linux-ext4 - Re: How should e2fsck clear s_errno/j

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Date:	Mon, 23 Jul 2012 15:21:45 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	"Theodore Ts'o" <tytso@....edu>
CC:	ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: How should e2fsck clear s_errno/j_errno on an ro mount?

On 7/23/12 2:14 PM, Theodore Ts'o wrote:
>> nWell, I tested e2fsprogs from git and saw the same trouble.  Let me
>> look more closely at that commit.
> 
> Hmm, would it be possible to send me /tmp/loop3.qcow.bz2 after running:
> 
>      e2image -Q /dev/loop3 /tmp/loop3.qcow
>      bzip2 /tmp/loop3.qcow
> 
> Regardless of what the problem ends up being, this looks like
> something for our regression test suite....
> 
> 					- Ted
> 

Sure I can do that, will do it offline.

FWIW, the commit you mentioned changes e2fsck_check_ext3_journal, and
we only get there from main() like this:

        if ((ctx->mount_flags & EXT2_MF_MOUNTED) &&
            !(sb->s_feature_incompat & EXT3_FEATURE_INCOMPAT_RECOVER))
                goto skip_journal;

        retval = e2fsck_check_ext3_journal(ctx);

In my case I am mounted ro and recovery is done, so
EXT3_FEATURE_INCOMPAT_RECOVER is not, set, and so we skip over it with
the goto.

or else from here:

        if (sb->s_feature_incompat & EXT3_FEATURE_INCOMPAT_RECOVER) {
                if (ctx->options & E2F_OPT_READONLY) {
			...
                } else {
			...
                        retval = e2fsck_run_ext3_journal(ctx);

And again, I've already done recovery and am mounted RO so we won't go that way.

If make the first test above a little later:



diff --git a/e2fsck/unix.c b/e2fsck/unix.c
index 94260bd..73aa028 100644
--- a/e2fsck/unix.c
+++ b/e2fsck/unix.c
@@ -1424,10 +1424,6 @@ failure:
 		fprintf(ctx->logf, "Filesystem UUID: %s\n",
 			e2p_uuid2str(sb->s_uuid));
 
-	if ((ctx->mount_flags & EXT2_MF_MOUNTED) &&
-	    !(sb->s_feature_incompat & EXT3_FEATURE_INCOMPAT_RECOVER))
-		goto skip_journal;
-
 	/*
 	 * Make sure the ext3 superblock fields are consistent.
 	 */
@@ -1439,6 +1435,10 @@ failure:
 		fatal_error(ctx, 0);
 	}
 
+	if ((ctx->mount_flags & EXT2_MF_MOUNTED) &&
+	    !(sb->s_feature_incompat & EXT3_FEATURE_INCOMPAT_RECOVER))
+		goto skip_journal;
+
 	/*
 	 * Check to see if we need to do ext3-style recovery.  If so,
 	 * do it, and then restart the fsck.


it clears it up for me but TBH I'm not totally clear on what all is going
on here.

-Eric
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