[net-next-2.6.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);
	segbuf->sb_segent = NULL;
	return segbuf;
}

void nilfs_segbuf_free(struct nilfs_segment_buffer *segbuf)
{
	struct nilfs_segment_entry *ent = segbuf->sb_segent;

	if (ent != NULL && list_empty(&ent->list)) {
		/* free isolated segment list head */
		nilfs_free_segment_entry(segbuf->sb_segent);
		segbuf->sb_segent = NULL;
	}
	kmem_cache_free(nilfs_segbuf_cachep, segbuf);
}

int nilfs_segbuf_map(struct nilfs_segment_buffer *segbuf, __u64 segnum,
		     unsigned long offset, struct the_nilfs *nilfs)
{
	struct nilfs_segment_entry *ent;

	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;

	/* Attach a segment list head */
	ent = segbuf->sb_segent;
	if (ent == NULL) {
		segbuf->sb_segent = nilfs_alloc_segment_entry(segnum);
		if (unlikely(!segbuf->sb_segent))
			return -ENOMEM;
	} else {
		BUG_ON(ent->bh_su || !list_empty(&ent->list));
		ent->segnum = segnum;
	}
	return 0;
}

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);
67	segbuf->sb_segent = NULL;
68	return segbuf;
69	}
70
71	void nilfs_segbuf_free(struct nilfs_segment_buffer *segbuf)
72	{
73	struct nilfs_segment_entry *ent = segbuf->sb_segent;
74
75	if (ent != NULL && list_empty(&ent->list)) {
76	/* free isolated segment list head */
77	nilfs_free_segment_entry(segbuf->sb_segent);
78	segbuf->sb_segent = NULL;
79	}
80	kmem_cache_free(nilfs_segbuf_cachep, segbuf);
81	}
82
83	int nilfs_segbuf_map(struct nilfs_segment_buffer *segbuf, __u64 segnum,
84	unsigned long offset, struct the_nilfs *nilfs)
85	{
86	struct nilfs_segment_entry *ent;
87
88	segbuf->sb_segnum = segnum;
89	nilfs_get_segment_range(nilfs, segnum, &segbuf->sb_fseg_start,
90	&segbuf->sb_fseg_end);
91
92	segbuf->sb_pseg_start = segbuf->sb_fseg_start + offset;
93	segbuf->sb_rest_blocks =
94	segbuf->sb_fseg_end - segbuf->sb_pseg_start + 1;
95
96	/* Attach a segment list head */
97	ent = segbuf->sb_segent;
98	if (ent == NULL) {
99	segbuf->sb_segent = nilfs_alloc_segment_entry(segnum);
100	if (unlikely(!segbuf->sb_segent))
101	return -ENOMEM;
102	} else {
103	BUG_ON(ent->bh_su \|\| !list_empty(&ent->list));
104	ent->segnum = segnum;
105	}
106	return 0;
107	}
108
109	void nilfs_segbuf_set_next_segnum(struct nilfs_segment_buffer *segbuf,
110	__u64 nextnum, struct the_nilfs *nilfs)
111	{
112	segbuf->sb_nextnum = nextnum;
113	segbuf->sb_sum.next = nilfs_get_segment_start_blocknr(nilfs, nextnum);
114	}
115
116	int nilfs_segbuf_extend_segsum(struct nilfs_segment_buffer *segbuf)
117	{
118	struct buffer_head *bh;
119
120	bh = sb_getblk(segbuf->sb_super,
121	segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk);
122	if (unlikely(!bh))
123	return -ENOMEM;
124
125	nilfs_segbuf_add_segsum_buffer(segbuf, bh);
126	return 0;
127	}
128
129	int nilfs_segbuf_extend_payload(struct nilfs_segment_buffer *segbuf,
130	struct buffer_head **bhp)
131	{
132	struct buffer_head *bh;
133
134	bh = sb_getblk(segbuf->sb_super,
135	segbuf->sb_pseg_start + segbuf->sb_sum.nblocks);
136	if (unlikely(!bh))
137	return -ENOMEM;
138
139	nilfs_segbuf_add_payload_buffer(segbuf, bh);
140	*bhp = bh;
141	return 0;
142	}
143
144	int nilfs_segbuf_reset(struct nilfs_segment_buffer *segbuf, unsigned flags,
145	time_t ctime)
146	{
147	int err;
148
149	segbuf->sb_sum.nblocks = segbuf->sb_sum.nsumblk = 0;
150	err = nilfs_segbuf_extend_segsum(segbuf);
151	if (unlikely(err))
152	return err;
153
154	segbuf->sb_sum.flags = flags;
155	segbuf->sb_sum.sumbytes = sizeof(struct nilfs_segment_summary);
156	segbuf->sb_sum.nfinfo = segbuf->sb_sum.nfileblk = 0;
157	segbuf->sb_sum.ctime = ctime;
158
159	segbuf->sb_io_error = 0;
160	return 0;
161	}
162
163	/*
164	* Setup segument summary
165	*/
166	void nilfs_segbuf_fill_in_segsum(struct nilfs_segment_buffer *segbuf)
167	{
168	struct nilfs_segment_summary *raw_sum;
169	struct buffer_head *bh_sum;
170
171	bh_sum = list_entry(segbuf->sb_segsum_buffers.next,
172	struct buffer_head, b_assoc_buffers);
173	raw_sum = (struct nilfs_segment_summary *)bh_sum->b_data;
174
175	raw_sum->ss_magic = cpu_to_le32(NILFS_SEGSUM_MAGIC);
176	raw_sum->ss_bytes = cpu_to_le16(sizeof(*raw_sum));
177	raw_sum->ss_flags = cpu_to_le16(segbuf->sb_sum.flags);
178	raw_sum->ss_seq = cpu_to_le64(segbuf->sb_sum.seg_seq);
179	raw_sum->ss_create = cpu_to_le64(segbuf->sb_sum.ctime);
180	raw_sum->ss_next = cpu_to_le64(segbuf->sb_sum.next);
181	raw_sum->ss_nblocks = cpu_to_le32(segbuf->sb_sum.nblocks);
182	raw_sum->ss_nfinfo = cpu_to_le32(segbuf->sb_sum.nfinfo);
183	raw_sum->ss_sumbytes = cpu_to_le32(segbuf->sb_sum.sumbytes);
184	raw_sum->ss_pad = 0;
185	}
186
187	/*
188	* CRC calculation routines
189	*/
190	void nilfs_segbuf_fill_in_segsum_crc(struct nilfs_segment_buffer *segbuf,
191	u32 seed)
192	{
193	struct buffer_head *bh;
194	struct nilfs_segment_summary *raw_sum;
195	unsigned long size, bytes = segbuf->sb_sum.sumbytes;
196	u32 crc;
197
198	bh = list_entry(segbuf->sb_segsum_buffers.next, struct buffer_head,
199	b_assoc_buffers);
200
201	raw_sum = (struct nilfs_segment_summary *)bh->b_data;
202	size = min_t(unsigned long, bytes, bh->b_size);
203	crc = crc32_le(seed,
204	(unsigned char *)raw_sum +
205	sizeof(raw_sum->ss_datasum) + sizeof(raw_sum->ss_sumsum),
206	size - (sizeof(raw_sum->ss_datasum) +
207	sizeof(raw_sum->ss_sumsum)));
208
209	list_for_each_entry_continue(bh, &segbuf->sb_segsum_buffers,
210	b_assoc_buffers) {
211	bytes -= size;
212	size = min_t(unsigned long, bytes, bh->b_size);
213	crc = crc32_le(crc, bh->b_data, size);
214	}
215	raw_sum->ss_sumsum = cpu_to_le32(crc);
216	}
217
218	void nilfs_segbuf_fill_in_data_crc(struct nilfs_segment_buffer *segbuf,
219	u32 seed)
220	{
221	struct buffer_head *bh;
222	struct nilfs_segment_summary *raw_sum;
223	void *kaddr;
224	u32 crc;
225
226	bh = list_entry(segbuf->sb_segsum_buffers.next, struct buffer_head,
227	b_assoc_buffers);
228	raw_sum = (struct nilfs_segment_summary *)bh->b_data;
229	crc = crc32_le(seed,
230	(unsigned char *)raw_sum + sizeof(raw_sum->ss_datasum),
231	bh->b_size - sizeof(raw_sum->ss_datasum));
232
233	list_for_each_entry_continue(bh, &segbuf->sb_segsum_buffers,
234	b_assoc_buffers) {
235	crc = crc32_le(crc, bh->b_data, bh->b_size);
236	}
237	list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
238	kaddr = kmap_atomic(bh->b_page, KM_USER0);
239	crc = crc32_le(crc, kaddr + bh_offset(bh), bh->b_size);
240	kunmap_atomic(kaddr, KM_USER0);
241	}
242	raw_sum->ss_datasum = cpu_to_le32(crc);
243	}
244
245	void nilfs_release_buffers(struct list_head *list)
246	{
247	struct buffer_head bh, n;
248
249	list_for_each_entry_safe(bh, n, list, b_assoc_buffers) {
250	list_del_init(&bh->b_assoc_buffers);
251	if (buffer_nilfs_allocated(bh)) {
252	struct page *clone_page = bh->b_page;
253
254	/* remove clone page */
255	brelse(bh);
256	page_cache_release(clone_page); /* for each bh */
257	if (page_count(clone_page) <= 2) {
258	lock_page(clone_page);
259	nilfs_free_private_page(clone_page);
260	}
261	continue;
262	}
263	brelse(bh);
264	}
265	}
266
267	/*
268	* BIO operations
269	*/
270	static void nilfs_end_bio_write(struct bio *bio, int err)
271	{
272	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
273	struct nilfs_write_info *wi = bio->bi_private;
274
275	if (err == -EOPNOTSUPP) {
276	set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
277	bio_put(bio);
278	/* to be detected by submit_seg_bio() */
279	}
280
281	if (!uptodate)
282	atomic_inc(&wi->err);
283
284	bio_put(bio);
285	complete(&wi->bio_event);
286	}
287
288	static int nilfs_submit_seg_bio(struct nilfs_write_info *wi, int mode)
289	{
290	struct bio *bio = wi->bio;
291	int err;
292
293	if (wi->nbio > 0 && bdi_write_congested(wi->bdi)) {
294	wait_for_completion(&wi->bio_event);
295	wi->nbio--;
296	if (unlikely(atomic_read(&wi->err))) {
297	bio_put(bio);
298	err = -EIO;
299	goto failed;
300	}
301	}
302
303	bio->bi_end_io = nilfs_end_bio_write;
304	bio->bi_private = wi;
305	bio_get(bio);
306	submit_bio(mode, bio);
307	if (bio_flagged(bio, BIO_EOPNOTSUPP)) {
308	bio_put(bio);
309	err = -EOPNOTSUPP;
310	goto failed;
311	}
312	wi->nbio++;
313	bio_put(bio);
314
315	wi->bio = NULL;
316	wi->rest_blocks -= wi->end - wi->start;
317	wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
318	wi->start = wi->end;
319	return 0;
320
321	failed:
322	wi->bio = NULL;
323	return err;
324	}
325
326	/**
327	* nilfs_alloc_seg_bio - allocate a bio for writing segment.
328	* @sb: super block
329	* @start: beginning disk block number of this BIO.
330	* @nr_vecs: request size of page vector.
331	*
332	* alloc_seg_bio() allocates a new BIO structure and initialize it.
333	*
334	* Return Value: On success, pointer to the struct bio is returned.
335	* On error, NULL is returned.
336	*/
337	static struct bio nilfs_alloc_seg_bio(struct super_block sb, sector_t start,
338	int nr_vecs)
339	{
340	struct bio *bio;
341
342	bio = bio_alloc(GFP_NOWAIT, nr_vecs);
343	if (bio == NULL) {
344	while (!bio && (nr_vecs >>= 1))
345	bio = bio_alloc(GFP_NOWAIT, nr_vecs);
346	}
347	if (likely(bio)) {
348	bio->bi_bdev = sb->s_bdev;
349	bio->bi_sector = (sector_t)start << (sb->s_blocksize_bits - 9);
350	}
351	return bio;
352	}
353
354	void nilfs_segbuf_prepare_write(struct nilfs_segment_buffer *segbuf,
355	struct nilfs_write_info *wi)
356	{
357	wi->bio = NULL;
358	wi->rest_blocks = segbuf->sb_sum.nblocks;
359	wi->max_pages = bio_get_nr_vecs(wi->sb->s_bdev);
360	wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
361	wi->start = wi->end = 0;
362	wi->nbio = 0;
363	wi->blocknr = segbuf->sb_pseg_start;
364
365	atomic_set(&wi->err, 0);
366	init_completion(&wi->bio_event);
367	}
368
369	static int nilfs_submit_bh(struct nilfs_write_info wi, struct buffer_head bh,
370	int mode)
371	{
372	int len, err;
373
374	BUG_ON(wi->nr_vecs <= 0);
375	repeat:
376	if (!wi->bio) {
377	wi->bio = nilfs_alloc_seg_bio(wi->sb, wi->blocknr + wi->end,
378	wi->nr_vecs);
379	if (unlikely(!wi->bio))
380	return -ENOMEM;
381	}
382
383	len = bio_add_page(wi->bio, bh->b_page, bh->b_size, bh_offset(bh));
384	if (len == bh->b_size) {
385	wi->end++;
386	return 0;
387	}
388	/* bio is FULL */
389	err = nilfs_submit_seg_bio(wi, mode);
390	/* never submit current bh */
391	if (likely(!err))
392	goto repeat;
393	return err;
394	}
395
396	int nilfs_segbuf_write(struct nilfs_segment_buffer *segbuf,
397	struct nilfs_write_info *wi)
398	{
399	struct buffer_head *bh;
400	int res, rw = WRITE;
401
402	list_for_each_entry(bh, &segbuf->sb_segsum_buffers, b_assoc_buffers) {
403	res = nilfs_submit_bh(wi, bh, rw);
404	if (unlikely(res))
405	goto failed_bio;
406	}
407
408	list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
409	res = nilfs_submit_bh(wi, bh, rw);
410	if (unlikely(res))
411	goto failed_bio;
412	}
413
414	if (wi->bio) {
415	/*
416	* Last BIO is always sent through the following
417	* submission.
418	*/
419	rw \|= (1 << BIO_RW_SYNCIO);
420	res = nilfs_submit_seg_bio(wi, rw);
421	if (unlikely(res))
422	goto failed_bio;
423	}
424
425	res = 0;
426	out:
427	return res;
428
429	failed_bio:
430	atomic_inc(&wi->err);
431	goto out;
432	}
433
434	/**
435	* nilfs_segbuf_wait - wait for completion of requested BIOs
436	* @wi: nilfs_write_info
437	*
438	* Return Value: On Success, 0 is returned. On Error, one of the following
439	* negative error code is returned.
440	*
441	* %-EIO - I/O error
442	*/
443	int nilfs_segbuf_wait(struct nilfs_segment_buffer *segbuf,
444	struct nilfs_write_info *wi)
445	{
446	int err = 0;
447
448	if (!wi->nbio)
449	return 0;
450
451	do {
452	wait_for_completion(&wi->bio_event);
453	} while (--wi->nbio > 0);
454
455	if (unlikely(atomic_read(&wi->err) > 0)) {
456	printk(KERN_ERR "NILFS: IO error writing segment\n");
457	err = -EIO;
458	segbuf->sb_io_error = 1;
459	}
460	return err;
461	}