fs/xfs/xfs_log_rlimit.c

   1 /*
   2  * Copyright (c) 2013 Jie Liu.
   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_fs.h"
  20 #include "xfs_shared.h"
  21 #include "xfs_log.h"
  22 #include "xfs_trans.h"
  23 #include "xfs_ag.h"
  24 #include "xfs_sb.h"
  25 #include "xfs_mount.h"
  26 #include "xfs_da_format.h"
  27 #include "xfs_trans_space.h"
  28 #include "xfs_bmap_btree.h"
  29 #include "xfs_inode.h"
  30 #include "xfs_da_btree.h"
  31 #include "xfs_attr_leaf.h"
  32
  33 /*
  34  * Calculate the maximum length in bytes that would be required for a local
  35  * attribute value as large attributes out of line are not logged.
  36  */
  37 STATIC int
  38 xfs_log_calc_max_attrsetm_res(
  39         struct xfs_mount        *mp)
  40 {
  41         int                     size;
  42         int                     nblks;
  43
  44         size = xfs_attr_leaf_entsize_local_max(mp->m_sb.sb_blocksize) -
  45                MAXNAMELEN - 1;
  46         nblks = XFS_DAENTER_SPACE_RES(mp, XFS_ATTR_FORK);
  47         nblks += XFS_B_TO_FSB(mp, size);
  48         nblks += XFS_NEXTENTADD_SPACE_RES(mp, size, XFS_ATTR_FORK);
  49
  50         return  M_RES(mp)->tr_attrsetm.tr_logres +
  51                 M_RES(mp)->tr_attrsetrt.tr_logres * nblks;
  52 }
  53
  54 /*
  55  * Iterate over the log space reservation table to figure out and return
  56  * the maximum one in terms of the pre-calculated values which were done
  57  * at mount time.
  58  */
  59 STATIC void
  60 xfs_log_get_max_trans_res(
  61         struct xfs_mount        *mp,
  62         struct xfs_trans_res    *max_resp)
  63 {
  64         struct xfs_trans_res    *resp;
  65         struct xfs_trans_res    *end_resp;
  66         int                     log_space = 0;
  67         int                     attr_space;
  68
  69         attr_space = xfs_log_calc_max_attrsetm_res(mp);
  70
  71         resp = (struct xfs_trans_res *)M_RES(mp);
  72         end_resp = (struct xfs_trans_res *)(M_RES(mp) + 1);
  73         for (; resp < end_resp; resp++) {
  74                 int             tmp = resp->tr_logcount > 1 ?
  75                                       resp->tr_logres * resp->tr_logcount :
  76                                       resp->tr_logres;
  77                 if (log_space < tmp) {
  78                         log_space = tmp;
  79                         *max_resp = *resp;              /* struct copy */
  80                 }
  81         }
  82
  83         if (attr_space > log_space) {
  84                 *max_resp = M_RES(mp)->tr_attrsetm;     /* struct copy */
  85                 max_resp->tr_logres = attr_space;
  86         }
  87 }
  88
  89 /*
  90  * Calculate the minimum valid log size for the given superblock configuration.
  91  * Used to calculate the minimum log size at mkfs time, and to determine if
  92  * the log is large enough or not at mount time. Returns the minimum size in
  93  * filesystem block size units.
  94  */
  95 int
  96 xfs_log_calc_minimum_size(
  97         struct xfs_mount        *mp)
  98 {
  99         struct xfs_trans_res    tres = {0};
 100         int                     max_logres;
 101         int                     min_logblks = 0;
 102         int                     lsunit = 0;
 103
 104         xfs_log_get_max_trans_res(mp, &tres);
 105
 106         max_logres = xfs_log_calc_unit_res(mp, tres.tr_logres);
 107         if (tres.tr_logcount > 1)
 108                 max_logres *= tres.tr_logcount;
 109
 110         if (xfs_sb_version_haslogv2(&mp->m_sb) && mp->m_sb.sb_logsunit > 1)
 111                 lsunit = BTOBB(mp->m_sb.sb_logsunit);
 112
 113         /*
 114          * Two factors should be taken into account for calculating the minimum
 115          * log space.
 116          * 1) The fundamental limitation is that no single transaction can be
 117          *    larger than half size of the log.
 118          *
 119          *    From mkfs.xfs, this is considered by the XFS_MIN_LOG_FACTOR
 120          *    define, which is set to 3. That means we can definitely fit
 121          *    maximally sized 2 transactions in the log. We'll use this same
 122          *    value here.
 123          *
 124          * 2) If the lsunit option is specified, a transaction requires 2 LSU
 125          *    for the reservation because there are two log writes that can
 126          *    require padding - the transaction data and the commit record which
 127          *    are written separately and both can require padding to the LSU.
 128          *    Consider that we can have an active CIL reservation holding 2*LSU,
 129          *    but the CIL is not over a push threshold, in this case, if we
 130          *    don't have enough log space for at one new transaction, which
 131          *    includes another 2*LSU in the reservation, we will run into dead
 132          *    loop situation in log space grant procedure. i.e.
 133          *    xlog_grant_head_wait().
 134          *
 135          *    Hence the log size needs to be able to contain two maximally sized
 136          *    and padded transactions, which is (2 * (2 * LSU + maxlres)).
 137          *
 138          * Also, the log size should be a multiple of the log stripe unit, round
 139          * it up to lsunit boundary if lsunit is specified.
 140          */
 141         if (lsunit) {
 142                 min_logblks = roundup_64(BTOBB(max_logres), lsunit) +
 143                               2 * lsunit;
 144         } else
 145                 min_logblks = BTOBB(max_logres) + 2 * BBSIZE;
 146         min_logblks *= XFS_MIN_LOG_FACTOR;
 147
 148         return XFS_BB_TO_FSB(mp, min_logblks);
 149 }