----- Original Message -----

From: "NeilBrown" <redacted>
To: "Xiao Ni" <redacted>
Cc: linux-raid@vger.kernel.org
Sent: Wednesday, May 20, 2015 1:20:42 PM
Subject: Re: [PATCH] need read reshape_groress from sys

On Tue, 19 May 2015 22:35:35 -0400 (EDT) Xiao Ni [off-list ref] wrote:

quoted

Hi all

   Send the patch again. Because I don't see them at
   http://www.spinics.net/lists/raid/


----- Forwarded Message -----
From: "Xiao Ni" <redacted>
To: linux-raid@vger.kernel.org
Cc: "Xiao Ni" <redacted>
Sent: Friday, May 15, 2015 3:07:17 PM
Subject: [PATCH] need read reshape_groress from sys

Please actually explain the purpose of the patch.
Then  re-read it to ensure it makes sense and remove obvious typos.

and don't just remove unrelated blank lines.
Only include in the patch things that need to be in the patch.

Hi Neil

  I messed the mails, sorry for this. I have sent a mail which subject is "raid5 reshape is stuck" and 
two patch mails several days before. But I can't find them so I sent them again yesterday. 

  And I try to reproduce this with newest kernel and newest mdadm. The problem is fixed already. But I
still have a question which is below the steps I did.

  Now I paste the reason here:

  I encounter the problem when I reshape a 4-disks raid5 to 5-disks raid5. It just can
appear with loop devices.

   The steps are:

[root@dhcp-12-158 mdadm-3.3.2]# mdadm -CR /dev/md0 -l5 -n5 /dev/loop[0-4] --assume-clean
mdadm: /dev/loop0 appears to be part of a raid array:
       level=raid5 devices=6 ctime=Fri May 15 13:47:17 2015
mdadm: /dev/loop1 appears to be part of a raid array:
       level=raid5 devices=6 ctime=Fri May 15 13:47:17 2015
mdadm: /dev/loop2 appears to be part of a raid array:
       level=raid5 devices=6 ctime=Fri May 15 13:47:17 2015
mdadm: /dev/loop3 appears to be part of a raid array:
       level=raid5 devices=6 ctime=Fri May 15 13:47:17 2015
mdadm: /dev/loop4 appears to be part of a raid array:
       level=raid5 devices=6 ctime=Fri May 15 13:47:17 2015
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.
[root@dhcp-12-158 mdadm-3.3.2]# mdadm /dev/md0 -a /dev/loop5
mdadm: added /dev/loop5
[root@dhcp-12-158 mdadm-3.3.2]# mdadm --grow /dev/md0 --raid-devices 6
mdadm: Need to backup 10240K of critical section..
[root@dhcp-12-158 mdadm-3.3.2]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 loop5[5] loop4[4] loop3[3] loop2[2] loop1[1] loop0[0]
      8187904 blocks super 1.2 level 5, 512k chunk, algorithm 2 [6/6] [UUUUUU]
      [>....................]  reshape =  0.0% (0/2046976) finish=6396.8min speed=0K/sec
      
unused devices: <none>

   It because the sync_max is set to 0 when run the command --grow

[root@dhcp-12-158 mdadm-3.3.2]# cd /sys/block/md0/md/
[root@dhcp-12-158 md]# cat sync_max
0

   I tried reproduce with normal sata devices. The progress of reshape is no problem. Then
I checked the Grow.c. If I use sata devices, in function reshape_array, the return value
of set_new_data_offset is 0. But if I used loop devices, it return 1. Then it call the function
start_reshape.

   In the function start_reshape it set the sync_max to reshape_progress. But in sysfs_read it
doesn't read reshape_progress. So it's 0 and the sync_max is set to 0. Why it need to set the
sync_max at this? I'm not sure about this.

quoted

Signed-off-by: Xiao Ni <redacted>
---
 Grow.c  |   18 ++++++++++++------
 mdadm.h |    1 +
 sysfs.c |   15 +++++++++++++++
 3 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/Grow.c b/Grow.c
index 568e399..44ee8a7 100644
--- a/Grow.c
+++ b/Grow.c

@@ -710,11 +710,17 @@ int start_reshape(struct mdinfo *sra, int

already_running,
 	err = sysfs_set_num(sra, NULL, "suspend_hi", sra->reshape_progress);
 	err = err ?: sysfs_set_num(sra, NULL, "suspend_lo",
 				   sra->reshape_progress);
-	if (before_data_disks <= data_disks)
-		sync_max_to_set = sra->reshape_progress / data_disks;
-	else
-		sync_max_to_set = (sra->component_size * data_disks
-				   - sra->reshape_progress) / data_disks;
+
+	if (sra->reshape_progress == UINT64_MAX) {
+		err = err ?: sysfs_set_str(sra, NULL, "sync_max", "max");
+	} else {
+		if (before_data_disks <= data_disks)
+			sync_max_to_set = sra->reshape_progress / data_disks;
+		else
+			sync_max_to_set = (sra->component_size * 2 * data_disks
+										- sra->reshape_progress) / data_disks;
+	}
+
 	if (!already_running)
 		sysfs_set_num(sra, NULL, "sync_min", sync_max_to_set);
 	err = err ?: sysfs_set_num(sra, NULL, "sync_max", sync_max_to_set);

@@ -3075,7 +3081,7 @@ static int reshape_array(char *container, int fd,

char *devname,
 	}
 	sra = sysfs_read(fd, NULL,
 			 GET_COMPONENT|GET_DEVS|GET_OFFSET|GET_STATE|GET_CHUNK|
-			 GET_CACHE);
+			 GET_CACHE|GET_RESHAPE_PROGRESS);
 	if (!sra) {
 		pr_err("%s: Cannot get array details from sysfs\n",
 			devname);

diff --git a/mdadm.h b/mdadm.h
index 141f963..6fb17e1 100644
--- a/mdadm.h
+++ b/mdadm.h

@@ -526,6 +526,7 @@ enum sysfs_read_flags {
 	GET_DEGRADED	= (1 << 8),
 	GET_SAFEMODE	= (1 << 9),
 	GET_BITMAP_LOCATION = (1 << 10),
+	GET_RESHAPE_PROGRESS = (1 << 11),
 
 	GET_DEVS	= (1 << 20), /* gets role, major, minor */
 	GET_OFFSET	= (1 << 21),

diff --git a/sysfs.c b/sysfs.c
index 18f3df9..09b0c93 100644
--- a/sysfs.c
+++ b/sysfs.c

@@ -26,6 +26,7 @@
 #include	"mdadm.h"
 #include	<dirent.h>
 #include	<ctype.h>
+#include	<stdint.h>
 
 int load_sys(char *path, char *buf)
 {

@@ -210,6 +211,19 @@ struct mdinfo *sysfs_read(int fd, char *devnm,

unsigned long options)
 		msec = (msec * 1000) / scale;
 		sra->safe_mode_delay = msec;
 	}
+
+	if (options & GET_RESHAPE_PROGRESS) {
+
+		strcpy(base, "reshape_progress");
+		if (load_sys(fname, buf))
+			goto abort;
+
+		if (strncmp(buf, "max", 3) == 0)
+			sra->reshape_progress = UINT64_MAX;
+		else
+			sra->reshape_progress = strtol(buf, NULL, 10);
+	}
+
 	if (options & GET_BITMAP_LOCATION) {
 		strcpy(base, "bitmap/location");
 		if (load_sys(fname, buf))

@@ -224,6 +238,7 @@ struct mdinfo *sysfs_read(int fd, char *devnm, unsigned

long options)
 			goto abort;
 	}
 
+
 	if (! (options & GET_DEVS))
 		return sra;