From: Xiaoguang Wang Subject: [PATCH] filefrag: fix wrong extent count calculation when using FIBMAP Date: Mon, 6 Oct 2014 19:05:39 +0800 Message-ID: <1412593539-18328-1-git-send-email-wangxg.fnst@cn.fujitsu.com> References: <5422CAC2.7080409@redhat.com> Mime-Version: 1.0 Content-Type: text/plain Cc: , , Xiaoguang Wang To: Return-path: Received: from cn.fujitsu.com ([59.151.112.132]:64121 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751488AbaJFLGh (ORCPT ); Mon, 6 Oct 2014 07:06:37 -0400 In-Reply-To: <5422CAC2.7080409@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: When using FIBMAP and '-e' option is specified, the calculation for fiemap_extent is wrong, we wrongly updated fm_ext.fe_logical for every iteration, please see the code in the end of 'for' loop in fm_ext.fe_logical(). In an ext2 file system(block size is 1024 bytes), dd if=/dev/zero of=testfile bs=1k count=15 Using debugfs, corresponding physical blocks are "2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 1025 2061 2062 2063", 1025 is this indirect block. Before this patch, filefrag's output would be: filefrag -B -e testfile Filesystem type is: ef53 Filesystem cylinder groups approximately 16 File size of testfile is 15360 (15 blocks of 1024 bytes) ext: logical_offset: physical_offset: length: expected: flags: 0: 1.. 2: 2050.. 2051: 2: 2051: merged 1: 3.. 4: 2052.. 2053: 2: 2053: merged 2: 5.. 6: 2054.. 2055: 2: 2055: merged 3: 7.. 8: 2056.. 2057: 2: 2057: merged 4: 9.. 10: 2058.. 2059: 2: 2059: merged 5: 11.. 12: 2060.. 2061: 2: 2062: merged 6: 13.. 14: 2062.. 2063: 2: 2063: merged,eof 7: 14.. 14: 2063.. 2063: 1: 2063: merged,eof This output is not reasonable. Fix this bug and try to make it readable. After this patch, the output would be: ./filefrag -B -e mntpoint/testfile Filesystem type is: ef53 Filesystem cylinder groups approximately 16 File size of mntpoint/testfile is 15360 (15 blocks of 1024 bytes) ext: logical_offset: physical_offset: length: expected: flags: 0: 0.. 11: 2049.. 2060: 12: 2062: merged 1: 12.. 14: 2061.. 2063: 3: 2063: merged,eof mntpoint/testfile: 2 extents found, perfection would be 1 extent Signed-off-by: Xiaoguang Wang --- misc/filefrag.c | 37 +++++++++++++++++++++++-------------- 1 file changed, 23 insertions(+), 14 deletions(-) diff --git a/misc/filefrag.c b/misc/filefrag.c index c1a8684..e9f7e68 100644 --- a/misc/filefrag.c +++ b/misc/filefrag.c @@ -315,32 +315,41 @@ static int filefrag_fibmap(int fd, int blk_shift, int *num_extents, return rc; if (block == 0) continue; + count++; + if (*num_extents == 0) { (*num_extents)++; if (force_extent) { print_extent_header(); + fm_ext.fe_logical = logical; fm_ext.fe_physical = block * st->st_blksize; + fm_ext.fe_length = st->st_blksize; } + last_block = block; + continue; } - count++; - if (force_extent && last_block != 0 && - (block != last_block + 1 || - fm_ext.fe_logical + fm_ext.fe_length != logical)) { - print_extent_info(&fm_ext, *num_extents - 1, - (last_block + 1) * st->st_blksize, - blk_shift, st); - fm_ext.fe_length = 0; - (*num_extents)++; + + if (force_extent) { + if (block != last_block + 1 || + fm_ext.fe_length + fm_ext.fe_logical != logical) { + print_extent_info(&fm_ext, *num_extents - 1, + (last_block + 1) * + st->st_blksize, + blk_shift, st); + fm_ext.fe_logical = logical; + fm_ext.fe_physical = block * st->st_blksize; + fm_ext.fe_length = st->st_blksize; + (*num_extents)++; + } else { + fm_ext.fe_length += st->st_blksize; + } } else if (last_block && (block != last_block + 1)) { - if (verbose) + if (verbose) { printf("Discontinuity: Block %ld is at %lu (was " "%lu)\n", i, block, last_block + 1); - fm_ext.fe_length = 0; + } (*num_extents)++; } - fm_ext.fe_logical = logical; - fm_ext.fe_physical = block * st->st_blksize; - fm_ext.fe_length += st->st_blksize; last_block = block; } -- 1.8.2.1