/*
 * Copyright (C) 2010 Red Hat, Inc.
 * All Rights Reserved.
 *
 * 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.
 *
 * This program is distributed in the hope that it would 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 the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "xfs.h"
#include "xfs_sb.h"
#include "xfs_inum.h"
#include "xfs_log.h"
#include "xfs_ag.h"
#include "xfs_mount.h"
#include "xfs_quota.h"
#include "xfs_trans.h"
#include "xfs_alloc_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_btree.h"
#include "xfs_inode.h"
#include "xfs_alloc.h"
#include "xfs_error.h"
#include "xfs_discard.h"
#include "xfs_trace.h"

STATIC int
xfs_trim_extents(
        struct xfs_mount        *mp,
        xfs_agnumber_t          agno,
        xfs_fsblock_t           start,
        xfs_fsblock_t           len,
        xfs_fsblock_t           minlen,
        __uint64_t              *blocks_trimmed)
{
        struct block_device     *bdev = mp->m_ddev_targp->bt_bdev;
        struct xfs_btree_cur    *cur;
        struct xfs_buf          *agbp;
        struct xfs_perag        *pag;
        int                     error;
        int                     i;

        pag = xfs_perag_get(mp, agno);

        error = xfs_alloc_read_agf(mp, NULL, agno, 0, &agbp);
        if (error || !agbp)
                goto out_put_perag;

        cur = xfs_allocbt_init_cursor(mp, NULL, agbp, agno, XFS_BTNUM_CNT);

        /*
         * Force out the log.  This means any transactions that might have freed
         * space before we took the AGF buffer lock are now on disk, and the
         * volatile disk cache is flushed.
         */
        xfs_log_force(mp, XFS_LOG_SYNC);

        /*
         * Look up the longest btree in the AGF and start with it.
         */
        error = xfs_alloc_lookup_le(cur, 0,
                                    XFS_BUF_TO_AGF(agbp)->agf_longest, &i);
        if (error)
                goto out_del_cursor;

        /*
         * Loop until we are done with all extents that are large
         * enough to be worth discarding.
         */
        while (i) {
                xfs_agblock_t fbno;
                xfs_extlen_t flen;

                error = xfs_alloc_get_rec(cur, &fbno, &flen, &i);
                if (error)
                        goto out_del_cursor;
                XFS_WANT_CORRUPTED_GOTO(i == 1, out_del_cursor);
                ASSERT(flen <= XFS_BUF_TO_AGF(agbp)->agf_longest);

                /*
                 * Too small?  Give up.
                 */
                if (flen < minlen) {
                        trace_xfs_discard_toosmall(mp, agno, fbno, flen);
                        goto out_del_cursor;
                }

                /*
                 * If the extent is entirely outside of the range we are
                 * supposed to discard skip it.  Do not bother to trim
                 * down partially overlapping ranges for now.
                 */
                if (XFS_AGB_TO_FSB(mp, agno, fbno) + flen < start ||
                    XFS_AGB_TO_FSB(mp, agno, fbno) >= start + len) {
                        trace_xfs_discard_exclude(mp, agno, fbno, flen);
                        goto next_extent;
                }

                /*
                 * If any blocks in the range are still busy, skip the
                 * discard and try again the next time.
                 */
                if (xfs_alloc_busy_search(mp, agno, fbno, flen)) {
                        trace_xfs_discard_busy(mp, agno, fbno, flen);
                        goto next_extent;
                }

                trace_xfs_discard_extent(mp, agno, fbno, flen);
                error = -blkdev_issue_discard(bdev,
                                XFS_AGB_TO_DADDR(mp, agno, fbno),
                                XFS_FSB_TO_BB(mp, flen),
                                GFP_NOFS, 0);
                if (error)
                        goto out_del_cursor;
                *blocks_trimmed += flen;

next_extent:
                error = xfs_btree_decrement(cur, 0, &i);
                if (error)
                        goto out_del_cursor;
        }

out_del_cursor:
        xfs_btree_del_cursor(cur, error ? XFS_BTREE_ERROR : XFS_BTREE_NOERROR);
        xfs_buf_relse(agbp);
out_put_perag:
        xfs_perag_put(pag);
        return error;
}

int
xfs_ioc_trim(
        struct xfs_mount                *mp,
        struct fstrim_range __user      *urange)
{
        struct request_queue    *q = mp->m_ddev_targp->bt_bdev->bd_disk->queue;
        unsigned int            granularity = q->limits.discard_granularity;
        struct fstrim_range     range;
        xfs_fsblock_t           start, len, minlen;
        xfs_agnumber_t          start_agno, end_agno, agno;
        __uint64_t              blocks_trimmed = 0;
        int                     error, last_error = 0;

        if (!capable(CAP_SYS_ADMIN))
                return -XFS_ERROR(EPERM);
        if (!blk_queue_discard(q))
                return -XFS_ERROR(EOPNOTSUPP);
        if (copy_from_user(&range, urange, sizeof(range)))
                return -XFS_ERROR(EFAULT);

        /*
         * Truncating down the len isn't actually quite correct, but using
         * XFS_B_TO_FSB would mean we trivially get overflows for values
         * of ULLONG_MAX or slightly lower.  And ULLONG_MAX is the default
         * used by the fstrim application.  In the end it really doesn't
         * matter as trimming blocks is an advisory interface.
         */
        start = XFS_B_TO_FSBT(mp, range.start);
        len = XFS_B_TO_FSBT(mp, range.len);
        minlen = XFS_B_TO_FSB(mp, max_t(u64, granularity, range.minlen));

        start_agno = XFS_FSB_TO_AGNO(mp, start);
        if (start_agno >= mp->m_sb.sb_agcount)
                return -XFS_ERROR(EINVAL);

        end_agno = XFS_FSB_TO_AGNO(mp, start + len);
        if (end_agno >= mp->m_sb.sb_agcount)
                end_agno = mp->m_sb.sb_agcount - 1;

        for (agno = start_agno; agno <= end_agno; agno++) {
                error = -xfs_trim_extents(mp, agno, start, len, minlen,
                                          &blocks_trimmed);
                if (error)
                        last_error = error;
        }

        if (last_error)
                return last_error;

        range.len = XFS_FSB_TO_B(mp, blocks_trimmed);
        if (copy_to_user(urange, &range, sizeof(range)))
                return -XFS_ERROR(EFAULT);
        return 0;
}

int
xfs_discard_extents(
        struct xfs_mount        *mp,
        struct list_head        *list)
{
        struct xfs_busy_extent  *busyp;
        int                     error = 0;

        list_for_each_entry(busyp, list, list) {
                trace_xfs_discard_extent(mp, busyp->agno, busyp->bno,
                                         busyp->length);

                error = -blkdev_issue_discard(mp->m_ddev_targp->bt_bdev,
                                XFS_AGB_TO_DADDR(mp, busyp->agno, busyp->bno),
                                XFS_FSB_TO_BB(mp, busyp->length),
                                GFP_NOFS, 0);
                if (error && error != EOPNOTSUPP) {
                        xfs_info(mp,
         "discard failed for extent [0x%llu,%u], error %d",
                                 (unsigned long long)busyp->bno,
                                 busyp->length,
                                 error);
                        return error;
                }
        }

        return 0;
}