[saturnero@freesbie.org: Weird behaviour of mount_unionfs with executables]

Scott Long scottl at samsco.org
Mon Jul 4 00:21:27 GMT 2005

Stephan Uphoff wrote:
> On Sun, 2005-07-03 at 20:02, Scott Long wrote:
>>Stephan Uphoff wrote:
>>>I suspect the changes in revision 1.272 of kern_exec.c trigger the
>>>copy operation.
>>>Looks like you need a noatime option for union_fs.
>>Does this mean that every vnode that gets executed gets dirtied and all
>>its pages resynced to the backing store, or just the inode block?
> The kernel calls VOP_SETATTR to set the access time of the file.
> union_fs detects that it does not have an upper layer copy of the file
> to modify the attributes on and decides to copy it.
> The vm layer does not (directly) come into play on this. 
> Stephan

Ok, so this is just a limitation of unionfs, not the vnode pager.  You
had me scared that we'd be doing a whole lot of needless disk i/o.


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