/*
 * 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 <koji@osrg.net>.
 * Rivised by Ryusuke Konishi <ryusuke@osrg.net>.
 */

#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"


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 inline struct nilfs_sufile_header *
nilfs_sufile_block_get_header(const struct inode *sufile,
                              struct buffer_head *bh,
                              void *kaddr)
{
        return kaddr + bh_offset(bh);
}

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 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, KM_USER0);
        header = kaddr + bh_offset(header_bh);
        le64_add_cpu(&header->sh_ncleansegs, ncleanadd);
        le64_add_cpu(&header->sh_ndirtysegs, ndirtyadd);
        kunmap_atomic(kaddr, KM_USER0);

        nilfs_mdt_mark_buffer_dirty(header_bh);
}

/**
 * nilfs_sufile_updatev - modify multiple segment usages at a time
 * @sufile: inode of segment usage file
 * @segnumv: array of segment numbers
 * @nsegs: size of @segnumv array
 * @create: creation flag
 * @ndone: place to store number of modified segments on @segnumv
 * @dofunc: primitive operation for the update
 *
 * Description: nilfs_sufile_updatev() repeatedly calls @dofunc
 * against the given array of segments.  The @dofunc is called with
 * buffers of a header block and the sufile block in which the target
 * segment usage entry is contained.  If @ndone is given, the number
 * of successfully modified segments from the head is stored in the
 * place @ndone points to.
 *
 * Return Value: On success, zero is returned.  On error, one of the
 * following negative error codes is returned.
 *
 * %-EIO - I/O error.
 *
 * %-ENOMEM - Insufficient amount of memory available.
 *
 * %-ENOENT - Given segment usage is in hole block (may be returned if
 *            @create is zero)
 *
 * %-EINVAL - Invalid segment usage number
 */
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;
}

/**
 * nilfs_sufile_alloc - allocate a segment
 * @sufile: inode of segment usage file
 * @segnump: pointer to segment number
 *
 * Description: nilfs_sufile_alloc() allocates a clean segment.
 *
 * Return Value: On success, 0 is returned and the segment number of the
 * allocated segment is stored in the place pointed by @segnump. On error, one
 * of the following negative error codes is returned.
 *
 * %-EIO - I/O error.
 *
 * %-ENOMEM - Insufficient amount of memory available.
 *
 * %-ENOSPC - No clean segment left.
 */
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;
        size_t susz = NILFS_MDT(sufile)->mi_entry_size;
        __u64 segnum, maxsegnum, last_alloc;
        void *kaddr;
        unsigned long nsegments, ncleansegs, nsus;
        int ret, i, 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, KM_USER0);
        header = nilfs_sufile_block_get_header(sufile, header_bh, kaddr);
        ncleansegs = le64_to_cpu(header->sh_ncleansegs);
        last_alloc = le64_to_cpu(header->sh_last_alloc);
        kunmap_atomic(kaddr, KM_USER0);

        nsegments = nilfs_sufile_get_nsegments(sufile);
        segnum = last_alloc + 1;
        maxsegnum = nsegments - 1;
        for (i = 0; i < nsegments; i += nsus) {
                if (segnum >= nsegments) {
                        /* wrap around */
                        segnum = 0;
                        maxsegnum = last_alloc;
                }
                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, KM_USER0);
                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, KM_USER0);

                        kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
                        header = nilfs_sufile_block_get_header(
                                sufile, header_bh, kaddr);
                        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, KM_USER0);

                        nilfs_mdt_mark_buffer_dirty(header_bh);
                        nilfs_mdt_mark_buffer_dirty(su_bh);
                        nilfs_mdt_mark_dirty(sufile);
                        brelse(su_bh);
                        *segnump = segnum;
                        goto out_header;
                }

                kunmap_atomic(kaddr, KM_USER0);
                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, KM_USER0);
        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, KM_USER0);
                return;
        }
        nilfs_segment_usage_set_dirty(su);
        kunmap_atomic(kaddr, KM_USER0);

        nilfs_sufile_mod_counter(header_bh, -1, 1);
        nilfs_mdt_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, KM_USER0);
        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, KM_USER0);
                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, KM_USER0);

        nilfs_sufile_mod_counter(header_bh, clean ? (u64)-1 : 0, dirty ? 0 : 1);
        nilfs_mdt_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, KM_USER0);
        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, KM_USER0);
                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, KM_USER0);
        nilfs_mdt_mark_buffer_dirty(su_bh);

        nilfs_sufile_mod_counter(header_bh, 1, sudirty ? (u64)-1 : 0);
        nilfs_mdt_mark_dirty(sufile);
}

/**
 * nilfs_sufile_get_segment_usage - get a segment usage
 * @sufile: inode of segment usage file
 * @segnum: segment number
 * @sup: pointer to segment usage
 * @bhp: pointer to buffer head
 *
 * Description: nilfs_sufile_get_segment_usage() acquires the segment usage
 * specified by @segnum.
 *
 * Return Value: On success, 0 is returned, and the segment usage and the
 * buffer head of the buffer on which the segment usage is located are stored
 * in the place pointed by @sup and @bhp, respectively. On error, one of the
 * following negative error codes is returned.
 *
 * %-EIO - I/O error.
 *
 * %-ENOMEM - Insufficient amount of memory available.
 *
 * %-EINVAL - Invalid segment usage number.
 */
int nilfs_sufile_get_segment_usage(struct inode *sufile, __u64 segnum,
                                   struct nilfs_segment_usage **sup,
                                   struct buffer_head **bhp)
{
        struct buffer_head *bh;
        struct nilfs_segment_usage *su;
        void *kaddr;
        int ret;

        /* segnum is 0 origin */
        if (segnum >= nilfs_sufile_get_nsegments(sufile))
                return -EINVAL;
        down_write(&NILFS_MDT(sufile)->mi_sem);
        ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, 1, &bh);
        if (ret < 0)
                goto out_sem;
        kaddr = kmap(bh->b_page);
        su = nilfs_sufile_block_get_segment_usage(sufile, segnum, bh, kaddr);
        if (nilfs_segment_usage_error(su)) {
                kunmap(bh->b_page);
                brelse(bh);
                ret = -EINVAL;
                goto out_sem;
        }

        if (sup != NULL)
                *sup = su;
        *bhp = bh;

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

/**
 * nilfs_sufile_put_segment_usage - put a segment usage
 * @sufile: inode of segment usage file
 * @segnum: segment number
 * @bh: buffer head
 *
 * Description: nilfs_sufile_put_segment_usage() releases the segment usage
 * specified by @segnum. @bh must be the buffer head which have been returned
 * by a previous call to nilfs_sufile_get_segment_usage() with @segnum.
 */
void nilfs_sufile_put_segment_usage(struct inode *sufile, __u64 segnum,
                                    struct buffer_head *bh)
{
        kunmap(bh->b_page);
        brelse(bh);
}

/**
 * nilfs_sufile_get_stat - get segment usage statistics
 * @sufile: inode of segment usage file
 * @stat: pointer to a structure of segment usage statistics
 *
 * Description: nilfs_sufile_get_stat() returns information about segment
 * usage.
 *
 * Return Value: On success, 0 is returned, and segment usage information is
 * stored in the place pointed by @stat. On error, one of the following
 * negative error codes is returned.
 *
 * %-EIO - I/O error.
 *
 * %-ENOMEM - Insufficient amount of memory available.
 */
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 = NILFS_MDT(sufile)->mi_nilfs;
        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, KM_USER0);
        header = nilfs_sufile_block_get_header(sufile, header_bh, kaddr);
        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, KM_USER0);
        brelse(header_bh);

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

/**
 * nilfs_sufile_get_ncleansegs - get the number of clean segments
 * @sufile: inode of segment usage file
 * @nsegsp: pointer to the number of clean segments
 *
 * Description: nilfs_sufile_get_ncleansegs() acquires the number of clean
 * segments.
 *
 * Return Value: On success, 0 is returned and the number of clean segments is
 * stored in the place pointed by @nsegsp. On error, one of the following
 * negative error codes is returned.
 *
 * %-EIO - I/O error.
 *
 * %-ENOMEM - Insufficient amount of memory available.
 */
int nilfs_sufile_get_ncleansegs(struct inode *sufile, unsigned long *nsegsp)
{
        struct nilfs_sustat sustat;
        int ret;

        ret = nilfs_sufile_get_stat(sufile, &sustat);
        if (ret == 0)
                *nsegsp = sustat.ss_ncleansegs;
        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, KM_USER0);
        su = nilfs_sufile_block_get_segment_usage(sufile, segnum, su_bh, kaddr);
        if (nilfs_segment_usage_error(su)) {
                kunmap_atomic(kaddr, KM_USER0);
                return;
        }
        suclean = nilfs_segment_usage_clean(su);
        nilfs_segment_usage_set_error(su);
        kunmap_atomic(kaddr, KM_USER0);

        if (suclean)
                nilfs_sufile_mod_counter(header_bh, -1, 0);
        nilfs_mdt_mark_buffer_dirty(su_bh);
        nilfs_mdt_mark_dirty(sufile);
}

/**
 * nilfs_sufile_get_suinfo -
 * @sufile: inode of segment usage file
 * @segnum: segment number to start looking
 * @buf: array of suinfo
 * @sisz: byte size of suinfo
 * @nsi: size of suinfo array
 *
 * Description:
 *
 * Return Value: On success, 0 is returned and .... On error, one of the
 * following negative error codes is returned.
 *
 * %-EIO - I/O error.
 *
 * %-ENOMEM - Insufficient amount of memory available.
 */
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 = NILFS_MDT(sufile)->mi_nilfs;
        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, KM_USER0);
                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, KM_USER0);
                brelse(su_bh);
        }
        ret = nsegs;

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