From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Moyer Subject: Re: [RFC PATCH 0/7] Non-blockling buffered fs read (page cache only) Date: Tue, 16 Sep 2014 09:44:57 -0400 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain Cc: LKML , Christoph Hellwig , "linux-fsdevel\@vger.kernel.org" , linux-aio@kvack.org, Mel Gorman , Volker Lendecke , Tejun Heo , michael.kerrisk@gmail.com To: Milosz Tanski Return-path: In-Reply-To: (Milosz Tanski's message of "Mon, 15 Sep 2014 18:27:07 -0400") Sender: owner-linux-aio@kvack.org List-Id: linux-fsdevel.vger.kernel.org Milosz Tanski writes: > Jeff, > > This patchset creates a new read (readv2/preadv2) syscall(s) that take > a extra flag argument (kind of like recvmsg). What it doesn't do is > change the current behavior of of the O_NONBLOCK, if the file is > open() with O_NONBLOCK flag. It shouldn't break any existing > applications since you have to opt into using this by using the new > syscall. Hi, Milosz, Ah, I misread one of the patches. Now that I've applied the series, I see that you're testing the flag argument, not the file open flags. > I don't have a preference either way if we should create a new flag or > re-use O_NONBLOCK the flag. Instead, I'm hoping to get some consensus > here from senior kernel developers like yourself. Maybe a RWF_NONBLOCK > (I'm stealing from eventfd, EFD_NONBLOCK). I think I'd rather name the flag something other than O_NONBLOCK, if for no other reason that to avoid confusion. > As a side note, I noticed that EFD_NONBLOCK, SFD_NONBLOCK, etc... all > alias to the value of O_NONBLOCK and there's a bunch of bug checks in > the code like this: > BUILD_BUG_ON(EFD_NONBLOCK != O_NONBLOCK); That's because the flag is passed on to anon_inode_getfile. See also this define: #define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK) A general note on your subjects -- you should make them more specific to the subsystem you're updating. Commit titles like "documentation update" are a bit too broad. ;-) Cheers, Jeff -- To unsubscribe, send a message with 'unsubscribe linux-aio' in the body to majordomo@kvack.org. For more info on Linux AIO, see: http://www.kvack.org/aio/ Don't email: aart@kvack.org