fs/logfs/dev_bdev.c - arm/linux - Git at Google

 /*
  * 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>

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

 static void request_complete(struct bio *bio, int err)
 {
 	complete((struct completion *)bio->bi_private);
 }

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

 	bio_init(&bio);
 	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_idx = 0;
 	bio.bi_size = PAGE_SIZE;
 	bio.bi_bdev = bdev;
 	bio.bi_sector = page->index * (PAGE_SIZE >> 9);
 	init_completion(&complete);
 	bio.bi_private = &complete;
 	bio.bi_end_io = request_complete;

 	submit_bio(rw, &bio);
 	generic_unplug_device(bdev_get_queue(bdev));
 	wait_for_completion(&complete);
 	return test_bit(BIO_UPTODATE, &bio.bi_flags) ? 0 : -EIO;
 }

 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, int err)
 {
 	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 	struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
 	struct super_block *sb = bio->bi_private;
 	struct logfs_super *super = logfs_super(sb);
 	struct page *page;

 	BUG_ON(!uptodate); /* FIXME: Retry io or write elsewhere */
 	BUG_ON(err);
 	BUG_ON(bio->bi_vcnt == 0);
 	do {
 		page = bvec->bv_page;
 		if (--bvec >= bio->bi_io_vec)
 			prefetchw(&bvec->bv_page->flags);

 		end_page_writeback(page);
 	} while (bvec >= bio->bi_io_vec);
 	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;
 	struct request_queue *q = bdev_get_queue(sb->s_bdev);
 	unsigned int max_pages = queue_max_hw_sectors(q) >> (PAGE_SHIFT - 9);
 	int i;

 	bio = bio_alloc(GFP_NOFS, max_pages);
 	BUG_ON(!bio); /* FIXME: handle this */

 	for (i = 0; i < nr_pages; i++) {
 		if (i >= max_pages) {
 			/* Block layer cannot split bios :( */
 			bio->bi_vcnt = i;
 			bio->bi_idx = 0;
 			bio->bi_size = i * PAGE_SIZE;
 			bio->bi_bdev = super->s_bdev;
 			bio->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;

 		BUG_ON(PageWriteback(page));
 		set_page_writeback(page);
 		unlock_page(page);
 	}
 	bio->bi_vcnt = nr_pages;
 	bio->bi_idx = 0;
 	bio->bi_size = nr_pages * PAGE_SIZE;
 	bio->bi_bdev = super->s_bdev;
 	bio->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);
 	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);
 	generic_unplug_device(bdev_get_queue(logfs_super(sb)->s_bdev));
 }


 static void erase_end_io(struct bio *bio, int err)
 {
 	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 	struct super_block *sb = bio->bi_private;
 	struct logfs_super *super = logfs_super(sb);

 	BUG_ON(!uptodate); /* FIXME: Retry io or write elsewhere */
 	BUG_ON(err);
 	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;
 	struct request_queue *q = bdev_get_queue(sb->s_bdev);
 	unsigned int max_pages = queue_max_hw_sectors(q) >> (PAGE_SHIFT - 9);
 	int i;

 	bio = bio_alloc(GFP_NOFS, max_pages);
 	BUG_ON(!bio); /* FIXME: handle this */

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

 static struct page *bdev_find_first_sb(struct super_block *sb, u64 *ofs)
 {
 	struct logfs_super *super = logfs_super(sb);
 	struct address_space *mapping = super->s_mapping_inode->i_mapping;
 	filler_t *filler = bdev_readpage;

 	*ofs = 0;
 	return read_cache_page(mapping, 0, filler, sb);
 }

 static struct page *bdev_find_last_sb(struct super_block *sb, u64 *ofs)
 {
 	struct logfs_super *super = logfs_super(sb);
 	struct address_space *mapping = super->s_mapping_inode->i_mapping;
 	filler_t *filler = bdev_readpage;
 	u64 pos = (super->s_bdev->bd_inode->i_size & ~0xfffULL) - 0x1000;
 	pgoff_t index = pos >> PAGE_SHIFT;

 	*ofs = pos;
 	return read_cache_page(mapping, index, filler, sb);
 }

 static int bdev_write_sb(struct super_block *sb, struct page *page)
 {
 	struct block_device *bdev = logfs_super(sb)->s_bdev;

 	/* Nothing special to do for block devices. */
 	return sync_request(page, bdev, WRITE);
 }

 static void bdev_put_device(struct super_block *sb)
 {
 	close_bdev_exclusive(logfs_super(sb)->s_bdev, FMODE_READ|FMODE_WRITE);
 }

 static const struct logfs_device_ops bd_devops = {
 	.find_first_sb	= bdev_find_first_sb,
 	.find_last_sb	= bdev_find_last_sb,
 	.write_sb	= bdev_write_sb,
 	.readpage	= bdev_readpage,
 	.writeseg	= bdev_writeseg,
 	.erase		= bdev_erase,
 	.sync		= bdev_sync,
 	.put_device	= bdev_put_device,
 };

 int logfs_get_sb_bdev(struct file_system_type *type, int flags,
 		const char *devname, struct vfsmount *mnt)
 {
 	struct block_device *bdev;

 	bdev = open_bdev_exclusive(devname, FMODE_READ|FMODE_WRITE, type);
 	if (IS_ERR(bdev))
 		return PTR_ERR(bdev);

 	if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
 		int mtdnr = MINOR(bdev->bd_dev);
 		close_bdev_exclusive(bdev, FMODE_READ|FMODE_WRITE);
 		return logfs_get_sb_mtd(type, flags, mtdnr, mnt);
 	}

 	return logfs_get_sb_device(type, flags, NULL, bdev, &bd_devops, mnt);
 }
	/*
	* 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>

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

	static void request_complete(struct bio *bio, int err)
	{
	complete((struct completion *)bio->bi_private);
	}

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

	bio_init(&bio);
	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_idx = 0;
	bio.bi_size = PAGE_SIZE;
	bio.bi_bdev = bdev;
	bio.bi_sector = page->index * (PAGE_SIZE >> 9);
	init_completion(&complete);
	bio.bi_private = &complete;
	bio.bi_end_io = request_complete;

	submit_bio(rw, &bio);
	generic_unplug_device(bdev_get_queue(bdev));
	wait_for_completion(&complete);
	return test_bit(BIO_UPTODATE, &bio.bi_flags) ? 0 : -EIO;
	}

	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, int err)
	{
	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
	struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
	struct super_block *sb = bio->bi_private;
	struct logfs_super *super = logfs_super(sb);
	struct page *page;

	BUG_ON(!uptodate); /* FIXME: Retry io or write elsewhere */
	BUG_ON(err);
	BUG_ON(bio->bi_vcnt == 0);
	do {
	page = bvec->bv_page;
	if (--bvec >= bio->bi_io_vec)
	prefetchw(&bvec->bv_page->flags);

	end_page_writeback(page);
	} while (bvec >= bio->bi_io_vec);
	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;
	struct request_queue *q = bdev_get_queue(sb->s_bdev);
	unsigned int max_pages = queue_max_hw_sectors(q) >> (PAGE_SHIFT - 9);
	int i;

	bio = bio_alloc(GFP_NOFS, max_pages);
	BUG_ON(!bio); /* FIXME: handle this */

	for (i = 0; i < nr_pages; i++) {
	if (i >= max_pages) {
	/* Block layer cannot split bios :( */
	bio->bi_vcnt = i;
	bio->bi_idx = 0;
	bio->bi_size = i * PAGE_SIZE;
	bio->bi_bdev = super->s_bdev;
	bio->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;

	BUG_ON(PageWriteback(page));
	set_page_writeback(page);
	unlock_page(page);
	}
	bio->bi_vcnt = nr_pages;
	bio->bi_idx = 0;
	bio->bi_size = nr_pages * PAGE_SIZE;
	bio->bi_bdev = super->s_bdev;
	bio->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);
	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);
	generic_unplug_device(bdev_get_queue(logfs_super(sb)->s_bdev));
	}


	static void erase_end_io(struct bio *bio, int err)
	{
	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
	struct super_block *sb = bio->bi_private;
	struct logfs_super *super = logfs_super(sb);

	BUG_ON(!uptodate); /* FIXME: Retry io or write elsewhere */
	BUG_ON(err);
	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;
	struct request_queue *q = bdev_get_queue(sb->s_bdev);
	unsigned int max_pages = queue_max_hw_sectors(q) >> (PAGE_SHIFT - 9);
	int i;

	bio = bio_alloc(GFP_NOFS, max_pages);
	BUG_ON(!bio); /* FIXME: handle this */

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

	static struct page bdev_find_first_sb(struct super_block sb, u64 *ofs)
	{
	struct logfs_super *super = logfs_super(sb);
	struct address_space *mapping = super->s_mapping_inode->i_mapping;
	filler_t *filler = bdev_readpage;

	*ofs = 0;
	return read_cache_page(mapping, 0, filler, sb);
	}

	static struct page bdev_find_last_sb(struct super_block sb, u64 *ofs)
	{
	struct logfs_super *super = logfs_super(sb);
	struct address_space *mapping = super->s_mapping_inode->i_mapping;
	filler_t *filler = bdev_readpage;
	u64 pos = (super->s_bdev->bd_inode->i_size & ~0xfffULL) - 0x1000;
	pgoff_t index = pos >> PAGE_SHIFT;

	*ofs = pos;
	return read_cache_page(mapping, index, filler, sb);
	}

	static int bdev_write_sb(struct super_block sb, struct page page)
	{
	struct block_device *bdev = logfs_super(sb)->s_bdev;

	/* Nothing special to do for block devices. */
	return sync_request(page, bdev, WRITE);
	}

	static void bdev_put_device(struct super_block *sb)
	{
	close_bdev_exclusive(logfs_super(sb)->s_bdev, FMODE_READ\|FMODE_WRITE);
	}

	static const struct logfs_device_ops bd_devops = {
	.find_first_sb = bdev_find_first_sb,
	.find_last_sb = bdev_find_last_sb,
	.write_sb = bdev_write_sb,
	.readpage = bdev_readpage,
	.writeseg = bdev_writeseg,
	.erase = bdev_erase,
	.sync = bdev_sync,
	.put_device = bdev_put_device,
	};

	int logfs_get_sb_bdev(struct file_system_type *type, int flags,
	const char devname, struct vfsmount mnt)
	{
	struct block_device *bdev;

	bdev = open_bdev_exclusive(devname, FMODE_READ\|FMODE_WRITE, type);
	if (IS_ERR(bdev))
	return PTR_ERR(bdev);

	if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
	int mtdnr = MINOR(bdev->bd_dev);
	close_bdev_exclusive(bdev, FMODE_READ\|FMODE_WRITE);
	return logfs_get_sb_mtd(type, flags, mtdnr, mnt);
	}

	return logfs_get_sb_device(type, flags, NULL, bdev, &bd_devops, mnt);
	}