From: Badari Pulavarty Subject: [PATCH] ext3_getblk should handle HOLE correctly Date: Wed, 06 Sep 2006 10:39:06 -0700 Message-ID: <1157564346.23501.49.camel@dyn9047017100.beaverton.ibm.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: lkml , ext4 , Will Simoneau , cmm@us.ibm.com Return-path: Received: from e32.co.us.ibm.com ([32.97.110.150]:40109 "EHLO e32.co.us.ibm.com") by vger.kernel.org with ESMTP id S1751782AbWIFRfq (ORCPT ); Wed, 6 Sep 2006 13:35:46 -0400 To: akpm@osdl.org Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org Hi Andrew, Its been reported that ext3_getblk() is not doing the right thing and triggering following WARN(): BUG: warning at fs/ext3/inode.c:1016/ext3_getblk() ext3_getblk+0x98/0x2a6 md_wakeup_thread +0x26/0x2a ext3_bread+0x1f/0x88 ext3_quota_read+0x136/0x1ae v1_read_dqblk+0x61/0xac dquot_acquire+0xf6/0x107 ext3_acquire_dquot+0x46/0x68 dqget+0x155/0x1e7 dquot_transfer+0x3e0/0x3e9 dput+0x23/0x13e ext3_setattr+0xc3/0x240 current_fs_time +0x52/0x6a notify_change+0x2bd/0x30d chown_common+0x9c/0xc5 strncpy_from_user+0x3b/0x68 do_path_lookup +0xdf/0x266 __user_walk_fd+0x44/0x5a sys_chown+0x4a/0x55 vfs_write+0xe7/0x13c sys_mkdir+0x1f/0x23 syscall_call+0x7/0xb Looking at the code, it looks like its not handle HOLE correctly. It ends up returning -EIO. Here is the patch to fix it. If we really want to be paranoid, we can allow return values 0 (HOLE), 1 (we asked for one block) and return -EIO for more than 1 block. But I really don't see a reason for doing it - all we need is the block# here. (doesn't matter how many blocks are mapped). Thanks, Badari ext3_get_blocks_handle() returns number of blocks it mapped. It returns 0 in case of HOLE. ext3_getblk() should handle HOLE properly (currently its dumping warning stack and returning -EIO). Signed-off-by: Badari Pulavarty Acked-by: Mingming Cao --- fs/ext3/inode.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) Index: linux-2.6.18-rc5/fs/ext3/inode.c =================================================================== --- linux-2.6.18-rc5.orig/fs/ext3/inode.c 2006-08-27 20:41:48.000000000 -0700 +++ linux-2.6.18-rc5/fs/ext3/inode.c 2006-09-05 15:32:57.000000000 -0700 @@ -1009,11 +1009,12 @@ struct buffer_head *ext3_getblk(handle_t buffer_trace_init(&dummy.b_history); err = ext3_get_blocks_handle(handle, inode, block, 1, &dummy, create, 1); - if (err == 1) { + /* + * ext3_get_blocks_handle() returns number of blocks + * mapped. 0 in case of a HOLE. + */ + if (err > 0) { err = 0; - } else if (err >= 0) { - WARN_ON(1); - err = -EIO; } *errp = err; if (!err && buffer_mapped(&dummy)) {