From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
If the primary superblock's sb_unit leads to a rootino calculation that
doesn't match sb_rootino /but/ we can find a secondary superblock whose
sb_unit does match, fix the primary.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
libxfs/libxfs_api_defs.h | 1 +
repair/xfs_repair.c | 79 ++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 80 insertions(+)
diff --git a/libxfs/libxfs_api_defs.h b/libxfs/libxfs_api_defs.h
index 9ede0125..d9f497e0 100644
--- a/libxfs/libxfs_api_defs.h
+++ b/libxfs/libxfs_api_defs.h
@@ -178,5 +178,6 @@
#define xfs_finobt_calc_reserves libxfs_finobt_calc_reserves
#define xfs_rmapbt_calc_reserves libxfs_rmapbt_calc_reserves
#define xfs_read_agf libxfs_read_agf
+#define xfs_sb_read_secondary libxfs_sb_read_secondary
#endif /* __LIBXFS_API_DEFS_H__ */
diff --git a/repair/xfs_repair.c b/repair/xfs_repair.c
index 372616c4..66e2c335 100644
--- a/repair/xfs_repair.c
+++ b/repair/xfs_repair.c
@@ -457,6 +457,84 @@ has_plausible_rootdir(
return ret;
}
+/*
+ * If any of the secondary SBs contain a *correct* value for sunit, write that
+ * back to the primary superblock.
+ */
+static void
+guess_correct_sunit(
+ struct xfs_mount *mp)
+{
+ struct xfs_sb sb;
+ struct xfs_buf *bp;
+ xfs_ino_t calc_rootino = NULLFSINO;
+ xfs_agnumber_t agno;
+ unsigned int new_sunit;
+ unsigned int sunit_guess;
+ int error;
+
+ /* Try reading secondary supers to see if we find a good sb_unit. */
+ for (agno = 1; agno < mp->m_sb.sb_agcount; agno++) {
+ error = -libxfs_sb_read_secondary(mp, NULL, agno, &bp);
+ if (error)
+ continue;
+ libxfs_sb_from_disk(&sb, XFS_BUF_TO_SBP(bp));
+ libxfs_putbuf(bp);
+
+ calc_rootino = libxfs_ialloc_calc_rootino(mp, sb.sb_unit);
+ if (calc_rootino == mp->m_sb.sb_rootino)
+ break;
+ }
+
+ /* If we found a reasonable value, log where we found it. */
+ if (calc_rootino == mp->m_sb.sb_rootino) {
+ do_warn(_("AG %u superblock contains plausible sb_unit value\n"),
+ agno);
+ new_sunit = sb.sb_unit;
+ goto fix;
+ }
+
+ /* Try successive powers of two. */
+ for (sunit_guess = 1;
+ sunit_guess <= XFS_AG_MAX_BLOCKS(mp->m_sb.sb_blocklog);
+ sunit_guess *= 2) {
+ calc_rootino = libxfs_ialloc_calc_rootino(mp, sunit_guess);
+ if (calc_rootino == mp->m_sb.sb_rootino)
+ break;
+ }
+
+ /* If we found a reasonable value, log where we found it. */
+ if (calc_rootino == mp->m_sb.sb_rootino) {
+ do_warn(_("Found an sb_unit value that looks plausible\n"));
+ new_sunit = sunit_guess;
+ goto fix;
+ }
+
+ do_warn(_("Could not estimate a plausible sb_unit value\n"));
+ return;
+
+fix:
+ if (!no_modify)
+ do_warn(_("Resetting sb_unit to %u\n"), new_sunit);
+ else
+ do_warn(_("Would reset sb_unit to %u\n"), new_sunit);
+
+ /*
+ * Just set the value -- safe since the superblock doesn't get flushed
+ * out if no_modify is set.
+ */
+ mp->m_sb.sb_unit = new_sunit;
+
+ /* Make sure that swidth is still a multiple of sunit. */
+ if (mp->m_sb.sb_width % mp->m_sb.sb_unit == 0)
+ return;
+
+ if (!no_modify)
+ do_warn(_("Resetting sb_width to %u\n"), new_sunit);
+ else
+ do_warn(_("Would reset sb_width to %u\n"), new_sunit);
+}
+
/*
* Make sure that the first 3 inodes in the filesystem are the root directory,
* the realtime bitmap, and the realtime summary, in that order.
@@ -480,6 +558,7 @@ calc_mkfs(
do_warn(
_("sb root inode value %" PRIu64 " inconsistent with alignment (expected %"PRIu64")\n"),
mp->m_sb.sb_rootino, rootino);
+ guess_correct_sunit(mp);
rootino = mp->m_sb.sb_rootino;
}
