xfs_copy: check for dirty log on non-duplicate copies

xfs_copy either copies the log as-is or formats the log of the target(s)
based on whether duplicate copy mode is enabled. The target log is
formatted when non-duplicate mode is enabled because copies gain a new
fs UUID and the new UUID must be stamped into the log.

When non-duplicate mode is enabled, however, xfs_copy does not check
whether the source filesystem log is actually clean. If the source log
is dirty, the target filesystem is silently created with a clean log and
thus ends up in a potentially corrupted state.

Update xfs_copy to check the source log state and fail the copy if in
non-duplicate mode and the log is dirty. Encourage the user to mount the
filesystem or run xfs_repair to clear the log. Note that the log is
scanned unconditionally as opposed to only in non-duplicate mode because
v5 superblock log format support requires the current cycle number to
format the log correctly.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

Makefile

@@ -81,7 +81,7 @@ growfs: libxcmd
 io: libxcmd libhandle
 quota: libxcmd
 repair: libxlog
-
+copy: libxlog
 
 ifeq ($(HAVE_BUILDDEFS), yes)
 include $(BUILDRULES)

copy/Makefile

@@ -9,8 +9,8 @@ LTCOMMAND = xfs_copy
 CFILES = xfs_copy.c
 HFILES = xfs_copy.h
 
-LLDLIBS = $(LIBXFS) $(LIBUUID) $(LIBPTHREAD) $(LIBRT)
-LTDEPENDENCIES = $(LIBXFS)
+LLDLIBS = $(LIBXFS) $(LIBXLOG) $(LIBUUID) $(LIBPTHREAD) $(LIBRT)
+LTDEPENDENCIES = $(LIBXFS) $(LIBXLOG)
 LLDFLAGS = -static-libtool-libs
 
 default: depend $(LTCOMMAND)

copy/xfs_copy.c

@@ -23,6 +23,7 @@
 #include <signal.h>
 #include <stdarg.h>
 #include "xfs_copy.h"
+#include "libxlog.h"
 
 #define	rounddown(x, y)	(((x)/(y))*(y))
 #define uuid_equal(s,d) (platform_uuid_compare((s),(d)) == 0)
@@ -128,6 +129,12 @@ do_message(int flags, int code, const char *fmt, ...)
 			exit(1); \
 		} while (0)
 
+/* workaround craziness in the xlog routines */
+int xlog_recover_do_trans(struct xlog *log, struct xlog_recover *t, int p)
+{
+	return 0;
+}
+
 void
 check_errors(void)
 {
@@ -522,6 +529,7 @@ main(int argc, char **argv)
 	ag_header_t	ag_hdr;
 	xfs_mount_t	*mp;
 	xfs_mount_t	mbuf;
+	struct xlog	xlog;
 	xfs_buf_t	*sbp;
 	xfs_sb_t	*sb;
 	xfs_agnumber_t	num_ags, agno;
@@ -717,6 +725,31 @@ main(int argc, char **argv)
 		exit(1);
 	}
 
+
+	/*
+	 * Set up the mount pointer to access the log and check whether the log
+	 * is clean. Fail on a dirty or corrupt log in non-duplicate mode
+	 * because the log is formatted as part of the copy and we don't want to
+	 * destroy data. We also need the current log cycle to format v5
+	 * superblock logs correctly.
+	 */
+	memset(&xlog, 0, sizeof(struct xlog));
+	mp->m_log = &xlog;
+	c = xlog_is_dirty(mp, mp->m_log, &xargs, 0);
+	if (!duplicate) {
+		if (c == 1) {
+			do_log(_(
+"Error: source filesystem log is dirty. Mount the filesystem to replay the\n"
+"log, unmount and retry xfs_copy.\n"));
+			exit(1);
+		} else if (c < 0) {
+			do_log(_(
+"Error: could not determine the log head or tail of the source filesystem.\n"
+"Mount the filesystem to replay the log or run xfs_repair.\n"));
+			exit(1);
+		}
+	}
+
 	source_blocksize = mp->m_sb.sb_blocksize;
 	source_sectorsize = mp->m_sb.sb_sectsize;