linux-ext4 - [PATCH 20/51] e2fsck: Verify extent tree blocks and clear the bad ones

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Date:	Tue, 13 Dec 2011 17:15:31 -0800
From:	"Darrick J. Wong" <djwong@...ibm.com>
To:	Andreas Dilger <adilger.kernel@...ger.ca>,
	Theodore Tso <tytso@....edu>,
	"Darrick J. Wong" <djwong@...ibm.com>
Cc:	Sunil Mushran <sunil.mushran@...cle.com>,
	Amir Goldstein <amir73il@...il.com>,
	Andi Kleen <andi@...stfloor.org>,
	Mingming Cao <cmm@...ibm.com>,
	Joel Becker <jlbec@...lplan.org>, linux-ext4@...r.kernel.org,
	Coly Li <colyli@...il.com>
Subject: [PATCH 20/51] e2fsck: Verify extent tree blocks and clear the bad ones

When we encounter an extent tree block that passes the header check but fails
the checksum, offer to clear just that extent block instead of failing the
whole tree, which results in the entire inode being wiped out.

Signed-off-by: Darrick J. Wong <djwong@...ibm.com>
---
 e2fsck/pass1.c   |   11 +++++++++--
 e2fsck/problem.c |    6 ++++++
 e2fsck/problem.h |    3 +++
 3 files changed, 18 insertions(+), 2 deletions(-)


diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c
index 15320c6..7cfc739 100644
--- a/e2fsck/pass1.c
+++ b/e2fsck/pass1.c
@@ -1761,7 +1761,9 @@ static void scan_extent_node(e2fsck_t ctx, struct problem_context *pctx,
 
 	pctx->errcode = ext2fs_extent_get(ehandle, EXT2_EXTENT_FIRST_SIB,
 					  &extent);
-	while (!pctx->errcode && info.num_entries-- > 0) {
+	while ((pctx->errcode == 0 ||
+		pctx->errcode == EXT2_ET_EXTENT_CSUM_INVALID) &&
+	       info.num_entries-- > 0) {
 		is_leaf = extent.e_flags & EXT2_EXTENT_FLAGS_LEAF;
 		is_dir = LINUX_S_ISDIR(pctx->inode->i_mode);
 
@@ -1776,6 +1778,8 @@ static void scan_extent_node(e2fsck_t ctx, struct problem_context *pctx,
 			 (extent.e_pblk + extent.e_len) >
 			 ext2fs_blocks_count(ctx->fs->super))
 			problem = PR_1_EXTENT_ENDS_BEYOND;
+		else if (pctx->errcode == EXT2_ET_EXTENT_CSUM_INVALID)
+			problem = PR_1_EXTENT_CSUM_INVALID;
 
 		if (problem) {
 		report_problem:
@@ -1809,7 +1813,10 @@ static void scan_extent_node(e2fsck_t ctx, struct problem_context *pctx,
 			if (pctx->errcode) {
 				pctx->str = "EXT2_EXTENT_DOWN";
 				problem = PR_1_EXTENT_HEADER_INVALID;
-				if (pctx->errcode == EXT2_ET_EXTENT_HEADER_BAD)
+				if (pctx->errcode ==
+					EXT2_ET_EXTENT_HEADER_BAD ||
+				    pctx->errcode ==
+					EXT2_ET_EXTENT_CSUM_INVALID)
 					goto report_problem;
 				return;
 			}
diff --git a/e2fsck/problem.c b/e2fsck/problem.c
index e74ad79..96b0de5 100644
--- a/e2fsck/problem.c
+++ b/e2fsck/problem.c
@@ -946,6 +946,12 @@ static struct e2fsck_problem problem_table[] = {
 	  N_("The bad @b @i looks @n.  "),
 	  PROMPT_CLEAR, 0 },
 
+	/* Extent block does not match extent */
+	{ PR_1_EXTENT_CSUM_INVALID,
+	  N_("@i %i extent block checksum does not match extent\n\t(logical @b "
+	     "%c, @n 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 1d63598..a1e7ffb 100644
--- a/e2fsck/problem.h
+++ b/e2fsck/problem.h
@@ -553,6 +553,9 @@ struct problem_context {
 /* inode checksum does not match inode */
 #define PR_1_INODE_CSUM_INVALID		0x010066
 
+/* extent block checksum does not match extent block */
+#define PR_1_EXTENT_CSUM_INVALID	0x010067
+
 /*
  * Pass 1b errors
  */

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