xfs_discard.c

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/*
 * 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_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_extent_busy.h"
#include "xfs_discard.h"
#include "xfs_trace.h"

STATIC int
xfs_trim_extents(
    struct xfs_mount    *mp,
    xfs_agnumber_t      agno,
    xfs_daddr_t     start,
    xfs_daddr_t     end,
    xfs_daddr_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_ge(cur, 0,
                be32_to_cpu(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;
        xfs_daddr_t dbno;
        xfs_extlen_t    dlen;

        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 <= be32_to_cpu(XFS_BUF_TO_AGF(agbp)->agf_longest));

        /*
         * use daddr format for all range/len calculations as that is
         * the format the range/len variables are supplied in by
         * userspace.
         */
        dbno = XFS_AGB_TO_DADDR(mp, agno, fbno);
        dlen = XFS_FSB_TO_BB(mp, flen);

        /*
         * Too small?  Give up.
         */
        if (dlen < 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 (dbno + dlen < start || dbno > end) {
            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_extent_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, dbno, dlen, 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;
}

/*
 * 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.
 */
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_daddr_t     start, end, 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
     * 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.
     */
    if (range.start >= XFS_FSB_TO_B(mp, mp->m_sb.sb_dblocks) ||
        range.minlen > XFS_FSB_TO_B(mp, XFS_ALLOC_AG_MAX_USABLE(mp)))
        return -XFS_ERROR(EINVAL);

    start = BTOBB(range.start);
    end = start + BTOBBT(range.len) - 1;
    minlen = BTOBB(max_t(u64, granularity, range.minlen));

    if (end > XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks) - 1)
        end = XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks)- 1;

    start_agno = xfs_daddr_to_agno(mp, start);
    end_agno = xfs_daddr_to_agno(mp, end);

    for (agno = start_agno; agno <= end_agno; agno++) {
        error = -xfs_trim_extents(mp, agno, start, end, 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_extent_busy  *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;
}