/*
 * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
 *
 * This code is derived from software contributed to The DragonFly Project
 * by Matthew Dillon <dillon@backplane.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name of The DragonFly Project nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific, prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $DragonFly: src/sbin/hammer/cmd_softprune.c,v 1.7 2008/08/21 23:28:43 thomas Exp $
 */

#include "hammer.h"

struct softprune {
        struct softprune *next;
        struct statfs fs;
        char *filesystem;
        struct hammer_ioc_prune prune;
        int maxelms;
        int prune_min;
};

static void hammer_softprune_scandir(struct softprune **basep,
                        struct hammer_ioc_prune *template,
                        const char *dirname);
static int hammer_softprune_scanmeta(int fd, struct softprune *scan,
                        int delete_all);
static void hammer_meta_flushdelete(int fd, struct hammer_ioc_snapshot *dsnap);
static struct softprune *hammer_softprune_addentry(struct softprune **basep,
                        struct hammer_ioc_prune *template,
                        const char *dirpath, const char *denname,
                        struct stat *st,
                        const char *linkbuf, const char *tidptr);
static void hammer_softprune_addelm(struct softprune *scan, hammer_tid_t tid,
                        time_t ct, time_t mt);
static void hammer_softprune_finalize(struct softprune *scan);
static void softprune_usage(int code);

/*
 * prune <softlink-dir>
 * prune-everything <filesystem>
 */
void
hammer_cmd_softprune(char **av, int ac, int everything_opt)
{
        struct hammer_ioc_prune template;
        struct hammer_ioc_pseudofs_rw pfs;
        struct softprune *base, *scan;
        int fd;
        int rcode;

        base = NULL;
        rcode = 0;
        if (TimeoutOpt > 0)
                alarm(TimeoutOpt);

        clrpfs(&pfs, NULL, -1);

        /*
         * NOTE: To restrict to a single file XXX we have to set
         * the localization the same (not yet implemented).  Typically
         * two passes would be needed, one using HAMMER_LOCALIZE_MISC
         * and one using HAMMER_LOCALIZE_INODE.
         */

        bzero(&template, sizeof(template));
        template.key_beg.localization = HAMMER_MIN_LOCALIZATION;
        template.key_beg.obj_id = HAMMER_MIN_OBJID;
        template.key_end.localization = HAMMER_MAX_LOCALIZATION;
        template.key_end.obj_id = HAMMER_MAX_OBJID;
        hammer_get_cycle(&template.key_end, NULL);
        template.stat_oldest_tid = HAMMER_MAX_TID;

        /*
         * For now just allow one directory
         */
        if (ac == 0 || ac > 1) {
                softprune_usage(1);
                /* not reached */
        }

        /*
         * Scan the softlink directory.
         */
        if (everything_opt) {
                const char *dummylink = "";
                scan = hammer_softprune_addentry(&base, &template,
                                                 *av, NULL, NULL,
                                                 dummylink, dummylink);
                if (scan == NULL) {
                        softprune_usage(1);
                        /* not reached */
                }
                scan->prune.nelms = 0;
                scan->prune.head.flags |= HAMMER_IOC_PRUNE_ALL;
        } else {
                hammer_softprune_scandir(&base, &template, *av);
                if (base == NULL) {
                        const char *dummylink = "";
                        scan = hammer_softprune_addentry(&base, &template,
                                                         *av, NULL, NULL,
                                                         dummylink, dummylink);
                        if (scan == NULL) {
                                softprune_usage(1);
                                /* not reached */
                        }
                        scan->prune.nelms = 0;
                }
                ++av;
                --ac;
        }

        /*
         * XXX future (need to store separate cycles for each filesystem)
         */
        if (base->next) {
                errx(1, "Currently only one HAMMER filesystem may "
                        "be specified in the softlink scan");
                /* not reached */
        }

        /*
         * Issue the prunes
         */
        for (scan = base; scan; scan = scan->next) {
                /*
                 * Open the filesystem for ioctl calls and extract the
                 * PFS.
                 */
                fd = open(scan->filesystem, O_RDONLY);
                if (fd < 0) {
                        warn("Unable to open %s", scan->filesystem);
                        rcode = 1;
                        continue;
                }

                if (ioctl(fd, HAMMERIOC_GET_PSEUDOFS, &pfs) < 0) {
                        warn("Filesystem %s is not HAMMER", scan->filesystem);
                        rcode = 1;
                        close(fd);
                        continue;
                }
                scan->prune_min = pfs.ondisk->prune_min;

                /*
                 * Incorporate meta-data snapshots into the pruning regimen.
                 * If pruning everything we delete the meta-data snapshots.
                 */
                if (hammer_softprune_scanmeta(fd, scan, everything_opt) < 0) {
                        warn("Filesystem %s could not scan meta-data snaps",
                             scan->filesystem);
                        rcode = 1;
                        close(fd);
                        continue;
                }

                /*
                 * Finalize operations
                 */
                hammer_softprune_finalize(scan);
                if (everything_opt) {
                        printf("Prune %s: EVERYTHING\n",
                               scan->filesystem);
                } else {
                        printf("Prune %s: %d snapshots\n",
                               scan->filesystem, scan->prune.nelms);
                }
                if (scan->prune.nelms == 0 &&
                    (scan->prune.head.flags & HAMMER_IOC_PRUNE_ALL) == 0) {
                        fprintf(stderr, "No snapshots found\n");
                        continue;
                }

                printf("Prune %s: objspace %016jx:%04x %016jx:%04x "
                       "pfs_id %d\n",
                       scan->filesystem,
                       (uintmax_t)scan->prune.key_beg.obj_id,
                       scan->prune.key_beg.localization,
                       (uintmax_t)scan->prune.key_end.obj_id,
                       scan->prune.key_end.localization,
                       pfs.pfs_id);
                printf("Prune %s: prune_min is %dd/%02d:%02d:%02d\n",
                       scan->filesystem,
                        pfs.ondisk->prune_min / (24 * 60 * 60),
                        pfs.ondisk->prune_min / 60 / 60 % 24,
                        pfs.ondisk->prune_min / 60 % 60,
                        pfs.ondisk->prune_min % 60);

                RunningIoctl = 1;
                if (ioctl(fd, HAMMERIOC_PRUNE, &scan->prune) < 0) {
                        printf("Prune %s failed: %s\n",
                               scan->filesystem, strerror(errno));
                        rcode = 2;
                } else if (scan->prune.head.flags & HAMMER_IOC_HEAD_INTR) {
                        printf("Prune %s interrupted by timer at "
                               "%016jx %04x\n",
                               scan->filesystem,
                               (uintmax_t)scan->prune.key_cur.obj_id,
                               scan->prune.key_cur.localization);
                        if (CyclePath)
                                hammer_set_cycle(&scan->prune.key_cur, 0);
                        rcode = 0;
                } else {
                        if (CyclePath)
                                hammer_reset_cycle();
                        printf("Prune %s succeeded\n", scan->filesystem);
                }
                printf("Pruned %jd/%jd records (%jd directory entries) "
                       "and %jd bytes\n",
                        (uintmax_t)scan->prune.stat_rawrecords,
                        (uintmax_t)scan->prune.stat_scanrecords,
                        (uintmax_t)scan->prune.stat_dirrecords,
                        (uintmax_t)scan->prune.stat_bytes
                );
                RunningIoctl = 0;
                close(fd);
        }
        if (rcode)
                exit(rcode);
}

/*
 * Scan a directory for softlinks representing snapshots and build
 * associated softprune structures.
 *
 * NOTE: Once a filesystem is completely converted to the meta-data
 *       snapshot mechanic we don't have to scan softlinks any more
 *       and can just use the meta-data.  But for now we do both.
 */
static
void
hammer_softprune_scandir(struct softprune **basep,
                         struct hammer_ioc_prune *template,
                         const char *dirname)
{
        struct stat st;
        struct dirent *den;
        DIR *dir;
        char *path;
        int len;
        char *linkbuf;
        char *ptr;

        path = NULL;
        linkbuf = malloc(MAXPATHLEN);

        if ((dir = opendir(dirname)) == NULL) {
                err(1, "Cannot open directory %s", dirname);
                /* not reached */
        }
        while ((den = readdir(dir)) != NULL) {
                if (strcmp(den->d_name, ".") == 0)
                        continue;
                if (strcmp(den->d_name, "..") == 0)
                        continue;
                if (path)
                        free(path);
                asprintf(&path, "%s/%s", dirname, den->d_name);
                if (lstat(path, &st) < 0)
                        continue;
                if (!S_ISLNK(st.st_mode))
                        continue;
                if ((len = readlink(path, linkbuf, MAXPATHLEN - 1)) < 0)
                        continue;
                linkbuf[len] = 0;
                if ((ptr = strrchr(linkbuf, '@')) &&
                    ptr > linkbuf && ptr[-1] == '@') {
                        hammer_softprune_addentry(basep, template,
                                                  dirname, den->d_name, &st,
                                                  linkbuf, ptr - 1);
                }
        }
        free(linkbuf);
        if (path)
                free(path);
}

/*
 * Scan a directory for softlinks representing snapshots.
 * Return 1 if the directory contains snapshots, otherwise 0.
 */
int
hammer_softprune_testdir(const char *dirname)
{
        struct softprune *base = NULL;
        struct hammer_ioc_prune dummy_template;

        bzero(&dummy_template, sizeof(dummy_template));
        hammer_softprune_scandir(&base, &dummy_template, dirname);

        if (base)
                return(1);
        return(0);
}

/*
 * Scan the metadata snapshots for the filesystem and either delete them
 * or add them to the pruning list.
 */
static
int
hammer_softprune_scanmeta(int fd, struct softprune *scan, int delete_all)
{
        struct hammer_ioc_version       version;
        struct hammer_ioc_snapshot      snapshot;
        struct hammer_ioc_snapshot      dsnapshot;
        hammer_snapshot_data_t          snap;
        time_t ct;

        /*
         * Stop if we can't get the version.  Meta-data snapshots only
         * exist for HAMMER version 3 or greater.
         */
        bzero(&version, sizeof(version));
        if (ioctl(fd, HAMMERIOC_GET_VERSION, &version) < 0)
                return(-1);
        HammerVersion = version.cur_version;
        if (version.cur_version < 3)
                return(0);

        bzero(&snapshot, sizeof(snapshot));
        bzero(&dsnapshot, sizeof(dsnapshot));

        /*
         * Scan meta-data snapshots, either add them to the prune list or
         * delete them.  When deleting, just skip any entries which cannot
         * be deleted.
         */
        for (;;) {
                if (ioctl(fd, HAMMERIOC_GET_SNAPSHOT, &snapshot) < 0) {
                        printf("hammer prune: Unable to access "
                               "meta-data snaps: %s\n", strerror(errno));
                        return(-1);
                }
                while (snapshot.index < snapshot.count) {
                        snap = &snapshot.snaps[snapshot.index];
                        if (delete_all) {
                                dsnapshot.snaps[dsnapshot.count++] = *snap;
                                if (dsnapshot.count == HAMMER_SNAPS_PER_IOCTL)
                                        hammer_meta_flushdelete(fd, &dsnapshot);
                        } else {
                                ct = snap->ts / 1000000ULL;
                                hammer_softprune_addelm(scan, snap->tid,
                                                        ct, ct);
                        }
                        ++snapshot.index;
                }
                if (snapshot.head.flags & HAMMER_IOC_SNAPSHOT_EOF)
                        break;
                snapshot.index = 0;
        }
        if (delete_all)
                hammer_meta_flushdelete(fd, &dsnapshot);
        return(0);
}

/*
 * Flush any entries built up in the deletion snapshot ioctl structure.
 * Used during a prune-everything.
 */
static
void
hammer_meta_flushdelete(int fd, struct hammer_ioc_snapshot *dsnap)
{
        while (dsnap->index < dsnap->count) {
                if (ioctl(fd, HAMMERIOC_DEL_SNAPSHOT, dsnap) < 0)
                        break;
                if (dsnap->head.error == 0)
                        break;
                ++dsnap->index;
        }
        dsnap->index = 0;
        dsnap->count = 0;
}

/*
 * Add the softlink to the appropriate softprune structure, creating a new
 * one if necessary.
 */
static
struct softprune *
hammer_softprune_addentry(struct softprune **basep,
                         struct hammer_ioc_prune *template,
                         const char *dirpath, const char *denname __unused,
                         struct stat *st,
                         const char *linkbuf, const char *tidptr)
{
        struct softprune *scan;
        struct statfs fs;
        char *fspath;

        /*
         * Calculate filesystem path.
         */
        if (linkbuf[0] == '/') {
                asprintf(&fspath, "%*.*s",
                         (int)(tidptr - linkbuf), (int)(tidptr - linkbuf),
                         linkbuf);
        } else {
                asprintf(&fspath, "%s/%*.*s", dirpath,
                         (int)(tidptr - linkbuf), (int)(tidptr - linkbuf),
                         linkbuf);
        }
        if (statfs(fspath, &fs) < 0) {
                free(fspath);
                return(NULL);
        }

        /*
         * Locate the filesystem in an existing softprune structure
         */
        for (scan = *basep; scan; scan = scan->next) {
                if (bcmp(&fs.f_fsid, &scan->fs.f_fsid, sizeof(fs.f_fsid)) != 0)
                        continue;
                if (strcmp(fs.f_mntonname, scan->fs.f_mntonname) != 0)
                        continue;
                break;
        }

        /*
         * Create a new softprune structure if necessasry
         */
        if (scan == NULL) {
                scan = malloc(sizeof(*scan));
                bzero(scan, sizeof(*scan));

                scan->fs = fs;
                scan->filesystem = fspath;
                scan->prune = *template;
                scan->maxelms = 32;
                scan->prune.elms = malloc(sizeof(struct hammer_ioc_prune_elm) *
                                          scan->maxelms);
                scan->next = *basep;
                *basep = scan;
        } else {
                free(fspath);
        }
        hammer_softprune_addelm(scan,
                                (hammer_tid_t)strtoull(tidptr + 2, NULL, 0),
                                (st ? st->st_ctime : 0),
                                (st ? st->st_mtime : 0));
        return(scan);
}

/*
 * Add the entry (unsorted).  Just set the beg_tid, we will sort
 * and set the remaining entries later.
 *
 * Always leave one entry free for our terminator.
 */
static
void
hammer_softprune_addelm(struct softprune *scan, hammer_tid_t tid,
                        time_t ct, time_t mt)
{
        struct hammer_ioc_prune_elm *elm;

        if (scan->prune.nelms >= scan->maxelms - 1) {
                scan->maxelms = (scan->maxelms * 3 / 2);
                scan->prune.elms = realloc(scan->prune.elms,
                                           sizeof(*elm) * scan->maxelms);
        }

        /*
         * NOTE: Temporarily store the snapshot timestamp in mod_tid.
         *       This will be cleaned up in the finalization phase.
         */
        elm = &scan->prune.elms[scan->prune.nelms];
        elm->beg_tid = tid;
        elm->end_tid = 0;
        elm->mod_tid = 0;
        if (ct < mt)
                elm->mod_tid = ct;
        else
                elm->mod_tid = mt;
        ++scan->prune.nelms;
}

/*
 * Finalize a softprune structure after scanning in its softlinks.
 * Sort the elements, remove duplicates, and then fill in end_tid and
 * mod_tid.
 *
 * The array must end up in descending order.
 */
static
int
hammer_softprune_qsort_cmp(const void *arg1, const void *arg2)
{
        const struct hammer_ioc_prune_elm *elm1 = arg1;
        const struct hammer_ioc_prune_elm *elm2 = arg2;

        if (elm1->beg_tid < elm2->beg_tid)
                return(1);
        if (elm1->beg_tid > elm2->beg_tid)
                return(-1);
        return(0);
}

static
void
hammer_softprune_finalize(struct softprune *scan)
{
        struct hammer_ioc_prune_elm *elm;
        time_t t;
        long delta;
        int i;

        /*
         * Don't do anything if there are no elements.
         */
        if (scan->prune.nelms == 0)
                return;

        /*
         * Sort the elements in descending order, remove duplicates, and
         * fill in any missing bits.
         */
        qsort(scan->prune.elms, scan->prune.nelms, sizeof(*elm),
              hammer_softprune_qsort_cmp);

        for (i = 0; i < scan->prune.nelms; ++i) {
                elm = &scan->prune.elms[i];
                if (i == 0) {
                        /*
                         * First (highest TID) (also last if only one element)
                         */
                        elm->end_tid = HAMMER_MAX_TID;
                } else if (elm[0].beg_tid == elm[-1].beg_tid) {
                        /*
                         * Remove duplicate
                         */
                        --scan->prune.nelms;
                        if (i != scan->prune.nelms) {
                                bcopy(elm + 1, elm,
                                      (scan->prune.nelms - i) * sizeof(*elm));
                        }
                        --i;
                        continue;
                } else {
                        /*
                         * Middle or last.
                         */
                        elm->end_tid = elm[-1].beg_tid;
                }
        }

        /*
         * If a minimum retention time (in seconds) is configured for the
         * PFS, remove any snapshots from the pruning list that are within
         * the period.
         */
        if (scan->prune_min) {
                t = time(NULL);
                for (i = scan->prune.nelms - 1; i >= 0; --i) {
                        elm = &scan->prune.elms[i];
                        if (elm->mod_tid == 0)
                                continue;
                        delta = (long)(t - (time_t)elm->mod_tid);
                        if (delta < scan->prune_min)
                                break;
                }
                ++i;
                if (i) {
                        printf("Prune %s: prune_min: Will not clean between "
                               "the teeth of the first %d snapshots\n",
                               scan->filesystem, i);
                        bcopy(&scan->prune.elms[i], &scan->prune.elms[0],
                              (scan->prune.nelms - i) * sizeof(scan->prune.elms[0]));
                        scan->prune.elms[0].end_tid = HAMMER_MAX_TID;
                        scan->prune.nelms -= i;
                }
        }

        /*
         * Remove the first entry.  This entry represents the prune from
         * the most recent snapshot to current.  We wish to retain the
         * fine-grained history for this region.
         */
        if (scan->prune.nelms) {
                bcopy(&scan->prune.elms[1], &scan->prune.elms[0],
                      (scan->prune.nelms - 1) * sizeof(scan->prune.elms[0]));
                --scan->prune.nelms;
        }

        /*
         * Add a final element to prune everything from transaction id
         * 0 to the lowest transaction id (aka last so far).
         */
        if (scan->prune.nelms) {
                assert(scan->prune.nelms < scan->maxelms);
                elm = &scan->prune.elms[scan->prune.nelms];
                elm->beg_tid = 1;
                elm->end_tid = elm[-1].beg_tid;
                ++scan->prune.nelms;
        }

        /*
         * Adjust mod_tid to what the ioctl() expects.
         */
        for (i = 0; i < scan->prune.nelms; ++i) {
                elm = &scan->prune.elms[i];
                elm->mod_tid = elm->end_tid - elm->beg_tid;
                printf("TID %016jx - %016jx\n",
                       (uintmax_t)elm->beg_tid, (uintmax_t)elm->end_tid);
        }
}

static
void
softprune_usage(int code)
{
        fprintf(stderr, "Badly formed prune command, use:\n");
        fprintf(stderr, "hammer prune <softlink-dir>\n");
        fprintf(stderr, "hammer prune-everything <filesystem>\n");
        exit(code);
}