[net-next-2.6.git] / fs / logfs / dev_bdev.c

/*
 * 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);
		page_cache_release(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;

	if (max_pages > BIO_MAX_PAGES)
		max_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_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;

	if (max_pages > BIO_MAX_PAGES)
		max_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_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 logfs_super *s)
{
	close_bdev_exclusive(s->s_bdev, FMODE_READ|FMODE_WRITE);
}

static int bdev_can_write_buf(struct super_block *sb, u64 ofs)
{
	return 0;
}

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,
	.can_write_buf	= bdev_can_write_buf,
	.sync		= bdev_sync,
	.put_device	= bdev_put_device,
};

int logfs_get_sb_bdev(struct logfs_super *p, struct file_system_type *type,
		const char *devname)
{
	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(p, mtdnr);
	}

	p->s_bdev = bdev;
	p->s_mtd = NULL;
	p->s_devops = &bd_devops;
	return 0;
}
Commit	Line	Data
5db53f3e JE	1	/*
	2	* fs/logfs/dev_bdev.c - Device access methods for block devices
	3	*
	4	* As should be obvious for Linux kernel code, license is GPLv2
	5	*
	6	* Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
	7	*/
	8	#include "logfs.h"
	9	#include <linux/bio.h>
	10	#include <linux/blkdev.h>
	11	#include <linux/buffer_head.h>
5a0e3ad6	12	#include <linux/gfp.h>
5db53f3e JE	13
	14	#define PAGE_OFS(ofs) ((ofs) & (PAGE_SIZE-1))
	15
	16	static void request_complete(struct bio *bio, int err)
	17	{
	18	complete((struct completion *)bio->bi_private);
	19	}
	20
	21	static int sync_request(struct page page, struct block_device bdev, int rw)
	22	{
	23	struct bio bio;
	24	struct bio_vec bio_vec;
	25	struct completion complete;
	26
	27	bio_init(&bio);
	28	bio.bi_io_vec = &bio_vec;
	29	bio_vec.bv_page = page;
	30	bio_vec.bv_len = PAGE_SIZE;
	31	bio_vec.bv_offset = 0;
	32	bio.bi_vcnt = 1;
	33	bio.bi_idx = 0;
	34	bio.bi_size = PAGE_SIZE;
	35	bio.bi_bdev = bdev;
	36	bio.bi_sector = page->index * (PAGE_SIZE >> 9);
	37	init_completion(&complete);
	38	bio.bi_private = &complete;
	39	bio.bi_end_io = request_complete;
	40
	41	submit_bio(rw, &bio);
	42	generic_unplug_device(bdev_get_queue(bdev));
	43	wait_for_completion(&complete);
	44	return test_bit(BIO_UPTODATE, &bio.bi_flags) ? 0 : -EIO;
	45	}
	46
	47	static int bdev_readpage(void _sb, struct page page)
	48	{
	49	struct super_block *sb = _sb;
	50	struct block_device *bdev = logfs_super(sb)->s_bdev;
	51	int err;
	52
	53	err = sync_request(page, bdev, READ);
	54	if (err) {
	55	ClearPageUptodate(page);
	56	SetPageError(page);
	57	} else {
	58	SetPageUptodate(page);
	59	ClearPageError(page);
	60	}
	61	unlock_page(page);
	62	return err;
	63	}
	64
	65	static DECLARE_WAIT_QUEUE_HEAD(wq);
	66
	67	static void writeseg_end_io(struct bio *bio, int err)
	68	{
	69	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
	70	struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
	71	struct super_block *sb = bio->bi_private;
	72	struct logfs_super *super = logfs_super(sb);
	73	struct page *page;
	74
	75	BUG_ON(!uptodate); /* FIXME: Retry io or write elsewhere */
	76	BUG_ON(err);
77	BUG_ON(bio->bi_vcnt == 0);
78	do {
79	page = bvec->bv_page;
80	if (--bvec >= bio->bi_io_vec)
81	prefetchw(&bvec->bv_page->flags);
82
83	end_page_writeback(page);
e07bf553	84	page_cache_release(page);
5db53f3e JE	85	} while (bvec >= bio->bi_io_vec);
	86	bio_put(bio);
	87	if (atomic_dec_and_test(&super->s_pending_writes))
	88	wake_up(&wq);
	89	}
	90
	91	static int __bdev_writeseg(struct super_block *sb, u64 ofs, pgoff_t index,
	92	size_t nr_pages)
	93	{
	94	struct logfs_super *super = logfs_super(sb);
	95	struct address_space *mapping = super->s_mapping_inode->i_mapping;
	96	struct bio *bio;
	97	struct page *page;
	98	struct request_queue *q = bdev_get_queue(sb->s_bdev);
	99	unsigned int max_pages = queue_max_hw_sectors(q) >> (PAGE_SHIFT - 9);
	100	int i;
	101
59fe27c0 JE	102	if (max_pages > BIO_MAX_PAGES)
59fe27c0 JE	103	max_pages = BIO_MAX_PAGES;
5db53f3e	104	bio = bio_alloc(GFP_NOFS, max_pages);
59fe27c0	105	BUG_ON(!bio);
5db53f3e JE	106
	107	for (i = 0; i < nr_pages; i++) {
	108	if (i >= max_pages) {
	109	/* Block layer cannot split bios :( */
	110	bio->bi_vcnt = i;
	111	bio->bi_idx = 0;
	112	bio->bi_size = i * PAGE_SIZE;
	113	bio->bi_bdev = super->s_bdev;
	114	bio->bi_sector = ofs >> 9;
	115	bio->bi_private = sb;
	116	bio->bi_end_io = writeseg_end_io;
	117	atomic_inc(&super->s_pending_writes);
	118	submit_bio(WRITE, bio);
	119
	120	ofs += i * PAGE_SIZE;
	121	index += i;
	122	nr_pages -= i;
	123	i = 0;
	124
	125	bio = bio_alloc(GFP_NOFS, max_pages);
	126	BUG_ON(!bio);
	127	}
	128	page = find_lock_page(mapping, index + i);
	129	BUG_ON(!page);
	130	bio->bi_io_vec[i].bv_page = page;
	131	bio->bi_io_vec[i].bv_len = PAGE_SIZE;
	132	bio->bi_io_vec[i].bv_offset = 0;
	133
	134	BUG_ON(PageWriteback(page));
	135	set_page_writeback(page);
	136	unlock_page(page);
	137	}
	138	bio->bi_vcnt = nr_pages;
	139	bio->bi_idx = 0;
	140	bio->bi_size = nr_pages * PAGE_SIZE;
	141	bio->bi_bdev = super->s_bdev;
	142	bio->bi_sector = ofs >> 9;
	143	bio->bi_private = sb;
	144	bio->bi_end_io = writeseg_end_io;
	145	atomic_inc(&super->s_pending_writes);
	146	submit_bio(WRITE, bio);
	147	return 0;
	148	}
	149
	150	static void bdev_writeseg(struct super_block *sb, u64 ofs, size_t len)
	151	{
	152	struct logfs_super *super = logfs_super(sb);
	153	int head;
	154
	155	BUG_ON(super->s_flags & LOGFS_SB_FLAG_RO);
	156
	157	if (len == 0) {
	158	/* This can happen when the object fit perfectly into a
	159	* segment, the segment gets written per sync and subsequently
	160	* closed.
	161	*/
	162	return;
	163	}
	164	head = ofs & (PAGE_SIZE - 1);
	165	if (head) {
	166	ofs -= head;
	167	len += head;
	168	}
	169	len = PAGE_ALIGN(len);
170	__bdev_writeseg(sb, ofs, ofs >> PAGE_SHIFT, len >> PAGE_SHIFT);
171	generic_unplug_device(bdev_get_queue(logfs_super(sb)->s_bdev));
172	}
173
9421502b JE	174
	175	static void erase_end_io(struct bio *bio, int err)
	176	{
	177	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
	178	struct super_block *sb = bio->bi_private;
	179	struct logfs_super *super = logfs_super(sb);
	180
	181	BUG_ON(!uptodate); /* FIXME: Retry io or write elsewhere */
	182	BUG_ON(err);
	183	BUG_ON(bio->bi_vcnt == 0);
	184	bio_put(bio);
	185	if (atomic_dec_and_test(&super->s_pending_writes))
	186	wake_up(&wq);
	187	}
	188
	189	static int do_erase(struct super_block *sb, u64 ofs, pgoff_t index,
	190	size_t nr_pages)
	191	{
	192	struct logfs_super *super = logfs_super(sb);
	193	struct bio *bio;
	194	struct request_queue *q = bdev_get_queue(sb->s_bdev);
	195	unsigned int max_pages = queue_max_hw_sectors(q) >> (PAGE_SHIFT - 9);
	196	int i;
	197
59fe27c0 JE	198	if (max_pages > BIO_MAX_PAGES)
59fe27c0 JE	199	max_pages = BIO_MAX_PAGES;
9421502b	200	bio = bio_alloc(GFP_NOFS, max_pages);
59fe27c0	201	BUG_ON(!bio);
9421502b JE	202
	203	for (i = 0; i < nr_pages; i++) {
	204	if (i >= max_pages) {
	205	/* Block layer cannot split bios :( */
	206	bio->bi_vcnt = i;
	207	bio->bi_idx = 0;
	208	bio->bi_size = i * PAGE_SIZE;
	209	bio->bi_bdev = super->s_bdev;
	210	bio->bi_sector = ofs >> 9;
	211	bio->bi_private = sb;
	212	bio->bi_end_io = erase_end_io;
	213	atomic_inc(&super->s_pending_writes);
	214	submit_bio(WRITE, bio);
	215
	216	ofs += i * PAGE_SIZE;
	217	index += i;
	218	nr_pages -= i;
	219	i = 0;
	220
	221	bio = bio_alloc(GFP_NOFS, max_pages);
	222	BUG_ON(!bio);
	223	}
	224	bio->bi_io_vec[i].bv_page = super->s_erase_page;
	225	bio->bi_io_vec[i].bv_len = PAGE_SIZE;
	226	bio->bi_io_vec[i].bv_offset = 0;
	227	}
	228	bio->bi_vcnt = nr_pages;
	229	bio->bi_idx = 0;
	230	bio->bi_size = nr_pages * PAGE_SIZE;
	231	bio->bi_bdev = super->s_bdev;
	232	bio->bi_sector = ofs >> 9;
	233	bio->bi_private = sb;
	234	bio->bi_end_io = erase_end_io;
	235	atomic_inc(&super->s_pending_writes);
	236	submit_bio(WRITE, bio);
	237	return 0;
	238	}
	239
	240	static int bdev_erase(struct super_block *sb, loff_t to, size_t len,
	241	int ensure_write)
5db53f3e JE	242	{
5db53f3e JE	243	struct logfs_super *super = logfs_super(sb);
5db53f3e JE	244
	245	BUG_ON(to & (PAGE_SIZE - 1));
	246	BUG_ON(len & (PAGE_SIZE - 1));
	247
9421502b	248	if (super->s_flags & LOGFS_SB_FLAG_RO)
5db53f3e JE	249	return -EROFS;
5db53f3e JE	250
9421502b JE	251	if (ensure_write) {
	252	/*
	253	* Object store doesn't care whether erases happen or not.
	254	* But for the journal they are required. Otherwise a scan
	255	* can find an old commit entry and assume it is the current
	256	* one, travelling back in time.
	257	*/
	258	do_erase(sb, to, to >> PAGE_SHIFT, len >> PAGE_SHIFT);
5db53f3e	259	}
9421502b	260
5db53f3e JE	261	return 0;
	262	}
	263
	264	static void bdev_sync(struct super_block *sb)
	265	{
	266	struct logfs_super *super = logfs_super(sb);
	267
	268	wait_event(wq, atomic_read(&super->s_pending_writes) == 0);
	269	}
	270
	271	static struct page bdev_find_first_sb(struct super_block sb, u64 *ofs)
	272	{
	273	struct logfs_super *super = logfs_super(sb);
	274	struct address_space *mapping = super->s_mapping_inode->i_mapping;
	275	filler_t *filler = bdev_readpage;
	276
	277	*ofs = 0;
	278	return read_cache_page(mapping, 0, filler, sb);
	279	}
	280
	281	static struct page bdev_find_last_sb(struct super_block sb, u64 *ofs)
	282	{
	283	struct logfs_super *super = logfs_super(sb);
	284	struct address_space *mapping = super->s_mapping_inode->i_mapping;
	285	filler_t *filler = bdev_readpage;
	286	u64 pos = (super->s_bdev->bd_inode->i_size & ~0xfffULL) - 0x1000;
	287	pgoff_t index = pos >> PAGE_SHIFT;
	288
	289	*ofs = pos;
	290	return read_cache_page(mapping, index, filler, sb);
	291	}
	292
	293	static int bdev_write_sb(struct super_block sb, struct page page)
	294	{
	295	struct block_device *bdev = logfs_super(sb)->s_bdev;
	296
	297	/* Nothing special to do for block devices. */
	298	return sync_request(page, bdev, WRITE);
	299	}
	300
e5a0726a	301	static void bdev_put_device(struct logfs_super *s)
5db53f3e	302	{
e5a0726a	303	close_bdev_exclusive(s->s_bdev, FMODE_READ\|FMODE_WRITE);
5db53f3e JE	304	}
5db53f3e JE	305
6f485b41 JE	306	static int bdev_can_write_buf(struct super_block *sb, u64 ofs)
	307	{
	308	return 0;
	309	}
	310
5db53f3e JE	311	static const struct logfs_device_ops bd_devops = {
	312	.find_first_sb = bdev_find_first_sb,
	313	.find_last_sb = bdev_find_last_sb,
	314	.write_sb = bdev_write_sb,
	315	.readpage = bdev_readpage,
	316	.writeseg = bdev_writeseg,
	317	.erase = bdev_erase,
6f485b41	318	.can_write_buf = bdev_can_write_buf,
5db53f3e JE	319	.sync = bdev_sync,
	320	.put_device = bdev_put_device,
	321	};
	322
7d945a3a AV	323	int logfs_get_sb_bdev(struct logfs_super p, struct file_system_type type,
7d945a3a AV	324	const char *devname)
5db53f3e JE	325	{
	326	struct block_device *bdev;
	327
	328	bdev = open_bdev_exclusive(devname, FMODE_READ\|FMODE_WRITE, type);
7d945a3a	329	if (IS_ERR(bdev))
5db53f3e JE	330	return PTR_ERR(bdev);
	331
	332	if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
	333	int mtdnr = MINOR(bdev->bd_dev);
	334	close_bdev_exclusive(bdev, FMODE_READ\|FMODE_WRITE);
7d945a3a	335	return logfs_get_sb_mtd(p, mtdnr);
5db53f3e JE	336	}
5db53f3e JE	337
0d85c799 AV	338	p->s_bdev = bdev;
	339	p->s_mtd = NULL;
	340	p->s_devops = &bd_devops;
7d945a3a	341	return 0;
5db53f3e	342	}