From mboxrd@z Thu Jan 1 00:00:00 1970 In-reply-to: (message from Linus Torvalds on Fri, 18 Jan 2008 10:43:35 -0800 (PST)) Subject: Re: [PATCH -v6 2/2] Updating ctime and mtime for memory-mapped files References: <12006091182260-git-send-email-salikhmetov@gmail.com> <12006091211208-git-send-email-salikhmetov@gmail.com> <1200651337.5920.9.camel@twins> <1200651958.5920.12.camel@twins> Message-Id: From: Miklos Szeredi Date: Fri, 18 Jan 2008 19:57:17 +0100 Sender: owner-linux-mm@kvack.org Return-Path: To: torvalds@linux-foundation.org Cc: miklos@szeredi.hu, peterz@infradead.org, salikhmetov@gmail.com, linux-mm@kvack.org, jakob@unthought.net, linux-kernel@vger.kernel.org, valdis.kletnieks@vt.edu, riel@redhat.com, ksm@42.dk, staubach@redhat.com, jesper.juhl@gmail.com, akpm@linux-foundation.org, protasnb@gmail.com, r.e.wolff@bitwizard.nl, hidave.darkstar@gmail.com, hch@infradead.org List-ID: > > That would need a new page flag (PG_mmap_dirty?). Do we have one > > available? > > Yeah, that would be bad. We probably have flags free, but those page flags > are always a pain. Scratch that. > > How about just setting a per-vma dirty flag, and then instead of updating > the mtime when taking the dirty-page fault, we just set that flag? > > Then, on unmap and msync, we just do > > if (vma->dirty-flag) { > vma->dirty_flag = 0; > update_file_times(vma->vm_file); > } > > and be done with it? But then background writeout, sync(2), etc, wouldn't update the times. Dunno. I don't think actual _physical_ writeout matters much, so it's not worse to be 30s early with the timestamp, than to be 30s or more late. Miklos -- 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