From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: For UBIFS users: be aware of write-back! From: Artem Bityutskiy To: David Woodhouse In-Reply-To: <1223020676.3328.28.camel@macbook.infradead.org> References: <1222840288.8051.24.camel@sauron> <1223018149.3328.21.camel@macbook.infradead.org> <1223019946.8051.45.camel@sauron> <1223020676.3328.28.camel@macbook.infradead.org> Content-Type: text/plain; charset=utf-8 Date: Fri, 03 Oct 2008 11:03:30 +0300 Message-Id: <1223021010.8051.61.camel@sauron> Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Cc: linux-mtd@lists.infradead.org, Bruce_Leonard@selinc.com Reply-To: dedekind@infradead.org List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, 2008-10-03 at 08:57 +0100, David Woodhouse wrote: > On Fri, 2008-10-03 at 10:45 +0300, Artem Bityutskiy wrote: > > "In contrast, JFFS2 does not have write-back support and all the JFFS2 > > file system changes go the flash synchronously. Well, this is not > > completely true and JFFS2 does have a small buffer of a NAND page > > size, but it is small and we may treat JFFS2 as completely > > synchronous." >=20 > That's quite poorly phrased. You may _not_ treat JFFS2 as completely > synchronous. You treat it like a normal file system, or it's going to > eat your babies. >=20 > There was a reason I was perfectly happy to make the change which made > JFFS2 start requiring fsync() like normal file systems -- it was because > people should have been doing it _anyway_. >=20 > Anyone who was skipping the required sync handling because they 'knew' > that it didn't matter on JFFS2, even though it didn't cost them anything > anyway -- and who didn't wake up at 3am every morning in a cold sweat, > worrying that it might have broken today -- deserves to be taken out > back and shot. >=20 > When it comes to correctness, people shouldn't have to do anything > special for different file systems. If there is _anything_ fs-specific > about the correctness issues, you are doing something WRONG (cf. NFS). Well, this is what I actually assume. I'll change the docs to make them telling loudly about this. --=20 Best regards, Artem Bityutskiy (=D0=91=D0=B8=D1=82=D1=8E=D1=86=D0=BA=D0=B8=D0=B9 =D0=90= =D1=80=D1=82=D1=91=D0=BC)