block/blk-lib.c

Source file repositories/reference/linux-study-clean/block/blk-lib.c

File Facts

System
Linux kernel
Corpus path
block/blk-lib.c
Extension
.c
Size
9783 bytes
Lines
358
Domain
Representative Device Path
Bucket
PCIe NVMe Storage Path
Inferred role
Representative Device Path: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Part of the selected hardware vertical slice: PCI discovery, driver binding, NVMe queues, block requests, DMA, interrupts, and completion.

Dependency Surface

Detected Declarations

Annotated Snippet

// 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(BIO_MAX_SIZE, discard_granularity) >> SECTOR_SHIFT;
}

struct bio *blk_alloc_discard_bio(struct block_device *bdev,
		sector_t *sector, sector_t *nr_sects, gfp_t gfp_mask)
{
	sector_t bio_sects = min(*nr_sects, bio_discard_limit(bdev, *sector));
	struct bio *bio;

	if (!bio_sects)
		return NULL;

	bio = bio_alloc(bdev, 0, REQ_OP_DISCARD, gfp_mask);
	if (!bio)
		return NULL;
	bio->bi_iter.bi_sector = *sector;
	bio->bi_iter.bi_size = bio_sects << SECTOR_SHIFT;
	*sector += bio_sects;
	*nr_sects -= bio_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();
	return bio;
}

void __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
		sector_t nr_sects, gfp_t gfp_mask, struct bio **biop)
{
	struct bio *bio;

	while ((bio = blk_alloc_discard_bio(bdev, &sector, &nr_sects,
			gfp_mask)))
		*biop = bio_chain_and_submit(*biop, bio);
}
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 = 0;

Annotation

Implementation Notes