From: Theodore Tso Subject: Re: [PATCH-e2fsprogs] filefrag: accept positive ioctl return value Date: Tue, 2 Jun 2009 08:59:14 -0400 Message-ID: <20090602125914.GT31943@mit.edu> References: <1243944761-18673-1-git-send-email-bergwolf@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org To: Peng Tao Return-path: Received: from thunk.org ([69.25.196.29]:51004 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752975AbZFBM7V (ORCPT ); Tue, 2 Jun 2009 08:59:21 -0400 Content-Disposition: inline In-Reply-To: <1243944761-18673-1-git-send-email-bergwolf@gmail.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue, Jun 02, 2009 at 08:12:41PM +0800, Peng Tao wrote: > Some ioctl() returns non-negative value on success. filefrag_fiemap should > treat positive ioctl() return values as success. > This can be triggered by running filefrag on btrfs partitions. Thanks for reporting this! It turns out that wasn't the only bug in that code; the syscall infrastructure will take a negative return value and maps that to -1, and moves the (negative) error code to a positive value in errno. So the more appropriate patch is as follows. - Ted commit e78968f7a42fb1fa75c356dd323d957b307b887f Author: Theodore Ts'o Date: Tue Jun 2 08:45:22 2009 -0400 filefrag: Fix error checking for the fiemap ioctl Thanks to Peng Tao for reporting this problem. Signed-off-by: "Theodore Ts'o" diff --git a/misc/filefrag.c b/misc/filefrag.c index 80ac05c..7095949 100644 --- a/misc/filefrag.c +++ b/misc/filefrag.c @@ -201,15 +201,14 @@ int filefrag_fiemap(int fd, int blk_shift, int *num_extents) fiemap->fm_flags = flags; fiemap->fm_extent_count = count; rc = ioctl(fd, FS_IOC_FIEMAP, (unsigned long) fiemap); - if (rc == -EBADR) { - if (fiemap_incompat_printed == 0) { + if (rc < 0) { + if (errno == EBADR && fiemap_incompat_printed == 0) { printf("FIEMAP failed with unsupported " "flags %x\n", fiemap->fm_flags); fiemap_incompat_printed = 1; } - } - if (rc) return rc; + } if (!verbose) { *num_extents = fiemap->fm_mapped_extents;