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Re: [dm-devel] [PATCH] use uptodate bit to test status of bios



On Friday 05 March 2004 3:32 pm, Mike Christie wrote:
> If there is an error on a partially completed bio it's uptodate
> bit is cleared and an error value is retured, but DM will see
> that bi_size is not yet zero and ignore it. SCSI will fail the rest
> of the IO if the fail fast bit is set, so DM multipath will
> eventually see the error from them. However, if that behavior is not
> a requirement the patch below would be needed to detect errors in
> bios where the begining is not uptodate but the end completed without
> errors.
>
> SCSI will not always fail the rest of the IO when the fail fast bit
> is not set, so this may be a bug in dm-crypt and dm-raid1.
>
> Mike Christie
>
>
> --- linux-2.6.4-rc1-udm1.orig/drivers/md/dm-mpath.c	2004-03-03
> 19:56:43.000000000 -0800 +++
> linux-2.6.4-rc1-udm1/drivers/md/dm-mpath.c	2004-03-03 19:52:55.000000000
> -0800 @@ -551,8 +551,9 @@ static int do_end_io(struct multipath *m
>   		     int error, struct mpath_io *io)
>   {
>   	int r;
> +	int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
>
> -	if (error) {
> +	if (uptodate) {
>   		spin_lock(&m->lock);
>   		if (!m->nr_valid_paths) {
>   			spin_unlock(&m->lock);

It looks like this test should be "if (!uptodate) {".

Also, couldn't we do this in clone_endio() in dm.c and not have to change all 
the targets? Something like this.

-- 
Kevin Corry
kevcorry us ibm com
http://evms.sourceforge.net/


--- diff/drivers/md/dm.c	2004-03-05 15:47:55.000000000 -0600
+++ source/drivers/md/dm.c	2004-03-05 15:47:36.000000000 -0600
@@ -278,6 +278,8 @@
 	if (bio->bi_size)
 		return 1;
 
+	error = test_bit(BIO_UPTODATE, &bio->bi_flags) ? 0 : -EIO;
+
 	if (endio) {
 		r = endio(tio->ti, bio, error, &tio->info);
 		if (r < 0)



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