PATCH] xfs: implement .dirty_inode to fix timestamp handling

[Felix Blyakher]

On Aug 26, 2009, at 10:12 PM, Christoph Hellwig wrote:

> [Note: this patch needs the O_SYNC patch applies first]

I assume O_SYNC is not a prerequisite to this patch, it's just
needed to apply the current patch cleanly.

>
> This is picking up on Felix's repost of Dave's patch to implement a
> .dirty_inode method.  We really need this notification because
> the VFS keeps writing directly into the inode structure instead
> of going through methods to update this state.  In addition to
> the long-known atime issue we now also have a caller in VM code
> that updates c/mtime that way for shared writeable mmaps.  And
> I found another one that no one has noticed in practice in the FIFO
> code.
>
> So implement ->dirty_inode to set i_update_core whenever the
> inode gets externally dirties, and switch the c/mtime handling to
> the same scheme we already use for atime (always picking up
> the value from the Linux inode).
>
> Note that this patch also removes the xfs_synchronize_atime call
> in xfs_reclaim - it was not only superflous (we'll never reclaim
> a dirty inode), but also didn't do anything (I_CLEAR is always set
> at this point).  I replaced it with a myriad of ASSERTs for now
> to make my point.

I like that ^)

>
>
> Also switch to just using file_update_time for regular reads/writes -
> that will get us all optimization done to it for free and make
> sure we notice early when it breaks.
>
>
> Signed-off-by: Christoph Hellwig <hch at lst.de>

Reviewed-by: Felix Blyakher <felixb at sgi.com>