Re: [PATCH] Btrfs: fix crash while a ranged msync() is ongoing

[Filipe David Manana <fdmanana@gmail.com>]

On Fri, Aug 29, 2014 at 3:51 PM, Christoph Hellwig <hch@infradead.org> wrote:
> On Fri, Aug 29, 2014 at 01:37:48PM +0100, Filipe Manana wrote:
>> After the commit 7fc34a62ca4434a79c68e23e70ed26111b7a4cf8 (titled
>> "mm/msync.c: sync only the requested range in msync()"), our fsync
>> callback can be called with a range that covers only part of the
>> file and not the whole file anymore.
>
> Not that there have been other users of range fsyncs around for a long
> time.  The SCSI target code is one, the NFS server another, and last but
> not least generic_write_sync() which is used by most filesystems
> including btrfs to implement O_SYNC writes.

Point taken Christoph, this isn't specific to msync nor impossible to
happen before 7fc34a62ca4434a79c68e23e70ed26111b7a4cf8.
I'll update the commit log to reflect that.

Thanks for looking.

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-- 
Filipe David Manana,

"Reasonable men adapt themselves to the world.
 Unreasonable men adapt the world to themselves.
 That's why all progress depends on unreasonable men."