segbuf.c

Go to the documentation of this file.

/*
 * 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 <[email protected]>
 *
 */

#include <linux/buffer_head.h>
#include <linux/writeback.h>
#include <linux/crc32.h>
#include <linux/backing-dev.h>
#include <linux/slab.h>
#include "page.h"
#include "segbuf.h"


struct nilfs_write_info {
    struct the_nilfs       *nilfs;
    struct bio         *bio;
    int         start, end; /* The region to be submitted */
    int         rest_blocks;
    int         max_pages;
    int         nr_vecs;
    sector_t        blocknr;
};

static int nilfs_segbuf_write(struct nilfs_segment_buffer *segbuf,
                  struct the_nilfs *nilfs);
static int nilfs_segbuf_wait(struct nilfs_segment_buffer *segbuf);

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_super_root = NULL;

    init_completion(&segbuf->sb_bio_event);
    atomic_set(&segbuf->sb_err, 0);
    segbuf->sb_nbio = 0;

    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_map_cont(struct nilfs_segment_buffer *segbuf,
               struct nilfs_segment_buffer *prev)
{
    segbuf->sb_segnum = prev->sb_segnum;
    segbuf->sb_fseg_start = prev->sb_fseg_start;
    segbuf->sb_fseg_end = prev->sb_fseg_end;
    segbuf->sb_pseg_start = prev->sb_pseg_start + prev->sb_sum.nblocks;
    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, __u64 cno)
{
    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_sum.cno = cno;
    return 0;
}

/*
 * Setup segment 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;
    raw_sum->ss_cno      = cpu_to_le64(segbuf->sb_sum.cno);
}

/*
 * CRC calculation routines
 */
static 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);
}

static 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);
        crc = crc32_le(crc, kaddr + bh_offset(bh), bh->b_size);
        kunmap_atomic(kaddr);
    }
    raw_sum->ss_datasum = cpu_to_le32(crc);
}

static void
nilfs_segbuf_fill_in_super_root_crc(struct nilfs_segment_buffer *segbuf,
                    u32 seed)
{
    struct nilfs_super_root *raw_sr;
    struct the_nilfs *nilfs = segbuf->sb_super->s_fs_info;
    unsigned srsize;
    u32 crc;

    raw_sr = (struct nilfs_super_root *)segbuf->sb_super_root->b_data;
    srsize = NILFS_SR_BYTES(nilfs->ns_inode_size);
    crc = crc32_le(seed,
               (unsigned char *)raw_sr + sizeof(raw_sr->sr_sum),
               srsize - sizeof(raw_sr->sr_sum));
    raw_sr->sr_sum = cpu_to_le32(crc);
}

static 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);
        brelse(bh);
    }
}

static void nilfs_segbuf_clear(struct nilfs_segment_buffer *segbuf)
{
    nilfs_release_buffers(&segbuf->sb_segsum_buffers);
    nilfs_release_buffers(&segbuf->sb_payload_buffers);
    segbuf->sb_super_root = NULL;
}

/*
 * Iterators for segment buffers
 */
void nilfs_clear_logs(struct list_head *logs)
{
    struct nilfs_segment_buffer *segbuf;

    list_for_each_entry(segbuf, logs, sb_list)
        nilfs_segbuf_clear(segbuf);
}

void nilfs_truncate_logs(struct list_head *logs,
             struct nilfs_segment_buffer *last)
{
    struct nilfs_segment_buffer *n, *segbuf;

    segbuf = list_prepare_entry(last, logs, sb_list);
    list_for_each_entry_safe_continue(segbuf, n, logs, sb_list) {
        list_del_init(&segbuf->sb_list);
        nilfs_segbuf_clear(segbuf);
        nilfs_segbuf_free(segbuf);
    }
}

int nilfs_write_logs(struct list_head *logs, struct the_nilfs *nilfs)
{
    struct nilfs_segment_buffer *segbuf;
    int ret = 0;

    list_for_each_entry(segbuf, logs, sb_list) {
        ret = nilfs_segbuf_write(segbuf, nilfs);
        if (ret)
            break;
    }
    return ret;
}

int nilfs_wait_on_logs(struct list_head *logs)
{
    struct nilfs_segment_buffer *segbuf;
    int err, ret = 0;

    list_for_each_entry(segbuf, logs, sb_list) {
        err = nilfs_segbuf_wait(segbuf);
        if (err && !ret)
            ret = err;
    }
    return ret;
}

void nilfs_add_checksums_on_logs(struct list_head *logs, u32 seed)
{
    struct nilfs_segment_buffer *segbuf;

    list_for_each_entry(segbuf, logs, sb_list) {
        if (segbuf->sb_super_root)
            nilfs_segbuf_fill_in_super_root_crc(segbuf, seed);
        nilfs_segbuf_fill_in_segsum_crc(segbuf, seed);
        nilfs_segbuf_fill_in_data_crc(segbuf, seed);
    }
}

/*
 * 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_segment_buffer *segbuf = 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(&segbuf->sb_err);

    bio_put(bio);
    complete(&segbuf->sb_bio_event);
}

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

    if (segbuf->sb_nbio > 0 &&
        bdi_write_congested(segbuf->sb_super->s_bdi)) {
        wait_for_completion(&segbuf->sb_bio_event);
        segbuf->sb_nbio--;
        if (unlikely(atomic_read(&segbuf->sb_err))) {
            bio_put(bio);
            err = -EIO;
            goto failed;
        }
    }

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

static struct bio *nilfs_alloc_seg_bio(struct the_nilfs *nilfs, sector_t start,
                       int nr_vecs)
{
    struct bio *bio;

    bio = bio_alloc(GFP_NOIO, nr_vecs);
    if (bio == NULL) {
        while (!bio && (nr_vecs >>= 1))
            bio = bio_alloc(GFP_NOIO, nr_vecs);
    }
    if (likely(bio)) {
        bio->bi_bdev = nilfs->ns_bdev;
        bio->bi_sector = start << (nilfs->ns_blocksize_bits - 9);
    }
    return bio;
}

static 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->nilfs->ns_bdev);
    wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
    wi->start = wi->end = 0;
    wi->blocknr = segbuf->sb_pseg_start;
}

static int nilfs_segbuf_submit_bh(struct nilfs_segment_buffer *segbuf,
                  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->nilfs, 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_segbuf_submit_bio(segbuf, wi, mode);
    /* never submit current bh */
    if (likely(!err))
        goto repeat;
    return err;
}

static int nilfs_segbuf_write(struct nilfs_segment_buffer *segbuf,
                  struct the_nilfs *nilfs)
{
    struct nilfs_write_info wi;
    struct buffer_head *bh;
    int res = 0, rw = WRITE;

    wi.nilfs = nilfs;
    nilfs_segbuf_prepare_write(segbuf, &wi);

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

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

    if (wi.bio) {
        /*
         * Last BIO is always sent through the following
         * submission.
         */
        rw |= REQ_SYNC;
        res = nilfs_segbuf_submit_bio(segbuf, &wi, rw);
    }

 failed_bio:
    return res;
}

static int nilfs_segbuf_wait(struct nilfs_segment_buffer *segbuf)
{
    int err = 0;

    if (!segbuf->sb_nbio)
        return 0;

    do {
        wait_for_completion(&segbuf->sb_bio_event);
    } while (--segbuf->sb_nbio > 0);

    if (unlikely(atomic_read(&segbuf->sb_err) > 0)) {
        printk(KERN_ERR "NILFS: IO error writing segment\n");
        err = -EIO;
    }
    return err;
}