[deliverable/linux.git] / fs / nilfs2 / segbuf.c

/*
 * segbuf.c - NILFS segment buffer
 *
 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Written by Ryusuke Konishi <ryusuke@osrg.net>
 *
 */

#include <linux/buffer_head.h>
#include <linux/writeback.h>
#include <linux/crc32.h>
#include "page.h"
#include "segbuf.h"
#include "seglist.h"


static struct kmem_cache *nilfs_segbuf_cachep;

static void nilfs_segbuf_init_once(void *obj)
{
	memset(obj, 0, sizeof(struct nilfs_segment_buffer));
}

int __init nilfs_init_segbuf_cache(void)
{
	nilfs_segbuf_cachep =
		kmem_cache_create("nilfs2_segbuf_cache",
				  sizeof(struct nilfs_segment_buffer),
				  0, SLAB_RECLAIM_ACCOUNT,
				  nilfs_segbuf_init_once);

	return (nilfs_segbuf_cachep == NULL) ? -ENOMEM : 0;
}

void nilfs_destroy_segbuf_cache(void)
{
	kmem_cache_destroy(nilfs_segbuf_cachep);
}

struct nilfs_segment_buffer *nilfs_segbuf_new(struct super_block *sb)
{
	struct nilfs_segment_buffer *segbuf;

	segbuf = kmem_cache_alloc(nilfs_segbuf_cachep, GFP_NOFS);
	if (unlikely(!segbuf))
		return NULL;

	segbuf->sb_super = sb;
	INIT_LIST_HEAD(&segbuf->sb_list);
	INIT_LIST_HEAD(&segbuf->sb_segsum_buffers);
	INIT_LIST_HEAD(&segbuf->sb_payload_buffers);
	return segbuf;
}

void nilfs_segbuf_free(struct nilfs_segment_buffer *segbuf)
{
	kmem_cache_free(nilfs_segbuf_cachep, segbuf);
}

void nilfs_segbuf_map(struct nilfs_segment_buffer *segbuf, __u64 segnum,
		     unsigned long offset, struct the_nilfs *nilfs)
{
	segbuf->sb_segnum = segnum;
	nilfs_get_segment_range(nilfs, segnum, &segbuf->sb_fseg_start,
				&segbuf->sb_fseg_end);

	segbuf->sb_pseg_start = segbuf->sb_fseg_start + offset;
	segbuf->sb_rest_blocks =
		segbuf->sb_fseg_end - segbuf->sb_pseg_start + 1;
}

void nilfs_segbuf_set_next_segnum(struct nilfs_segment_buffer *segbuf,
				  __u64 nextnum, struct the_nilfs *nilfs)
{
	segbuf->sb_nextnum = nextnum;
	segbuf->sb_sum.next = nilfs_get_segment_start_blocknr(nilfs, nextnum);
}

int nilfs_segbuf_extend_segsum(struct nilfs_segment_buffer *segbuf)
{
	struct buffer_head *bh;

	bh = sb_getblk(segbuf->sb_super,
		       segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk);
	if (unlikely(!bh))
		return -ENOMEM;

	nilfs_segbuf_add_segsum_buffer(segbuf, bh);
	return 0;
}

int nilfs_segbuf_extend_payload(struct nilfs_segment_buffer *segbuf,
				struct buffer_head **bhp)
{
	struct buffer_head *bh;

	bh = sb_getblk(segbuf->sb_super,
		       segbuf->sb_pseg_start + segbuf->sb_sum.nblocks);
	if (unlikely(!bh))
		return -ENOMEM;

	nilfs_segbuf_add_payload_buffer(segbuf, bh);
	*bhp = bh;
	return 0;
}

int nilfs_segbuf_reset(struct nilfs_segment_buffer *segbuf, unsigned flags,
		       time_t ctime)
{
	int err;

	segbuf->sb_sum.nblocks = segbuf->sb_sum.nsumblk = 0;
	err = nilfs_segbuf_extend_segsum(segbuf);
	if (unlikely(err))
		return err;

	segbuf->sb_sum.flags = flags;
	segbuf->sb_sum.sumbytes = sizeof(struct nilfs_segment_summary);
	segbuf->sb_sum.nfinfo = segbuf->sb_sum.nfileblk = 0;
	segbuf->sb_sum.ctime = ctime;

	segbuf->sb_io_error = 0;
	return 0;
}

/*
 * Setup segument summary
 */
void nilfs_segbuf_fill_in_segsum(struct nilfs_segment_buffer *segbuf)
{
	struct nilfs_segment_summary *raw_sum;
	struct buffer_head *bh_sum;

	bh_sum = list_entry(segbuf->sb_segsum_buffers.next,
			    struct buffer_head, b_assoc_buffers);
	raw_sum = (struct nilfs_segment_summary *)bh_sum->b_data;

	raw_sum->ss_magic    = cpu_to_le32(NILFS_SEGSUM_MAGIC);
	raw_sum->ss_bytes    = cpu_to_le16(sizeof(*raw_sum));
	raw_sum->ss_flags    = cpu_to_le16(segbuf->sb_sum.flags);
	raw_sum->ss_seq      = cpu_to_le64(segbuf->sb_sum.seg_seq);
	raw_sum->ss_create   = cpu_to_le64(segbuf->sb_sum.ctime);
	raw_sum->ss_next     = cpu_to_le64(segbuf->sb_sum.next);
	raw_sum->ss_nblocks  = cpu_to_le32(segbuf->sb_sum.nblocks);
	raw_sum->ss_nfinfo   = cpu_to_le32(segbuf->sb_sum.nfinfo);
	raw_sum->ss_sumbytes = cpu_to_le32(segbuf->sb_sum.sumbytes);
	raw_sum->ss_pad      = 0;
}

/*
 * CRC calculation routines
 */
void nilfs_segbuf_fill_in_segsum_crc(struct nilfs_segment_buffer *segbuf,
				     u32 seed)
{
	struct buffer_head *bh;
	struct nilfs_segment_summary *raw_sum;
	unsigned long size, bytes = segbuf->sb_sum.sumbytes;
	u32 crc;

	bh = list_entry(segbuf->sb_segsum_buffers.next, struct buffer_head,
			b_assoc_buffers);

	raw_sum = (struct nilfs_segment_summary *)bh->b_data;
	size = min_t(unsigned long, bytes, bh->b_size);
	crc = crc32_le(seed,
		       (unsigned char *)raw_sum +
		       sizeof(raw_sum->ss_datasum) + sizeof(raw_sum->ss_sumsum),
		       size - (sizeof(raw_sum->ss_datasum) +
			       sizeof(raw_sum->ss_sumsum)));

	list_for_each_entry_continue(bh, &segbuf->sb_segsum_buffers,
				     b_assoc_buffers) {
		bytes -= size;
		size = min_t(unsigned long, bytes, bh->b_size);
		crc = crc32_le(crc, bh->b_data, size);
	}
	raw_sum->ss_sumsum = cpu_to_le32(crc);
}

void nilfs_segbuf_fill_in_data_crc(struct nilfs_segment_buffer *segbuf,
				   u32 seed)
{
	struct buffer_head *bh;
	struct nilfs_segment_summary *raw_sum;
	void *kaddr;
	u32 crc;

	bh = list_entry(segbuf->sb_segsum_buffers.next, struct buffer_head,
			b_assoc_buffers);
	raw_sum = (struct nilfs_segment_summary *)bh->b_data;
	crc = crc32_le(seed,
		       (unsigned char *)raw_sum + sizeof(raw_sum->ss_datasum),
		       bh->b_size - sizeof(raw_sum->ss_datasum));

	list_for_each_entry_continue(bh, &segbuf->sb_segsum_buffers,
				     b_assoc_buffers) {
		crc = crc32_le(crc, bh->b_data, bh->b_size);
	}
	list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
		kaddr = kmap_atomic(bh->b_page, KM_USER0);
		crc = crc32_le(crc, kaddr + bh_offset(bh), bh->b_size);
		kunmap_atomic(kaddr, KM_USER0);
	}
	raw_sum->ss_datasum = cpu_to_le32(crc);
}

void nilfs_release_buffers(struct list_head *list)
{
	struct buffer_head *bh, *n;

	list_for_each_entry_safe(bh, n, list, b_assoc_buffers) {
		list_del_init(&bh->b_assoc_buffers);
		if (buffer_nilfs_allocated(bh)) {
			struct page *clone_page = bh->b_page;

			/* remove clone page */
			brelse(bh);
			page_cache_release(clone_page); /* for each bh */
			if (page_count(clone_page) <= 2) {
				lock_page(clone_page);
				nilfs_free_private_page(clone_page);
			}
			continue;
		}
		brelse(bh);
	}
}

/*
 * BIO operations
 */
static void nilfs_end_bio_write(struct bio *bio, int err)
{
	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
	struct nilfs_write_info *wi = bio->bi_private;

	if (err == -EOPNOTSUPP) {
		set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
		bio_put(bio);
		/* to be detected by submit_seg_bio() */
	}

	if (!uptodate)
		atomic_inc(&wi->err);

	bio_put(bio);
	complete(&wi->bio_event);
}

static int nilfs_submit_seg_bio(struct nilfs_write_info *wi, int mode)
{
	struct bio *bio = wi->bio;
	int err;

	if (wi->nbio > 0 && bdi_write_congested(wi->bdi)) {
		wait_for_completion(&wi->bio_event);
		wi->nbio--;
		if (unlikely(atomic_read(&wi->err))) {
			bio_put(bio);
			err = -EIO;
			goto failed;
		}
	}

	bio->bi_end_io = nilfs_end_bio_write;
	bio->bi_private = wi;
	bio_get(bio);
	submit_bio(mode, bio);
	if (bio_flagged(bio, BIO_EOPNOTSUPP)) {
		bio_put(bio);
		err = -EOPNOTSUPP;
		goto failed;
	}
	wi->nbio++;
	bio_put(bio);

	wi->bio = NULL;
	wi->rest_blocks -= wi->end - wi->start;
	wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
	wi->start = wi->end;
	return 0;

 failed:
	wi->bio = NULL;
	return err;
}

/**
 * nilfs_alloc_seg_bio - allocate a bio for writing segment.
 * @sb: super block
 * @start: beginning disk block number of this BIO.
 * @nr_vecs: request size of page vector.
 *
 * alloc_seg_bio() allocates a new BIO structure and initialize it.
 *
 * Return Value: On success, pointer to the struct bio is returned.
 * On error, NULL is returned.
 */
static struct bio *nilfs_alloc_seg_bio(struct super_block *sb, sector_t start,
				       int nr_vecs)
{
	struct bio *bio;

	bio = bio_alloc(GFP_NOWAIT, nr_vecs);
	if (bio == NULL) {
		while (!bio && (nr_vecs >>= 1))
			bio = bio_alloc(GFP_NOWAIT, nr_vecs);
	}
	if (likely(bio)) {
		bio->bi_bdev = sb->s_bdev;
		bio->bi_sector = (sector_t)start << (sb->s_blocksize_bits - 9);
	}
	return bio;
}

void nilfs_segbuf_prepare_write(struct nilfs_segment_buffer *segbuf,
				struct nilfs_write_info *wi)
{
	wi->bio = NULL;
	wi->rest_blocks = segbuf->sb_sum.nblocks;
	wi->max_pages = bio_get_nr_vecs(wi->sb->s_bdev);
	wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
	wi->start = wi->end = 0;
	wi->nbio = 0;
	wi->blocknr = segbuf->sb_pseg_start;

	atomic_set(&wi->err, 0);
	init_completion(&wi->bio_event);
}

static int nilfs_submit_bh(struct nilfs_write_info *wi, struct buffer_head *bh,
			   int mode)
{
	int len, err;

	BUG_ON(wi->nr_vecs <= 0);
 repeat:
	if (!wi->bio) {
		wi->bio = nilfs_alloc_seg_bio(wi->sb, wi->blocknr + wi->end,
					      wi->nr_vecs);
		if (unlikely(!wi->bio))
			return -ENOMEM;
	}

	len = bio_add_page(wi->bio, bh->b_page, bh->b_size, bh_offset(bh));
	if (len == bh->b_size) {
		wi->end++;
		return 0;
	}
	/* bio is FULL */
	err = nilfs_submit_seg_bio(wi, mode);
	/* never submit current bh */
	if (likely(!err))
		goto repeat;
	return err;
}

int nilfs_segbuf_write(struct nilfs_segment_buffer *segbuf,
		       struct nilfs_write_info *wi)
{
	struct buffer_head *bh;
	int res, rw = WRITE;

	list_for_each_entry(bh, &segbuf->sb_segsum_buffers, b_assoc_buffers) {
		res = nilfs_submit_bh(wi, bh, rw);
		if (unlikely(res))
			goto failed_bio;
	}

	list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
		res = nilfs_submit_bh(wi, bh, rw);
		if (unlikely(res))
			goto failed_bio;
	}

	if (wi->bio) {
		/*
		 * Last BIO is always sent through the following
		 * submission.
		 */
		rw |= (1 << BIO_RW_SYNCIO);
		res = nilfs_submit_seg_bio(wi, rw);
		if (unlikely(res))
			goto failed_bio;
	}

	res = 0;
 out:
	return res;

 failed_bio:
	atomic_inc(&wi->err);
	goto out;
}

/**
 * nilfs_segbuf_wait - wait for completion of requested BIOs
 * @wi: nilfs_write_info
 *
 * Return Value: On Success, 0 is returned. On Error, one of the following
 * negative error code is returned.
 *
 * %-EIO - I/O error
 */
int nilfs_segbuf_wait(struct nilfs_segment_buffer *segbuf,
		      struct nilfs_write_info *wi)
{
	int err = 0;

	if (!wi->nbio)
		return 0;

	do {
		wait_for_completion(&wi->bio_event);
	} while (--wi->nbio > 0);

	if (unlikely(atomic_read(&wi->err) > 0)) {
		printk(KERN_ERR "NILFS: IO error writing segment\n");
		err = -EIO;
		segbuf->sb_io_error = 1;
	}
	return err;
}
Commit	Line	Data
64b5a32e RK	1	/*
	2	* segbuf.c - NILFS segment buffer
	3	*
	4	* Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License as published by
	8	* the Free Software Foundation; either version 2 of the License, or
	9	* (at your option) any later version.
	10	*
	11	* This program is distributed in the hope that it will be useful,
	12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	* GNU General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU General Public License
	17	* along with this program; if not, write to the Free Software
	18	* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
	19	*
	20	* Written by Ryusuke Konishi <ryusuke@osrg.net>
	21	*
	22	*/
	23
	24	#include <linux/buffer_head.h>
	25	#include <linux/writeback.h>
	26	#include <linux/crc32.h>
	27	#include "page.h"
	28	#include "segbuf.h"
	29	#include "seglist.h"
	30
	31
	32	static struct kmem_cache *nilfs_segbuf_cachep;
	33
	34	static void nilfs_segbuf_init_once(void *obj)
	35	{
	36	memset(obj, 0, sizeof(struct nilfs_segment_buffer));
	37	}
	38
	39	int __init nilfs_init_segbuf_cache(void)
	40	{
	41	nilfs_segbuf_cachep =
	42	kmem_cache_create("nilfs2_segbuf_cache",
	43	sizeof(struct nilfs_segment_buffer),
	44	0, SLAB_RECLAIM_ACCOUNT,
	45	nilfs_segbuf_init_once);
	46
	47	return (nilfs_segbuf_cachep == NULL) ? -ENOMEM : 0;
	48	}
	49
	50	void nilfs_destroy_segbuf_cache(void)
	51	{
	52	kmem_cache_destroy(nilfs_segbuf_cachep);
	53	}
	54
	55	struct nilfs_segment_buffer nilfs_segbuf_new(struct super_block sb)
	56	{
	57	struct nilfs_segment_buffer *segbuf;
	58
	59	segbuf = kmem_cache_alloc(nilfs_segbuf_cachep, GFP_NOFS);
	60	if (unlikely(!segbuf))
	61	return NULL;
	62
	63	segbuf->sb_super = sb;
	64	INIT_LIST_HEAD(&segbuf->sb_list);
65	INIT_LIST_HEAD(&segbuf->sb_segsum_buffers);
66	INIT_LIST_HEAD(&segbuf->sb_payload_buffers);
64b5a32e RK	67	return segbuf;
	68	}
	69
	70	void nilfs_segbuf_free(struct nilfs_segment_buffer *segbuf)
	71	{
64b5a32e RK	72	kmem_cache_free(nilfs_segbuf_cachep, segbuf);
	73	}
	74
cece5520	75	void nilfs_segbuf_map(struct nilfs_segment_buffer *segbuf, __u64 segnum,
64b5a32e RK	76	unsigned long offset, struct the_nilfs *nilfs)
64b5a32e RK	77	{
64b5a32e RK	78	segbuf->sb_segnum = segnum;
	79	nilfs_get_segment_range(nilfs, segnum, &segbuf->sb_fseg_start,
	80	&segbuf->sb_fseg_end);
	81
	82	segbuf->sb_pseg_start = segbuf->sb_fseg_start + offset;
	83	segbuf->sb_rest_blocks =
	84	segbuf->sb_fseg_end - segbuf->sb_pseg_start + 1;
64b5a32e RK	85	}
	86
	87	void nilfs_segbuf_set_next_segnum(struct nilfs_segment_buffer *segbuf,
	88	__u64 nextnum, struct the_nilfs *nilfs)
	89	{
	90	segbuf->sb_nextnum = nextnum;
	91	segbuf->sb_sum.next = nilfs_get_segment_start_blocknr(nilfs, nextnum);
	92	}
	93
	94	int nilfs_segbuf_extend_segsum(struct nilfs_segment_buffer *segbuf)
	95	{
	96	struct buffer_head *bh;
	97
	98	bh = sb_getblk(segbuf->sb_super,
	99	segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk);
	100	if (unlikely(!bh))
	101	return -ENOMEM;
	102
	103	nilfs_segbuf_add_segsum_buffer(segbuf, bh);
	104	return 0;
	105	}
	106
	107	int nilfs_segbuf_extend_payload(struct nilfs_segment_buffer *segbuf,
	108	struct buffer_head **bhp)
	109	{
	110	struct buffer_head *bh;
	111
	112	bh = sb_getblk(segbuf->sb_super,
	113	segbuf->sb_pseg_start + segbuf->sb_sum.nblocks);
	114	if (unlikely(!bh))
	115	return -ENOMEM;
	116
	117	nilfs_segbuf_add_payload_buffer(segbuf, bh);
	118	*bhp = bh;
	119	return 0;
	120	}
	121
	122	int nilfs_segbuf_reset(struct nilfs_segment_buffer *segbuf, unsigned flags,
	123	time_t ctime)
	124	{
	125	int err;
	126
	127	segbuf->sb_sum.nblocks = segbuf->sb_sum.nsumblk = 0;
	128	err = nilfs_segbuf_extend_segsum(segbuf);
	129	if (unlikely(err))
	130	return err;
	131
	132	segbuf->sb_sum.flags = flags;
	133	segbuf->sb_sum.sumbytes = sizeof(struct nilfs_segment_summary);
	134	segbuf->sb_sum.nfinfo = segbuf->sb_sum.nfileblk = 0;
	135	segbuf->sb_sum.ctime = ctime;
	136
	137	segbuf->sb_io_error = 0;
	138	return 0;
	139	}
	140
	141	/*
	142	* Setup segument summary
	143	*/
	144	void nilfs_segbuf_fill_in_segsum(struct nilfs_segment_buffer *segbuf)
	145	{
	146	struct nilfs_segment_summary *raw_sum;
	147	struct buffer_head *bh_sum;
	148
149	bh_sum = list_entry(segbuf->sb_segsum_buffers.next,
150	struct buffer_head, b_assoc_buffers);
151	raw_sum = (struct nilfs_segment_summary *)bh_sum->b_data;
152
153	raw_sum->ss_magic = cpu_to_le32(NILFS_SEGSUM_MAGIC);
154	raw_sum->ss_bytes = cpu_to_le16(sizeof(*raw_sum));
155	raw_sum->ss_flags = cpu_to_le16(segbuf->sb_sum.flags);
156	raw_sum->ss_seq = cpu_to_le64(segbuf->sb_sum.seg_seq);
157	raw_sum->ss_create = cpu_to_le64(segbuf->sb_sum.ctime);
158	raw_sum->ss_next = cpu_to_le64(segbuf->sb_sum.next);
159	raw_sum->ss_nblocks = cpu_to_le32(segbuf->sb_sum.nblocks);
160	raw_sum->ss_nfinfo = cpu_to_le32(segbuf->sb_sum.nfinfo);
161	raw_sum->ss_sumbytes = cpu_to_le32(segbuf->sb_sum.sumbytes);
162	raw_sum->ss_pad = 0;
163	}
164
165	/*
166	* CRC calculation routines
167	*/
168	void nilfs_segbuf_fill_in_segsum_crc(struct nilfs_segment_buffer *segbuf,
169	u32 seed)
170	{
171	struct buffer_head *bh;
172	struct nilfs_segment_summary *raw_sum;
173	unsigned long size, bytes = segbuf->sb_sum.sumbytes;
174	u32 crc;
175
176	bh = list_entry(segbuf->sb_segsum_buffers.next, struct buffer_head,
177	b_assoc_buffers);
178
179	raw_sum = (struct nilfs_segment_summary *)bh->b_data;
180	size = min_t(unsigned long, bytes, bh->b_size);
181	crc = crc32_le(seed,
182	(unsigned char *)raw_sum +
183	sizeof(raw_sum->ss_datasum) + sizeof(raw_sum->ss_sumsum),
184	size - (sizeof(raw_sum->ss_datasum) +
185	sizeof(raw_sum->ss_sumsum)));
186
187	list_for_each_entry_continue(bh, &segbuf->sb_segsum_buffers,
188	b_assoc_buffers) {
189	bytes -= size;
190	size = min_t(unsigned long, bytes, bh->b_size);
191	crc = crc32_le(crc, bh->b_data, size);
192	}
193	raw_sum->ss_sumsum = cpu_to_le32(crc);
194	}
195
196	void nilfs_segbuf_fill_in_data_crc(struct nilfs_segment_buffer *segbuf,
197	u32 seed)
198	{
199	struct buffer_head *bh;
200	struct nilfs_segment_summary *raw_sum;
201	void *kaddr;
202	u32 crc;
203
204	bh = list_entry(segbuf->sb_segsum_buffers.next, struct buffer_head,
205	b_assoc_buffers);
206	raw_sum = (struct nilfs_segment_summary *)bh->b_data;
207	crc = crc32_le(seed,
208	(unsigned char *)raw_sum + sizeof(raw_sum->ss_datasum),
209	bh->b_size - sizeof(raw_sum->ss_datasum));
210
211	list_for_each_entry_continue(bh, &segbuf->sb_segsum_buffers,
212	b_assoc_buffers) {
213	crc = crc32_le(crc, bh->b_data, bh->b_size);
214	}
215	list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
216	kaddr = kmap_atomic(bh->b_page, KM_USER0);
217	crc = crc32_le(crc, kaddr + bh_offset(bh), bh->b_size);
218	kunmap_atomic(kaddr, KM_USER0);
219	}
220	raw_sum->ss_datasum = cpu_to_le32(crc);
221	}
222
223	void nilfs_release_buffers(struct list_head *list)
224	{
225	struct buffer_head bh, n;
226
227	list_for_each_entry_safe(bh, n, list, b_assoc_buffers) {
228	list_del_init(&bh->b_assoc_buffers);
229	if (buffer_nilfs_allocated(bh)) {
230	struct page *clone_page = bh->b_page;
231
232	/* remove clone page */
233	brelse(bh);
234	page_cache_release(clone_page); /* for each bh */
235	if (page_count(clone_page) <= 2) {
236	lock_page(clone_page);
237	nilfs_free_private_page(clone_page);
238	}
239	continue;
240	}
241	brelse(bh);
242	}
243	}
244
245	/*
246	* BIO operations
247	*/
248	static void nilfs_end_bio_write(struct bio *bio, int err)
249	{
250	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
251	struct nilfs_write_info *wi = bio->bi_private;
252
253	if (err == -EOPNOTSUPP) {
254	set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
255	bio_put(bio);
256	/* to be detected by submit_seg_bio() */
257	}
258
259	if (!uptodate)
260	atomic_inc(&wi->err);
261
262	bio_put(bio);
263	complete(&wi->bio_event);
264	}
265
266	static int nilfs_submit_seg_bio(struct nilfs_write_info *wi, int mode)
267	{
268	struct bio *bio = wi->bio;
269	int err;
270
271	if (wi->nbio > 0 && bdi_write_congested(wi->bdi)) {
272	wait_for_completion(&wi->bio_event);
273	wi->nbio--;
274	if (unlikely(atomic_read(&wi->err))) {
275	bio_put(bio);
276	err = -EIO;
277	goto failed;
278	}
279	}
280
281	bio->bi_end_io = nilfs_end_bio_write;
282	bio->bi_private = wi;
283	bio_get(bio);
284	submit_bio(mode, bio);
285	if (bio_flagged(bio, BIO_EOPNOTSUPP)) {
286	bio_put(bio);
287	err = -EOPNOTSUPP;
288	goto failed;
289	}
290	wi->nbio++;
291	bio_put(bio);
292
293	wi->bio = NULL;
294	wi->rest_blocks -= wi->end - wi->start;
295	wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
296	wi->start = wi->end;
297	return 0;
298
299	failed:
300	wi->bio = NULL;
301	return err;
302	}
303
304	/**
305	* nilfs_alloc_seg_bio - allocate a bio for writing segment.
306	* @sb: super block
307	* @start: beginning disk block number of this BIO.
308	* @nr_vecs: request size of page vector.
309	*
310	* alloc_seg_bio() allocates a new BIO structure and initialize it.
311	*
312	* Return Value: On success, pointer to the struct bio is returned.
313	* On error, NULL is returned.
314	*/
315	static struct bio nilfs_alloc_seg_bio(struct super_block sb, sector_t start,
316	int nr_vecs)
317	{
318	struct bio *bio;
319
320	bio = bio_alloc(GFP_NOWAIT, nr_vecs);
321	if (bio == NULL) {
322	while (!bio && (nr_vecs >>= 1))
323	bio = bio_alloc(GFP_NOWAIT, nr_vecs);
324	}
325	if (likely(bio)) {
326	bio->bi_bdev = sb->s_bdev;
327	bio->bi_sector = (sector_t)start << (sb->s_blocksize_bits - 9);
328	}
329	return bio;
330	}
331
332	void nilfs_segbuf_prepare_write(struct nilfs_segment_buffer *segbuf,
333	struct nilfs_write_info *wi)
334	{
335	wi->bio = NULL;
336	wi->rest_blocks = segbuf->sb_sum.nblocks;
337	wi->max_pages = bio_get_nr_vecs(wi->sb->s_bdev);
338	wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
339	wi->start = wi->end = 0;
340	wi->nbio = 0;
341	wi->blocknr = segbuf->sb_pseg_start;
342
343	atomic_set(&wi->err, 0);
344	init_completion(&wi->bio_event);
345	}
346
347	static int nilfs_submit_bh(struct nilfs_write_info wi, struct buffer_head bh,
348	int mode)
349	{
350	int len, err;
351
352	BUG_ON(wi->nr_vecs <= 0);
353	repeat:
354	if (!wi->bio) {
355	wi->bio = nilfs_alloc_seg_bio(wi->sb, wi->blocknr + wi->end,
356	wi->nr_vecs);
357	if (unlikely(!wi->bio))
358	return -ENOMEM;
359	}
360
361	len = bio_add_page(wi->bio, bh->b_page, bh->b_size, bh_offset(bh));
362	if (len == bh->b_size) {
363	wi->end++;
364	return 0;
365	}
366	/* bio is FULL */
367	err = nilfs_submit_seg_bio(wi, mode);
368	/* never submit current bh */
369	if (likely(!err))
370	goto repeat;
371	return err;
372	}
373
374	int nilfs_segbuf_write(struct nilfs_segment_buffer *segbuf,
375	struct nilfs_write_info *wi)
376	{
377	struct buffer_head *bh;
378	int res, rw = WRITE;
379
380	list_for_each_entry(bh, &segbuf->sb_segsum_buffers, b_assoc_buffers) {
381	res = nilfs_submit_bh(wi, bh, rw);
382	if (unlikely(res))
383	goto failed_bio;
384	}
385
386	list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
387	res = nilfs_submit_bh(wi, bh, rw);
388	if (unlikely(res))
389	goto failed_bio;
390	}
391
392	if (wi->bio) {
393	/*
394	* Last BIO is always sent through the following
395	* submission.
396	*/
397	rw \|= (1 << BIO_RW_SYNCIO);
398	res = nilfs_submit_seg_bio(wi, rw);
399	if (unlikely(res))
400	goto failed_bio;
401	}
402
403	res = 0;
404	out:
405	return res;
406
407	failed_bio:
408	atomic_inc(&wi->err);
409	goto out;
410	}
411
412	/**
413	* nilfs_segbuf_wait - wait for completion of requested BIOs
414	* @wi: nilfs_write_info
415	*
416	* Return Value: On Success, 0 is returned. On Error, one of the following
417	* negative error code is returned.
418	*
419	* %-EIO - I/O error
420	*/
421	int nilfs_segbuf_wait(struct nilfs_segment_buffer *segbuf,
422	struct nilfs_write_info *wi)
423	{
424	int err = 0;
425
426	if (!wi->nbio)
427	return 0;
428
429	do {
430	wait_for_completion(&wi->bio_event);
431	} while (--wi->nbio > 0);
432
433	if (unlikely(atomic_read(&wi->err) > 0)) {
434	printk(KERN_ERR "NILFS: IO error writing segment\n");
435	err = -EIO;
436	segbuf->sb_io_error = 1;
437	}
438	return err;
439	}