From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
If sb_rootino doesn't point to where we think mkfs was supposed to have
preallocated an inode chunk, check to see if the alleged root directory
actually looks like a root directory. If so, we'll let it go because
someone could have changed sunit since formatting time.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
repair/xfs_repair.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 49 insertions(+), 1 deletion(-)
diff --git a/repair/xfs_repair.c b/repair/xfs_repair.c
index 6798b88c..f6134cca 100644
--- a/repair/xfs_repair.c
+++ b/repair/xfs_repair.c
@@ -395,12 +395,60 @@ do_log(char const *msg, ...)
va_end(args);
}
+/*
+ * If sb_rootino points to a different inode than we were expecting, try
+ * loading the alleged root inode to see if it's a plausibly a root directory.
+ * If so, we'll readjust the computations.
+ */
+static void
+check_misaligned_root(
+ struct xfs_mount *mp)
+{
+ struct xfs_inode *ip;
+ xfs_ino_t ino;
+ int error;
+
+ error = -libxfs_iget(mp, NULL, mp->m_sb.sb_rootino, 0, &ip,
+ &xfs_default_ifork_ops);
+ if (error)
+ return;
+ if (!S_ISDIR(VFS_I(ip)->i_mode))
+ goto out_rele;
+
+ error = -libxfs_dir_lookup(NULL, ip, &xfs_name_dotdot, &ino, NULL);
+ if (error)
+ goto out_rele;
+
+ if (ino == mp->m_sb.sb_rootino) {
+ do_warn(
+_("sb root inode value %" PRIu64 " inconsistent with calculated value %u but looks like a root directory\n"),
+ mp->m_sb.sb_rootino, first_prealloc_ino);
+ last_prealloc_ino += (int)ino - first_prealloc_ino;
+ first_prealloc_ino = ino;
+ }
+
+out_rele:
+ libxfs_irele(ip);
+}
+
static void
-calc_mkfs(xfs_mount_t *mp)
+calc_mkfs(
+ struct xfs_mount *mp)
{
libxfs_ialloc_find_prealloc(mp, &first_prealloc_ino,
&last_prealloc_ino);
+ /*
+ * If the root inode isn't where we think it is, check its plausibility
+ * as a root directory. It's possible that somebody changed sunit since
+ * the filesystem was created, which can change the value of the above
+ * computation. Try to avoid blowing up the filesystem if this is the
+ * case.
+ */
+ if (mp->m_sb.sb_rootino != NULLFSINO &&
+ mp->m_sb.sb_rootino != first_prealloc_ino)
+ check_misaligned_root(mp);
+
/*
* now the first 3 inodes in the system
*/
