Hi! On Fri, 2011-03-11 at 11:09:07 +0100, Sven Mueller wrote: > Am 29.12.2010 20:04, schrieb Guillem Jover: > > On Wed, 2010-12-29 at 17:58:41 +0100, Raphael Hertzog wrote: > >> It is ok since fsync() is still called afterwards. Both are only useful > >> to avoid the speed-penalty that fsync() was giving us, but fsync() is > >> still executed (and is usualy a no-op since the work has already been done > >> thanks to the sync_file_range calls). > > > > Exactly, and although SYNC_FILE_RANGE_WAIT_BEFORE can return with EIO > > or ENOSPC, if that would happen the pages would not have been flushed > > and would still be dirty, and fsync() would go over them again. > > > [...] > > > > This was done on purpose, as those actions should be considered > > equivalent to asynchronous hints for the kernel from dpkg's code PoV. > > Forgive me if this was already done, but should this be documented in > the code? I mean something like "We are ignoring the return value of > SYNC_FILE_RANGE_WAIT_BEFORE on purpose since we call fsync() later on > anyhow." near the SYNC_FILE... call and a "don't remove the fsync call > unless you check the SYNC_FILE_.... system call return values" near the > fsync call. > In other words: Add comments why you do it the way you do it. Don't > bother with comments that explain what you do.
I've added now some comments around the writeback code explaining this: <http://git.debian.org/?p=dpkg/dpkg.git;a=commitdiff;h=a468c108> thanks, guillem -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected] Archive: http://lists.debian.org/[email protected]
