Messages in this thread | | | Date | Wed, 21 Feb 2007 13:54:57 -0500 | From | Peter Staubach <> | Subject | Re: [PATCH] update ctime and mtime for mmaped write |
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Miklos Szeredi wrote: >>> Inspired by Peter Staubach's patch and the resulting comments. >>> >>> >>> >> An updated version of the original patch was submitted to LKML >> yesterday... :-) >> > > Strange coincidence :) > > >>> file = vma->vm_file; >>> start = vma->vm_end; >>> + mapping_update_time(file); >>> if ((flags & MS_SYNC) && file && >>> (vma->vm_flags & VM_SHARED)) { >>> get_file(file); >>> >>> >> It seems to me that this might lead to file times being updated for >> non-MAP_SHARED mappings. >> > > In theory no, because the COW-ed pages become anonymous and are not > part of the original mapping any more. > >
I must profess to having a incomplete understanding of all of this support, but then why would it be necessary to test VM_SHARED at this point in msync()?
I ran into problems early on with file times being updated incorrectly so I am a little sensitive this aspect.
>>> +int set_page_dirty_mapping(struct page *page); >>> >>> >> This aspect of the design seems intrusive to me. I didn't see a strong >> reason to introduce new versions of many of the routines just to handle >> these semantics. What motivated this part of your design? Why the new >> _mapping versions of routines? >> > > Because there's no way to know inside the set_page_dirty() functions > if the dirtying comes from a memory mapping or from a modification > through a normal write(). And they have different semantics, for > write() the modification times are updated immediately.
Perhaps I didn't understand what page_mapped() does, but it does seem to have the right semantics as far as I could see.
Thanx...
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