xfs: xfs_dquot prealloc throttling watermarks and low free space

Enable tracking of high and low watermarks for preallocation
throttling of files under quota restrictions. These values are
calculated when the quota limit is read from disk or modified and
cached for later use by the throttling algorithm.

The high watermark specifies when preallocation is disabled, the
low watermark specifies when throttling is enabled and the low free
space data structure contains precalculated low free space limits
to serve as input to determine the level of throttling required.

Note that the low free space data structure is based on the
existing global low free space data structure with the exception of
using three stages (5%, 3% and 1%) rather than five to reduce the
impact of xfs_dquot memory overhead.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

4 files changed, 57 insertions, 7 deletions

diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
index 9c5869e60f97..45bb08f6ba17 100644
--- a/fs/xfs/xfs_dquot.c
+++ b/fs/xfs/xfs_dquot.c
@@ -90,13 +90,18 @@ xfs_qm_adjust_dqlimits(
 {
         struct xfs_quotainfo    *q = mp->m_quotainfo;
         struct xfs_disk_dquot   *d = &dq->q_core;
+        int                     prealloc = 0;
 
         ASSERT(d->d_id);
 
-        if (q->qi_bsoftlimit && !d->d_blk_softlimit)
+        if (q->qi_bsoftlimit && !d->d_blk_softlimit) {
                 d->d_blk_softlimit = cpu_to_be64(q->qi_bsoftlimit);
-        if (q->qi_bhardlimit && !d->d_blk_hardlimit)
+                prealloc = 1;
+        }
+        if (q->qi_bhardlimit && !d->d_blk_hardlimit) {
                 d->d_blk_hardlimit = cpu_to_be64(q->qi_bhardlimit);
+                prealloc = 1;
+        }
         if (q->qi_isoftlimit && !d->d_ino_softlimit)
                 d->d_ino_softlimit = cpu_to_be64(q->qi_isoftlimit);
         if (q->qi_ihardlimit && !d->d_ino_hardlimit)
@@ -105,6 +110,9 @@ xfs_qm_adjust_dqlimits(
                 d->d_rtb_softlimit = cpu_to_be64(q->qi_rtbsoftlimit);
         if (q->qi_rtbhardlimit && !d->d_rtb_hardlimit)
                 d->d_rtb_hardlimit = cpu_to_be64(q->qi_rtbhardlimit);
+
+        if (prealloc)
+                xfs_dquot_set_prealloc_limits(dq);
 }
 
 /*
@@ -249,6 +257,32 @@ xfs_qm_init_dquot_blk(
         xfs_trans_log_buf(tp, bp, 0, BBTOB(q->qi_dqchunklen) - 1);
 }
 
+/*
+ * Initialize the dynamic speculative preallocation thresholds. The lo/hi
+ * watermarks correspond to the soft and hard limits by default. If a soft limit
+ * is not specified, we use 95% of the hard limit.
+ */
+void
+xfs_dquot_set_prealloc_limits(struct xfs_dquot *dqp)
+{
+        __uint64_t space;
+
+        dqp->q_prealloc_hi_wmark = be64_to_cpu(dqp->q_core.d_blk_hardlimit);
+        dqp->q_prealloc_lo_wmark = be64_to_cpu(dqp->q_core.d_blk_softlimit);
+        if (!dqp->q_prealloc_lo_wmark) {
+                dqp->q_prealloc_lo_wmark = dqp->q_prealloc_hi_wmark;
+                do_div(dqp->q_prealloc_lo_wmark, 100);
+                dqp->q_prealloc_lo_wmark *= 95;
+        }
+
+        space = dqp->q_prealloc_hi_wmark;
+
+        do_div(space, 100);
+        dqp->q_low_space[XFS_QLOWSP_1_PCNT] = space;
+        dqp->q_low_space[XFS_QLOWSP_3_PCNT] = space * 3;
+        dqp->q_low_space[XFS_QLOWSP_5_PCNT] = space * 5;
+}
+
 static void
 xfs_dquot_buf_verify(
         struct xfs_buf          *bp)
@@ -649,6 +683,9 @@ xfs_qm_dqread(
         dqp->q_res_icount = be64_to_cpu(ddqp->d_icount);
         dqp->q_res_rtbcount = be64_to_cpu(ddqp->d_rtbcount);
 
+        /* initialize the dquot speculative prealloc thresholds */
+        xfs_dquot_set_prealloc_limits(dqp);
+
         /* Mark the buf so that this will stay incore a little longer */
         xfs_buf_set_ref(bp, XFS_DQUOT_REF);
 
diff --git a/fs/xfs/xfs_dquot.h b/fs/xfs/xfs_dquot.h
index f77b711455b1..4f0ebfc43cc9 100644
--- a/fs/xfs/xfs_dquot.h
+++ b/fs/xfs/xfs_dquot.h
@@ -32,6 +32,13 @@
 struct xfs_mount;
 struct xfs_trans;
 
+enum {
+        XFS_QLOWSP_1_PCNT = 0,
+        XFS_QLOWSP_3_PCNT,
+        XFS_QLOWSP_5_PCNT,
+        XFS_QLOWSP_MAX
+};
+
 /*
  * The incore dquot structure
  */
@@ -51,6 +58,9 @@ typedef struct xfs_dquot {
         xfs_qcnt_t       q_res_bcount;  /* total regular nblks used+reserved */
         xfs_qcnt_t       q_res_icount;  /* total inos allocd+reserved */
         xfs_qcnt_t       q_res_rtbcount;/* total realtime blks used+reserved */
+        xfs_qcnt_t       q_prealloc_lo_wmark;/* prealloc throttle wmark */
+        xfs_qcnt_t       q_prealloc_hi_wmark;/* prealloc disabled wmark */
+        int64_t          q_low_space[XFS_QLOWSP_MAX];
         struct mutex     q_qlock;       /* quota lock */
         struct completion q_flush;      /* flush completion queue */
         atomic_t          q_pincount;   /* dquot pin count */
@@ -153,6 +163,8 @@ extern void		xfs_qm_dqput(xfs_dquot_t *);
 
 extern void             xfs_dqlock2(struct xfs_dquot *, struct xfs_dquot *);
 
+extern void             xfs_dquot_set_prealloc_limits(struct xfs_dquot *);
+
 static inline struct xfs_dquot *xfs_qm_dqhold(struct xfs_dquot *dqp)
 {
         xfs_dqlock(dqp);
diff --git a/fs/xfs/xfs_qm.h b/fs/xfs/xfs_qm.h
index 44b858b79d71..82c21084587b 100644
--- a/fs/xfs/xfs_qm.h
+++ b/fs/xfs/xfs_qm.h
@@ -116,7 +116,7 @@ extern void		xfs_qm_dqrele_all_inodes(xfs_mount_t *, uint);
 extern int              xfs_qm_scall_trunc_qfiles(xfs_mount_t *, uint);
 extern int              xfs_qm_scall_getquota(xfs_mount_t *, xfs_dqid_t, uint,
                                         fs_disk_quota_t *);
-extern int              xfs_qm_scall_setqlim(xfs_mount_t *, xfs_dqid_t, uint,
+extern int              xfs_qm_scall_setqlim(struct xfs_mount *, xfs_dqid_t, uint,
                                         fs_disk_quota_t *);
 extern int              xfs_qm_scall_getqstat(xfs_mount_t *, fs_quota_stat_t *);
 extern int              xfs_qm_scall_quotaon(xfs_mount_t *, uint);
diff --git a/fs/xfs/xfs_qm_syscalls.c b/fs/xfs/xfs_qm_syscalls.c
index cf9a34051e07..c41190cad6e9 100644
--- a/fs/xfs/xfs_qm_syscalls.c
+++ b/fs/xfs/xfs_qm_syscalls.c
@@ -472,15 +472,15 @@ xfs_qm_scall_getqstat(
  */
 int
 xfs_qm_scall_setqlim(
-        xfs_mount_t             *mp,
+        struct xfs_mount        *mp,
         xfs_dqid_t              id,
         uint                    type,
         fs_disk_quota_t         *newlim)
 {
         struct xfs_quotainfo    *q = mp->m_quotainfo;
-        xfs_disk_dquot_t        *ddq;
-        xfs_dquot_t             *dqp;
-        xfs_trans_t             *tp;
+        struct xfs_disk_dquot   *ddq;
+        struct xfs_dquot        *dqp;
+        struct xfs_trans        *tp;
         int                     error;
         xfs_qcnt_t              hard, soft;
 
@@ -529,6 +529,7 @@ xfs_qm_scall_setqlim(
         if (hard == 0 || hard >= soft) {
                 ddq->d_blk_hardlimit = cpu_to_be64(hard);
                 ddq->d_blk_softlimit = cpu_to_be64(soft);
+                xfs_dquot_set_prealloc_limits(dqp);
                 if (id == 0) {
                         q->qi_bhardlimit = hard;
                         q->qi_bsoftlimit = soft;