From: Eric Sandeen Subject: Re: [PATCH] e2fsck: detect invalid extents at the end of an extent-block Date: Tue, 04 Jun 2013 16:54:03 -0500 Message-ID: <51AE61FB.8080402@redhat.com> References: <20130403190841.GA16276@fury.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: linux-ext4@vger.kernel.org To: David Jeffery Return-path: Received: from mx1.redhat.com ([209.132.183.28]:65139 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751520Ab3FDVyF (ORCPT ); Tue, 4 Jun 2013 17:54:05 -0400 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r54Ls5Bu009678 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Tue, 4 Jun 2013 17:54:05 -0400 In-Reply-To: <20130403190841.GA16276@fury.redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 4/3/13 2:08 PM, David Jeffery wrote: > e2fsck does not detect extents which are outside their location in the > extent tree. This can result in a bad extent at the end of an extent-block > not being detected. > > From a part of a dump_extents output: > > 1/ 2 37/ 68 143960 - 146679 123826181 2720 > 2/ 2 1/ 2 143960 - 146679 123785816 - 123788535 2720 > 2/ 2 2/ 2 146680 - 147583 123788536 - 123789439 904 Uninit <-bad extent > 1/ 2 38/ 68 146680 - 149391 123826182 2712 > 2/ 2 1/ 2 146680 - 147583 18486 - 19389 904 > 2/ 2 2/ 2 147584 - 149391 123789440 - 123791247 1808 > > e2fsck does not detect this bad extent which both overlaps another, valid > extent, and is invalid by being beyond the end of the extent above it in > the tree. > > This patch modifies e2fsck to detect this invalid extent and remove it. > > Signed-off-by: David Jeffery > --- > e2fsck/pass1.c | 13 +++++++++---- > e2fsck/problem.c | 6 ++++++ > e2fsck/problem.h | 1 + > 3 files changed, 16 insertions(+), 4 deletions(-) > > diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c > index a20b57b..198e9a0 100644 > --- a/e2fsck/pass1.c > +++ b/e2fsck/pass1.c > @@ -1848,7 +1848,7 @@ void e2fsck_clear_inode(e2fsck_t ctx, ext2_ino_t ino, > > static void scan_extent_node(e2fsck_t ctx, struct problem_context *pctx, > struct process_block_struct *pb, > - blk64_t start_block, > + blk64_t start_block, blk64_t end_block, > ext2_extent_handle_t ehandle) > { > struct ext2fs_extent extent; > @@ -1891,6 +1891,9 @@ static void scan_extent_node(e2fsck_t ctx, struct problem_context *pctx, > problem = PR_1_EXTENT_BAD_START_BLK; > else if (extent.e_lblk < start_block) > problem = PR_1_OUT_OF_ORDER_EXTENTS; > + else if (end_block && > + (extent.e_lblk + extent.e_len) > end_block) > + problem = PR_1_EXTENT_END_OUT_OF_BOUNDS; thinking out loud; let's say e_lblk is 10 and len is 10. So the extent covers blocks 10->19, and e_lbk + e_len is 20, though the last block in the range is 19. But you pass in the same value (lblk + len) as "last block" so I guess it matches up, it just requires some thought. It might be better to do this in the caller: lblk_end = extent.e_lblk + extent.e_len - 1; and this in the test: else if (end_block && (extent.e_lblk + extent.e_len - 1) > end_block) just so that "end_block" really is the end block? > else if (is_leaf && extent.e_len == 0) > problem = PR_1_EXTENT_LENGTH_ZERO; > else if (is_leaf && > @@ -1937,10 +1940,11 @@ fix_problem_now: > } > > if (!is_leaf) { > - blk64_t lblk; > + blk64_t lblk, lblk_end; > > blk = extent.e_pblk; > lblk = extent.e_lblk; > + lblk_end = extent.e_lblk + extent.e_len; maybe extent.e_lblk + extent.e_len - 1 ? > pctx->errcode = ext2fs_extent_get(ehandle, > EXT2_EXTENT_DOWN, &extent); > if (pctx->errcode) { > @@ -1965,7 +1969,8 @@ fix_problem_now: > if (fix_problem(ctx, problem, pctx)) > ext2fs_extent_fix_parents(ehandle); > } > - scan_extent_node(ctx, pctx, pb, extent.e_lblk, ehandle); > + scan_extent_node(ctx, pctx, pb, extent.e_lblk, > + lblk_end, ehandle); > if (pctx->errcode) > return; > pctx->errcode = ext2fs_extent_get(ehandle, > @@ -2084,7 +2089,7 @@ static void check_blocks_extents(e2fsck_t ctx, struct problem_context *pctx, > ctx->extent_depth_count[info.max_depth]++; > } > > - scan_extent_node(ctx, pctx, pb, 0, ehandle); > + scan_extent_node(ctx, pctx, pb, 0, 0, ehandle); Other than the above nitpick, I think this does what it advertises, so: Reviewed-by: Eric Sandeen Thanks, -Eric > if (pctx->errcode && > fix_problem(ctx, PR_1_EXTENT_ITERATE_FAILURE, pctx)) { > pb->num_blocks = 0; > diff --git a/e2fsck/problem.c b/e2fsck/problem.c > index 76bc1d5..b0a6e19 100644 > --- a/e2fsck/problem.c > +++ b/e2fsck/problem.c > @@ -1008,6 +1008,12 @@ static struct e2fsck_problem problem_table[] = { > "Logical start %b does not match logical start %c at next level. "), > PROMPT_FIX, 0 }, > > + /* Extent end is out of bounds for the tree */ > + { PR_1_EXTENT_END_OUT_OF_BOUNDS, > + N_("@i %i, end of extent exceeds allowed value\n\t(logical @b %c, physical @b %b, len %N)\n"), > + PROMPT_CLEAR, 0 }, > + > + > /* Pass 1b errors */ > > /* Pass 1B: Rescan for duplicate/bad blocks */ > diff --git a/e2fsck/problem.h b/e2fsck/problem.h > index d2b6df4..fcdc1a1 100644 > --- a/e2fsck/problem.h > +++ b/e2fsck/problem.h > @@ -589,6 +589,7 @@ struct problem_context { > /* Index start doesn't match start of next extent down */ > #define PR_1_EXTENT_INDEX_START_INVALID 0x01006D > > +#define PR_1_EXTENT_END_OUT_OF_BOUNDS 0x01006E > /* > * Pass 1b errors > */ > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >