sufile.c

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/*
 * sufile.c - NILFS segment usage file.
 *
 * Copyright (C) 2006-2008 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 Koji Sato <[email protected]>.
 * Revised by Ryusuke Konishi <[email protected]>.
 */

#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/buffer_head.h>
#include <linux/errno.h>
#include <linux/nilfs2_fs.h>
#include "mdt.h"
#include "sufile.h"

struct nilfs_sufile_info {
    struct nilfs_mdt_info mi;
    unsigned long ncleansegs;/* number of clean segments */
    __u64 allocmin;     /* lower limit of allocatable segment range */
    __u64 allocmax;     /* upper limit of allocatable segment range */
};

static inline struct nilfs_sufile_info *NILFS_SUI(struct inode *sufile)
{
    return (struct nilfs_sufile_info *)NILFS_MDT(sufile);
}

static inline unsigned long
nilfs_sufile_segment_usages_per_block(const struct inode *sufile)
{
    return NILFS_MDT(sufile)->mi_entries_per_block;
}

static unsigned long
nilfs_sufile_get_blkoff(const struct inode *sufile, __u64 segnum)
{
    __u64 t = segnum + NILFS_MDT(sufile)->mi_first_entry_offset;
    do_div(t, nilfs_sufile_segment_usages_per_block(sufile));
    return (unsigned long)t;
}

static unsigned long
nilfs_sufile_get_offset(const struct inode *sufile, __u64 segnum)
{
    __u64 t = segnum + NILFS_MDT(sufile)->mi_first_entry_offset;
    return do_div(t, nilfs_sufile_segment_usages_per_block(sufile));
}

static unsigned long
nilfs_sufile_segment_usages_in_block(const struct inode *sufile, __u64 curr,
                     __u64 max)
{
    return min_t(unsigned long,
             nilfs_sufile_segment_usages_per_block(sufile) -
             nilfs_sufile_get_offset(sufile, curr),
             max - curr + 1);
}

static struct nilfs_segment_usage *
nilfs_sufile_block_get_segment_usage(const struct inode *sufile, __u64 segnum,
                     struct buffer_head *bh, void *kaddr)
{
    return kaddr + bh_offset(bh) +
        nilfs_sufile_get_offset(sufile, segnum) *
        NILFS_MDT(sufile)->mi_entry_size;
}

static inline int nilfs_sufile_get_header_block(struct inode *sufile,
                        struct buffer_head **bhp)
{
    return nilfs_mdt_get_block(sufile, 0, 0, NULL, bhp);
}

static inline int
nilfs_sufile_get_segment_usage_block(struct inode *sufile, __u64 segnum,
                     int create, struct buffer_head **bhp)
{
    return nilfs_mdt_get_block(sufile,
                   nilfs_sufile_get_blkoff(sufile, segnum),
                   create, NULL, bhp);
}

static int nilfs_sufile_delete_segment_usage_block(struct inode *sufile,
                           __u64 segnum)
{
    return nilfs_mdt_delete_block(sufile,
                      nilfs_sufile_get_blkoff(sufile, segnum));
}

static void nilfs_sufile_mod_counter(struct buffer_head *header_bh,
                     u64 ncleanadd, u64 ndirtyadd)
{
    struct nilfs_sufile_header *header;
    void *kaddr;

    kaddr = kmap_atomic(header_bh->b_page);
    header = kaddr + bh_offset(header_bh);
    le64_add_cpu(&header->sh_ncleansegs, ncleanadd);
    le64_add_cpu(&header->sh_ndirtysegs, ndirtyadd);
    kunmap_atomic(kaddr);

    mark_buffer_dirty(header_bh);
}

unsigned long nilfs_sufile_get_ncleansegs(struct inode *sufile)
{
    return NILFS_SUI(sufile)->ncleansegs;
}

int nilfs_sufile_updatev(struct inode *sufile, __u64 *segnumv, size_t nsegs,
             int create, size_t *ndone,
             void (*dofunc)(struct inode *, __u64,
                    struct buffer_head *,
                    struct buffer_head *))
{
    struct buffer_head *header_bh, *bh;
    unsigned long blkoff, prev_blkoff;
    __u64 *seg;
    size_t nerr = 0, n = 0;
    int ret = 0;

    if (unlikely(nsegs == 0))
        goto out;

    down_write(&NILFS_MDT(sufile)->mi_sem);
    for (seg = segnumv; seg < segnumv + nsegs; seg++) {
        if (unlikely(*seg >= nilfs_sufile_get_nsegments(sufile))) {
            printk(KERN_WARNING
                   "%s: invalid segment number: %llu\n", __func__,
                   (unsigned long long)*seg);
            nerr++;
        }
    }
    if (nerr > 0) {
        ret = -EINVAL;
        goto out_sem;
    }

    ret = nilfs_sufile_get_header_block(sufile, &header_bh);
    if (ret < 0)
        goto out_sem;

    seg = segnumv;
    blkoff = nilfs_sufile_get_blkoff(sufile, *seg);
    ret = nilfs_mdt_get_block(sufile, blkoff, create, NULL, &bh);
    if (ret < 0)
        goto out_header;

    for (;;) {
        dofunc(sufile, *seg, header_bh, bh);

        if (++seg >= segnumv + nsegs)
            break;
        prev_blkoff = blkoff;
        blkoff = nilfs_sufile_get_blkoff(sufile, *seg);
        if (blkoff == prev_blkoff)
            continue;

        /* get different block */
        brelse(bh);
        ret = nilfs_mdt_get_block(sufile, blkoff, create, NULL, &bh);
        if (unlikely(ret < 0))
            goto out_header;
    }
    brelse(bh);

 out_header:
    n = seg - segnumv;
    brelse(header_bh);
 out_sem:
    up_write(&NILFS_MDT(sufile)->mi_sem);
 out:
    if (ndone)
        *ndone = n;
    return ret;
}

int nilfs_sufile_update(struct inode *sufile, __u64 segnum, int create,
            void (*dofunc)(struct inode *, __u64,
                       struct buffer_head *,
                       struct buffer_head *))
{
    struct buffer_head *header_bh, *bh;
    int ret;

    if (unlikely(segnum >= nilfs_sufile_get_nsegments(sufile))) {
        printk(KERN_WARNING "%s: invalid segment number: %llu\n",
               __func__, (unsigned long long)segnum);
        return -EINVAL;
    }
    down_write(&NILFS_MDT(sufile)->mi_sem);

    ret = nilfs_sufile_get_header_block(sufile, &header_bh);
    if (ret < 0)
        goto out_sem;

    ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, create, &bh);
    if (!ret) {
        dofunc(sufile, segnum, header_bh, bh);
        brelse(bh);
    }
    brelse(header_bh);

 out_sem:
    up_write(&NILFS_MDT(sufile)->mi_sem);
    return ret;
}

int nilfs_sufile_set_alloc_range(struct inode *sufile, __u64 start, __u64 end)
{
    struct nilfs_sufile_info *sui = NILFS_SUI(sufile);
    __u64 nsegs;
    int ret = -ERANGE;

    down_write(&NILFS_MDT(sufile)->mi_sem);
    nsegs = nilfs_sufile_get_nsegments(sufile);

    if (start <= end && end < nsegs) {
        sui->allocmin = start;
        sui->allocmax = end;
        ret = 0;
    }
    up_write(&NILFS_MDT(sufile)->mi_sem);
    return ret;
}

int nilfs_sufile_alloc(struct inode *sufile, __u64 *segnump)
{
    struct buffer_head *header_bh, *su_bh;
    struct nilfs_sufile_header *header;
    struct nilfs_segment_usage *su;
    struct nilfs_sufile_info *sui = NILFS_SUI(sufile);
    size_t susz = NILFS_MDT(sufile)->mi_entry_size;
    __u64 segnum, maxsegnum, last_alloc;
    void *kaddr;
    unsigned long nsegments, ncleansegs, nsus, cnt;
    int ret, j;

    down_write(&NILFS_MDT(sufile)->mi_sem);

    ret = nilfs_sufile_get_header_block(sufile, &header_bh);
    if (ret < 0)
        goto out_sem;
    kaddr = kmap_atomic(header_bh->b_page);
    header = kaddr + bh_offset(header_bh);
    ncleansegs = le64_to_cpu(header->sh_ncleansegs);
    last_alloc = le64_to_cpu(header->sh_last_alloc);
    kunmap_atomic(kaddr);

    nsegments = nilfs_sufile_get_nsegments(sufile);
    maxsegnum = sui->allocmax;
    segnum = last_alloc + 1;
    if (segnum < sui->allocmin || segnum > sui->allocmax)
        segnum = sui->allocmin;

    for (cnt = 0; cnt < nsegments; cnt += nsus) {
        if (segnum > maxsegnum) {
            if (cnt < sui->allocmax - sui->allocmin + 1) {
                /*
                 * wrap around in the limited region.
                 * if allocation started from
                 * sui->allocmin, this never happens.
                 */
                segnum = sui->allocmin;
                maxsegnum = last_alloc;
            } else if (segnum > sui->allocmin &&
                   sui->allocmax + 1 < nsegments) {
                segnum = sui->allocmax + 1;
                maxsegnum = nsegments - 1;
            } else if (sui->allocmin > 0)  {
                segnum = 0;
                maxsegnum = sui->allocmin - 1;
            } else {
                break; /* never happens */
            }
        }
        ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, 1,
                               &su_bh);
        if (ret < 0)
            goto out_header;
        kaddr = kmap_atomic(su_bh->b_page);
        su = nilfs_sufile_block_get_segment_usage(
            sufile, segnum, su_bh, kaddr);

        nsus = nilfs_sufile_segment_usages_in_block(
            sufile, segnum, maxsegnum);
        for (j = 0; j < nsus; j++, su = (void *)su + susz, segnum++) {
            if (!nilfs_segment_usage_clean(su))
                continue;
            /* found a clean segment */
            nilfs_segment_usage_set_dirty(su);
            kunmap_atomic(kaddr);

            kaddr = kmap_atomic(header_bh->b_page);
            header = kaddr + bh_offset(header_bh);
            le64_add_cpu(&header->sh_ncleansegs, -1);
            le64_add_cpu(&header->sh_ndirtysegs, 1);
            header->sh_last_alloc = cpu_to_le64(segnum);
            kunmap_atomic(kaddr);

            sui->ncleansegs--;
            mark_buffer_dirty(header_bh);
            mark_buffer_dirty(su_bh);
            nilfs_mdt_mark_dirty(sufile);
            brelse(su_bh);
            *segnump = segnum;
            goto out_header;
        }

        kunmap_atomic(kaddr);
        brelse(su_bh);
    }

    /* no segments left */
    ret = -ENOSPC;

 out_header:
    brelse(header_bh);

 out_sem:
    up_write(&NILFS_MDT(sufile)->mi_sem);
    return ret;
}

void nilfs_sufile_do_cancel_free(struct inode *sufile, __u64 segnum,
                 struct buffer_head *header_bh,
                 struct buffer_head *su_bh)
{
    struct nilfs_segment_usage *su;
    void *kaddr;

    kaddr = kmap_atomic(su_bh->b_page);
    su = nilfs_sufile_block_get_segment_usage(sufile, segnum, su_bh, kaddr);
    if (unlikely(!nilfs_segment_usage_clean(su))) {
        printk(KERN_WARNING "%s: segment %llu must be clean\n",
               __func__, (unsigned long long)segnum);
        kunmap_atomic(kaddr);
        return;
    }
    nilfs_segment_usage_set_dirty(su);
    kunmap_atomic(kaddr);

    nilfs_sufile_mod_counter(header_bh, -1, 1);
    NILFS_SUI(sufile)->ncleansegs--;

    mark_buffer_dirty(su_bh);
    nilfs_mdt_mark_dirty(sufile);
}

void nilfs_sufile_do_scrap(struct inode *sufile, __u64 segnum,
               struct buffer_head *header_bh,
               struct buffer_head *su_bh)
{
    struct nilfs_segment_usage *su;
    void *kaddr;
    int clean, dirty;

    kaddr = kmap_atomic(su_bh->b_page);
    su = nilfs_sufile_block_get_segment_usage(sufile, segnum, su_bh, kaddr);
    if (su->su_flags == cpu_to_le32(1UL << NILFS_SEGMENT_USAGE_DIRTY) &&
        su->su_nblocks == cpu_to_le32(0)) {
        kunmap_atomic(kaddr);
        return;
    }
    clean = nilfs_segment_usage_clean(su);
    dirty = nilfs_segment_usage_dirty(su);

    /* make the segment garbage */
    su->su_lastmod = cpu_to_le64(0);
    su->su_nblocks = cpu_to_le32(0);
    su->su_flags = cpu_to_le32(1UL << NILFS_SEGMENT_USAGE_DIRTY);
    kunmap_atomic(kaddr);

    nilfs_sufile_mod_counter(header_bh, clean ? (u64)-1 : 0, dirty ? 0 : 1);
    NILFS_SUI(sufile)->ncleansegs -= clean;

    mark_buffer_dirty(su_bh);
    nilfs_mdt_mark_dirty(sufile);
}

void nilfs_sufile_do_free(struct inode *sufile, __u64 segnum,
              struct buffer_head *header_bh,
              struct buffer_head *su_bh)
{
    struct nilfs_segment_usage *su;
    void *kaddr;
    int sudirty;

    kaddr = kmap_atomic(su_bh->b_page);
    su = nilfs_sufile_block_get_segment_usage(sufile, segnum, su_bh, kaddr);
    if (nilfs_segment_usage_clean(su)) {
        printk(KERN_WARNING "%s: segment %llu is already clean\n",
               __func__, (unsigned long long)segnum);
        kunmap_atomic(kaddr);
        return;
    }
    WARN_ON(nilfs_segment_usage_error(su));
    WARN_ON(!nilfs_segment_usage_dirty(su));

    sudirty = nilfs_segment_usage_dirty(su);
    nilfs_segment_usage_set_clean(su);
    kunmap_atomic(kaddr);
    mark_buffer_dirty(su_bh);

    nilfs_sufile_mod_counter(header_bh, 1, sudirty ? (u64)-1 : 0);
    NILFS_SUI(sufile)->ncleansegs++;

    nilfs_mdt_mark_dirty(sufile);
}

int nilfs_sufile_mark_dirty(struct inode *sufile, __u64 segnum)
{
    struct buffer_head *bh;
    int ret;

    ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, 0, &bh);
    if (!ret) {
        mark_buffer_dirty(bh);
        nilfs_mdt_mark_dirty(sufile);
        brelse(bh);
    }
    return ret;
}

int nilfs_sufile_set_segment_usage(struct inode *sufile, __u64 segnum,
                   unsigned long nblocks, time_t modtime)
{
    struct buffer_head *bh;
    struct nilfs_segment_usage *su;
    void *kaddr;
    int ret;

    down_write(&NILFS_MDT(sufile)->mi_sem);
    ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, 0, &bh);
    if (ret < 0)
        goto out_sem;

    kaddr = kmap_atomic(bh->b_page);
    su = nilfs_sufile_block_get_segment_usage(sufile, segnum, bh, kaddr);
    WARN_ON(nilfs_segment_usage_error(su));
    if (modtime)
        su->su_lastmod = cpu_to_le64(modtime);
    su->su_nblocks = cpu_to_le32(nblocks);
    kunmap_atomic(kaddr);

    mark_buffer_dirty(bh);
    nilfs_mdt_mark_dirty(sufile);
    brelse(bh);

 out_sem:
    up_write(&NILFS_MDT(sufile)->mi_sem);
    return ret;
}

int nilfs_sufile_get_stat(struct inode *sufile, struct nilfs_sustat *sustat)
{
    struct buffer_head *header_bh;
    struct nilfs_sufile_header *header;
    struct the_nilfs *nilfs = sufile->i_sb->s_fs_info;
    void *kaddr;
    int ret;

    down_read(&NILFS_MDT(sufile)->mi_sem);

    ret = nilfs_sufile_get_header_block(sufile, &header_bh);
    if (ret < 0)
        goto out_sem;

    kaddr = kmap_atomic(header_bh->b_page);
    header = kaddr + bh_offset(header_bh);
    sustat->ss_nsegs = nilfs_sufile_get_nsegments(sufile);
    sustat->ss_ncleansegs = le64_to_cpu(header->sh_ncleansegs);
    sustat->ss_ndirtysegs = le64_to_cpu(header->sh_ndirtysegs);
    sustat->ss_ctime = nilfs->ns_ctime;
    sustat->ss_nongc_ctime = nilfs->ns_nongc_ctime;
    spin_lock(&nilfs->ns_last_segment_lock);
    sustat->ss_prot_seq = nilfs->ns_prot_seq;
    spin_unlock(&nilfs->ns_last_segment_lock);
    kunmap_atomic(kaddr);
    brelse(header_bh);

 out_sem:
    up_read(&NILFS_MDT(sufile)->mi_sem);
    return ret;
}

void nilfs_sufile_do_set_error(struct inode *sufile, __u64 segnum,
                   struct buffer_head *header_bh,
                   struct buffer_head *su_bh)
{
    struct nilfs_segment_usage *su;
    void *kaddr;
    int suclean;

    kaddr = kmap_atomic(su_bh->b_page);
    su = nilfs_sufile_block_get_segment_usage(sufile, segnum, su_bh, kaddr);
    if (nilfs_segment_usage_error(su)) {
        kunmap_atomic(kaddr);
        return;
    }
    suclean = nilfs_segment_usage_clean(su);
    nilfs_segment_usage_set_error(su);
    kunmap_atomic(kaddr);

    if (suclean) {
        nilfs_sufile_mod_counter(header_bh, -1, 0);
        NILFS_SUI(sufile)->ncleansegs--;
    }
    mark_buffer_dirty(su_bh);
    nilfs_mdt_mark_dirty(sufile);
}

static int nilfs_sufile_truncate_range(struct inode *sufile,
                       __u64 start, __u64 end)
{
    struct the_nilfs *nilfs = sufile->i_sb->s_fs_info;
    struct buffer_head *header_bh;
    struct buffer_head *su_bh;
    struct nilfs_segment_usage *su, *su2;
    size_t susz = NILFS_MDT(sufile)->mi_entry_size;
    unsigned long segusages_per_block;
    unsigned long nsegs, ncleaned;
    __u64 segnum;
    void *kaddr;
    ssize_t n, nc;
    int ret;
    int j;

    nsegs = nilfs_sufile_get_nsegments(sufile);

    ret = -EINVAL;
    if (start > end || start >= nsegs)
        goto out;

    ret = nilfs_sufile_get_header_block(sufile, &header_bh);
    if (ret < 0)
        goto out;

    segusages_per_block = nilfs_sufile_segment_usages_per_block(sufile);
    ncleaned = 0;

    for (segnum = start; segnum <= end; segnum += n) {
        n = min_t(unsigned long,
              segusages_per_block -
                  nilfs_sufile_get_offset(sufile, segnum),
              end - segnum + 1);
        ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, 0,
                               &su_bh);
        if (ret < 0) {
            if (ret != -ENOENT)
                goto out_header;
            /* hole */
            continue;
        }
        kaddr = kmap_atomic(su_bh->b_page);
        su = nilfs_sufile_block_get_segment_usage(
            sufile, segnum, su_bh, kaddr);
        su2 = su;
        for (j = 0; j < n; j++, su = (void *)su + susz) {
            if ((le32_to_cpu(su->su_flags) &
                 ~(1UL << NILFS_SEGMENT_USAGE_ERROR)) ||
                nilfs_segment_is_active(nilfs, segnum + j)) {
                ret = -EBUSY;
                kunmap_atomic(kaddr);
                brelse(su_bh);
                goto out_header;
            }
        }
        nc = 0;
        for (su = su2, j = 0; j < n; j++, su = (void *)su + susz) {
            if (nilfs_segment_usage_error(su)) {
                nilfs_segment_usage_set_clean(su);
                nc++;
            }
        }
        kunmap_atomic(kaddr);
        if (nc > 0) {
            mark_buffer_dirty(su_bh);
            ncleaned += nc;
        }
        brelse(su_bh);

        if (n == segusages_per_block) {
            /* make hole */
            nilfs_sufile_delete_segment_usage_block(sufile, segnum);
        }
    }
    ret = 0;

out_header:
    if (ncleaned > 0) {
        NILFS_SUI(sufile)->ncleansegs += ncleaned;
        nilfs_sufile_mod_counter(header_bh, ncleaned, 0);
        nilfs_mdt_mark_dirty(sufile);
    }
    brelse(header_bh);
out:
    return ret;
}

int nilfs_sufile_resize(struct inode *sufile, __u64 newnsegs)
{
    struct the_nilfs *nilfs = sufile->i_sb->s_fs_info;
    struct buffer_head *header_bh;
    struct nilfs_sufile_header *header;
    struct nilfs_sufile_info *sui = NILFS_SUI(sufile);
    void *kaddr;
    unsigned long nsegs, nrsvsegs;
    int ret = 0;

    down_write(&NILFS_MDT(sufile)->mi_sem);

    nsegs = nilfs_sufile_get_nsegments(sufile);
    if (nsegs == newnsegs)
        goto out;

    ret = -ENOSPC;
    nrsvsegs = nilfs_nrsvsegs(nilfs, newnsegs);
    if (newnsegs < nsegs && nsegs - newnsegs + nrsvsegs > sui->ncleansegs)
        goto out;

    ret = nilfs_sufile_get_header_block(sufile, &header_bh);
    if (ret < 0)
        goto out;

    if (newnsegs > nsegs) {
        sui->ncleansegs += newnsegs - nsegs;
    } else /* newnsegs < nsegs */ {
        ret = nilfs_sufile_truncate_range(sufile, newnsegs, nsegs - 1);
        if (ret < 0)
            goto out_header;

        sui->ncleansegs -= nsegs - newnsegs;
    }

    kaddr = kmap_atomic(header_bh->b_page);
    header = kaddr + bh_offset(header_bh);
    header->sh_ncleansegs = cpu_to_le64(sui->ncleansegs);
    kunmap_atomic(kaddr);

    mark_buffer_dirty(header_bh);
    nilfs_mdt_mark_dirty(sufile);
    nilfs_set_nsegments(nilfs, newnsegs);

out_header:
    brelse(header_bh);
out:
    up_write(&NILFS_MDT(sufile)->mi_sem);
    return ret;
}

ssize_t nilfs_sufile_get_suinfo(struct inode *sufile, __u64 segnum, void *buf,
                unsigned sisz, size_t nsi)
{
    struct buffer_head *su_bh;
    struct nilfs_segment_usage *su;
    struct nilfs_suinfo *si = buf;
    size_t susz = NILFS_MDT(sufile)->mi_entry_size;
    struct the_nilfs *nilfs = sufile->i_sb->s_fs_info;
    void *kaddr;
    unsigned long nsegs, segusages_per_block;
    ssize_t n;
    int ret, i, j;

    down_read(&NILFS_MDT(sufile)->mi_sem);

    segusages_per_block = nilfs_sufile_segment_usages_per_block(sufile);
    nsegs = min_t(unsigned long,
              nilfs_sufile_get_nsegments(sufile) - segnum,
              nsi);
    for (i = 0; i < nsegs; i += n, segnum += n) {
        n = min_t(unsigned long,
              segusages_per_block -
                  nilfs_sufile_get_offset(sufile, segnum),
              nsegs - i);
        ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, 0,
                               &su_bh);
        if (ret < 0) {
            if (ret != -ENOENT)
                goto out;
            /* hole */
            memset(si, 0, sisz * n);
            si = (void *)si + sisz * n;
            continue;
        }

        kaddr = kmap_atomic(su_bh->b_page);
        su = nilfs_sufile_block_get_segment_usage(
            sufile, segnum, su_bh, kaddr);
        for (j = 0; j < n;
             j++, su = (void *)su + susz, si = (void *)si + sisz) {
            si->sui_lastmod = le64_to_cpu(su->su_lastmod);
            si->sui_nblocks = le32_to_cpu(su->su_nblocks);
            si->sui_flags = le32_to_cpu(su->su_flags) &
                ~(1UL << NILFS_SEGMENT_USAGE_ACTIVE);
            if (nilfs_segment_is_active(nilfs, segnum + j))
                si->sui_flags |=
                    (1UL << NILFS_SEGMENT_USAGE_ACTIVE);
        }
        kunmap_atomic(kaddr);
        brelse(su_bh);
    }
    ret = nsegs;

 out:
    up_read(&NILFS_MDT(sufile)->mi_sem);
    return ret;
}

int nilfs_sufile_read(struct super_block *sb, size_t susize,
              struct nilfs_inode *raw_inode, struct inode **inodep)
{
    struct inode *sufile;
    struct nilfs_sufile_info *sui;
    struct buffer_head *header_bh;
    struct nilfs_sufile_header *header;
    void *kaddr;
    int err;

    sufile = nilfs_iget_locked(sb, NULL, NILFS_SUFILE_INO);
    if (unlikely(!sufile))
        return -ENOMEM;
    if (!(sufile->i_state & I_NEW))
        goto out;

    err = nilfs_mdt_init(sufile, NILFS_MDT_GFP, sizeof(*sui));
    if (err)
        goto failed;

    nilfs_mdt_set_entry_size(sufile, susize,
                 sizeof(struct nilfs_sufile_header));

    err = nilfs_read_inode_common(sufile, raw_inode);
    if (err)
        goto failed;

    err = nilfs_sufile_get_header_block(sufile, &header_bh);
    if (err)
        goto failed;

    sui = NILFS_SUI(sufile);
    kaddr = kmap_atomic(header_bh->b_page);
    header = kaddr + bh_offset(header_bh);
    sui->ncleansegs = le64_to_cpu(header->sh_ncleansegs);
    kunmap_atomic(kaddr);
    brelse(header_bh);

    sui->allocmax = nilfs_sufile_get_nsegments(sufile) - 1;
    sui->allocmin = 0;

    unlock_new_inode(sufile);
 out:
    *inodep = sufile;
    return 0;
 failed:
    iget_failed(sufile);
    return err;
}