[PATCH] xfs_metadump: tag metadump image with attribute flags

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After the long discussion about warning the user and/or consumer
of xfs_metadumps about dirty logs, it crossed my mind that we
could use the reserved slot in the metadump header to tag the
file with attributes, so the consumer of the metadump knows how
it was created.

This patch adds 3 flags to describe the metadump: dirty log,
obfuscated, and full blocks (unused portions of metadata blocks
are not zeroed out).

It then adds a new option to xfs_mdrestore, "-i" to show info,
which can be used with or without a target file:

# xfs_mdrestore -i metadumpfile
metadumpfile: not obfuscated, clean log, full metadata blocks

Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
---

diff --git a/db/metadump.c b/db/metadump.c
index fe068ef..2062415 100644
--- a/db/metadump.c
+++ b/db/metadump.c
@@ -2820,6 +2820,27 @@ metadump_f(
 	metablock->mb_blocklog = BBSHIFT;
 	metablock->mb_magic = cpu_to_be32(XFS_MD_MAGIC);
 
+	/* Set flags indicating state of metadump */
+	if (obfuscate)
+		metablock->mb_flags = XFS_METADUMP_OBFUSCATED;
+	if (!zero_stale_data)
+		metablock->mb_flags |= XFS_METADUMP_FULLBLOCKS;
+
+	/* If we'll copy the log, see if the log is dirty */
+	if (mp->m_sb.sb_logstart) {
+		push_cur();
+		set_cur(&typtab[TYP_LOG],
+			XFS_FSB_TO_DADDR(mp, mp->m_sb.sb_logstart),
+			mp->m_sb.sb_logblocks * blkbb, DB_RING_IGN, NULL);
+		if (iocur_top->data) {	/* best effort */
+			struct xlog	log;
+
+			if (xlog_is_dirty(mp, &log, &x, 0))
+				metablock->mb_flags |= XFS_METADUMP_DIRTYLOG;
+		}
+		pop_cur();
+	}
+
 	block_index = (__be64 *)((char *)metablock + sizeof(xfs_metablock_t));
 	block_buffer = (char *)metablock + BBSIZE;
 	num_indices = (BBSIZE - sizeof(xfs_metablock_t)) / sizeof(__be64);
diff --git a/include/xfs_metadump.h b/include/xfs_metadump.h
index f4be51b..dfe804c 100644
--- a/include/xfs_metadump.h
+++ b/include/xfs_metadump.h
@@ -25,8 +25,13 @@ typedef struct xfs_metablock {
 	__be32		mb_magic;
 	__be16		mb_count;
 	__uint8_t	mb_blocklog;
-	__uint8_t	mb_reserved;
+	__uint8_t	mb_flags;
 	/* followed by an array of xfs_daddr_t */
 } xfs_metablock_t;
 
+/* mb_flags */
+#define XFS_METADUMP_OBFUSCATED	(1 << 0)
+#define XFS_METADUMP_FULLBLOCKS	(1 << 1)
+#define XFS_METADUMP_DIRTYLOG	(1 << 2)
+
 #endif /* _XFS_METADUMP_H_ */
diff --git a/man/man8/xfs_mdrestore.8 b/man/man8/xfs_mdrestore.8
index 2095f15..10c00b2 100644
--- a/man/man8/xfs_mdrestore.8
+++ b/man/man8/xfs_mdrestore.8
@@ -4,11 +4,15 @@ xfs_mdrestore \- restores an XFS metadump image to a filesystem image
 .SH SYNOPSIS
 .B xfs_mdrestore
 [
-.B \-g
+.B \-gi
 ]
 .I source
 .I target
 .br
+.B xfs_mdrestore
+.B \-i
+.I source
+.br
 .B xfs_mdrestore \-V
 .SH DESCRIPTION
 .B xfs_mdrestore
@@ -39,6 +43,11 @@ can be destroyed.
 .B \-g
 Shows restore progress on stdout.
 .TP
+.B \-i
+Shows metadump information on stdout.  If no
+.I target
+is specified, exits after displaying information.
+.TP
 .B \-V
 Prints the version number and exits.
 .SH DIAGNOSTICS
diff --git a/mdrestore/xfs_mdrestore.c b/mdrestore/xfs_mdrestore.c
index 0d399f1..1fbb1e6 100644
--- a/mdrestore/xfs_mdrestore.c
+++ b/mdrestore/xfs_mdrestore.c
@@ -21,6 +21,7 @@
 
 char 		*progname;
 int		show_progress = 0;
+int		show_info = 0;
 int		progress_since_warning = 0;
 
 static void
@@ -213,11 +214,14 @@ main(
 
 	progname = basename(argv[0]);
 
-	while ((c = getopt(argc, argv, "gV")) != EOF) {
+	while ((c = getopt(argc, argv, "giV")) != EOF) {
 		switch (c) {
 			case 'g':
 				show_progress = 1;
 				break;
+			case 'i':
+				show_info = 1;
+				break;
 			case 'V':
 				printf("%s version %s\n", progname, VERSION);
 				exit(0);
@@ -226,7 +230,11 @@ main(
 		}
 	}
 
-	if (argc - optind != 2)
+	if (argc - optind < 1 || argc - optind > 2)
+		usage();
+
+	/* show_info without a target is ok */
+	if (!show_info && argc - optind != 2)
 		usage();
 
 	/* open source */
@@ -239,6 +247,29 @@ main(
 		if (src_f == NULL)
 			fatal("cannot open source dump file\n");
 	}
+
+	if (show_info) {
+		xfs_metablock_t		mb;
+
+		if (fread(&mb, sizeof(mb), 1, src_f) != 1)
+			fatal("error reading from file: %s\n", strerror(errno));
+
+		if (be32_to_cpu(mb.mb_magic) != XFS_MD_MAGIC)
+			fatal("specified file is not a metadata dump\n");
+
+		printf("%s: %sobfuscated, %s log, %s metadata blocks\n",
+			argv[optind],
+			mb.mb_flags & XFS_METADUMP_OBFUSCATED ? "" : "not ",
+			mb.mb_flags & XFS_METADUMP_DIRTYLOG ? "dirty" : "clean",
+			mb.mb_flags & XFS_METADUMP_FULLBLOCKS ? "full" : "zeroed");
+
+		if (argc - optind == 1)
+			exit(0);
+
+		/* Go back to the beginning for the restore function */
+		fseek(src_f, 0L, SEEK_SET);
+	}
+
 	optind++;
 
 	/* check and open target */

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