From: Shaohua Li <shli@fb.com>
Date: Thu, 25 Feb 2016 01:38:28 +0000 (-0800)
Subject: RAID5: check_reshape() shouldn't call mddev_suspend
X-Git-Tag: v4.6-rc1~59^2~14
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=27a353c026a879a1001e5eac4bda75b16262c44a;p=linux.git

RAID5: check_reshape() shouldn't call mddev_suspend

check_reshape() is called from raid5d thread. raid5d thread shouldn't
call mddev_suspend(), because mddev_suspend() waits for all IO finish
but IO is handled in raid5d thread, we could easily deadlock here.

This issue is introduced by
738a273 ("md/raid5: fix allocation of 'scribble' array.")

Cc: stable@vger.kernel.org (v4.1+)
Reported-and-tested-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
---

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 7f770b0c0348..b628cd525b32 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2089,6 +2089,14 @@ static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors)
 	unsigned long cpu;
 	int err = 0;
 
+	/*
+	 * Never shrink. And mddev_suspend() could deadlock if this is called
+	 * from raid5d. In that case, scribble_disks and scribble_sectors
+	 * should equal to new_disks and new_sectors
+	 */
+	if (conf->scribble_disks >= new_disks &&
+	    conf->scribble_sectors >= new_sectors)
+		return 0;
 	mddev_suspend(conf->mddev);
 	get_online_cpus();
 	for_each_present_cpu(cpu) {
@@ -2110,6 +2118,10 @@ static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors)
 	}
 	put_online_cpus();
 	mddev_resume(conf->mddev);
+	if (!err) {
+		conf->scribble_disks = new_disks;
+		conf->scribble_sectors = new_sectors;
+	}
 	return err;
 }
 
@@ -6413,6 +6425,12 @@ static int raid5_alloc_percpu(struct r5conf *conf)
 	}
 	put_online_cpus();
 
+	if (!err) {
+		conf->scribble_disks = max(conf->raid_disks,
+			conf->previous_raid_disks);
+		conf->scribble_sectors = max(conf->chunk_sectors,
+			conf->prev_chunk_sectors);
+	}
 	return err;
 }
 
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index a415e1cd39b8..ae6068deefdf 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -510,6 +510,8 @@ struct r5conf {
 					      * conversions
 					      */
 	} __percpu *percpu;
+	int scribble_disks;
+	int scribble_sectors;
 #ifdef CONFIG_HOTPLUG_CPU
 	struct notifier_block	cpu_notify;
 #endif