+++ /dev/null
-Date: Fri, Sep 26 2008 15:20:10 +1000
-From: Peter Leckie <pleckie@sgi.com>
-References: SGI:PV986789 bnc#482148
-Subject: Clean up dquot pincount code
-Patch-mainline: 2.6.28
-
-Clean up dquot pincount code.
-
-This is a code cleanup and optimization that removes a per mount point
-spinlock from the quota code and cleans up the code.
-
-The patch changes the pincount from being an int protected by a spinlock
-to an atomic_t allowing the pincount to be manipulated without holding
-the spinlock.
-
-This cleanup also protects against random wakup's of both the aild and
-xfssyncd by reevaluating the pincount after been woken. Two latter patches
-will address the Spurious wakeups.
-
-Signed-off-by: Peter Leckie <pleckie@sgi.com>
-Acked-by: Jan Kara <jack@suse.cz>
-
-Index: linux/fs/xfs/quota/xfs_dquot_item.c
-===================================================================
---- linux.orig/fs/xfs/quota/xfs_dquot_item.c 2008-10-09 17:13:53.000000000 -0500
-+++ linux/fs/xfs/quota/xfs_dquot_item.c 2009-03-09 10:24:24.000000000 -0500
-@@ -88,25 +88,23 @@ xfs_qm_dquot_logitem_format(
-
- /*
- * Increment the pin count of the given dquot.
-- * This value is protected by pinlock spinlock in the xQM structure.
- */
- STATIC void
- xfs_qm_dquot_logitem_pin(
- xfs_dq_logitem_t *logitem)
- {
-- xfs_dquot_t *dqp;
-+ xfs_dquot_t *dqp = logitem->qli_dquot;
-
-- dqp = logitem->qli_dquot;
- ASSERT(XFS_DQ_IS_LOCKED(dqp));
-- spin_lock(&(XFS_DQ_TO_QINF(dqp)->qi_pinlock));
-- dqp->q_pincount++;
-- spin_unlock(&(XFS_DQ_TO_QINF(dqp)->qi_pinlock));
-+ atomic_inc(&dqp->q_pincount);
-+
- }
-
- /*
- * Decrement the pin count of the given dquot, and wake up
- * anyone in xfs_dqwait_unpin() if the count goes to 0. The
-- * dquot must have been previously pinned with a call to xfs_dqpin().
-+ * dquot must have been previously pinned with a call to
-+ * xfs_qm_dquot_logitem_pin().
- */
- /* ARGSUSED */
- STATIC void
-@@ -114,16 +112,12 @@ xfs_qm_dquot_logitem_unpin(
- xfs_dq_logitem_t *logitem,
- int stale)
- {
-- xfs_dquot_t *dqp;
-+xfs_dquot_t *dqp = logitem->qli_dquot;
-+
-+ ASSERT(atomic_read(&dqp->q_pincount) > 0);
-+ if (atomic_dec_and_test(&dqp->q_pincount))
-+ wake_up(&dqp->q_pinwait);
-
-- dqp = logitem->qli_dquot;
-- ASSERT(dqp->q_pincount > 0);
-- spin_lock(&(XFS_DQ_TO_QINF(dqp)->qi_pinlock));
-- dqp->q_pincount--;
-- if (dqp->q_pincount == 0) {
-- sv_broadcast(&dqp->q_pinwait);
-- }
-- spin_unlock(&(XFS_DQ_TO_QINF(dqp)->qi_pinlock));
- }
-
- /* ARGSUSED */
-@@ -193,7 +187,7 @@ xfs_qm_dqunpin_wait(
- xfs_dquot_t *dqp)
- {
- ASSERT(XFS_DQ_IS_LOCKED(dqp));
-- if (dqp->q_pincount == 0) {
-+ if (atomic_read(&dqp->q_pincount) == 0) {
- return;
- }
-
-@@ -201,13 +195,7 @@ xfs_qm_dqunpin_wait(
- * Give the log a push so we don't wait here too long.
- */
- xfs_log_force(dqp->q_mount, (xfs_lsn_t)0, XFS_LOG_FORCE);
-- spin_lock(&(XFS_DQ_TO_QINF(dqp)->qi_pinlock));
-- if (dqp->q_pincount == 0) {
-- spin_unlock(&(XFS_DQ_TO_QINF(dqp)->qi_pinlock));
-- return;
-- }
-- sv_wait(&(dqp->q_pinwait), PINOD,
-- &(XFS_DQ_TO_QINF(dqp)->qi_pinlock), s);
-+ wait_event(dqp->q_pinwait, (atomic_read(&dqp->q_pincount) == 0));
- }
-
- /*
-@@ -310,7 +298,7 @@ xfs_qm_dquot_logitem_trylock(
- uint retval;
-
- dqp = qip->qli_dquot;
-- if (dqp->q_pincount > 0)
-+ if (atomic_read(&dqp->q_pincount) > 0)
- return (XFS_ITEM_PINNED);
-
- if (! xfs_qm_dqlock_nowait(dqp))
-Index: linux/fs/xfs/quota/xfs_dquot.h
-===================================================================
---- linux.orig/fs/xfs/quota/xfs_dquot.h 2008-10-09 17:13:53.000000000 -0500
-+++ linux/fs/xfs/quota/xfs_dquot.h 2009-03-09 10:36:25.000000000 -0500
-@@ -83,8 +83,9 @@ typedef struct xfs_dquot {
- xfs_qcnt_t q_res_rtbcount;/* total realtime blks used+reserved */
- mutex_t q_qlock; /* quota lock */
- struct completion q_flush; /* flush completion queue */
-- uint q_pincount; /* pin count for this dquot */
-- sv_t q_pinwait; /* sync var for pinning */
-+ atomic_t q_pincount; /* dquot pin count */
-+ wait_queue_head_t q_pinwait; /* dquot pinning wait queue */
-+
- #ifdef XFS_DQUOT_TRACE
- struct ktrace *q_trace; /* trace header structure */
- #endif
-Index: linux/fs/xfs/quota/xfs_dquot.c
-===================================================================
---- linux.orig/fs/xfs/quota/xfs_dquot.c 2008-10-09 17:13:53.000000000 -0500
-+++ linux/fs/xfs/quota/xfs_dquot.c 2009-03-09 10:38:06.000000000 -0500
-@@ -101,7 +101,7 @@ xfs_qm_dqinit(
- if (brandnewdquot) {
- dqp->dq_flnext = dqp->dq_flprev = dqp;
- mutex_init(&dqp->q_qlock);
-- sv_init(&dqp->q_pinwait, SV_DEFAULT, "pdq");
-+ init_waitqueue_head(&dqp->q_pinwait);
-
- /*
- * Because we want to use a counting completion, complete
-@@ -131,7 +131,7 @@ xfs_qm_dqinit(
- dqp->q_res_bcount = 0;
- dqp->q_res_icount = 0;
- dqp->q_res_rtbcount = 0;
-- dqp->q_pincount = 0;
-+ atomic_set(&dqp->q_pincount, 0);
- dqp->q_hash = NULL;
- ASSERT(dqp->dq_flnext == dqp->dq_flprev);
-
-@@ -1489,7 +1489,7 @@ xfs_qm_dqpurge(
- "xfs_qm_dqpurge: dquot %p flush failed", dqp);
- xfs_dqflock(dqp);
- }
-- ASSERT(dqp->q_pincount == 0);
-+ ASSERT(atomic_read(&dqp->q_pincount) == 0);
- ASSERT(XFS_FORCED_SHUTDOWN(mp) ||
- !(dqp->q_logitem.qli_item.li_flags & XFS_LI_IN_AIL));
-
-Index: linux/fs/xfs/quota/xfs_qm.h
-===================================================================
---- linux.orig/fs/xfs/quota/xfs_qm.h 2008-10-09 17:13:53.000000000 -0500
-+++ linux/fs/xfs/quota/xfs_qm.h 2009-03-09 10:11:15.000000000 -0500
-@@ -106,7 +106,6 @@ typedef struct xfs_qm {
- typedef struct xfs_quotainfo {
- xfs_inode_t *qi_uquotaip; /* user quota inode */
- xfs_inode_t *qi_gquotaip; /* group quota inode */
-- spinlock_t qi_pinlock; /* dquot pinning lock */
- xfs_dqlist_t qi_dqlist; /* all dquots in filesys */
- int qi_dqreclaims; /* a change here indicates
- a removal in the dqlist */
-Index: linux/fs/xfs/quota/xfs_qm.c
-===================================================================
---- linux.orig/fs/xfs/quota/xfs_qm.c 2008-10-09 17:13:53.000000000 -0500
-+++ linux/fs/xfs/quota/xfs_qm.c 2009-03-09 10:12:12.000000000 -0500
-@@ -1137,7 +1137,6 @@ xfs_qm_init_quotainfo(
- return error;
- }
-
-- spin_lock_init(&qinf->qi_pinlock);
- xfs_qm_list_init(&qinf->qi_dqlist, "mpdqlist", 0);
- qinf->qi_dqreclaims = 0;
-
-@@ -1234,7 +1233,6 @@ xfs_qm_destroy_quotainfo(
- */
- xfs_qm_rele_quotafs_ref(mp);
-
-- spinlock_destroy(&qi->qi_pinlock);
- xfs_qm_list_destroy(&qi->qi_dqlist);
-
- if (qi->qi_uquotaip) {
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