that can fit into a BIO.
+ * Also make sure that the result is always at least 1 (page) for the cases
+ * where nr_sects is lower than the number of sectors in a page.
+ */
+static unsigned int __blkdev_sectors_to_bio_pages(sector_t nr_sects)
+{
+	sector_t pages = DIV_ROUND_UP_SECTOR_T(nr_sects, PAGE_SIZE / 512);
+
+	return min(pages, (sector_t)BIO_MAX_VECS);
+}
+
+static int __blkdev_issue_zero_pages(struct block_device *bdev,
+		sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
+		struct bio **biop)
+{
+	struct bio *bio = *biop;
+	int bi_size = 0;
+	unsigned int sz;
+
+	if (bdev_read_only(bdev))
+		return -EPERM;
+
+	while (nr_sects != 0) {
+		bio = blk_next_bio(bio, bdev, __blkdev_sectors_to_bio_pages(nr_sects),
+				   REQ_OP_WRITE, gfp_mask);
+		bio->bi_iter.bi_sector = sector;
+
+		while (nr_sects != 0) {
+			sz = min((sector_t) PAGE_SIZE, nr_sects << 9);
+			bi_size = bio_add_page(bio, ZERO_PAGE(0), sz, 0);
+			nr_sects -= bi_size >> 9;
+			sector += bi_size >> 9;
+			if (bi_size < sz)
+				break;
+		}
+		cond_resched();
+	}
+
+	*biop = bio;
+	return 0;
+}
+
+/**
+ * __blkdev_issue_zeroout - generate number of zero filed write bios
+ * @bdev:	blockdev to issue
+ * @sector:	start sector
+ * @nr_sects:	number of sectors to write
+ * @gfp_mask:	memory allocation flags (for bio_alloc)
+ * @biop:	pointer to anchor bio
+ * @flags:	controls detailed behavior
+ *
+ * Description:
+ *  Zero-fill a block range, either using hardware offload or by explicitly
+ *  writing zeroes to the device.
+ *
+ *  If a device is using logical block provisioning, the underlying space will
+ *  not be released if %flags contains BLKDEV_ZERO_NOUNMAP.
+ *
+ *  If %flags contains BLKDEV_ZERO_NOFALLBACK, the function will return
+ *  -EOPNOTSUPP if no explicit hardware offload for zeroing is provided.
+ */
+int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
+		sector_t nr_sects, gfp_t gfp_mask, struct bio **biop,
+		unsigned flags)
+{
+	int ret;
+	sector_t bs_mask;
+
+	bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
+	if ((sector | nr_sects) & bs_mask)
+		return -EINVAL;
+
+	ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects, gfp_mask,
+			biop, flags);
+	if (ret != -EOPNOTSUPP || (flags & BLKDEV_ZERO_NOFALLBACK))
+		return ret;
+
+	return __blkdev_issue_zero_pages(bdev, sector, nr_sects, gfp_mask,
+					 biop);
+}
+EXPORT_SYMBOL(__blkdev_issue_zeroout);
+
+/**
+ * blkdev_issue_zeroout - zero-fill a block range
+ * @bdev:	blockdev to write
+ * @sector:	start sector
+ * @nr_sects:	number of sectors to write
+ * @gfp_mask:	memory allocation flags (for bio_alloc)
+ * @flags:	controls detailed behavior
+ *
+ * Description:
+ *  Zero-fill a block range, either using hardware offload or by explicitly
+ *  writing zeroes to the device.  See __blkdev_issue_zeroout() for the
+ *  valid values for %flags.
+ */
+int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
+		sector_t nr_sects, gfp_t gfp_mask, unsigned flags)
+{
+	int ret = 0;
+	sector_t bs_mask;
+	struct bio *bio;
+	struct blk_plug plug;
+	bool try_write_zeroes = !!bdev_write_zeroes_sectors(bdev);
+
+	bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
+	if ((sector | nr_sects) & bs_mask)
+		return -EINVAL;
+
+retry:
+	bio = NULL;
+	blk_start_plug(&plug);
+	if (try_write_zeroes) {
+		ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects,
+						  gfp_mask, &bio, flags);
+	} else if (!(flags & BLKDEV_ZERO_NOFALLBACK)) {
+		ret = __blkdev_issue_zero_pages(bdev, sector, nr_sects,
+						gfp_mask, &bio);
+	} else {
+		/* No zeroing offload support */
+		ret = -EOPNOTSUPP;
+	}
+	if (ret == 0 && bio) {
+		ret = submit_bio_wait(bio);
+		bio_put(bio);
+	}
+	blk_finish_plug(&plug);
+	if (ret && try_write_zeroes) {
+		if (!(flags & BLKDEV_ZERO_NOFALLBACK)) {
+			try_write_zeroes = false;
+			goto retry;
+		}
+		if (!bdev_write_zeroes_sectors(bdev)) {
+			/*
+			 * Zeroing offload support was indicated, but the
+			 * device reported ILLEGAL REQUEST (for some devices
+			 * there is no non-destructive way to verify whether
+			 * WRITE ZEROES is actually supported).
+			 */
+			ret = -EOPNOTSUPP;
+		}
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(blkdev_issue_zeroout);
+
+int blkdev_issue_secure_erase(struct block_device *bdev, sector_t sector,
+		sector_t nr_sects, gfp_t gfp)
+{
+	sector_t bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
+	unsigned int max_sectors = bdev_max_secure_erase_sectors(bdev);
+	struct bio *bio = NULL;
+	struct blk_plug plug;
+	int ret = 0;
+
+	/* make sure that "len << SECTOR_SHIFT" doesn't overflow */
+	if (max_sectors > UINT_MAX >> SECTOR_SHIFT)
+		max_sectors = UINT_MAX >> SECTOR_SHIFT;
+	max_sectors &= ~bs_mask;
+
+	if (max_sectors == 0)
+		return -EOPNOTSUPP;
+	if ((sector | nr_sects) & bs_mask)
+		return -EINVAL;
+	if (bdev_read_only(bdev))
+		return -EPERM;
+
+	blk_start_plug(&plug);
+	for (;;) {
+		unsigned int len = min_t(sector_t, nr_sects, max_sectors);
+
+		bio = blk_next_bio(bio, bdev, 0, REQ_OP_SECURE_ERASE, gfp);
+		bio->bi_iter.bi_sector = sector;
+		bio->bi_iter.bi_size = len << SECTOR_SHIFT;
+
+		sector += len;
+		nr_sects -= len;
+		if (!nr_sects) {
+			ret = submit_bio_wait(bio);
+			bio_put(bio);
+			break;
+		}
+		cond_resched();
+	}
+	blk_finish_plug(&plug);
+
+	return ret;
+}
+EXPORT_SYMBOL(blkdev_issue_secure_erase);