Re: [Nbd] [PATCH v2 0/9] fix max discard sectors limit
- To: Namjae Jeon <linkinjeon@...17...>
- Cc: axboe@...161..., nbd-general@lists.sourceforge.net, linux-raid@...25..., npiggin@...161..., linux-scsi@...25..., neilb@...122..., dwmw2@...1270..., Namjae Jeon <namjae.jeon@...1329...>, Paul.Clements@...124..., adrian.hunter@...1303..., JBottomley@...1298..., linux-kernel@...25..., James.Bottomley@...1336..., jcmvbkbc@...17..., linux-mtd@...1331..., linux-mmc@...25..., cjb@...1330..., shli@...1285...
- Subject: Re: [Nbd] [PATCH v2 0/9] fix max discard sectors limit
- From: Kent Overstreet <koverstreet@...79...>
- Date: Mon, 22 Apr 2013 14:23:24 -0700
- Message-id: <20130422212324.GB4704@...162...>
- In-reply-to: <1366389602-19313-1-git-send-email-linkinjeon@...17...>
- References: <1366389602-19313-1-git-send-email-linkinjeon@...17...>
On Sat, Apr 20, 2013 at 01:40:02AM +0900, Namjae Jeon wrote:
> From: Namjae Jeon <namjae.jeon@...1329...>
>
> linux-v3.8-rc1 and later support for plug for blkdev_issue_discard with
> commit 0cfbcafcae8b7364b5fa96c2b26ccde7a3a296a9
> (block: add plug for blkdev_issue_discard )
>
> For example,
> 1) DISCARD rq-1 with size size 4GB
> 2) DISCARD rq-2 with size size 1GB
>
> If these 2 discard requests get merged, final request size will be 5GB.
>
> In this case, request's __data_len field may overflow as it can store
> max 4GB(unsigned int).
Complete NACK - like James said, this fix is nonsensical. This should be
fixed by just checking for overflow before merging requests, not with
weird hacks in the drivers.
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