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[PATCH] xfsprogs/repair: only check secondary sb->sb_pquotino for v5 sup

To: xfs@xxxxxxxxxxx
Subject: [PATCH] xfsprogs/repair: only check secondary sb->sb_pquotino for v5 superblocks
From: Brian Foster <bfoster@xxxxxxxxxx>
Date: Mon, 30 Mar 2015 10:53:26 -0400
Cc: gux.fnst@xxxxxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
xfs_repair scans for garbage data beyond the last valid superblock field
for the particular sb version in secondary_sb_wack(). If any non-zero
data is detected, the entire range is reset to zero. Subsequently,
various valid superblock fields are checked for valid/expected data.

The sb_pquotino field is checked unconditionally as part of this
sequence even though it is a v5 only field. As a result, repair
complains about a non-null project quota field if any garbage data
exists for a v4 secondary sb. This is reproduced by xfs/070 against a v4
superblock and is also easily reproduced manually as follows:

$ mkfs.xfs -f -m crc=0 <dev>
$ xfs_db -x -c "sb 3" -c "write lsn 1" <dev>
$ xfs_repair <dev>
...
zeroing unused portion of secondary superblock (AG #3)
non-null project quota inode field in superblock 3
...

This occurs because the garbage data detection mechanism has reset
sb->sb_pquotino to 0 while the validity check expects a value of
NULLFSINO.

Update secondary_sb_wack() to only check sb->sb_pquotino for validity on
supers where it is a valid field. If it is anything other than 0 on
pre-v5 superblocks, it is explicitly reset to 0 by the garbage data
checks earlier in the function.

Reported-by: Xing Gu <gux.fnst@xxxxxxxxxxxxxx>
Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
---
 repair/agheader.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/repair/agheader.c b/repair/agheader.c
index 416dbd8..5dbf992 100644
--- a/repair/agheader.c
+++ b/repair/agheader.c
@@ -377,7 +377,13 @@ secondary_sb_wack(
                        rval |= XR_AG_SB_SEC;
        }
 
-       if (sb->sb_inprogress == 1 && sb->sb_pquotino != NULLFSINO)  {
+       /*
+        * Note that sb_pquotino is not considered a valid sb field for pre-v5
+        * superblocks. If it is anything other than 0 it is considered garbage
+        * data beyond the valid sb and explicitly zeroed above.
+        */
+       if (xfs_sb_version_has_pquotino(&mp->m_sb) &&
+           sb->sb_inprogress == 1 && sb->sb_pquotino != NULLFSINO)  {
                if (!no_modify) {
                        sb->sb_pquotino = 0;
                        dsb->sb_pquotino = 0;
-- 
1.9.3

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