[PATCH] IMSM: retry reading sync_completed during reshape

[PATCH] IMSM: retry reading sync_completed during reshape

[Pawel Baldysiak]

The sync_completed after restarting a reshape
(for example - after reboot) is set to "delayed" until
mdmon changes the state. Mdadm does not wait for that change with
old kernels. If this condition occurs - it exits and reshape
is not continuing. This patch adds retry of reading sync_complete
with a delay. It gives time for mdmon to change the "delayed" state.

Signed-off-by: Pawel Baldysiak <pawel.baldysiak@intel.com>
---
 super-intel.c |   17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/super-intel.c b/super-intel.c
index ba3ee48..7e2860c 100644
--- a/super-intel.c
+++ b/super-intel.c
@@ -10378,6 +10378,7 @@ exit_imsm_reshape_super:
 int wait_for_reshape_imsm(struct mdinfo *sra, int ndata)
 {
 	int fd = sysfs_get_fd(sra, NULL, "sync_completed");
+	int retry = 3;
 	unsigned long long completed;
 	/* to_complete : new sync_max position */
 	unsigned long long to_complete = sra->reshape_progress;
@@ -10388,11 +10389,17 @@ int wait_for_reshape_imsm(struct mdinfo *sra, int ndata)
 		return 1;
 	}
 
-	if (sysfs_fd_get_ll(fd, &completed) < 0) {
-		dprintf("cannot read reshape_position (no reshape in progres)\n");
-		close(fd);
-		return 1;
-	}
+	do {
+		if (sysfs_fd_get_ll(fd, &completed) < 0) {
+			if (!retry) {
+				dprintf("cannot read reshape_position (no reshape in progres)\n");
+				close(fd);
+				return 1;
+			}
+			usleep(30000);
+		} else
+			break;
+	} while (retry--);
 
 	if (completed > position_to_set) {
 		dprintf("wrong next position to set %llu (%llu)\n",

Re: [PATCH] IMSM: retry reading sync_completed during reshape

[Jes Sorensen]

Pawel Baldysiak <pawel.baldysiak@intel.com> writes:
> The sync_completed after restarting a reshape
> (for example - after reboot) is set to "delayed" until
> mdmon changes the state. Mdadm does not wait for that change with
> old kernels. If this condition occurs - it exits and reshape
> is not continuing. This patch adds retry of reading sync_complete
> with a delay. It gives time for mdmon to change the "delayed" state.
>
> Signed-off-by: Pawel Baldysiak <pawel.baldysiak@intel.com>
> ---
>  super-intel.c |   17 ++++++++++++-----
>  1 file changed, 12 insertions(+), 5 deletions(-)

Hi Pawel,

Applied, thanks!

I have to admit I don't like this kind of fixes very much, delaying and
hoping for something to happen in time, but with the APIs we have it's
probably the best we can do.

Cheers,
Jes