[PATCH 22/22] xfs: implement extended feature masks

Dave Chinner
2013-04-03T05:12:46Z

From: Dave Chinner <dchinner@redhat.com>

The version 5 superblock has extended feature masks for compatible,
incompatible and read-only compatible feature sets. Implement the
masking and mount-time checking for these feature masks.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/xfs_log_recover.c | 19 +++++++++++++
fs/xfs/xfs_mount.c | 48 +++++++++++++++++++++++++++----
fs/xfs/xfs_sb.h | 70 ++++++++++++++++++++++++++++++++++++++++++++--
3 files changed, 129 insertions(+), 8 deletions(-)

diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 5303b3d..35ac504 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -3959,6 +3959,25 @@ xlog_recover(
return error;
}

+ /*
+ * Version 5 superblock log feature mask validation. We know the
+ * log is dirty so check if there are any unknown log features
+ * in what we need to recover. If there are unknown features
+ * (e.g. unsupported transactions, then simply reject the
+ * attempt at recovery before touching anything.
+ */
+ if (XFS_SB_VERSION_NUM(&log->l_mp->m_sb) == XFS_SB_VERSION_5 &&
+ xfs_sb_has_incompat_log_feature(&log->l_mp->m_sb,
+ XFS_SB_FEAT_INCOMPAT_LOG_UNKNOWN)) {
+ xfs_warn(log->l_mp,
+"Superblock has unknown incompatible log features (0x%x) enabled.\n"
+"The log can not be fully and/or safely recovered by this kernel.\n"
+"Please recover the log on a kernel that supports the unknown features.",
+ (log->l_mp->m_sb.sb_features_log_incompat &
+ XFS_SB_FEAT_INCOMPAT_LOG_UNKNOWN));
+ return EINVAL;
+ }
+
xfs_notice(log->l_mp, "Starting recovery (logdev: %s)",
log->l_mp->m_logname ? log->l_mp->m_logname
: "internal");
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 140136c..f6bfbd7 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -114,7 +114,9 @@ static const struct {
{ offsetof(xfs_sb_t, sb_features_compat), 0 },
{ offsetof(xfs_sb_t, sb_features_ro_compat), 0 },
{ offsetof(xfs_sb_t, sb_features_incompat), 0 },
+ { offsetof(xfs_sb_t, sb_features_log_incompat), 0 },
{ offsetof(xfs_sb_t, sb_crc), 0 },
+ { offsetof(xfs_sb_t, sb_pad), 0 },
{ offsetof(xfs_sb_t, sb_pquotino), 0 },
{ offsetof(xfs_sb_t, sb_lsn), 0 },
{ sizeof(xfs_sb_t), 0 }
@@ -334,14 +336,45 @@ xfs_mount_validate_sb(
}

/*
- * Do not allow Version 5 superblocks to mount right now, even though
- * support is in place. We need to implement the proper feature masks
- * first.
+ * Version 5 superblock feature mask validation. Reject combinations the
+ * kernel cannot support up front before checking anything else.
*/
if (XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5) {
xfs_alert(mp,
- "Version 5 superblock detected. Experimental support not yet enabled!");
- return XFS_ERROR(EINVAL);
+"Version 5 superblock detected. This kernel has EXPERIMENTAL support enabled!\n"
+"Use of these features in this kernel is at your own risk!");
+
+ if (xfs_sb_has_compat_feature(sbp,
+ XFS_SB_FEAT_COMPAT_UNKNOWN)) {
+ xfs_warn(mp,
+"Superblock has unknown compatible features (0x%x) enabled.\n"
+"Using a more recent kernel is recommended.",
+ (sbp->sb_features_compat &
+ XFS_SB_FEAT_COMPAT_UNKNOWN));
+ }
+
+ if (xfs_sb_has_ro_compat_feature(sbp,
+ XFS_SB_FEAT_RO_COMPAT_UNKNOWN)) {
+ xfs_alert(mp,
+"Superblock has unknown read-only compatible features (0x%x) enabled.",
+ (sbp->sb_features_ro_compat &
+ XFS_SB_FEAT_RO_COMPAT_UNKNOWN));
+ if (!(mp->m_flags & XFS_MOUNT_RDONLY)) {
+ xfs_warn(mp,
+"Attempted to mount read-only compatible filesystem read-write.\n"
+"Filesystem can only be safely mounted read only.");
+ return XFS_ERROR(EINVAL);
+ }
+ }
+ if (xfs_sb_has_incompat_feature(sbp,
+ XFS_SB_FEAT_INCOMPAT_UNKNOWN)) {
+ xfs_warn(mp,
+"Superblock has unknown incompatible features (0x%x) enabled.\n"
+"Filesystem can not be safely mounted by this kernel.",
+ (sbp->sb_features_incompat &
+ XFS_SB_FEAT_INCOMPAT_UNKNOWN));
+ return XFS_ERROR(EINVAL);
+ }
}

if (unlikely(
@@ -580,6 +613,9 @@ xfs_sb_from_disk(
to->sb_features_compat = be32_to_cpu(from->sb_features_compat);
to->sb_features_ro_compat = be32_to_cpu(from->sb_features_ro_compat);
to->sb_features_incompat = be32_to_cpu(from->sb_features_incompat);
+ to->sb_features_log_incompat =
+ be32_to_cpu(from->sb_features_log_incompat);
+ to->sb_pad = 0;
to->sb_pquotino = be64_to_cpu(from->sb_pquotino);
to->sb_lsn = be64_to_cpu(from->sb_lsn);
}
@@ -786,7 +822,7 @@ reread:
if (bp->b_error) {
error = bp->b_error;
if (loud)
- xfs_warn(mp, "SB validate failed");
+ xfs_warn(mp, "SB validate failed with error %d.", error);
goto release_buf;
}

diff --git a/fs/xfs/xfs_sb.h b/fs/xfs/xfs_sb.h
index 457fefa..2de58a8 100644
--- a/fs/xfs/xfs_sb.h
+++ b/fs/xfs/xfs_sb.h
@@ -168,8 +168,10 @@ typedef struct xfs_sb {
__uint32_t sb_features_compat;
__uint32_t sb_features_ro_compat;
__uint32_t sb_features_incompat;
+ __uint32_t sb_features_log_incompat;

__uint32_t sb_crc; /* superblock crc */
+ __uint32_t sb_pad;

xfs_ino_t sb_pquotino; /* project quota inode */
xfs_lsn_t sb_lsn; /* last write sequence */
@@ -250,8 +252,10 @@ typedef struct xfs_dsb {
__be32 sb_features_compat;
__be32 sb_features_ro_compat;
__be32 sb_features_incompat;
+ __be32 sb_features_log_incompat;

__le32 sb_crc; /* superblock crc */
+ __be32 sb_pad;

__be64 sb_pquotino; /* project quota inode */
__be64 sb_lsn; /* last write sequence */
@@ -276,7 +280,8 @@ typedef enum {
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_BAD_FEATURES2, XFS_SBS_FEATURES_COMPAT,
- XFS_SBS_FEATURES_RO_COMPAT, XFS_SBS_FEATURES_INCOMPAT, XFS_SBS_CRC,
+ XFS_SBS_FEATURES_RO_COMPAT, XFS_SBS_FEATURES_INCOMPAT,
+ XFS_SBS_FEATURES_LOG_INCOMPAT, XFS_SBS_CRC, XFS_SBS_PAD,
XFS_SBS_PQUOTINO, XFS_SBS_LSN,
XFS_SBS_FIELDCOUNT
} xfs_sb_field_t;
@@ -306,6 +311,7 @@ typedef enum {
#define XFS_SB_FEATURES_COMPAT XFS_SB_MVAL(FEATURES_COMPAT)
#define XFS_SB_FEATURES_RO_COMPAT XFS_SB_MVAL(FEATURES_RO_COMPAT)
#define XFS_SB_FEATURES_INCOMPAT XFS_SB_MVAL(FEATURES_INCOMPAT)
+#define XFS_SB_FEATURES_LOG_INCOMPAT XFS_SB_MVAL(FEATURES_LOG_INCOMPAT)
#define XFS_SB_CRC XFS_SB_MVAL(CRC)
#define XFS_SB_PQUOTINO XFS_SB_MVAL(PQUOTINO)
#define XFS_SB_NUM_BITS ((int)XFS_SBS_FIELDCOUNT)
@@ -316,7 +322,8 @@ typedef enum {
XFS_SB_QFLAGS | XFS_SB_SHARED_VN | XFS_SB_UNIT | XFS_SB_WIDTH | \
XFS_SB_ICOUNT | XFS_SB_IFREE | XFS_SB_FDBLOCKS | XFS_SB_FEATURES2 | \
XFS_SB_BAD_FEATURES2 | XFS_SB_FEATURES_COMPAT | \
- XFS_SB_FEATURES_RO_COMPAT | XFS_SB_FEATURES_INCOMPAT | XFS_SB_PQUOTINO)
+ XFS_SB_FEATURES_RO_COMPAT | XFS_SB_FEATURES_INCOMPAT | \
+ XFS_SB_FEATURES_LOG_INCOMPAT | XFS_SB_PQUOTINO)

/*
@@ -552,6 +559,65 @@ static inline int xfs_sb_version_hascrc(xfs_sb_t *sbp)
return XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5;
}

+
+/*
+ * Extended v5 superblock feature masks. These are to be used for new v5
+ * superblock features only.
+ *
+ * Compat features are new features that old kernels will not notice or affect
+ * and so can mount read-write without issues.
+ *
+ * RO-Compat (read only) are features that old kernels can read but will break
+ * if they write. Hence only read-only mounts of such filesystems are allowed on
+ * kernels that don't support the feature bit.
+ *
+ * InCompat features are features which old kernels will not understand and so
+ * must not mount.
+ *
+ * Log-InCompat features are for changes to log formats or new transactions that
+ * can't be replayed on older kernels. The fields are set when the filesystem is
+ * mounted, and a clean unmount clears the fields.
+ */
+#define XFS_SB_FEAT_COMPAT_ALL 0
+#define XFS_SB_FEAT_COMPAT_UNKNOWN ~XFS_SB_FEAT_COMPAT_ALL
+static inline bool
+xfs_sb_has_compat_feature(
+ struct xfs_sb *sbp,
+ __uint32_t feature)
+{
+ return (sbp->sb_features_compat & feature) != 0;
+}
+
+#define XFS_SB_FEAT_RO_COMPAT_ALL 0
+#define XFS_SB_FEAT_RO_COMPAT_UNKNOWN ~XFS_SB_FEAT_RO_COMPAT_ALL
+static inline bool
+xfs_sb_has_ro_compat_feature(
+ struct xfs_sb *sbp,
+ __uint32_t feature)
+{
+ return (sbp->sb_features_ro_compat & feature) != 0;
+}
+
+#define XFS_SB_FEAT_INCOMPAT_ALL 0
+#define XFS_SB_FEAT_INCOMPAT_UNKNOWN ~XFS_SB_FEAT_INCOMPAT_ALL
+static inline bool
+xfs_sb_has_incompat_feature(
+ struct xfs_sb *sbp,
+ __uint32_t feature)
+{
+ return (sbp->sb_features_incompat & feature) != 0;
+}
+
+#define XFS_SB_FEAT_INCOMPAT_LOG_ALL 0
+#define XFS_SB_FEAT_INCOMPAT_LOG_UNKNOWN ~XFS_SB_FEAT_INCOMPAT_LOG_ALL
+static inline bool
+xfs_sb_has_incompat_log_feature(
+ struct xfs_sb *sbp,
+ __uint32_t feature)
+{
+ return (sbp->sb_features_log_incompat & feature) != 0;
+}
+
/*
* end of superblock version macros
*/
--
1.7.10.4