File xfsprogs-xfs_repair-check-plausibility-of-root-... of Package xfsprogs.21555

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File xfsprogs-xfs_repair-check-plausibility-of-root-dir-pointer-be.patch of Package xfsprogs.21555

From ded6b55889acf0edf0a8e12744cc05a6d4677e29 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <darrick.wong@oracle.com>
Date: Thu, 27 Feb 2020 15:05:47 -0500
Subject: [PATCH] xfs_repair: check plausibility of root dir pointer before
 trashing it
Git-commit: ded6b55889acf0edf0a8e12744cc05a6d4677e29
Patch-mainline: v5.5.0-rc1
References: bsc#1188651

If sb_rootino doesn't point to where we think mkfs should have allocated
the root directory, check to see if the alleged root directory actually
looks like a root directory.  If so, we'll let it live because someone
could have changed sunit since formatting time, and that changes the
root directory inode estimate.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Acked-by: Anthony Iliopoulos <ailiop@suse.com>
---
 repair/xfs_repair.c | 46 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/repair/xfs_repair.c b/repair/xfs_repair.c
index 0e24bdd5ba93..c6237453c9b9 100644
--- a/repair/xfs_repair.c
+++ b/repair/xfs_repair.c
@@ -426,6 +426,37 @@ _("would reset superblock %s inode pointer to %"PRIu64"\n"),
 	*ino = expected_ino;
 }
 
+/* Does the root directory inode look like a plausible root directory? */
+static bool
+has_plausible_rootdir(
+	struct xfs_mount	*mp)
+{
+	struct xfs_inode	*ip;
+	xfs_ino_t		ino;
+	int			error;
+	bool			ret = false;
+
+	error = -libxfs_iget(mp, NULL, mp->m_sb.sb_rootino, 0, &ip,
+			&xfs_default_ifork_ops);
+	if (error)
+		goto out;
+	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;
+
+	/* The root directory '..' entry points to the directory. */
+	if (ino == mp->m_sb.sb_rootino)
+		ret = true;
+
+out_rele:
+	IRELE(ip);
+out:
+	return ret;
+}
+
 static void
 calc_mkfs(xfs_mount_t *mp)
 {
@@ -499,6 +530,21 @@ calc_mkfs(xfs_mount_t *mp)
 	else
 		last_prealloc_ino = XFS_OFFBNO_TO_AGINO(mp, fino_bno + 1, 0);
 
+	/*
+	 * 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.  Don't blow up the root directory if this is the
+	 * case.
+	 */
+	if (mp->m_sb.sb_rootino != first_prealloc_ino &&
+			has_plausible_rootdir(mp)) {
+		do_warn(
+_("sb root inode value %" PRIu64 " valid but in unaligned location (expected %"PRIu32") possibly due to sunit change\n"),
+			mp->m_sb.sb_rootino, first_prealloc_ino);
+		first_prealloc_ino = mp->m_sb.sb_rootino;
+	}
+
 	/*
 	 * now the first 3 inodes in the system
 	 */
-- 
2.32.0

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