Re: [PATCH 1/2] blkdev: fix merge_bvec_fn return value checks

From: Dmitry Monakhov
Date: Tue Mar 02 2010 - 22:49:53 EST

Jens Axboe <jens.axboe@xxxxxxxxxx> writes:

> On Sat, Feb 27 2010, Dmitry Monakhov wrote:
>> merge_bvec_fn() returns bvec->bv_len on success. So we have to check
>> against this value. But in case of fs_optimization merge we compare
>> with wrong value. This patch must be included in
>> b428cd6da7e6559aca69aa2e3a526037d3f20403
>> But accidentally i've forgot to add this in the initial patch.
>> To make things straight let's replace all such checks.
>> In fact this makes code easy to understand.
> Agree, applied.
Ohh.. as you already know this patch break dm-layer. Sorry.
This is because dm->merge may return more than requested. So correct
check must test against less what requested. Correct patch attached.