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generated by cgit v1.2.2 (git 2.25.0) at 2026-04-28 16:19:33 -0400
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/*
 * fs/logfs/dev_bdev.c	- Device access methods for block devices
 *
 * As should be obvious for Linux kernel code, license is GPLv2
 *
 * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
 */
#include "logfs.h"
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/buffer_head.h>
#include <linux/gfp.h>
#include <linux/prefetch.h>

#define PAGE_OFS(ofs) ((ofs) & (PAGE_SIZE-1))

static int sync_request(struct page *page, struct block_device *bdev, int rw)
{
	struct bio bio;
	struct bio_vec bio_vec;

	bio_init(&bio);
	bio.bi_max_vecs = 1;
	bio.bi_io_vec = &bio_vec;
	bio_vec.bv_page = page;
	bio_vec.bv_len = PAGE_SIZE;
	bio_vec.bv_offset = 0;
	bio.bi_vcnt = 1;
	bio.bi_bdev = bdev;
	bio.bi_iter.bi_sector = page->index * (PAGE_SIZE >> 9);
	bio.bi_iter.bi_size = PAGE_SIZE;

	return submit_bio_wait(rw, &bio);
}

static int bdev_readpage(void *_sb, struct page *page)
{
	struct super_block *sb = _sb;
	struct block_device *bdev = logfs_super(sb)->s_bdev;
	int err;

	err = sync_request(page, bdev, READ);
	if (err) {
		ClearPageUptodate(page);
		SetPageError(page);
	} else {
		SetPageUptodate(page);
		ClearPageError(page);
	}
	unlock_page(page);
	return err;
}

static DECLARE_WAIT_QUEUE_HEAD(wq);

static void writeseg_end_io(struct bio *bio)
{
	struct bio_vec *bvec;
	int i;
	struct super_block *sb = bio->bi_private;
	struct logfs_super *super = logfs_super(sb);

	BUG_ON(bio->bi_error); /* FIXME: Retry io or write elsewhere */

	bio_for_each_segment_all(bvec, bio, i) {
		end_page_writeback(bvec->bv_page);
		page_cache_release(bvec->bv_page);
	}
	bio_put(bio);
	if (atomic_dec_and_test(&super->s_pending_writes))
		wake_up(&wq);
}

static int __bdev_writeseg(struct super_block *sb, u64 ofs, pgoff_t index,
		size_t nr_pages)
{
	struct logfs_super *super = logfs_super(sb);
	struct address_space *mapping = super->s_mapping_inode->i_mapping;
	struct bio *bio;
	struct page *page;
	unsigned int max_pages;
	int i;

	max_pages = min_t(size_t, nr_pages, BIO_MAX_PAGES);

	bio = bio_alloc(GFP_NOFS, max_pages);
	BUG_ON(!bio);

	for (i = 0; i < nr_pages; i++) {
		if (i >= max_pages) {
			/* Block layer cannot split bios :( */
			bio->bi_vcnt = i;
			bio->bi_iter.bi_size = i * PAGE_SIZE;
			bio->bi_bdev = super->s_bdev;
			bio->bi_iter.bi_sector = ofs >> 9;
			bio->bi_private = sb;
			bio->bi_end_io = writeseg_end_io;
			atomic_inc(&super->s_pending_writes);
			submit_bio(WRITE, bio);

			ofs += i * PAGE_SIZE;
			index += i;
			nr_pages -= i;
			i = 0;

			bio = bio_alloc(GFP_NOFS, max_pages);
			BUG_ON(!bio);
		}
		page = find_lock_page(mapping, index + i);
		BUG_ON(!page);
		bio->bi_io_vec[i].bv_page = page;
		bio->bi_io_vec[i].bv_len = PAGE_SIZE;
		bio->bi_io_vec[i].bv_offset = 0;