linux-kernel - Re: Resend: [PATCH] blkdev: fix blkdev_issue

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Date:	Fri, 06 Aug 2010 12:56:14 +0200
From:	Jens Axboe <axboe@...nel.dk>
To:	Dmitry Monakhov <dmonakhov@...nvz.org>
CC:	linux-kernel@...r.kernel.org
Subject: Re: Resend: [PATCH] blkdev: fix blkdev_issue_zeroout return value

On 2010-08-06 12:42, Dmitry Monakhov wrote:
> Hi Jens,
> Seems that my first mail was missed somewhere.  
> I've found couple of trivial issues in blkdev_issue_zeroout()
> implementation. Unfortunately I've miss during initial testing phase
> because always called it with BARRIER|WAIT flags.

BTW, this:

@@ -218,15 +222,18 @@ submit:
 		/* One of bios in the batch was completed with error.*/
 		ret = -EIO;
 
-	if (ret)
+	if (ret && ret != -ENOMEM)
 		goto out;
 
 	if (test_bit(BIO_EOPNOTSUPP, &bb.flags)) {
 		ret = -EOPNOTSUPP;
 		goto out;
 	}
-	if (nr_sects != 0)
+	if (nr_sects != 0) {
+		if (ret == -ENOMEM)
+			io_schedule();
 		goto submit;
+	}
 out:
 	return ret;
 }

is broken. Either the caller sets __GFP_WAIT and then bio_alloc() will
not fail, or GFP_ATOMIC is used knowing that the call can fail and
return ENOMEM. Don't code in retry logic like this.

-- 
Jens Axboe

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