2008/1/10, Rik van Riel <[EMAIL PROTECTED]>: > On Thu, 10 Jan 2008 13:53:59 +0300 > "Anton Salikhmetov" <[EMAIL PROTECTED]> wrote: > > > Indeed, if msync() is called with MS_SYNC an explicit sync is > > triggered, and Rik's suggestion would work. However, the POSIX > > standard requires a call to msync() with MS_ASYNC to update the > > st_ctime and st_mtime stamps too. No explicit sync of the inode data > > is triggered in the current implementation of msync(). Hence Rik's > > suggestion would fail to satisfy POSIX in the latter case. > > Since your patch is already changing msync(), has it occurred > to you that your patch could change msync() to do the right > thing?
No, not quite. Peter Staubach mentioned an issue in my solution: >>> > The patch adds a call to the file_update_time() function to change > the file metadata before syncing. The patch also contains > substantial code cleanup: consolidated error check > for function parameters, using the PAGE_ALIGN() macro instead of > "manual" alignment check, improved readability of the loop, > which traverses the process memory regions, updated comments. > > These changes catch the simple case, where the file is mmap'd, modified via the mmap'd region, and then an msync is done, all on a mostly quiet system. However, I don't see how they will work if there has been something like a sync(2) done after the mmap'd region is modified and the msync call. When the inode is written out as part of the sync process, I_DIRTY_PAGES will be cleared, thus causing a miss in this code. The I_DIRTY_PAGES check here is good, but I think that there needs to be some code elsewhere too, to catch the case where I_DIRTY_PAGES is being cleared, but the time fields still need to be updated. <<< So I'm working on my next solution for this bug now. > > -- > All rights reversed. > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/