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authorDave Chinner <dchinner@redhat.com>2014-05-05 17:30:15 +1000
committerDave Chinner <david@fromorbit.com>2014-05-05 17:30:15 +1000
commit3c353375761d81abfb66eb054aacceef31658e24 (patch)
tree709ca6211697a56c57dd58a21127582d581be32d /fs/xfs/xfs_qm.c
parentf58522c5a47a1862c6b3fad97ea9285c5d68199d (diff)
xfs: remove dquot hints
group and project quota hints are currently stored on the user dquot. If we are attaching quotas to the inode, then the group and project dquots are stored as hints on the user dquot to save having to look them up again later. The thing is, the hints are not used for that inode for the rest of the life of the inode - the dquots are attached directly to the inode itself - so the only time the hints are used is when an inode first has dquots attached. When the hints on the user dquot don't match the dquots being attache dto the inode, they are then removed and replaced with the new hints. If a user is concurrently modifying files in different group and/or project contexts, then this leads to thrashing of the hints attached to user dquot. If user quotas are not enabled, then hints are never even used. So, if the hints are used to avoid the cost of the lookup, is the cost of the lookup significant enough to justify the hint infrstructure? Maybe it was once, when there was a global quota manager shared between all XFS filesystems and was hash table based. However, lookups are now much simpler, requiring only a single lock and radix tree lookup local to the filesystem and no hash or LRU manipulations to be made. Hence the cost of lookup is much lower than when hints were implemented. Turns out that benchmarks show that, too, with thir being no differnce in performance when doing file creation workloads as a single user with user, group and project quotas enabled - the hints do not make the code go any faster. In fact, removing the hints shows a 2-3% reduction in the time it takes to create 50 million inodes.... So, let's just get rid of the hints and the complexity around them. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dave Chinner <david@fromorbit.com>
Diffstat (limited to 'fs/xfs/xfs_qm.c')
-rw-r--r--fs/xfs/xfs_qm.c214
1 files changed, 21 insertions, 193 deletions
diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
index 348e4d2ed6e6..72bd0e8a5954 100644
--- a/fs/xfs/xfs_qm.c
+++ b/fs/xfs/xfs_qm.c
@@ -193,47 +193,6 @@ xfs_qm_dqpurge(
}
/*
- * Release the group or project dquot pointers the user dquots maybe carrying
- * around as a hint, and proceed to purge the user dquot cache if requested.
-*/
-STATIC int
-xfs_qm_dqpurge_hints(
- struct xfs_dquot *dqp,
- void *data)
-{
- struct xfs_dquot *gdqp = NULL;
- struct xfs_dquot *pdqp = NULL;
- uint flags = *((uint *)data);
-
- xfs_dqlock(dqp);
- if (dqp->dq_flags & XFS_DQ_FREEING) {
- xfs_dqunlock(dqp);
- return EAGAIN;
- }
-
- /* If this quota has a hint attached, prepare for releasing it now */
- gdqp = dqp->q_gdquot;
- if (gdqp)
- dqp->q_gdquot = NULL;
-
- pdqp = dqp->q_pdquot;
- if (pdqp)
- dqp->q_pdquot = NULL;
-
- xfs_dqunlock(dqp);
-
- if (gdqp)
- xfs_qm_dqrele(gdqp);
- if (pdqp)
- xfs_qm_dqrele(pdqp);
-
- if (flags & XFS_QMOPT_UQUOTA)
- return xfs_qm_dqpurge(dqp, NULL);
-
- return 0;
-}
-
-/*
* Purge the dquot cache.
*/
void
@@ -241,18 +200,8 @@ xfs_qm_dqpurge_all(
struct xfs_mount *mp,
uint flags)
{
- /*
- * We have to release group/project dquot hint(s) from the user dquot
- * at first if they are there, otherwise we would run into an infinite
- * loop while walking through radix tree to purge other type of dquots
- * since their refcount is not zero if the user dquot refers to them
- * as hint.
- *
- * Call the special xfs_qm_dqpurge_hints() will end up go through the
- * general xfs_qm_dqpurge() against user dquot cache if requested.
- */
- xfs_qm_dquot_walk(mp, XFS_DQ_USER, xfs_qm_dqpurge_hints, &flags);
-
+ if (flags & XFS_QMOPT_UQUOTA)
+ xfs_qm_dquot_walk(mp, XFS_DQ_USER, xfs_qm_dqpurge, NULL);
if (flags & XFS_QMOPT_GQUOTA)
xfs_qm_dquot_walk(mp, XFS_DQ_GROUP, xfs_qm_dqpurge, NULL);
if (flags & XFS_QMOPT_PQUOTA)
@@ -409,7 +358,6 @@ xfs_qm_dqattach_one(
xfs_dqid_t id,
uint type,
uint doalloc,
- xfs_dquot_t *udqhint, /* hint */
xfs_dquot_t **IO_idqpp)
{
xfs_dquot_t *dqp;
@@ -419,9 +367,9 @@ xfs_qm_dqattach_one(
error = 0;
/*
- * See if we already have it in the inode itself. IO_idqpp is
- * &i_udquot or &i_gdquot. This made the code look weird, but
- * made the logic a lot simpler.
+ * See if we already have it in the inode itself. IO_idqpp is &i_udquot
+ * or &i_gdquot. This made the code look weird, but made the logic a lot
+ * simpler.
*/
dqp = *IO_idqpp;
if (dqp) {
@@ -430,49 +378,10 @@ xfs_qm_dqattach_one(
}
/*
- * udqhint is the i_udquot field in inode, and is non-NULL only
- * when the type arg is group/project. Its purpose is to save a
- * lookup by dqid (xfs_qm_dqget) by caching a group dquot inside
- * the user dquot.
- */
- if (udqhint) {
- ASSERT(type == XFS_DQ_GROUP || type == XFS_DQ_PROJ);
- xfs_dqlock(udqhint);
-
- /*
- * No need to take dqlock to look at the id.
- *
- * The ID can't change until it gets reclaimed, and it won't
- * be reclaimed as long as we have a ref from inode and we
- * hold the ilock.
- */
- if (type == XFS_DQ_GROUP)
- dqp = udqhint->q_gdquot;
- else
- dqp = udqhint->q_pdquot;
- if (dqp && be32_to_cpu(dqp->q_core.d_id) == id) {
- ASSERT(*IO_idqpp == NULL);
-
- *IO_idqpp = xfs_qm_dqhold(dqp);
- xfs_dqunlock(udqhint);
- return 0;
- }
-
- /*
- * We can't hold a dquot lock when we call the dqget code.
- * We'll deadlock in no time, because of (not conforming to)
- * lock ordering - the inodelock comes before any dquot lock,
- * and we may drop and reacquire the ilock in xfs_qm_dqget().
- */
- xfs_dqunlock(udqhint);
- }
-
- /*
- * Find the dquot from somewhere. This bumps the
- * reference count of dquot and returns it locked.
- * This can return ENOENT if dquot didn't exist on
- * disk and we didn't ask it to allocate;
- * ESRCH if quotas got turned off suddenly.
+ * Find the dquot from somewhere. This bumps the reference count of
+ * dquot and returns it locked. This can return ENOENT if dquot didn't
+ * exist on disk and we didn't ask it to allocate; ESRCH if quotas got
+ * turned off suddenly.
*/
error = xfs_qm_dqget(ip->i_mount, ip, id, type,
doalloc | XFS_QMOPT_DOWARN, &dqp);
@@ -490,48 +399,6 @@ xfs_qm_dqattach_one(
return 0;
}
-
-/*
- * Given a udquot and group/project type, attach the group/project
- * dquot pointer to the udquot as a hint for future lookups.
- */
-STATIC void
-xfs_qm_dqattach_hint(
- struct xfs_inode *ip,
- int type)
-{
- struct xfs_dquot **dqhintp;
- struct xfs_dquot *dqp;
- struct xfs_dquot *udq = ip->i_udquot;
-
- ASSERT(type == XFS_DQ_GROUP || type == XFS_DQ_PROJ);
-
- xfs_dqlock(udq);
-
- if (type == XFS_DQ_GROUP) {
- dqp = ip->i_gdquot;
- dqhintp = &udq->q_gdquot;
- } else {
- dqp = ip->i_pdquot;
- dqhintp = &udq->q_pdquot;
- }
-
- if (*dqhintp) {
- struct xfs_dquot *tmp;
-
- if (*dqhintp == dqp)
- goto done;
-
- tmp = *dqhintp;
- *dqhintp = NULL;
- xfs_qm_dqrele(tmp);
- }
-
- *dqhintp = xfs_qm_dqhold(dqp);
-done:
- xfs_dqunlock(udq);
-}
-
static bool
xfs_qm_need_dqattach(
struct xfs_inode *ip)
@@ -562,7 +429,6 @@ xfs_qm_dqattach_locked(
uint flags)
{
xfs_mount_t *mp = ip->i_mount;
- uint nquotas = 0;
int error = 0;
if (!xfs_qm_need_dqattach(ip))
@@ -570,77 +436,39 @@ xfs_qm_dqattach_locked(
ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
- if (XFS_IS_UQUOTA_ON(mp)) {
+ if (XFS_IS_UQUOTA_ON(mp) && !ip->i_udquot) {
error = xfs_qm_dqattach_one(ip, ip->i_d.di_uid, XFS_DQ_USER,
flags & XFS_QMOPT_DQALLOC,
- NULL, &ip->i_udquot);
+ &ip->i_udquot);
if (error)
goto done;
- nquotas++;
+ ASSERT(ip->i_udquot);
}
- ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
- if (XFS_IS_GQUOTA_ON(mp)) {
+ if (XFS_IS_GQUOTA_ON(mp) && !ip->i_gdquot) {
error = xfs_qm_dqattach_one(ip, ip->i_d.di_gid, XFS_DQ_GROUP,
flags & XFS_QMOPT_DQALLOC,
- ip->i_udquot, &ip->i_gdquot);
- /*
- * Don't worry about the udquot that we may have
- * attached above. It'll get detached, if not already.
- */
+ &ip->i_gdquot);
if (error)
goto done;
- nquotas++;
+ ASSERT(ip->i_gdquot);
}
- ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
- if (XFS_IS_PQUOTA_ON(mp)) {
+ if (XFS_IS_PQUOTA_ON(mp) && !ip->i_pdquot) {
error = xfs_qm_dqattach_one(ip, xfs_get_projid(ip), XFS_DQ_PROJ,
flags & XFS_QMOPT_DQALLOC,
- ip->i_udquot, &ip->i_pdquot);
- /*
- * Don't worry about the udquot that we may have
- * attached above. It'll get detached, if not already.
- */
+ &ip->i_pdquot);
if (error)
goto done;
- nquotas++;
+ ASSERT(ip->i_pdquot);
}
+done:
/*
- * Attach this group/project quota to the user quota as a hint.
- * This WON'T, in general, result in a thrash.
+ * Don't worry about the dquots that we may have attached before any
+ * error - they'll get detached later if it has not already been done.
*/
- if (nquotas > 1 && ip->i_udquot) {
- ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
- ASSERT(ip->i_gdquot || !XFS_IS_GQUOTA_ON(mp));
- ASSERT(ip->i_pdquot || !XFS_IS_PQUOTA_ON(mp));
-
- /*
- * We do not have i_udquot locked at this point, but this check
- * is OK since we don't depend on the i_gdquot to be accurate
- * 100% all the time. It is just a hint, and this will
- * succeed in general.
- */
- if (ip->i_udquot->q_gdquot != ip->i_gdquot)
- xfs_qm_dqattach_hint(ip, XFS_DQ_GROUP);
-
- if (ip->i_udquot->q_pdquot != ip->i_pdquot)
- xfs_qm_dqattach_hint(ip, XFS_DQ_PROJ);
- }
-
- done:
-#ifdef DEBUG
- if (!error) {
- if (XFS_IS_UQUOTA_ON(mp))
- ASSERT(ip->i_udquot);
- if (XFS_IS_GQUOTA_ON(mp))
- ASSERT(ip->i_gdquot);
- if (XFS_IS_PQUOTA_ON(mp))
- ASSERT(ip->i_pdquot);
- }
ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
-#endif
return error;
}