nilfs2: segment buffer

/*

 * 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;

}

/*

 * segbuf.h - NILFS Segment buffer prototypes and definitions

 *

 * 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>

 *

 */

#ifndef _NILFS_SEGBUF_H

#define _NILFS_SEGBUF_H

#include <linux/fs.h>

#include <linux/buffer_head.h>

#include <linux/bio.h>

#include <linux/completion.h>

#include <linux/backing-dev.h>

/**

 * struct nilfs_segsum_info - On-memory segment summary

 * @flags: Flags

 * @nfinfo: Number of file information structures

 * @nblocks: Number of blocks included in the partial segment

 * @nsumblk: Number of summary blocks

 * @sumbytes: Byte count of segment summary

 * @nfileblk: Total number of file blocks

 * @seg_seq: Segment sequence number

 * @ctime: Creation time

 * @next: Block number of the next full segment

 */

struct nilfs_segsum_info {

	unsigned int		flags;

	unsigned long		nfinfo;

	unsigned long		nblocks;

	unsigned long		nsumblk;

	unsigned long		sumbytes;

	unsigned long		nfileblk;

	u64			seg_seq;

	time_t			ctime;

	sector_t		next;

};

/* macro for the flags */

#define NILFS_SEG_HAS_SR(sum)    ((sum)->flags & NILFS_SS_SR)

#define NILFS_SEG_LOGBGN(sum)    ((sum)->flags & NILFS_SS_LOGBGN)

#define NILFS_SEG_LOGEND(sum)    ((sum)->flags & NILFS_SS_LOGEND)

#define NILFS_SEG_DSYNC(sum)     ((sum)->flags & NILFS_SS_SYNDT)

#define NILFS_SEG_SIMPLEX(sum) \

	(((sum)->flags & (NILFS_SS_LOGBGN | NILFS_SS_LOGEND)) == \

	 (NILFS_SS_LOGBGN | NILFS_SS_LOGEND))

#define NILFS_SEG_EMPTY(sum)	((sum)->nblocks == (sum)->nsumblk)

/**

 * struct nilfs_segment_buffer - Segment buffer

 * @sb_super: back pointer to a superblock struct

 * @sb_list: List head to chain this structure

 * @sb_segent: Pointer for attaching a segment entry

 * @sb_sum: On-memory segment summary

 * @sb_segnum: Index number of the full segment

 * @sb_nextnum: Index number of the next full segment

 * @sb_fseg_start: Start block number of the full segment

 * @sb_fseg_end: End block number of the full segment

 * @sb_pseg_start: Disk block number of partial segment

 * @sb_rest_blocks: Number of residual blocks in the current segment

 * @sb_segsum_buffers: List of buffers for segment summaries

 * @sb_payload_buffers: List of buffers for segment payload

 * @sb_io_error: I/O error status

 */

struct nilfs_segment_buffer {

	struct super_block     *sb_super;

	struct list_head	sb_list;

	struct nilfs_segment_entry *sb_segent;

	/* Segment information */

	struct nilfs_segsum_info sb_sum;

	__u64			sb_segnum;

	__u64			sb_nextnum;

	sector_t		sb_fseg_start, sb_fseg_end;

	sector_t		sb_pseg_start;

	unsigned		sb_rest_blocks;

	/* Buffers */

	struct list_head	sb_segsum_buffers;

	struct list_head	sb_payload_buffers; /* including super root */

	/* io status */

	int			sb_io_error;

};

#define NILFS_LIST_SEGBUF(head)  \

	list_entry((head), struct nilfs_segment_buffer, sb_list)

#define NILFS_NEXT_SEGBUF(segbuf)  NILFS_LIST_SEGBUF((segbuf)->sb_list.next)

#define NILFS_PREV_SEGBUF(segbuf)  NILFS_LIST_SEGBUF((segbuf)->sb_list.prev)

#define NILFS_LAST_SEGBUF(head)    NILFS_LIST_SEGBUF((head)->prev)

#define NILFS_FIRST_SEGBUF(head)   NILFS_LIST_SEGBUF((head)->next)

#define NILFS_SEGBUF_IS_LAST(segbuf, head)  ((segbuf)->sb_list.next == (head))

#define nilfs_for_each_segbuf_before(s, t, h) \

	for ((s) = NILFS_FIRST_SEGBUF(h); (s) != (t); \

	     (s) = NILFS_NEXT_SEGBUF(s))

#define NILFS_SEGBUF_FIRST_BH(head)  \

	(list_entry((head)->next, struct buffer_head, b_assoc_buffers))

#define NILFS_SEGBUF_NEXT_BH(bh)  \

	(list_entry((bh)->b_assoc_buffers.next, struct buffer_head, \

		    b_assoc_buffers))

#define NILFS_SEGBUF_BH_IS_LAST(bh, head)  ((bh)->b_assoc_buffers.next == head)

int __init nilfs_init_segbuf_cache(void);

void nilfs_destroy_segbuf_cache(void);

struct nilfs_segment_buffer *nilfs_segbuf_new(struct super_block *);

void nilfs_segbuf_free(struct nilfs_segment_buffer *);

int nilfs_segbuf_map(struct nilfs_segment_buffer *, __u64, unsigned long,

		     struct the_nilfs *);

void nilfs_segbuf_set_next_segnum(struct nilfs_segment_buffer *, __u64,

				  struct the_nilfs *);

int nilfs_segbuf_reset(struct nilfs_segment_buffer *, unsigned, time_t);

int nilfs_segbuf_extend_segsum(struct nilfs_segment_buffer *);

int nilfs_segbuf_extend_payload(struct nilfs_segment_buffer *,

				struct buffer_head **);

void nilfs_segbuf_fill_in_segsum(struct nilfs_segment_buffer *);

void nilfs_segbuf_fill_in_segsum_crc(struct nilfs_segment_buffer *, u32);

void nilfs_segbuf_fill_in_data_crc(struct nilfs_segment_buffer *, u32);

static inline void

nilfs_segbuf_add_segsum_buffer(struct nilfs_segment_buffer *segbuf,

			       struct buffer_head *bh)

{

	list_add_tail(&bh->b_assoc_buffers, &segbuf->sb_segsum_buffers);

	segbuf->sb_sum.nblocks++;

	segbuf->sb_sum.nsumblk++;

}

static inline void

nilfs_segbuf_add_payload_buffer(struct nilfs_segment_buffer *segbuf,

				struct buffer_head *bh)

{

	list_add_tail(&bh->b_assoc_buffers, &segbuf->sb_payload_buffers);

	segbuf->sb_sum.nblocks++;

}

static inline void

nilfs_segbuf_add_file_buffer(struct nilfs_segment_buffer *segbuf,

			     struct buffer_head *bh)

{

	get_bh(bh);

	nilfs_segbuf_add_payload_buffer(segbuf, bh);

	segbuf->sb_sum.nfileblk++;

}

void nilfs_release_buffers(struct list_head *);

static inline void nilfs_segbuf_clear(struct nilfs_segment_buffer *segbuf)

{

	nilfs_release_buffers(&segbuf->sb_segsum_buffers);

	nilfs_release_buffers(&segbuf->sb_payload_buffers);

}

struct nilfs_write_info {

	struct bio	       *bio;

	int 			start, end; /* The region to be submitted */

	int			rest_blocks;

	int			max_pages;

	int			nr_vecs;

	sector_t		blocknr;

	int			nbio;

	atomic_t		err;

	struct completion	bio_event;

				/* completion event of segment write */

	/*

	 * The following fields must be set explicitly

	 */

	struct super_block     *sb;

	struct backing_dev_info *bdi; /* backing dev info */

	struct buffer_head     *bh_sr;

};

void nilfs_segbuf_prepare_write(struct nilfs_segment_buffer *,

				struct nilfs_write_info *);

int nilfs_segbuf_write(struct nilfs_segment_buffer *,

		       struct nilfs_write_info *);

int nilfs_segbuf_wait(struct nilfs_segment_buffer *,

		      struct nilfs_write_info *);

#endif /* _NILFS_SEGBUF_H */