[Ocfs2-tools-devel] [PATCH 3/3] Fix superblock ECC

[Goldwyn Rodrigues]

Fix the ECC of the superblock by re-calculating if incorrect and writing
it out.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn at suse.de>
---
 fsck.ocfs2/fsck.c                 |   27 +++++++++++++++++++++++++--
 fsck.ocfs2/fsck.ocfs2.checks.8.in |    9 +++++++++
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/fsck.ocfs2/fsck.c b/fsck.ocfs2/fsck.c
index ea072c6..6568e27 100644
--- a/fsck.ocfs2/fsck.c
+++ b/fsck.ocfs2/fsck.c
@@ -79,6 +79,7 @@ static o2fsck_state _ost;
 static int cluster_locked = 0;

 static void mark_magical_clusters(o2fsck_state *ost);
+static errcode_t write_out_superblock(o2fsck_state *ost);

 static void handle_signal(int sig)
 {
@@ -231,19 +232,41 @@ errcode_t o2fsck_state_reinit(ocfs2_filesys *fs,
o2fsck_state *ost)

 static errcode_t check_superblock(o2fsck_state *ost)
 {
-	struct ocfs2_dinode *di = ost->ost_fs->fs_super;
-	struct ocfs2_super_block *sb = OCFS2_RAW_SB(di);
+	char *blk;
+	struct ocfs2_dinode *di;
+	ocfs2_filesys *fs = ost->ost_fs;
+	struct ocfs2_super_block *sb = OCFS2_RAW_SB(fs->fs_super);
 	errcode_t ret = 0;

+	ret = ocfs2_malloc_block(fs->fs_io, &blk);
+	if (ret)
+		return ret;
+	memcpy(blk, (char *)fs->fs_super, fs->fs_blocksize);
+	di = (struct ocfs2_dinode *)blk;
+
 	if (sb->s_max_slots == 0) {
 		printf("The superblock max_slots field is set to 0.\n");
 		ret = OCFS2_ET_CORRUPT_SUPERBLOCK;
 	}

+	if (ocfs2_meta_ecc(OCFS2_RAW_SB(ost->ost_fs->fs_super))) {
+		ret = ocfs2_block_check_validate(
+				(char *)di, fs->fs_blocksize, &di->i_check);
+		if ((ret) && prompt(ost, PN, PR_INVALID_SUPER_ECC,
+					"Superblock has invalid ECC. Fix?")) {
+			ret = write_out_superblock(ost);
+			if (ret)
+				com_err(whoami, ret,
+					"while writing superblock\n");
+		} else /* Just in case hamming fixed anything, copy back*/
+			memcpy(fs->fs_super, di, fs->fs_blocksize);
+	}
+
 	ost->ost_fs_generation = di->i_fs_generation;

 	/* XXX do we want checking for different revisions of ocfs2? */

+	ocfs2_free(&blk);
 	return ret;
 }

diff --git a/fsck.ocfs2/fsck.ocfs2.checks.8.in
b/fsck.ocfs2/fsck.ocfs2.checks.8.in
index e706ea5..e4f75f1 100644
--- a/fsck.ocfs2/fsck.ocfs2.checks.8.in
+++ b/fsck.ocfs2/fsck.ocfs2.checks.8.in
@@ -1137,6 +1137,15 @@ index entry will cause lookups on this name to fail.

 Answering yes will rebuild the directory index, restoring the missing entry.

+.SS "INVALID_SUPER_ECC"
+The superblock has incorrect Error Correcting Code (ECC). ECC is capable of
+correcting corruption upto 1 bit per block.Any corruptions higher that this
+may indicate corruption. In this case the filesystem reports an error with
+the read operation.
+
+Answering yes will recalculate the ECC and write the superblock with the
+calculated ECC.
+
 .SH "SEE ALSO"
 .BR fsck.ocfs2(8)

-- 
1.7.3.4


-- 
Goldwyn