drm/tests: Add test for drm_atomic_helper_check_modeset()

[drm/drm-misc.git] / fs / xfs / xfs_discard.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2010, 2023 Red Hat, Inc.
 * All Rights Reserved.
 */
#include "xfs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_trans.h"
#include "xfs_mount.h"
#include "xfs_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_alloc.h"
#include "xfs_discard.h"
#include "xfs_error.h"
#include "xfs_extent_busy.h"
#include "xfs_trace.h"
#include "xfs_log.h"
#include "xfs_ag.h"
#include "xfs_health.h"
#include "xfs_rtbitmap.h"
#include "xfs_rtgroup.h"

/*
 * Notes on an efficient, low latency fstrim algorithm
 *
 * We need to walk the filesystem free space and issue discards on the free
 * space that meet the search criteria (size and location). We cannot issue
 * discards on extents that might be in use, or are so recently in use they are
 * still marked as busy. To serialise against extent state changes whilst we are
 * gathering extents to trim, we must hold the AGF lock to lock out other
 * allocations and extent free operations that might change extent state.
 *
 * However, we cannot just hold the AGF for the entire AG free space walk whilst
 * we issue discards on each free space that is found. Storage devices can have
 * extremely slow discard implementations (e.g. ceph RBD) and so walking a
 * couple of million free extents and issuing synchronous discards on each
 * extent can take a *long* time. Whilst we are doing this walk, nothing else
 * can access the AGF, and we can stall transactions and hence the log whilst
 * modifications wait for the AGF lock to be released. This can lead hung tasks
 * kicking the hung task timer and rebooting the system. This is bad.
 *
 * Hence we need to take a leaf from the bulkstat playbook. It takes the AGI
 * lock, gathers a range of inode cluster buffers that are allocated, drops the
 * AGI lock and then reads all the inode cluster buffers and processes them. It
 * loops doing this, using a cursor to keep track of where it is up to in the AG
 * for each iteration to restart the INOBT lookup from.
 *
 * We can't do this exactly with free space - once we drop the AGF lock, the
 * state of the free extent is out of our control and we cannot run a discard
 * safely on it in this situation. Unless, of course, we've marked the free
 * extent as busy and undergoing a discard operation whilst we held the AGF
 * locked.
 *
 * This is exactly how online discard works - free extents are marked busy when
 * they are freed, and once the extent free has been committed to the journal,
 * the busy extent record is marked as "undergoing discard" and the discard is
 * then issued on the free extent. Once the discard completes, the busy extent
 * record is removed and the extent is able to be allocated again.
 *
 * In the context of fstrim, if we find a free extent we need to discard, we
 * don't have to discard it immediately. All we need to do it record that free
 * extent as being busy and under discard, and all the allocation routines will
 * now avoid trying to allocate it. Hence if we mark the extent as busy under
 * the AGF lock, we can safely discard it without holding the AGF lock because
 * nothing will attempt to allocate that free space until the discard completes.
 *
 * This also allows us to issue discards asynchronously like we do with online
 * discard, and so for fast devices fstrim will run much faster as we can have
 * multiple discard operations in flight at once, as well as pipeline the free
 * extent search so that it overlaps in flight discard IO.
 */

#define XFS_DISCARD_MAX_EXAMINE (100)

struct workqueue_struct *xfs_discard_wq;

static void
xfs_discard_endio_work(
        struct work_struct      *work)
{
        struct xfs_busy_extents *extents =
                container_of(work, struct xfs_busy_extents, endio_work);

        xfs_extent_busy_clear(&extents->extent_list, false);
        kfree(extents->owner);
}

/*
 * Queue up the actual completion to a thread to avoid IRQ-safe locking for
 * pagb_lock.
 */
static void
xfs_discard_endio(
        struct bio              *bio)
{
        struct xfs_busy_extents *extents = bio->bi_private;

        INIT_WORK(&extents->endio_work, xfs_discard_endio_work);
        queue_work(xfs_discard_wq, &extents->endio_work);
        bio_put(bio);
}

static inline struct block_device *
xfs_group_bdev(
        const struct xfs_group  *xg)
{
        struct xfs_mount        *mp = xg->xg_mount;

        switch (xg->xg_type) {
        case XG_TYPE_AG:
                return mp->m_ddev_targp->bt_bdev;
        case XG_TYPE_RTG:
                return mp->m_rtdev_targp->bt_bdev;
        default:
                ASSERT(0);
                break;
        }
        return NULL;
}

/*
 * Walk the discard list and issue discards on all the busy extents in the
 * list. We plug and chain the bios so that we only need a single completion
 * call to clear all the busy extents once the discards are complete.
 */
int
xfs_discard_extents(
        struct xfs_mount        *mp,
        struct xfs_busy_extents *extents)
{
        struct xfs_extent_busy  *busyp;
        struct bio              *bio = NULL;
        struct blk_plug         plug;
        int                     error = 0;

        blk_start_plug(&plug);
        list_for_each_entry(busyp, &extents->extent_list, list) {
                trace_xfs_discard_extent(busyp->group, busyp->bno,
                                busyp->length);

                error = __blkdev_issue_discard(xfs_group_bdev(busyp->group),
                                xfs_gbno_to_daddr(busyp->group, busyp->bno),
                                XFS_FSB_TO_BB(mp, busyp->length),
                                GFP_KERNEL, &bio);
                if (error && error != -EOPNOTSUPP) {
                        xfs_info(mp,
         "discard failed for extent [0x%llx,%u], error %d",
                                 (unsigned long long)busyp->bno,
                                 busyp->length,
                                 error);
                        break;
                }
        }

        if (bio) {
                bio->bi_private = extents;
                bio->bi_end_io = xfs_discard_endio;
                submit_bio(bio);
        } else {
                xfs_discard_endio_work(&extents->endio_work);
        }
        blk_finish_plug(&plug);

        return error;
}

struct xfs_trim_cur {
        xfs_agblock_t   start;
        xfs_extlen_t    count;
        xfs_agblock_t   end;
        xfs_extlen_t    minlen;
        bool            by_bno;
};

static int
xfs_trim_gather_extents(
        struct xfs_perag        *pag,
        struct xfs_trim_cur     *tcur,
        struct xfs_busy_extents *extents)
{
        struct xfs_mount        *mp = pag_mount(pag);
        struct xfs_trans        *tp;
        struct xfs_btree_cur    *cur;
        struct xfs_buf          *agbp;
        int                     error;
        int                     i;
        int                     batch = XFS_DISCARD_MAX_EXAMINE;

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

        error = xfs_trans_alloc_empty(mp, &tp);
        if (error)
                return error;

        error = xfs_alloc_read_agf(pag, tp, 0, &agbp);
        if (error)
                goto out_trans_cancel;

        if (tcur->by_bno) {
                /* sub-AG discard request always starts at tcur->start */
                cur = xfs_bnobt_init_cursor(mp, tp, agbp, pag);
                error = xfs_alloc_lookup_le(cur, tcur->start, 0, &i);
                if (!error && !i)
                        error = xfs_alloc_lookup_ge(cur, tcur->start, 0, &i);
        } else if (tcur->start == 0) {
                /* first time through a by-len starts with max length */
                cur = xfs_cntbt_init_cursor(mp, tp, agbp, pag);
                error = xfs_alloc_lookup_ge(cur, 0, tcur->count, &i);
        } else {
                /* nth time through a by-len starts where we left off */
                cur = xfs_cntbt_init_cursor(mp, tp, agbp, pag);
                error = xfs_alloc_lookup_le(cur, tcur->start, tcur->count, &i);
        }
        if (error)
                goto out_del_cursor;
        if (i == 0) {
                /* nothing of that length left in the AG, we are done */
                tcur->count = 0;
                goto out_del_cursor;
        }

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

                error = xfs_alloc_get_rec(cur, &fbno, &flen, &i);
                if (error)
                        break;
                if (XFS_IS_CORRUPT(mp, i != 1)) {
                        xfs_btree_mark_sick(cur);
                        error = -EFSCORRUPTED;
                        break;
                }

                if (--batch <= 0) {
                        /*
                         * Update the cursor to point at this extent so we
                         * restart the next batch from this extent.
                         */
                        tcur->start = fbno;
                        tcur->count = flen;
                        break;
                }

                /*
                 * If the extent is entirely outside of the range we are
                 * supposed to skip it.  Do not bother to trim down partially
                 * overlapping ranges for now.
                 */
                if (fbno + flen < tcur->start) {
                        trace_xfs_discard_exclude(pag_group(pag), fbno, flen);
                        goto next_extent;
                }
                if (fbno > tcur->end) {
                        trace_xfs_discard_exclude(pag_group(pag), fbno, flen);
                        if (tcur->by_bno) {
                                tcur->count = 0;
                                break;
                        }
                        goto next_extent;
                }

                /* Trim the extent returned to the range we want. */
                if (fbno < tcur->start) {
                        flen -= tcur->start - fbno;
                        fbno = tcur->start;
                }
                if (fbno + flen > tcur->end + 1)
                        flen = tcur->end - fbno + 1;

                /* Too small?  Give up. */
                if (flen < tcur->minlen) {
                        trace_xfs_discard_toosmall(pag_group(pag), fbno, flen);
                        if (tcur->by_bno)
                                goto next_extent;
                        tcur->count = 0;
                        break;
                }

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

                xfs_extent_busy_insert_discard(pag_group(pag), fbno, flen,
                                &extents->extent_list);
next_extent:
                if (tcur->by_bno)
                        error = xfs_btree_increment(cur, 0, &i);
                else
                        error = xfs_btree_decrement(cur, 0, &i);
                if (error)
                        break;

                /*
                 * If there's no more records in the tree, we are done. Set the
                 * cursor block count to 0 to indicate to the caller that there
                 * is no more extents to search.
                 */
                if (i == 0)
                        tcur->count = 0;
        }

        /*
         * If there was an error, release all the gathered busy extents because
         * we aren't going to issue a discard on them any more.
         */
        if (error)
                xfs_extent_busy_clear(&extents->extent_list, false);
out_del_cursor:
        xfs_btree_del_cursor(cur, error);
out_trans_cancel:
        xfs_trans_cancel(tp);
        return error;
}

static bool
xfs_trim_should_stop(void)
{
        return fatal_signal_pending(current) || freezing(current);
}

/*
 * Iterate the free list gathering extents and discarding them. We need a cursor
 * for the repeated iteration of gather/discard loop, so use the longest extent
 * we found in the last batch as the key to start the next.
 */
static int
xfs_trim_perag_extents(
        struct xfs_perag        *pag,
        xfs_agblock_t           start,
        xfs_agblock_t           end,
        xfs_extlen_t            minlen)
{
        struct xfs_trim_cur     tcur = {
                .start          = start,
                .count          = pag->pagf_longest,
                .end            = end,
                .minlen         = minlen,
        };
        int                     error = 0;

        if (start != 0 || end != pag_group(pag)->xg_block_count)
                tcur.by_bno = true;

        do {
                struct xfs_busy_extents *extents;

                extents = kzalloc(sizeof(*extents), GFP_KERNEL);
                if (!extents) {
                        error = -ENOMEM;
                        break;
                }

                extents->owner = extents;
                INIT_LIST_HEAD(&extents->extent_list);

                error = xfs_trim_gather_extents(pag, &tcur, extents);
                if (error) {
                        kfree(extents);
                        break;
                }

                /*
                 * We hand the extent list to the discard function here so the
                 * discarded extents can be removed from the busy extent list.
                 * This allows the discards to run asynchronously with gathering
                 * the next round of extents to discard.
                 *
                 * However, we must ensure that we do not reference the extent
                 * list  after this function call, as it may have been freed by
                 * the time control returns to us.
                 */
                error = xfs_discard_extents(pag_mount(pag), extents);
                if (error)
                        break;

                if (xfs_trim_should_stop())
                        break;

        } while (tcur.count != 0);

        return error;

}

static int
xfs_trim_datadev_extents(
        struct xfs_mount        *mp,
        xfs_daddr_t             start,
        xfs_daddr_t             end,
        xfs_extlen_t            minlen)
{
        xfs_agnumber_t          start_agno, end_agno;
        xfs_agblock_t           start_agbno, end_agbno;
        struct xfs_perag        *pag = NULL;
        xfs_daddr_t             ddev_end;
        int                     last_error = 0, error;

        ddev_end = min_t(xfs_daddr_t, end,
                         XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks) - 1);

        start_agno = xfs_daddr_to_agno(mp, start);
        start_agbno = xfs_daddr_to_agbno(mp, start);
        end_agno = xfs_daddr_to_agno(mp, ddev_end);
        end_agbno = xfs_daddr_to_agbno(mp, ddev_end);

        while ((pag = xfs_perag_next_range(mp, pag, start_agno, end_agno))) {
                xfs_agblock_t   agend = pag_group(pag)->xg_block_count;

                if (pag_agno(pag) == end_agno)
                        agend = end_agbno;
                error = xfs_trim_perag_extents(pag, start_agbno, agend, minlen);
                if (error)
                        last_error = error;

                if (xfs_trim_should_stop()) {
                        xfs_perag_rele(pag);
                        break;
                }
                start_agbno = 0;
        }

        return last_error;
}

#ifdef CONFIG_XFS_RT
struct xfs_trim_rtdev {
        /* list of rt extents to free */
        struct list_head        extent_list;

        /* minimum length that caller allows us to trim */
        xfs_rtblock_t           minlen_fsb;

        /* restart point for the rtbitmap walk */
        xfs_rtxnum_t            restart_rtx;

        /* stopping point for the current rtbitmap walk */
        xfs_rtxnum_t            stop_rtx;
};

struct xfs_rtx_busy {
        struct list_head        list;
        xfs_rtblock_t           bno;
        xfs_rtblock_t           length;
};

static void
xfs_discard_free_rtdev_extents(
        struct xfs_trim_rtdev   *tr)
{
        struct xfs_rtx_busy     *busyp, *n;

        list_for_each_entry_safe(busyp, n, &tr->extent_list, list) {
                list_del_init(&busyp->list);
                kfree(busyp);
        }
}

/*
 * Walk the discard list and issue discards on all the busy extents in the
 * list. We plug and chain the bios so that we only need a single completion
 * call to clear all the busy extents once the discards are complete.
 */
static int
xfs_discard_rtdev_extents(
        struct xfs_mount        *mp,
        struct xfs_trim_rtdev   *tr)
{
        struct block_device     *bdev = mp->m_rtdev_targp->bt_bdev;
        struct xfs_rtx_busy     *busyp;
        struct bio              *bio = NULL;
        struct blk_plug         plug;
        xfs_rtblock_t           start = NULLRTBLOCK, length = 0;
        int                     error = 0;

        blk_start_plug(&plug);
        list_for_each_entry(busyp, &tr->extent_list, list) {
                if (start == NULLRTBLOCK)
                        start = busyp->bno;
                length += busyp->length;

                trace_xfs_discard_rtextent(mp, busyp->bno, busyp->length);

                error = __blkdev_issue_discard(bdev,
                                xfs_rtb_to_daddr(mp, busyp->bno),
                                XFS_FSB_TO_BB(mp, busyp->length),
                                GFP_NOFS, &bio);
                if (error)
                        break;
        }
        xfs_discard_free_rtdev_extents(tr);

        if (bio) {
                error = submit_bio_wait(bio);
                if (error == -EOPNOTSUPP)
                        error = 0;
                if (error)
                        xfs_info(mp,
         "discard failed for rtextent [0x%llx,%llu], error %d",
                                 (unsigned long long)start,
                                 (unsigned long long)length,
                                 error);
                bio_put(bio);
        }
        blk_finish_plug(&plug);

        return error;
}

static int
xfs_trim_gather_rtextent(
        struct xfs_rtgroup              *rtg,
        struct xfs_trans                *tp,
        const struct xfs_rtalloc_rec    *rec,
        void                            *priv)
{
        struct xfs_trim_rtdev           *tr = priv;
        struct xfs_rtx_busy             *busyp;
        xfs_rtblock_t                   rbno, rlen;

        if (rec->ar_startext > tr->stop_rtx) {
                /*
                 * If we've scanned a large number of rtbitmap blocks, update
                 * the cursor to point at this extent so we restart the next
                 * batch from this extent.
                 */
                tr->restart_rtx = rec->ar_startext;
                return -ECANCELED;
        }

        rbno = xfs_rtx_to_rtb(rtg, rec->ar_startext);
        rlen = xfs_rtbxlen_to_blen(rtg_mount(rtg), rec->ar_extcount);

        /* Ignore too small. */
        if (rlen < tr->minlen_fsb) {
                trace_xfs_discard_rttoosmall(rtg_mount(rtg), rbno, rlen);
                return 0;
        }

        busyp = kzalloc(sizeof(struct xfs_rtx_busy), GFP_KERNEL);
        if (!busyp)
                return -ENOMEM;

        busyp->bno = rbno;
        busyp->length = rlen;
        INIT_LIST_HEAD(&busyp->list);
        list_add_tail(&busyp->list, &tr->extent_list);

        tr->restart_rtx = rec->ar_startext + rec->ar_extcount;
        return 0;
}

/* Trim extents on an !rtgroups realtime device */
static int
xfs_trim_rtextents(
        struct xfs_rtgroup      *rtg,
        xfs_rtxnum_t            low,
        xfs_rtxnum_t            high,
        xfs_daddr_t             minlen)
{
        struct xfs_mount        *mp = rtg_mount(rtg);
        struct xfs_trim_rtdev   tr = {
                .minlen_fsb     = XFS_BB_TO_FSB(mp, minlen),
                .extent_list    = LIST_HEAD_INIT(tr.extent_list),
        };
        struct xfs_trans        *tp;
        int                     error;

        error = xfs_trans_alloc_empty(mp, &tp);
        if (error)
                return error;

        /*
         * Walk the free ranges between low and high.  The query_range function
         * trims the extents returned.
         */
        do {
                tr.stop_rtx = low + xfs_rtbitmap_rtx_per_rbmblock(mp);
                xfs_rtgroup_lock(rtg, XFS_RTGLOCK_BITMAP_SHARED);
                error = xfs_rtalloc_query_range(rtg, tp, low, high,
                                xfs_trim_gather_rtextent, &tr);

                if (error == -ECANCELED)
                        error = 0;
                if (error) {
                        xfs_rtgroup_unlock(rtg, XFS_RTGLOCK_BITMAP_SHARED);
                        xfs_discard_free_rtdev_extents(&tr);
                        break;
                }

                if (list_empty(&tr.extent_list)) {
                        xfs_rtgroup_unlock(rtg, XFS_RTGLOCK_BITMAP_SHARED);
                        break;
                }

                error = xfs_discard_rtdev_extents(mp, &tr);
                xfs_rtgroup_unlock(rtg, XFS_RTGLOCK_BITMAP_SHARED);
                if (error)
                        break;

                low = tr.restart_rtx;
        } while (!xfs_trim_should_stop() && low <= high);

        xfs_trans_cancel(tp);
        return error;
}

struct xfs_trim_rtgroup {
        /* list of rtgroup extents to free */
        struct xfs_busy_extents *extents;

        /* minimum length that caller allows us to trim */
        xfs_rtblock_t           minlen_fsb;

        /* restart point for the rtbitmap walk */
        xfs_rtxnum_t            restart_rtx;

        /* number of extents to examine before stopping to issue discard ios */
        int                     batch;

        /* number of extents queued for discard */
        int                     queued;
};

static int
xfs_trim_gather_rtgroup_extent(
        struct xfs_rtgroup              *rtg,
        struct xfs_trans                *tp,
        const struct xfs_rtalloc_rec    *rec,
        void                            *priv)
{
        struct xfs_trim_rtgroup         *tr = priv;
        xfs_rgblock_t                   rgbno;
        xfs_extlen_t                    len;

        if (--tr->batch <= 0) {
                /*
                 * If we've checked a large number of extents, update the
                 * cursor to point at this extent so we restart the next batch
                 * from this extent.
                 */
                tr->restart_rtx = rec->ar_startext;
                return -ECANCELED;
        }

        rgbno = xfs_rtx_to_rgbno(rtg, rec->ar_startext);
        len = xfs_rtxlen_to_extlen(rtg_mount(rtg), rec->ar_extcount);

        /* Ignore too small. */
        if (len < tr->minlen_fsb) {
                trace_xfs_discard_toosmall(rtg_group(rtg), rgbno, len);
                return 0;
        }

        /*
         * If any blocks in the range are still busy, skip the discard and try
         * again the next time.
         */
        if (xfs_extent_busy_search(rtg_group(rtg), rgbno, len)) {
                trace_xfs_discard_busy(rtg_group(rtg), rgbno, len);
                return 0;
        }

        xfs_extent_busy_insert_discard(rtg_group(rtg), rgbno, len,
                        &tr->extents->extent_list);

        tr->queued++;
        tr->restart_rtx = rec->ar_startext + rec->ar_extcount;
        return 0;
}

/* Trim extents in this rtgroup using the busy extent machinery. */
static int
xfs_trim_rtgroup_extents(
        struct xfs_rtgroup      *rtg,
        xfs_rtxnum_t            low,
        xfs_rtxnum_t            high,
        xfs_daddr_t             minlen)
{
        struct xfs_mount        *mp = rtg_mount(rtg);
        struct xfs_trim_rtgroup tr = {
                .minlen_fsb     = XFS_BB_TO_FSB(mp, minlen),
        };
        struct xfs_trans        *tp;
        int                     error;

        error = xfs_trans_alloc_empty(mp, &tp);
        if (error)
                return error;

        /*
         * Walk the free ranges between low and high.  The query_range function
         * trims the extents returned.
         */
        do {
                tr.extents = kzalloc(sizeof(*tr.extents), GFP_KERNEL);
                if (!tr.extents) {
                        error = -ENOMEM;
                        break;
                }

                tr.queued = 0;
                tr.batch = XFS_DISCARD_MAX_EXAMINE;
                tr.extents->owner = tr.extents;
                INIT_LIST_HEAD(&tr.extents->extent_list);

                xfs_rtgroup_lock(rtg, XFS_RTGLOCK_BITMAP_SHARED);
                error = xfs_rtalloc_query_range(rtg, tp, low, high,
                                xfs_trim_gather_rtgroup_extent, &tr);
                xfs_rtgroup_unlock(rtg, XFS_RTGLOCK_BITMAP_SHARED);
                if (error == -ECANCELED)
                        error = 0;
                if (error) {
                        kfree(tr.extents);
                        break;
                }

                if (!tr.queued)
                        break;

                /*
                 * We hand the extent list to the discard function here so the
                 * discarded extents can be removed from the busy extent list.
                 * This allows the discards to run asynchronously with
                 * gathering the next round of extents to discard.
                 *
                 * However, we must ensure that we do not reference the extent
                 * list  after this function call, as it may have been freed by
                 * the time control returns to us.
                 */
                error = xfs_discard_extents(rtg_mount(rtg), tr.extents);
                if (error)
                        break;

                low = tr.restart_rtx;
        } while (!xfs_trim_should_stop() && low <= high);

        xfs_trans_cancel(tp);
        return error;
}

static int
xfs_trim_rtdev_extents(
        struct xfs_mount        *mp,
        xfs_daddr_t             start,
        xfs_daddr_t             end,
        xfs_daddr_t             minlen)
{
        xfs_rtblock_t           start_rtbno, end_rtbno;
        xfs_rtxnum_t            start_rtx, end_rtx;
        xfs_rgnumber_t          start_rgno, end_rgno;
        xfs_daddr_t             daddr_offset;
        int                     last_error = 0, error;
        struct xfs_rtgroup      *rtg = NULL;

        /* Shift the start and end downwards to match the rt device. */
        daddr_offset = XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks);
        if (start > daddr_offset)
                start -= daddr_offset;
        else
                start = 0;
        start_rtbno = xfs_daddr_to_rtb(mp, start);
        start_rtx = xfs_rtb_to_rtx(mp, start_rtbno);
        start_rgno = xfs_rtb_to_rgno(mp, start_rtbno);

        if (end <= daddr_offset)
                return 0;
        else
                end -= daddr_offset;
        end_rtbno = xfs_daddr_to_rtb(mp, end);
        end_rtx = xfs_rtb_to_rtx(mp, end_rtbno + mp->m_sb.sb_rextsize - 1);
        end_rgno = xfs_rtb_to_rgno(mp, end_rtbno);

        while ((rtg = xfs_rtgroup_next_range(mp, rtg, start_rgno, end_rgno))) {
                xfs_rtxnum_t    rtg_end = rtg->rtg_extents;

                if (rtg_rgno(rtg) == end_rgno)
                        rtg_end = min(rtg_end, end_rtx);

                if (xfs_has_rtgroups(mp))
                        error = xfs_trim_rtgroup_extents(rtg, start_rtx,
                                        rtg_end, minlen);
                else
                        error = xfs_trim_rtextents(rtg, start_rtx, rtg_end,
                                        minlen);
                if (error)
                        last_error = error;

                if (xfs_trim_should_stop()) {
                        xfs_rtgroup_rele(rtg);
                        break;
                }
                start_rtx = 0;
        }

        return last_error;
}
#else
# define xfs_trim_rtdev_extents(...)    (-EOPNOTSUPP)
#endif /* CONFIG_XFS_RT */

/*
 * trim a range of the filesystem.
 *
 * Note: the parameters passed from userspace are byte ranges into the
 * filesystem which does not match to the format we use for filesystem block
 * addressing. FSB addressing is sparse (AGNO|AGBNO), while the incoming format
 * is a linear address range. Hence we need to use DADDR based conversions and
 * comparisons for determining the correct offset and regions to trim.
 *
 * The realtime device is mapped into the FITRIM "address space" immediately
 * after the data device.
 */
int
xfs_ioc_trim(
        struct xfs_mount                *mp,
        struct fstrim_range __user      *urange)
{
        unsigned int            granularity =
                bdev_discard_granularity(mp->m_ddev_targp->bt_bdev);
        struct block_device     *rt_bdev = NULL;
        struct fstrim_range     range;
        xfs_daddr_t             start, end;
        xfs_extlen_t            minlen;
        xfs_rfsblock_t          max_blocks;
        int                     error, last_error = 0;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;
        if (mp->m_rtdev_targp &&
            bdev_max_discard_sectors(mp->m_rtdev_targp->bt_bdev))
                rt_bdev = mp->m_rtdev_targp->bt_bdev;
        if (!bdev_max_discard_sectors(mp->m_ddev_targp->bt_bdev) && !rt_bdev)
                return -EOPNOTSUPP;

        if (rt_bdev)
                granularity = max(granularity,
                                  bdev_discard_granularity(rt_bdev));

        /*
         * We haven't recovered the log, so we cannot use our bnobt-guided
         * storage zapping commands.
         */
        if (xfs_has_norecovery(mp))
                return -EROFS;

        if (copy_from_user(&range, urange, sizeof(range)))
                return -EFAULT;

        range.minlen = max_t(u64, granularity, range.minlen);
        minlen = XFS_B_TO_FSB(mp, range.minlen);

        /*
         * Truncating down the len isn't actually quite correct, but using
         * BBTOB 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.
         */
        max_blocks = mp->m_sb.sb_dblocks + mp->m_sb.sb_rblocks;
        if (range.start >= XFS_FSB_TO_B(mp, max_blocks) ||
            range.minlen > XFS_FSB_TO_B(mp, mp->m_ag_max_usable) ||
            range.len < mp->m_sb.sb_blocksize)
                return -EINVAL;

        start = BTOBB(range.start);
        end = start + BTOBBT(range.len) - 1;

        if (bdev_max_discard_sectors(mp->m_ddev_targp->bt_bdev)) {
                error = xfs_trim_datadev_extents(mp, start, end, minlen);
                if (error)
                        last_error = error;
        }

        if (rt_bdev && !xfs_trim_should_stop()) {
                error = xfs_trim_rtdev_extents(mp, start, end, minlen);
                if (error)
                        last_error = error;
        }

        if (last_error)
                return last_error;

        range.len = min_t(unsigned long long, range.len,
                          XFS_FSB_TO_B(mp, max_blocks) - range.start);
        if (copy_to_user(urange, &range, sizeof(range)))
                return -EFAULT;
        return 0;
}