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FAILED: patch "[PATCH] staging: lustre: ldlm: pl_recalc time handling is wrong" failed to apply to 4.4-stable tree

PATCH [email protected] 1 participant 1 message Jan 6, 2017

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The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

Quoted 1 line

From b8cb86fd95bb461c3496e1f4b4083b198c963a9c Mon Sep 17 00:00:00 2001

From: Arnd Bergmann <[email protected]>
Date: Thu, 10 Nov 2016 16:21:20 +0100
Subject: [PATCH] staging: lustre: ldlm: pl_recalc time handling is wrong

James Simmons reports:

Quoted 7 lines

The ldlm_pool field pl_recalc_time is set to the current monotonic clock value but the interval period is calculated with the wall clock. This means the interval period will always be far larger than the pl_recalc_period, which is just a small interval time period. The correct thing to do is to use monotomic clock current value instead of the wall clocks value when calculating recalc_interval_sec.

This broke when I converted the 32-bit get_seconds() into ktime_get_{real_,}seconds() inconsistently. Either one of those two would have worked, but mixing them does not.

Staying with the original intention of the patch, this changes the ktime_get_seconds() calls into ktime_get_real_seconds(), using real time instead of mononic time.

Cc [email protected] # v4.4+
Fixes 8f83409cf238 ("staging/lustre: use 64-bit time for pl_recalc")
Reported-by James Simmons <[email protected]>
Signed-off-by Arnd Bergmann <[email protected]>
Reviewed-by James Simmons <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
drivers/staging/lustre/lustre/ldlm/ldlm_pool.c +4 -4
index 19831c555c49..b820309d70e3 100644
@@ -356,10 +356,10 @@ static int ldlm_pool_recalc(struct ldlm_pool *pl)
 	u32 recalc_interval_sec;
 	int count;
 
-	recalc_interval_sec = ktime_get_seconds() - pl->pl_recalc_time;
+	recalc_interval_sec = ktime_get_real_seconds() - pl->pl_recalc_time;
 	if (recalc_interval_sec > 0) {
 		spin_lock(&pl->pl_lock);
-		recalc_interval_sec = ktime_get_seconds() - pl->pl_recalc_time;
+		recalc_interval_sec = ktime_get_real_seconds() - pl->pl_recalc_time;
 
 		if (recalc_interval_sec > 0) {
 			/*

@@ -382,7 +382,7 @@ static int ldlm_pool_recalc(struct ldlm_pool *pl)
 				    count);
 	}
 
-	recalc_interval_sec = pl->pl_recalc_time - ktime_get_seconds() +
+	recalc_interval_sec = pl->pl_recalc_time - ktime_get_real_seconds() +
 			      pl->pl_recalc_period;
 	if (recalc_interval_sec <= 0) {
 		/* DEBUG: should be re-removed after LU-4536 is fixed */

@@ -657,7 +657,7 @@ int ldlm_pool_init(struct ldlm_pool *pl, struct ldlm_namespace *ns,
 
 	spin_lock_init(&pl->pl_lock);
 	atomic_set(&pl->pl_granted, 0);
-	pl->pl_recalc_time = ktime_get_seconds();
+	pl->pl_recalc_time = ktime_get_real_seconds();
 	atomic_set(&pl->pl_lock_volume_factor, 1);
 
 	atomic_set(&pl->pl_grant_rate, 0);