From: Vivek Goyal <vgoyal@redhat.com>
To: Phillip Susi <psusi@cfl.rr.com>
Cc: Karel Zak <kzak@redhat.com>,
linux-kernel@vger.kernel.org, Jens Axboe <jaxboe@fusionio.com>
Subject: Re: [PATCH 1/2] Add partition resize function to BLKPG ioctl
Date: Thu, 8 Dec 2011 11:28:47 -0500 [thread overview]
Message-ID: <20111208162847.GB9281@redhat.com> (raw)
In-Reply-To: <4EE0E085.8000907@cfl.rr.com>
On Thu, Dec 08, 2011 at 11:06:29AM -0500, Phillip Susi wrote:
> On 12/8/2011 10:58 AM, Vivek Goyal wrote:
> >So, if there is an IO in flight while partition shrinking is happening,
> >then IO can end up happening outside the partition?
>
> Yes. Of course if there was an in flight IO at the time you
> truncate the partition, then you did something wrong ( didn't shrink
> the fs first ).
Ok, so one needs to shrink filesystem. So if partition is part of a
volume group one is supposed to first reduce the size using pvresize
and then shrink actual partition?
>
> >part->nr_sects can be 64 bits on 32bit machines and update will be
> >non-atomic. I had used sequence counter to make sure read is able
> >to get to intermediate value. May be it is a good idea to address
> >this concenrn.
>
> Isn't that what the mutex is for?
I thought I have found couple of places where we don't take mutex. For
example.
drive_stat_acct()
disk_map_sector_rcu()
sector_in_part()
--> read part->nr_sects without mutex.
printk_all_partitions()
---> read part->nr_sects without mutex.
show_partition()
---> read part->nr_sects without mutex.
Thanks
Vivek
next prev parent reply other threads:[~2011-12-08 16:28 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <cover.1322709471.git.psusi@cfl.rr.com>
2011-12-01 3:23 ` [PATCH 1/2] Add partition resize function to BLKPG ioctl Phillip Susi
2011-12-08 12:30 ` Karel Zak
2011-12-08 14:22 ` Phillip Susi
2011-12-08 15:16 ` Karel Zak
2011-12-08 15:25 ` Phillip Susi
2011-12-08 15:58 ` Vivek Goyal
2011-12-08 16:06 ` Phillip Susi
2011-12-08 16:28 ` Vivek Goyal [this message]
2011-12-08 16:55 ` Phillip Susi
2011-12-09 2:53 ` Phillip Susi
2011-12-12 14:53 ` Vivek Goyal
2011-12-12 17:43 ` Phillip Susi
2011-12-12 17:49 ` Joe Perches
2011-12-12 18:04 ` Vivek Goyal
2011-12-13 0:15 ` Phillip Susi
2011-12-13 0:16 ` Phillip Susi
2011-12-13 0:16 ` [PATCH 2/2] Add BLKPG_GET_PARTITION operation Phillip Susi
2011-12-19 20:25 ` [PATCH 1/2] Add partition resize function to BLKPG ioctl Vivek Goyal
2011-12-21 1:53 ` Phillip Susi
2011-12-21 1:54 ` Phillip Susi
2011-12-21 1:54 ` [PATCH 2/2] Add BLKPG_GET_PARTITION operation Phillip Susi
2011-12-21 20:46 ` [PATCH 1/2] Add partition resize function to BLKPG ioctl Vivek Goyal
2011-12-24 21:36 ` Phillip Susi
2011-12-24 22:21 ` Phillip Susi
2011-12-24 22:21 ` [PATCH 2/2] Add BLKPG_GET_PARTITION operation Phillip Susi
2011-12-01 3:23 ` Phillip Susi
2011-12-08 12:35 ` Karel Zak
2011-12-08 14:25 ` Phillip Susi
2011-12-29 17:06 [PATCH 1/2] Add partition resize function to BLKPG ioctl Maxim Patlasov
2011-12-30 0:09 ` Phillip Susi
2012-01-01 21:49 ` Phillip Susi
2012-01-26 19:01 ` Vivek Goyal
2012-01-26 20:35 ` Phillip Susi
2012-01-26 21:04 ` Vivek Goyal
2012-01-26 21:48 ` Phillip Susi
2012-01-30 15:49 ` Vivek Goyal
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