From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <45DDF9C1.4090003@redhat.com> Date: Thu, 22 Feb 2007 15:14:57 -0500 From: Peter Staubach MIME-Version: 1.0 Subject: Re: [PATCH] update ctime and mtime for mmaped write References: <20070221202615.a0a167f4.akpm@linux-foundation.org> <45DDD55F.4060106@redhat.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Miklos Szeredi Cc: akpm@linux-foundation.org, hugh@veritas.com, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: Miklos Szeredi wrote: >>>> Why is the flag checked in __fput()? >>>> >>>> >>> It's because of this bit in the standard: >>> >>> If there is no such call and if the underlying file is modified >>> as a result of a write reference, then these fields shall be >>> marked for update at some time after the write reference. >>> >>> It could be done in munmap/mremap, but it seemed more difficult to >>> track down all the places where the vma is removed. But yes, that may >>> be a nicer solution. >>> >> It seems to me that, with this support, a file, which is mmap'd, >> modified, but never msync'd or munmap'd, will never get its mtime >> updated. Or did I miss that? >> >> I also don't see how an mmap'd block device will get its mtime >> updated either. >> > > __fput() will be called when there are no more references to 'file', > then it will update the time if the flag is set. This applies to > regular files as well as devices. > > I suspect that you will find that, for a block device, the wrong inode gets updated. That's where the bd_inode_update_time() portion of my proposed patch came from. > But I've moved the check from __fput to remove_vma() in the next > revision of the patch, which would give slightly nicer semantics, and > be equally conforming. This still does not address the situation where a file is 'permanently' mmap'd, does it? Thanx... ps -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org