Re: [PATCH v5 5/7] ata: libata: Fix FUA handling in ata_build_rw_tf()

From: Chaitanya Kulkarni <chaitanyak@nvidia.com>
To: Damien Le Moal <damien.lemoal@opensource.wdc.com>,
	"linux-ide@vger.kernel.org" <linux-ide@vger.kernel.org>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	Jens Axboe <axboe@kernel.dk>
Cc: "Maciej S . Szmigiero" <mail@maciej.szmigiero.name>,
	Hannes Reinecke <hare@suse.de>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v5 5/7] ata: libata: Fix FUA handling in ata_build_rw_tf()
Date: Mon, 7 Nov 2022 05:45:03 +0000	[thread overview]
Message-ID: <2d924281-5deb-3f68-846c-26aff763c58c@nvidia.com> (raw)
In-Reply-To: <20221107005021.1327692-6-damien.lemoal@opensource.wdc.com>

On 11/6/2022 4:50 PM, Damien Le Moal wrote:
> If a user issues a write command with the FUA bit set for a device with
> NCQ support disabled (that is, the device queue depth was set to 1), the
> LBA 48 command WRITE DMA FUA EXT must be used. However,
> ata_build_rw_tf() ignores this and first tests if LBA 28 can be used
> based on the write command sector and number of blocks. That is, for
> small FUA writes at low LBAs, ata_rwcmd_protocol() will cause the write
> to fail.
> 
> Fix this by preventing the use of LBA 28 for any FUA write request.
> 
> Given that the WRITE MULTI FUA EXT command is marked as obsolete iin the
> ATA specification since ACS-3 (published in 2013), remove the
> ATA_CMD_WRITE_MULTI_FUA_EXT command from the ata_rw_cmds array.
> 
> Finally, since the block layer should never issue a FUA read
> request, warn in ata_build_rw_tf() if we see such request.
> 
> Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
> Reviewed-by: Hannes Reinecke <hare@suse.de>
> ---


Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>

-ck