Re: Does unmount() sync dirty buffers

[Ravishankar <cyberax82@xxxxxxxxx>]

On Wed, Feb 15, 2012 at 2:08 PM, Manish Katiyar <mkatiyar@xxxxxxxxx> wrote:

[Apparently I forgot to cc list]

On Tue, Feb 14, 2012 at 10:04 PM, Manish Katiyar <mkatiyar@xxxxxxxxx> wrote:
> On Tue, Feb 14, 2012 at 7:43 PM, Ravishankar <cyberax82@xxxxxxxxx> wrote:
>> Hello,
>>
>> When we unmount a file system with the umount command or the umount() system
>> call, does the kernel sync the dirty buffers before the file system is
>> unmounted?I am assuming that the file system is not 'busy' (i.e no open
>> files etc) and no force options are specified. When I did a walk-through of
>> do_umount() call in fs/namespace.c, I could not find calls to sync any dirty
>> pages that might exist.
>
> yes, most of the filesystem have their own function to sync fs. Look
> for the function pointer "sync_fs"
>
> For eg..for ext4
>
> generic_shutdown_super -> sync_filesystem -> __sync_filesystem ->
> sync_fs -> ext4_sync_fs
> --
> Thanks -
> Manish

--
Thanks -
Manish

Thanks a lot.Just to add,  generic_shutdown_super() is called thus:

umount systemcall -->mntput_no_expire()-->__mntput()-->deactivate_super()-->deactivate_locked_super()-->kill_block_super()-->generic_shutdown_super()

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