From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: Nick Piggin <npiggin@suse.de>
Cc: Chris Mason <chris.mason@oracle.com>,
James Bottomley <James.Bottomley@suse.de>,
Matthew Wilcox <matthew@wil.cx>,
Christof Schmitt <christof.schmitt@de.ibm.com>,
Boaz Harrosh <bharrosh@panasas.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org
Subject: Re: Wrong DIF guard tag on ext2 write
Date: Wed, 02 Jun 2010 09:17:56 -0400 [thread overview]
Message-ID: <yq17hmhbmkb.fsf@sermon.lab.mkp.net> (raw)
In-Reply-To: <20100602032030.GF9453@laptop> (Nick Piggin's message of "Wed, 2 Jun 2010 13:20:30 +1000")
>>>>> "Nick" == Nick Piggin <npiggin@suse.de> writes:
>> 1) filesystem changed it
>> 2) corruption on the wire or in the raid controller
>> 3) the page was corrupted while the IO layer was doing the IO.
>>
>> 1 and 2 are easy, we bounce, retry and everyone continues on with
>> their lives. With #3, we'll recrc and send the IO down again
>> thinking the data is correct when really we're writing garbage.
>>
>> How can we tell these three cases apart?
Nick> Do we really need to handle #3? It could have happened before the
Nick> checksum was calculated.
Reason #3 is one of the main reasons for having the checksum in the
first place. The whole premise of the data integrity extensions is that
the checksum is calculated in close temporal proximity to the data
creation. I.e. eventually in userland.
Filesystems will inevitably have to be integrity-aware for that to work.
And it will be their job to keep the data pages stable during DMA.
--
Martin K. Petersen Oracle Linux Engineering
next prev parent reply other threads:[~2010-06-02 13:17 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-31 11:28 Wrong DIF guard tag on ext2 write Christof Schmitt
2010-05-31 11:34 ` Christof Schmitt
2010-05-31 14:20 ` Martin K. Petersen
2010-05-31 14:46 ` Christof Schmitt
2010-06-01 13:16 ` Martin K. Petersen
2010-06-02 13:37 ` Christof Schmitt
2010-06-02 23:20 ` Dave Chinner
2010-06-04 1:34 ` Martin K. Petersen
2010-06-04 2:32 ` Dave Chinner
2010-06-07 16:20 ` Martin K. Petersen
2010-06-07 17:22 ` Boaz Harrosh
2010-06-07 17:40 ` Martin K. Petersen
2010-06-08 7:15 ` Christof Schmitt
2010-06-08 8:47 ` Dave Chinner
2010-06-08 8:52 ` Nick Piggin
2010-05-31 14:49 ` Nick Piggin
2010-06-01 13:17 ` Martin K. Petersen
2010-05-31 15:01 ` James Bottomley
2010-05-31 15:30 ` Boaz Harrosh
2010-05-31 15:49 ` Nick Piggin
2010-05-31 16:25 ` Boaz Harrosh
2010-06-01 13:22 ` Martin K. Petersen
2010-06-01 10:30 ` Christof Schmitt
2010-06-01 10:49 ` Boaz Harrosh
2010-06-01 13:03 ` Chris Mason
2010-06-01 13:50 ` Christof Schmitt
2010-06-01 13:58 ` Chris Mason
2010-06-08 7:18 ` Christof Schmitt
2010-06-08 7:18 ` Christof Schmitt
2010-06-08 7:18 ` Christof Schmitt
2010-06-01 14:26 ` Nick Piggin
2010-06-01 13:50 ` Christof Schmitt
2010-06-01 13:50 ` Christof Schmitt
2010-06-01 13:27 ` James Bottomley
2010-06-01 13:33 ` Chris Mason
2010-06-01 13:40 ` James Bottomley
2010-06-01 13:49 ` Chris Mason
2010-06-01 16:29 ` Matthew Wilcox
2010-06-01 16:29 ` Matthew Wilcox
2010-06-01 16:47 ` Chris Mason
2010-06-01 16:54 ` James Bottomley
2010-06-01 18:09 ` Chris Mason
2010-06-01 18:46 ` Nick Piggin
2010-06-01 18:46 ` Nick Piggin
2010-06-01 18:46 ` Nick Piggin
2010-06-01 19:35 ` Chris Mason
2010-06-02 3:20 ` Nick Piggin
2010-06-02 3:20 ` Nick Piggin
2010-06-02 13:17 ` Martin K. Petersen [this message]
2010-06-02 13:41 ` Nick Piggin
2010-06-03 15:46 ` Chris Mason
2010-06-03 16:27 ` Nick Piggin
2010-06-03 16:27 ` Nick Piggin
2010-06-04 1:46 ` Martin K. Petersen
2010-06-04 3:09 ` Nick Piggin
2010-06-03 16:27 ` Nick Piggin
2010-06-04 2:02 ` Dave Chinner
2010-06-04 2:02 ` Dave Chinner
2010-06-04 15:32 ` Jan Kara
2010-06-04 2:02 ` Dave Chinner
2010-06-04 1:30 ` Martin K. Petersen
2010-06-02 3:20 ` Nick Piggin
2010-06-01 21:07 ` James Bottomley
2010-06-01 22:49 ` Chris Mason
2010-06-01 16:29 ` Matthew Wilcox
2010-06-01 13:50 ` Martin K. Petersen
2010-06-01 14:28 ` Nick Piggin
2010-06-01 14:32 ` James Bottomley
2010-06-01 14:54 ` Martin K. Petersen
2010-06-03 11:20 ` Vladislav Bolkhovitin
2010-06-03 12:07 ` Boaz Harrosh
2010-06-03 12:41 ` Vladislav Bolkhovitin
2010-06-03 12:46 ` Vladislav Bolkhovitin
2010-06-09 15:58 ` Vladislav Bolkhovitin
2010-06-03 13:06 ` Boaz Harrosh
2010-06-03 13:23 ` Vladislav Bolkhovitin
2010-07-23 17:59 ` Gennadiy Nerubayev
2010-07-23 17:59 ` Gennadiy Nerubayev
2010-07-23 19:16 ` Vladislav Bolkhovitin
2010-07-23 20:51 ` Gennadiy Nerubayev
2010-07-26 12:22 ` Vladislav Bolkhovitin
2010-07-26 17:00 ` Gennadiy Nerubayev
2010-07-26 19:26 ` Vladislav Bolkhovitin
2010-07-24 1:03 ` Dave Chinner
2010-06-01 2:40 ` FUJITA Tomonori
2010-06-03 16:09 ` [LFS/VM TOPIC] Stable pages while IO (was Wrong DIF guard tag on ext2 write) Boaz Harrosh
2010-06-03 16:09 ` Boaz Harrosh
2010-06-03 16:09 ` Boaz Harrosh
2010-06-03 16:30 ` [Lsf10-pc] " J. Bruce Fields
2010-06-03 17:41 ` Vladislav Bolkhovitin
2010-06-04 16:23 ` Jan Kara
2010-06-04 16:30 ` [Lsf10-pc] " J. Bruce Fields
2010-06-04 17:11 ` Jan Kara
2010-06-06 9:35 ` Boaz Harrosh
2010-06-06 23:37 ` Jan Kara
2010-06-07 8:30 ` Boaz Harrosh
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