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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 op)
{
struct bio bio;
struct bio_vec bio_vec;
bio_init(&bio, &bio_vec, 1);
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;
bio_set_op_attrs(&bio, op, 0);
return submit_bio_wait(&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);
put_page(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;
bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
atomic_inc(&super->s_pending_writes);
submit_bio(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;
BUG_ON(PageWriteback(page));
set_page_writeback(page);
unlock_page(page);
}
bio->bi_vcnt = nr_pages;
bio->bi_iter.bi_size = nr_pages * 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;
bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
atomic_inc(&super->s_pending_writes);
submit_bio(bio);
return 0;
}
static void bdev_writeseg(struct super_block *sb, u64 ofs, size_t len)
{
struct logfs_super *super = logfs_super(sb);
int head;
BUG_ON(super->s_flags & LOGFS_SB_FLAG_RO);
if (len == 0) {
/* This can happen when the object fit perfectly into a
* segment, the segment gets written per sync and subsequently
* closed.
*/
return;
}
head = ofs & (PAGE_SIZE - 1);
if (head) {
ofs -= head;
len += head;
}
len = PAGE_ALIGN(len);
__bdev_writeseg(sb, ofs, ofs >> PAGE_SHIFT, len >> PAGE_SHIFT);
}
static void erase_end_io(struct bio *bio)
{
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 */
BUG_ON(bio->bi_vcnt == 0);
bio_put(bio);
if (atomic_dec_and_test(&super->s_pending_writes))
wake_up(&wq);
}
static int do_erase(struct super_block *sb, u64 ofs, pgoff_t index,
size_t nr_pages)
{
struct logfs_super *super = logfs_super(sb);
struct bio *bio;
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 = erase_end_io;
bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
atomic_inc(&super->s_pending_writes);
submit_bio(bio);
ofs += i * PAGE_SIZE;
index += i;
nr_pages -= i;
i = 0;
bio = bio_alloc(GFP_NOFS, max_pages);
BUG_ON(!bio);
}
bio->bi_io_vec[i].bv_page = super->s_erase_page;
bio->bi_io_vec[i].bv_len = PAGE_SIZE;
bio->bi_io_vec[i].bv_offset = 0;
}
bio->bi_vcnt = nr_pages;
bio->bi_iter.bi_size = nr_pages * PAGE_SIZE;
bio->bi_bdev = super->s_bdev;
bio->bi_iter.bi_sector = ofs >> 9;
bio->bi_private = sb;
bio->bi_end_io = erase_end_io;
bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
atomic_inc(&super->s_pending_writes);
submit_bio(bio);
return 0;
}
static int bdev_erase(struct super_block *sb, loff_t to, size_t len,
int ensure_write)
{
struct logfs_super *super = logfs_super(sb);
BUG_ON(to & (PAGE_SIZE - 1));
BUG_ON(len & (PAGE_SIZE - 1));
if (super->s_flags & LOGFS_SB_FLAG_RO)
return -EROFS;
if (ensure_write) {
/*
* Object store doesn't care whether erases happen or not.
* But for the journal they are required. Otherwise a scan
* can find an old commit entry and assume it is the current
* one, travelling back in time.
*/
do_erase(sb, to, to >> PAGE_SHIFT, len >> PAGE_SHIFT);
}
return 0;
}
static void bdev_sync(struct super_block *sb)
{
struct logfs_super *super = logfs_super(sb);
wait_event(wq, atomic_read(&super->s_pending_writes)
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