From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-fx0-f226.google.com ([209.85.220.226]) by bombadil.infradead.org with esmtp (Exim 4.69 #1 (Red Hat Linux)) id 1Mlm4o-0004fo-CR for linux-mtd@lists.infradead.org; Thu, 10 Sep 2009 16:00:55 +0000 Received: by fxm26 with SMTP id 26so215712fxm.18 for ; Thu, 10 Sep 2009 09:00:48 -0700 (PDT) Message-ID: <4AA922AF.8070001@billgatliff.com> Date: Thu, 10 Sep 2009 11:00:47 -0500 From: Bill Gatliff MIME-Version: 1.0 To: dedekind1@gmail.com Subject: Re: UBIFS power cut issues References: <2df346410909020235v5258eba3l30ff731841acc71@mail.gmail.com> <1252390936.5060.47.camel@localhost> <2df346410909090245v5995842asf3a94ae40da5fa72@mail.gmail.com> <1252597344.5060.99.camel@localhost> In-Reply-To: <1252597344.5060.99.camel@localhost> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-mtd@lists.infradead.org, JiSheng Zhang List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Artem Bityutskiy wrote: > And the text here, just in case someone would review it. > When you mean "something is lost", the correct spelling is "lose". To "loose" means to "disconnect", or "release" something. > However, UBIFS is sometimes used as a JFFS2 replacement and people may > want it to behave the same way as JFFS2 if it is mounted synchronously. > This is doable, but needs some non-trivial development, so this was not > implemented so far. On the other hand, there was no strong demand. You > may implement this as an excercise, or you may try to convince UBIFS > authors to do this. > In summary, the differences in results between JFFS2 and UBIFS in the case of interrupted, large synchronous writes are related to differences in how the two store and/or compute file sizes? Based on your documentation, my understanding is that with JFFS2 file sizes are stored along with the file data nodes, and are updated as the file grows in size--- so an interruption truncates the file at the point the interruption occurs. For UBIFS, in contrast, file sizes are stored in separate nodes which might not have been written at the point of interruption--- so the state if the file when power is restored depends highly upon the precise moment that the interruption occurs. b.g. -- Bill Gatliff bgat@billgatliff.com