Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 11 Dec 2001 04:03:41 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 11 Dec 2001 04:03:32 -0500 Received: from ikura.fe.dis.titech.ac.jp ([131.112.171.65]:17794 "HELO ikura.fe.dis.titech.ac.jp") by vger.kernel.org with SMTP id ; Tue, 11 Dec 2001 04:03:13 -0500 Date: Tue, 11 Dec 2001 18:03:08 +0900 Message-ID: From: GOTO Masanori To: torvalds@transmeta.com Cc: gotom@debian.org, marcelo@conectiva.com.br, linux-kernel@vger.kernel.org, andrea@suse.de Subject: Re: [PATCH] direct IO breaks root filesystem In-Reply-To: In your message of "Mon, 10 Dec 2001 09:10:24 -0800 (PST)" In-Reply-To:

User-Agent: Wanderlust/2.2.15 (More Than Words) EMIKO/1.13.9 (Euglena tripteris) FLIM/1.13.2 (Kasanui) APEL/10.2 MULE XEmacs/21.1 (patch 10) (Capitol Reef) (i386-debian-linux) MIME-Version: 1.0 (generated by EMIKO 1.13.9 - "Euglena tripteris") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org At Mon, 10 Dec 2001 09:10:24 -0800 (PST), Linus Torvalds wrote: > On Mon, 10 Dec 2001, GOTO Masanori wrote: > > > > > > "generic_direct_IO()" should just get the device from "bh->b_dev (which is > > > filled in correctly by "get_block()". > > > > Oh, that's right, the patch becomes more simple (and works well). > > Is this patch OK? Linus, Andrea, thank you for your comments! > This looks fine to me. At some point we _may_ end up with filesystems that > understand about multiple devices, so it's possible in theory that > "get_block()" might return different devices for different blocks, but > that does not happen currently, and I'm not really sure it ever will. I don't test for the multiple device with direct IO under current kernel..., I keep it in mind. > Marcelo, I do believe this should go into 2.4.x too.. Thanks Marcelo for including my patch :) I, however, found another problem. Accessing with inode size unit (== 4096 byte) is ok, but if I accessed with block size unit, generic_direct_IO() returns error. The reason is that blocksize is designated as inode->i_blkbits, and its value is not disk minimal block size (512), but inode's unit size (4096). Patch is here. If inode is S_ISBLK and is not mounted, then blocksize is set as hardsect_size. This implementation needs some computational cost, but I think it can be ignored. This patch works well for me. --- linux-2.4.17-pre8.vanilla/mm/filemap.c Tue Dec 11 15:54:57 2001 +++ linux-2.4.17-pre8/mm/filemap.c Tue Dec 11 16:21:40 2001 @@ -1508,8 +1508,22 @@ new_iobuf = 1; } - blocksize = 1 << inode->i_blkbits; - blocksize_bits = inode->i_blkbits; + /* + * If inode is BLK and it is not already mounted, + * blocksize change hardsect_size. + */ + if (S_ISBLK(inode->i_mode) && !is_mounted(inode->i_rdev)) { + int size; + + size = get_hardsect_size(inode->i_rdev); + blocksize = size; + for (blocksize_bits = 0; !(size & 1); ) + size >>= 1, blocksize_bits++; + } else { + blocksize = 1 << inode->i_blkbits; + blocksize_bits = inode->i_blkbits; + } + blocksize_mask = blocksize - 1; chunk_size = KIO_MAX_ATOMIC_IO << 10; The current problem is that is_mounted() checking is worked for /dev/sda1 (partition area) only, not for /dev/sda (total disk area), if /dev/sda1 is mounted. This problem is also existed in /dev/raw interface, but I think it's not important issue (should I fix it?) Thanks, -- gotom - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/