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[PATCH] xfs_repair: copy, don't clear, stripe geometry in backup SB

To: xfs-oss <xfs@xxxxxxxxxxx>
Subject: [PATCH] xfs_repair: copy, don't clear, stripe geometry in backup SB
From: Eric Sandeen <sandeen@xxxxxxxxxx>
Date: Fri, 11 Jul 2014 18:02:01 -0500
Delivered-to: xfs@xxxxxxxxxxx
Today, if we have a filesystem with stripe geometry and
a damaged primary superblock, we will zero out stripe geometry
if we have copied the backup.

I'm guessing this might be because changing geometry with mount
options only updates the primary, so backups aren't guaranteed
to be current or correct.

Unfortunately, that leaves us with sb 0 w/ no geom, and backups
*with* geom, so the next repair finds the mismatch, and complains.
(In other words, the 2nd repair does not come up clean.)_
And ... the second repair copies the backup stripe geometry back
into the primary!

Rather than clearing stripe geometry in this case, just leave it
at what was found in the backup super, and inform the user that this
was done.  This leaves a consistent filesystem, and gives the user
a heads-up to double-check the result.

This can all be demonstrated and tested by running xfs/030 with
geometry set in MKFS_OPTIONS.  (To really make the test pass, 
we need to filter the warning out of repair output.)

Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
---

diff --git a/repair/globals.h b/repair/globals.h
index f6e0a22..6207ca1 100644
--- a/repair/globals.h
+++ b/repair/globals.h
@@ -124,7 +124,7 @@ EXTERN int  lazy_count;             /* What to set if to if 
converting */
 
 EXTERN int             primary_sb_modified;
 EXTERN int             bad_ino_btree;
-EXTERN int             clear_sunit;
+EXTERN int             copied_sunit;
 EXTERN int             fs_is_dirty;
 
 /* for hunting down the root inode */
diff --git a/repair/sb.c b/repair/sb.c
index bc421cc..ad27756 100644
--- a/repair/sb.c
+++ b/repair/sb.c
@@ -151,7 +151,7 @@ find_secondary_sb(xfs_sb_t *rsb)
                         */
                        memmove(rsb, &bufsb, sizeof(xfs_sb_t));
                        rsb->sb_inprogress = 0;
-                       clear_sunit = 1;
+                       copied_sunit = 1;
 
                        if (verify_set_primary_sb(rsb, 0, &dirty) == XR_OK)  {
                                do_warn(
diff --git a/repair/xfs_repair.c b/repair/xfs_repair.c
index 9eb2fa4..834697a 100644
--- a/repair/xfs_repair.c
+++ b/repair/xfs_repair.c
@@ -193,7 +193,7 @@ process_args(int argc, char **argv)
        delete_attr_ok = 1;
        force_geo = 0;
        assume_xfs = 0;
-       clear_sunit = 0;
+       copied_sunit = 0;
        sb_inoalignmt = 0;
        sb_unit = 0;
        sb_width = 0;
@@ -898,13 +898,11 @@ _("Warning:  project quota information would be 
cleared.\n"
                dsb->sb_qflags &= cpu_to_be16(~XFS_ALL_QUOTA_CHKD);
        }
 
-       if (clear_sunit) {
+       if (copied_sunit) {
                do_warn(
-_("Note - stripe unit (%d) and width (%d) fields have been reset.\n"
-  "Please set with mount -o sunit=<value>,swidth=<value>\n"),
+_("Note - stripe unit (%d) and width (%d) were copied from a backup 
superblock.\n"
+  "Please reset with mount -o sunit=<value>,swidth=<value> if necessary\n"),
                        be32_to_cpu(dsb->sb_unit), be32_to_cpu(dsb->sb_width));
-               dsb->sb_unit = 0;
-               dsb->sb_width = 0;
        }
 
        libxfs_writebuf(sbp, 0);

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