linux-kernel - Re: [PATCH v3 15/15] nvme: Ensure atomic writes will be executed atomically

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date: Fri, 26 Jan 2024 03:50:54 +0000
From: Chaitanya Kulkarni <chaitanyak@...dia.com>
To: Keith Busch <kbusch@...nel.org>, John Garry <john.g.garry@...cle.com>
CC: "axboe@...nel.dk" <axboe@...nel.dk>, "hch@....de" <hch@....de>,
	"sagi@...mberg.me" <sagi@...mberg.me>, "jejb@...ux.ibm.com"
	<jejb@...ux.ibm.com>, "martin.petersen@...cle.com"
	<martin.petersen@...cle.com>, "djwong@...nel.org" <djwong@...nel.org>,
	"viro@...iv.linux.org.uk" <viro@...iv.linux.org.uk>, "brauner@...nel.org"
	<brauner@...nel.org>, "dchinner@...hat.com" <dchinner@...hat.com>,
	"jack@...e.cz" <jack@...e.cz>, "linux-block@...r.kernel.org"
	<linux-block@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-nvme@...ts.infradead.org"
	<linux-nvme@...ts.infradead.org>, "linux-xfs@...r.kernel.org"
	<linux-xfs@...r.kernel.org>, "linux-fsdevel@...r.kernel.org"
	<linux-fsdevel@...r.kernel.org>, "tytso@....edu" <tytso@....edu>,
	"jbongio@...gle.com" <jbongio@...gle.com>, "linux-scsi@...r.kernel.org"
	<linux-scsi@...r.kernel.org>, "ming.lei@...hat.com" <ming.lei@...hat.com>,
	"ojaswin@...ux.ibm.com" <ojaswin@...ux.ibm.com>, "bvanassche@....org"
	<bvanassche@....org>, Alan Adamson <alan.adamson@...cle.com>
Subject: Re: [PATCH v3 15/15] nvme: Ensure atomic writes will be executed
 atomically

On 1/24/2024 4:52 PM, Keith Busch wrote:
> On Wed, Jan 24, 2024 at 11:38:41AM +0000, John Garry wrote:
>> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
>> index 5045c84f2516..6a34a5d92088 100644
>> --- a/drivers/nvme/host/core.c
>> +++ b/drivers/nvme/host/core.c
>> @@ -911,6 +911,32 @@ static inline blk_status_t nvme_setup_rw(struct nvme_ns *ns,
>>   	if (req->cmd_flags & REQ_RAHEAD)
>>   		dsmgmt |= NVME_RW_DSM_FREQ_PREFETCH;
>>   
>> +	/*
>> +	 * Ensure that nothing has been sent which cannot be executed
>> +	 * atomically.
>> +	 */
>> +	if (req->cmd_flags & REQ_ATOMIC) {
>> +		struct nvme_ns_head *head = ns->head;
>> +		u32 boundary_bytes = head->atomic_boundary;
>> +
>> +		if (blk_rq_bytes(req) > ns->head->atomic_max)
>> +			return BLK_STS_IOERR;
>> +
>> +		if (boundary_bytes) {
>> +			u32 mask = boundary_bytes - 1, imask = ~mask;
>> +			u32 start = blk_rq_pos(req) << SECTOR_SHIFT;
>> +			u32 end = start + blk_rq_bytes(req);
>> +
>> +			if (blk_rq_bytes(req) > boundary_bytes)
>> +				return BLK_STS_IOERR;
>> +
>> +			if (((start & imask) != (end & imask)) &&
>> +			    (end & mask)) {
>> +				return BLK_STS_IOERR;
>> +			}
>> +		}
>> +	}
> 
> Aren't these new fields, atomic_max and atomic_boundary, duplicates of
> the equivalent queue limits? Let's just use the queue limits instead.
> 
> And couldn't we generically validate the constraints are not violated in
> submit_bio_noacct() instead of doing that in the low level driver? The
> driver assumes all other requests are already sanity checked, so I don't
> think we should change the responsibility for that just for this flag.
> 

does it makes sense to move about code to the helper ? perhaps inline ?

-ck