[patch] [2.6.12-rc6-mm1] Handle READA requests in dm-mpath.c

[patch] [2.6.12-rc6-mm1] Handle READA requests in dm-mpath.c

[Lars Marowsky-Bree]

READA errors failing with EWOULDBLOCK/EAGAIN do not constitute a valid
reason for failing the path; this lead to erratic errors on DM multipath
devices. This error can be safely propagated upwards without failing the
path.

Acked-by: Kevin Corry <kevcorry@us.ibm.com>
Acked-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Lars Marowsky-Bree <lmb@suse.de>

--- linux-2.6.12-rc6-mm1.orig/drivers/md/dm-mpath.c	2005-06-08 12:51:02.741055000 +0200
+++ linux-2.6.12-rc6-mm1/drivers/md/dm-mpath.c	2005-06-08 12:57:55.757828867 +0200
@@ -985,6 +985,9 @@
 	if (!error)
 		return 0;	/* I/O complete */
 
+	if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio))
+		return error;
+
 	spin_lock(&m->lock);
 	if (!m->nr_valid_paths) {
 		if (!m->queue_if_no_path || m->suspended) {


-- 
High Availability & Clustering
SUSE Labs, Research and Development
SUSE LINUX Products GmbH - A Novell Business	 -- Charles Darwin
"Ignorance more frequently begets confidence than does knowledge"

Re: [patch] [2.6.12-rc6-mm1] Handle READA requests in dm-mpath.c

[Andrew Morton]

Lars Marowsky-Bree <lmb@suse.de> wrote:
>
> READA errors failing with EWOULDBLOCK/EAGAIN do not constitute a valid
> reason for failing the path; this lead to erratic errors on DM multipath
> devices. This error can be safely propagated upwards without failing the
> path.
> 

Why do you describe this as a -mm patch?  We want this in 2.6.12, no?

> --- linux-2.6.12-rc6-mm1.orig/drivers/md/dm-mpath.c	2005-06-08 12:51:02.741055000 +0200
> +++ linux-2.6.12-rc6-mm1/drivers/md/dm-mpath.c	2005-06-08 12:57:55.757828867 +0200
> @@ -985,6 +985,9 @@
>  	if (!error)
>  		return 0;	/* I/O complete */
>  
> +	if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio))
> +		return error;
> +
>  	spin_lock(&m->lock);
>  	if (!m->nr_valid_paths) {
>  		if (!m->queue_if_no_path || m->suspended) {
> 
> 
> -- 
> High Availability & Clustering
> SUSE Labs, Research and Development
> SUSE LINUX Products GmbH - A Novell Business	 -- Charles Darwin
> "Ignorance more frequently begets confidence than does knowledge"

Re: [patch] [2.6.12-rc6-mm1] Handle READA requests in dm-mpath.c

[Lars Marowsky-Bree]

On 2005-06-08T04:33:47, Andrew Morton <akpm@osdl.org> wrote:

> Lars Marowsky-Bree <lmb@suse.de> wrote:
> >
> > READA errors failing with EWOULDBLOCK/EAGAIN do not constitute a valid
> > reason for failing the path; this lead to erratic errors on DM multipath
> > devices. This error can be safely propagated upwards without failing the
> > path.
> > 
> 
> Why do you describe this as a -mm patch?  We want this in 2.6.12, no?

Uhm, right. I just diff'ed it against -mm out of habit, I guess, because
I also assumed you were the fastest path to Linus ;-)


Sincerely,
    Lars Marowsky-Brée <lmb@suse.de>

-- 
High Availability & Clustering
SUSE Labs, Research and Development
SUSE LINUX Products GmbH - A Novell Business	 -- Charles Darwin
"Ignorance more frequently begets confidence than does knowledge"