fs/xfs/linux-2.6/xfs_discard.c

   1 /*
   2  * Copyright (C) 2010 Red Hat, Inc.
   3  * All Rights Reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write the Free Software Foundation,
  16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17  */
  18 #include "xfs.h"
  19 #include "xfs_sb.h"
  20 #include "xfs_inum.h"
  21 #include "xfs_log.h"
  22 #include "xfs_ag.h"
  23 #include "xfs_mount.h"
  24 #include "xfs_quota.h"
  25 #include "xfs_trans.h"
  26 #include "xfs_alloc_btree.h"
  27 #include "xfs_bmap_btree.h"
  28 #include "xfs_ialloc_btree.h"
  29 #include "xfs_btree.h"
  30 #include "xfs_inode.h"
  31 #include "xfs_alloc.h"
  32 #include "xfs_error.h"
  33 #include "xfs_discard.h"
  34 #include "xfs_trace.h"
  35
  36 STATIC int
  37 xfs_trim_extents(
  38         struct xfs_mount        *mp,
  39         xfs_agnumber_t          agno,
  40         xfs_fsblock_t           start,
  41         xfs_fsblock_t           len,
  42         xfs_fsblock_t           minlen,
  43         __uint64_t              *blocks_trimmed)
  44 {
  45         struct block_device     *bdev = mp->m_ddev_targp->bt_bdev;
  46         struct xfs_btree_cur    *cur;
  47         struct xfs_buf          *agbp;
  48         struct xfs_perag        *pag;
  49         int                     error;
  50         int                     i;
  51
  52         pag = xfs_perag_get(mp, agno);
  53
  54         error = xfs_alloc_read_agf(mp, NULL, agno, 0, &agbp);
  55         if (error || !agbp)
  56                 goto out_put_perag;
  57
  58         cur = xfs_allocbt_init_cursor(mp, NULL, agbp, agno, XFS_BTNUM_CNT);
  59
  60         /*
  61          * Force out the log.  This means any transactions that might have freed
  62          * space before we took the AGF buffer lock are now on disk, and the
  63          * volatile disk cache is flushed.
  64          */
  65         xfs_log_force(mp, XFS_LOG_SYNC);
  66
  67         /*
  68          * Look up the longest btree in the AGF and start with it.
  69          */
  70         error = xfs_alloc_lookup_le(cur, 0,
  71                                     XFS_BUF_TO_AGF(agbp)->agf_longest, &i);
  72         if (error)
  73                 goto out_del_cursor;
  74
  75         /*
  76          * Loop until we are done with all extents that are large
  77          * enough to be worth discarding.
  78          */
  79         while (i) {
  80                 xfs_agblock_t fbno;
  81                 xfs_extlen_t flen;
  82
  83                 error = xfs_alloc_get_rec(cur, &fbno, &flen, &i);
  84                 if (error)
  85                         goto out_del_cursor;
  86                 XFS_WANT_CORRUPTED_GOTO(i == 1, out_del_cursor);
  87                 ASSERT(flen <= XFS_BUF_TO_AGF(agbp)->agf_longest);
  88
  89                 /*
  90                  * Too small?  Give up.
  91                  */
  92                 if (flen < minlen) {
  93                         trace_xfs_discard_toosmall(mp, agno, fbno, flen);
  94                         goto out_del_cursor;
  95                 }
  96
  97                 /*
  98                  * If the extent is entirely outside of the range we are
  99                  * supposed to discard skip it.  Do not bother to trim
 100                  * down partially overlapping ranges for now.
 101                  */
 102                 if (XFS_AGB_TO_FSB(mp, agno, fbno) + flen < start ||
 103                     XFS_AGB_TO_FSB(mp, agno, fbno) >= start + len) {
 104                         trace_xfs_discard_exclude(mp, agno, fbno, flen);
 105                         goto next_extent;
 106                 }
 107
 108                 /*
 109                  * If any blocks in the range are still busy, skip the
 110                  * discard and try again the next time.
 111                  */
 112                 if (xfs_alloc_busy_search(mp, agno, fbno, flen)) {
 113                         trace_xfs_discard_busy(mp, agno, fbno, flen);
 114                         goto next_extent;
 115                 }
 116
 117                 trace_xfs_discard_extent(mp, agno, fbno, flen);
 118                 error = -blkdev_issue_discard(bdev,
 119                                 XFS_AGB_TO_DADDR(mp, agno, fbno),
 120                                 XFS_FSB_TO_BB(mp, flen),
 121                                 GFP_NOFS, 0);
 122                 if (error)
 123                         goto out_del_cursor;
 124                 *blocks_trimmed += flen;
 125
 126 next_extent:
 127                 error = xfs_btree_decrement(cur, 0, &i);
 128                 if (error)
 129                         goto out_del_cursor;
 130         }
 131
 132 out_del_cursor:
 133         xfs_btree_del_cursor(cur, error ? XFS_BTREE_ERROR : XFS_BTREE_NOERROR);
 134         xfs_buf_relse(agbp);
 135 out_put_perag:
 136         xfs_perag_put(pag);
 137         return error;
 138 }
 139
 140 int
 141 xfs_ioc_trim(
 142         struct xfs_mount                *mp,
 143         struct fstrim_range __user      *urange)
 144 {
 145         struct request_queue    *q = mp->m_ddev_targp->bt_bdev->bd_disk->queue;
 146         unsigned int            granularity = q->limits.discard_granularity;
 147         struct fstrim_range     range;
 148         xfs_fsblock_t           start, len, minlen;
 149         xfs_agnumber_t          start_agno, end_agno, agno;
 150         __uint64_t              blocks_trimmed = 0;
 151         int                     error, last_error = 0;
 152
 153         if (!capable(CAP_SYS_ADMIN))
 154                 return -XFS_ERROR(EPERM);
 155         if (!blk_queue_discard(q))
 156                 return -XFS_ERROR(EOPNOTSUPP);
 157         if (copy_from_user(&range, urange, sizeof(range)))
 158                 return -XFS_ERROR(EFAULT);
 159
 160         /*
 161          * Truncating down the len isn't actually quite correct, but using
 162          * XFS_B_TO_FSB would mean we trivially get overflows for values
 163          * of ULLONG_MAX or slightly lower.  And ULLONG_MAX is the default
 164          * used by the fstrim application.  In the end it really doesn't
 165          * matter as trimming blocks is an advisory interface.
 166          */
 167         start = XFS_B_TO_FSBT(mp, range.start);
 168         len = XFS_B_TO_FSBT(mp, range.len);
 169         minlen = XFS_B_TO_FSB(mp, max_t(u64, granularity, range.minlen));
 170
 171         start_agno = XFS_FSB_TO_AGNO(mp, start);
 172         if (start_agno >= mp->m_sb.sb_agcount)
 173                 return -XFS_ERROR(EINVAL);
 174
 175         end_agno = XFS_FSB_TO_AGNO(mp, start + len);
 176         if (end_agno >= mp->m_sb.sb_agcount)
 177                 end_agno = mp->m_sb.sb_agcount - 1;
 178
 179         for (agno = start_agno; agno <= end_agno; agno++) {
 180                 error = -xfs_trim_extents(mp, agno, start, len, minlen,
 181                                           &blocks_trimmed);
 182                 if (error)
 183                         last_error = error;
 184         }
 185
 186         if (last_error)
 187                 return last_error;
 188
 189         range.len = XFS_FSB_TO_B(mp, blocks_trimmed);
 190         if (copy_to_user(urange, &range, sizeof(range)))
 191                 return -XFS_ERROR(EFAULT);
 192         return 0;
 193 }