Due to the issue of mounting filesystem with older kernels and
potentially reading sb_features2 from the wrong location. It
seems the best course of action is to always make sb_features2
and sb_bad_features2 the same. This is pretty important as
new bits in this are supposed to stop older kernels from
mounting filesystems with unsupported features.
If sb_bad_features2 is zero, and the old kernel tries to read
sb_features2 from this location during mount, it will succeed
as it will read zero.
So, this patch changes mkfs.xfs to set sb_bad_features2 to
the same as sb_features2, xfs_check and xfs_repair now also
makes sure they are the same.
Barry.
--
===========================================================================
xfsprogs/db/check.c
===========================================================================
--- a/xfsprogs/db/check.c 2008-03-05 15:30:54.000000000 +1100
+++ b/xfsprogs/db/check.c 2008-03-05 15:28:58.638097511 +1100
@@ -869,6 +869,14 @@ blockget_f(
mp->m_sb.sb_frextents, frextents);
error++;
}
+ if (mp->m_sb.sb_bad_features2 != mp->m_sb.sb_features2) {
+ if (!sflag)
+ dbprintf("sb_features2 (0x%x) not same as "
+ "sb_bad_features2 (0x%x)\n",
+ mp->m_sb.sb_features2,
+ mp->m_sb.sb_bad_features2);
+ error++;
+ }
if ((sbversion & XFS_SB_VERSION_ATTRBIT) &&
!XFS_SB_VERSION_HASATTR(&mp->m_sb)) {
if (!sflag)
===========================================================================
xfsprogs/db/sb.c
===========================================================================
--- a/xfsprogs/db/sb.c 2008-03-05 15:30:54.000000000 +1100
+++ b/xfsprogs/db/sb.c 2008-02-29 17:16:33.770423296 +1100
@@ -108,6 +108,7 @@ const field_t sb_flds[] = {
{ "logsectsize", FLDT_UINT16D, OI(OFF(logsectsize)), C1, 0,
TYP_NONE },
{ "logsunit", FLDT_UINT32D, OI(OFF(logsunit)), C1, 0, TYP_NONE },
{ "features2", FLDT_UINT32X, OI(OFF(features2)), C1, 0, TYP_NONE },
+ { "bad_features2", FLDT_UINT32X, OI(OFF(bad_features2)), C1, 0,
TYP_NONE },
{ NULL }
};
===========================================================================
xfsprogs/include/xfs_sb.h
===========================================================================
--- a/xfsprogs/include/xfs_sb.h 2008-03-05 15:30:54.000000000 +1100
+++ b/xfsprogs/include/xfs_sb.h 2008-02-29 17:16:33.814417687 +1100
@@ -151,6 +151,7 @@ typedef struct xfs_sb
__uint16_t sb_logsectsize; /* sector size for the log, bytes */
__uint32_t sb_logsunit; /* stripe unit size for the log */
__uint32_t sb_features2; /* additional feature bits */
+ __uint32_t sb_bad_features2; /* unusable space */
} xfs_sb_t;
/*
@@ -169,7 +170,7 @@ typedef enum {
XFS_SBS_GQUOTINO, XFS_SBS_QFLAGS, XFS_SBS_FLAGS, XFS_SBS_SHARED_VN,
XFS_SBS_INOALIGNMT, XFS_SBS_UNIT, XFS_SBS_WIDTH, XFS_SBS_DIRBLKLOG,
XFS_SBS_LOGSECTLOG, XFS_SBS_LOGSECTSIZE, XFS_SBS_LOGSUNIT,
- XFS_SBS_FEATURES2,
+ XFS_SBS_FEATURES2, XFS_SBS_BAD_FEATURES2,
XFS_SBS_FIELDCOUNT
} xfs_sb_field_t;
===========================================================================
xfsprogs/libxfs/xfs_mount.c
===========================================================================
--- a/xfsprogs/libxfs/xfs_mount.c 2008-03-05 15:30:54.000000000 +1100
+++ b/xfsprogs/libxfs/xfs_mount.c 2008-02-29 17:16:33.834415138 +1100
@@ -140,6 +140,7 @@ static struct {
{ offsetof(xfs_sb_t, sb_logsectsize),0 },
{ offsetof(xfs_sb_t, sb_logsunit), 0 },
{ offsetof(xfs_sb_t, sb_features2), 0 },
+ { offsetof(xfs_sb_t, sb_bad_features2), 0 },
{ sizeof(xfs_sb_t), 0 }
};
===========================================================================
xfsprogs/mkfs/xfs_mkfs.c
===========================================================================
--- a/xfsprogs/mkfs/xfs_mkfs.c 2008-03-05 15:30:54.000000000 +1100
+++ b/xfsprogs/mkfs/xfs_mkfs.c 2008-03-05 15:27:37.568461787 +1100
@@ -2103,6 +2103,13 @@ an AG size that is one stripe unit small
dirversion == 2, logversion == 2, attrversion == 1,
(sectorsize != BBSIZE || lsectorsize != BBSIZE),
sbp->sb_features2 != 0);
+ /*
+ * Due to a structure alignment issue, sb_features2 ended up in one
+ * of two locations, the second "incorrect" location represented by
+ * the sb_bad_features2 field. To avoid older kernels mounting
+ * filesystems they shouldn't, set both field to the same value.
+ */
+ sbp->sb_bad_features2 = sbp->sb_features2;
if (force_overwrite)
zero_old_xfs_structures(&xi, sbp);
===========================================================================
xfsprogs/repair/phase1.c
===========================================================================
--- a/xfsprogs/repair/phase1.c 2008-03-05 15:30:54.000000000 +1100
+++ b/xfsprogs/repair/phase1.c 2008-03-05 15:19:09.513415413 +1100
@@ -91,6 +91,19 @@ phase1(xfs_mount_t *mp)
primary_sb_modified = 1;
}
+ /*
+ * Check bad_features2 and make sure features2 the same as
+ * bad_features (ORing the two together). Leave bad_features2
+ * set so older kernels can still use it and not mount unsupported
+ * filesystems when it reads bad_features2.
+ */
+ if (sb->sb_bad_features2 != sb->sb_features2) {
+ sb->sb_features2 |= sb->sb_bad_features2;
+ sb->sb_bad_features2 = sb->sb_features2;
+ primary_sb_modified = 1;
+ do_warn(_("superblock has a features2 mismatch, correcting\n"));
+ }
+
if (primary_sb_modified) {
if (!no_modify) {
do_warn(_("writing modified primary superblock\n"));