src/patches/suse-2.6.27.25/patches.fixes/xfs-kern_32215a_Clean-up-dquot-pincount-code.patch

   1 Date: Fri, Sep 26 2008 15:20:10 +1000
   2 From: Peter Leckie <pleckie@sgi.com>
   3 References: SGI:PV986789 bnc#482148
   4 Subject: Clean up dquot pincount code
   5 Patch-mainline: 2.6.28
   6
   7 Clean up dquot pincount code.
   8
   9 This is a code cleanup and optimization that removes a per mount point
  10 spinlock from the quota code and cleans up the code.
  11
  12 The patch changes the pincount from being an int protected by a spinlock
  13 to an atomic_t allowing the pincount to be manipulated without holding
  14 the spinlock.
  15
  16 This cleanup also protects against random wakup's of both the aild and
  17 xfssyncd by reevaluating the pincount after been woken. Two latter patches
  18 will address the Spurious wakeups.
  19
  20 Signed-off-by: Peter Leckie <pleckie@sgi.com>
  21 Acked-by: Jan Kara <jack@suse.cz>
  22
  23 Index: linux/fs/xfs/quota/xfs_dquot_item.c
  24 ===================================================================
  25 --- linux.orig/fs/xfs/quota/xfs_dquot_item.c    2008-10-09 17:13:53.000000000 -0500
  26 +++ linux/fs/xfs/quota/xfs_dquot_item.c 2009-03-09 10:24:24.000000000 -0500
  27 @@ -88,25 +88,23 @@ xfs_qm_dquot_logitem_format(
  28
  29  /*
  30   * Increment the pin count of the given dquot.
  31 - * This value is protected by pinlock spinlock in the xQM structure.
  32   */
  33  STATIC void
  34  xfs_qm_dquot_logitem_pin(
  35         xfs_dq_logitem_t *logitem)
  36  {
  37 -       xfs_dquot_t *dqp;
  38 +       xfs_dquot_t *dqp = logitem->qli_dquot;
  39
  40 -       dqp = logitem->qli_dquot;
  41         ASSERT(XFS_DQ_IS_LOCKED(dqp));
  42 -       spin_lock(&(XFS_DQ_TO_QINF(dqp)->qi_pinlock));
  43 -       dqp->q_pincount++;
  44 -       spin_unlock(&(XFS_DQ_TO_QINF(dqp)->qi_pinlock));
  45 +       atomic_inc(&dqp->q_pincount);
  46 +
  47  }
  48
  49  /*
  50   * Decrement the pin count of the given dquot, and wake up
  51   * anyone in xfs_dqwait_unpin() if the count goes to 0.         The
  52 - * dquot must have been previously pinned with a call to xfs_dqpin().
  53 + * dquot must have been previously pinned with a call to
  54 + * xfs_qm_dquot_logitem_pin().
  55   */
  56  /* ARGSUSED */
  57  STATIC void
  58 @@ -114,16 +112,12 @@ xfs_qm_dquot_logitem_unpin(
  59         xfs_dq_logitem_t *logitem,
  60         int               stale)
  61  {
  62 -       xfs_dquot_t *dqp;
  63 +xfs_dquot_t *dqp = logitem->qli_dquot;
  64 +
  65 +       ASSERT(atomic_read(&dqp->q_pincount) > 0);
  66 +       if (atomic_dec_and_test(&dqp->q_pincount))
  67 +               wake_up(&dqp->q_pinwait);
  68
  69 -       dqp = logitem->qli_dquot;
  70 -       ASSERT(dqp->q_pincount > 0);
  71 -       spin_lock(&(XFS_DQ_TO_QINF(dqp)->qi_pinlock));
  72 -       dqp->q_pincount--;
  73 -       if (dqp->q_pincount == 0) {
  74 -               sv_broadcast(&dqp->q_pinwait);
  75 -       }
  76 -       spin_unlock(&(XFS_DQ_TO_QINF(dqp)->qi_pinlock));
  77  }
  78
  79  /* ARGSUSED */
  80 @@ -193,7 +187,7 @@ xfs_qm_dqunpin_wait(
  81         xfs_dquot_t     *dqp)
  82  {
  83         ASSERT(XFS_DQ_IS_LOCKED(dqp));
  84 -       if (dqp->q_pincount == 0) {
  85 +       if (atomic_read(&dqp->q_pincount) == 0) {
  86                 return;
  87         }
  88
  89 @@ -201,13 +195,7 @@ xfs_qm_dqunpin_wait(
  90          * Give the log a push so we don't wait here too long.
  91          */
  92         xfs_log_force(dqp->q_mount, (xfs_lsn_t)0, XFS_LOG_FORCE);
  93 -       spin_lock(&(XFS_DQ_TO_QINF(dqp)->qi_pinlock));
  94 -       if (dqp->q_pincount == 0) {
  95 -               spin_unlock(&(XFS_DQ_TO_QINF(dqp)->qi_pinlock));
  96 -               return;
  97 -       }
  98 -       sv_wait(&(dqp->q_pinwait), PINOD,
  99 -               &(XFS_DQ_TO_QINF(dqp)->qi_pinlock), s);
 100 +       wait_event(dqp->q_pinwait, (atomic_read(&dqp->q_pincount) == 0));
 101  }
 102
 103  /*
 104 @@ -310,7 +298,7 @@ xfs_qm_dquot_logitem_trylock(
 105         uint                    retval;
 106
 107         dqp = qip->qli_dquot;
 108 -       if (dqp->q_pincount > 0)
 109 +       if (atomic_read(&dqp->q_pincount) > 0)
 110                 return (XFS_ITEM_PINNED);
 111
 112         if (! xfs_qm_dqlock_nowait(dqp))
 113 Index: linux/fs/xfs/quota/xfs_dquot.h
 114 ===================================================================
 115 --- linux.orig/fs/xfs/quota/xfs_dquot.h 2008-10-09 17:13:53.000000000 -0500
 116 +++ linux/fs/xfs/quota/xfs_dquot.h      2009-03-09 10:36:25.000000000 -0500
 117 @@ -83,8 +83,9 @@ typedef struct xfs_dquot {
 118         xfs_qcnt_t       q_res_rtbcount;/* total realtime blks used+reserved */
 119         mutex_t          q_qlock;       /* quota lock */
 120         struct completion q_flush;      /* flush completion queue */
 121 -       uint             q_pincount;    /* pin count for this dquot */
 122 -       sv_t             q_pinwait;     /* sync var for pinning */
 123 +       atomic_t          q_pincount;   /* dquot pin count */
 124 +       wait_queue_head_t q_pinwait;    /* dquot pinning wait queue */
 125 +
 126  #ifdef XFS_DQUOT_TRACE
 127         struct ktrace   *q_trace;       /* trace header structure */
 128  #endif
 129 Index: linux/fs/xfs/quota/xfs_dquot.c
 130 ===================================================================
 131 --- linux.orig/fs/xfs/quota/xfs_dquot.c 2008-10-09 17:13:53.000000000 -0500
 132 +++ linux/fs/xfs/quota/xfs_dquot.c      2009-03-09 10:38:06.000000000 -0500
 133 @@ -101,7 +101,7 @@ xfs_qm_dqinit(
 134         if (brandnewdquot) {
 135                 dqp->dq_flnext = dqp->dq_flprev = dqp;
 136                 mutex_init(&dqp->q_qlock);
 137 -               sv_init(&dqp->q_pinwait, SV_DEFAULT, "pdq");
 138 +               init_waitqueue_head(&dqp->q_pinwait);
 139
 140                 /*
 141                  * Because we want to use a counting completion, complete
 142 @@ -131,7 +131,7 @@ xfs_qm_dqinit(
 143                  dqp->q_res_bcount = 0;
 144                  dqp->q_res_icount = 0;
 145                  dqp->q_res_rtbcount = 0;
 146 -                dqp->q_pincount = 0;
 147 +                atomic_set(&dqp->q_pincount, 0);
 148                  dqp->q_hash = NULL;
 149                  ASSERT(dqp->dq_flnext == dqp->dq_flprev);
 150
 151 @@ -1489,7 +1489,7 @@ xfs_qm_dqpurge(
 152                                 "xfs_qm_dqpurge: dquot %p flush failed", dqp);
 153                 xfs_dqflock(dqp);
 154         }
 155 -       ASSERT(dqp->q_pincount == 0);
 156 +       ASSERT(atomic_read(&dqp->q_pincount) == 0);
 157         ASSERT(XFS_FORCED_SHUTDOWN(mp) ||
 158                !(dqp->q_logitem.qli_item.li_flags & XFS_LI_IN_AIL));
 159
 160 Index: linux/fs/xfs/quota/xfs_qm.h
 161 ===================================================================
 162 --- linux.orig/fs/xfs/quota/xfs_qm.h    2008-10-09 17:13:53.000000000 -0500
 163 +++ linux/fs/xfs/quota/xfs_qm.h 2009-03-09 10:11:15.000000000 -0500
 164 @@ -106,7 +106,6 @@ typedef struct xfs_qm {
 165  typedef struct xfs_quotainfo {
 166         xfs_inode_t     *qi_uquotaip;    /* user quota inode */
 167         xfs_inode_t     *qi_gquotaip;    /* group quota inode */
 168 -       spinlock_t       qi_pinlock;     /* dquot pinning lock */
 169         xfs_dqlist_t     qi_dqlist;      /* all dquots in filesys */
 170         int              qi_dqreclaims;  /* a change here indicates
 171                                             a removal in the dqlist */
 172 Index: linux/fs/xfs/quota/xfs_qm.c
 173 ===================================================================
 174 --- linux.orig/fs/xfs/quota/xfs_qm.c    2008-10-09 17:13:53.000000000 -0500
 175 +++ linux/fs/xfs/quota/xfs_qm.c 2009-03-09 10:12:12.000000000 -0500
 176 @@ -1137,7 +1137,6 @@ xfs_qm_init_quotainfo(
 177                 return error;
 178         }
 179
 180 -       spin_lock_init(&qinf->qi_pinlock);
 181         xfs_qm_list_init(&qinf->qi_dqlist, "mpdqlist", 0);
 182         qinf->qi_dqreclaims = 0;
 183
 184 @@ -1234,7 +1233,6 @@ xfs_qm_destroy_quotainfo(
 185          */
 186         xfs_qm_rele_quotafs_ref(mp);
 187
 188 -       spinlock_destroy(&qi->qi_pinlock);
 189         xfs_qm_list_destroy(&qi->qi_dqlist);
 190
 191         if (qi->qi_uquotaip) {