[PATCH] Fix vfs_commit in case "eof mode" is not "none"

[Uri Simchoni]

On 10/08/2015 12:54 AM, Jeremy Allison wrote:
> On Wed, Oct 07, 2015 at 11:06:16PM +0300, Uri Simchoni wrote:
> I also have to wonder about calling SMB_VFS_FSTAT - seems like
> SMB_VFS_NEXT_FSTAT would be the correct thing to do.
> Actually, as this module doesn't implement FSTAT,
> then SMB_VFS_FSTAT == SMB_VFS_NEXT_FSTAT.
>
Well here's the thing - the SMB_VFS_XXX macros start with the 
"outermost" or "top" VFS module, whereas the SMB_VFS_NEXT_XXX start with 
the module "inside" or "below" my module.

Now, I don't know whether a general rule can be drawn here, but in the 
case of open(), the FD we've just obtained was supplied to us by the 
stack below us. As we go back up the stack, some modules may want to 
modify the FSP before they are ready to serve other calls such as 
stat(). So that's the potential problem with calling the top of the stack.

On the other hand, each VFS module logically provides a complete and 
consistent VFS to the module above it or to smbd if it's the topmost (it 
may do so by not implementing a call which implicitly delegates the 
__implementation__ to a lower module in the stack), there for calling 
SMB_VFS_NEXT_XXX seems generally safe.

As I said, not sure a general rule can be drawn here but what made me 
wondering.

Uri