xfs_db: Add support to read from external log device

This commit introduces a new function set_log_cur() allowing xfs_db to read
from an external log device. This is required by a future commit which will
add the ability to dump metadata from external log devices.

Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandan.babu@oracle.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

5 files changed, 131 insertions, 25 deletions

diff --git a/db/io.c b/db/io.c
index 3d2572364d..5ccfe3b536 100644
--- a/db/io.c
+++ b/db/io.c
@@ -508,18 +508,19 @@ write_cur(void)
 
 }
 
-void
-set_cur(
-	const typ_t	*type,
-	xfs_daddr_t	blknum,
-	int		len,
-	int		ring_flag,
-	bbmap_t		*bbmap)
+static void
+__set_cur(
+	struct xfs_buftarg	*btargp,
+	const typ_t		*type,
+	xfs_daddr_t		 blknum,
+	int			 len,
+	int			 ring_flag,
+	bbmap_t			*bbmap)
 {
-	struct xfs_buf	*bp;
-	xfs_ino_t	dirino;
-	xfs_ino_t	ino;
-	uint16_t	mode;
+	struct xfs_buf		*bp;
+	xfs_ino_t		dirino;
+	xfs_ino_t		ino;
+	uint16_t		mode;
 	const struct xfs_buf_ops *ops = type ? type->bops : NULL;
 	int		error;
 
@@ -548,11 +549,11 @@ set_cur(
 		if (!iocur_top->bbmap)
 			return;
 		memcpy(iocur_top->bbmap, bbmap, sizeof(struct bbmap));
-		error = -libxfs_buf_read_map(mp->m_ddev_targp, bbmap->b,
+		error = -libxfs_buf_read_map(btargp, bbmap->b,
 				bbmap->nmaps, LIBXFS_READBUF_SALVAGE, &bp,
 				ops);
 	} else {
-		error = -libxfs_buf_read(mp->m_ddev_targp, blknum, len,
+		error = -libxfs_buf_read(btargp, blknum, len,
 				LIBXFS_READBUF_SALVAGE, &bp, ops);
 		iocur_top->bbmap = NULL;
 	}
@@ -590,6 +591,35 @@ set_cur(
 }
 
 void
+set_cur(
+	const typ_t	*type,
+	xfs_daddr_t	blknum,
+	int		len,
+	int		ring_flag,
+	bbmap_t		*bbmap)
+{
+	__set_cur(mp->m_ddev_targp, type, blknum, len, ring_flag, bbmap);
+}
+
+void
+set_log_cur(
+	const typ_t	*type,
+	xfs_daddr_t	blknum,
+	int		len,
+	int		ring_flag,
+	bbmap_t		*bbmap)
+{
+	if (mp->m_logdev_targp->bt_bdev == mp->m_ddev_targp->bt_bdev) {
+		fprintf(stderr, "no external log specified\n");
+		exitcode = 1;
+		return;
+	}
+
+	__set_cur(mp->m_logdev_targp, type, blknum, len, ring_flag, bbmap);
+}
+
+
+void
 set_iocur_type(
 	const typ_t	*type)
 {
diff --git a/db/io.h b/db/io.h
index c29a748819..bd86c31f67 100644
--- a/db/io.h
+++ b/db/io.h
@@ -49,6 +49,8 @@ extern void	push_cur_and_set_type(void);
 extern void	write_cur(void);
 extern void	set_cur(const struct typ *type, xfs_daddr_t blknum,
 			int len, int ring_add, bbmap_t *bbmap);
+extern void	set_log_cur(const struct typ *type, xfs_daddr_t blknum,
+			int len, int ring_add, bbmap_t *bbmap);
 extern void     ring_add(void);
 extern void	set_iocur_type(const struct typ *type);
 extern void	xfs_dummy_verify(struct xfs_buf *bp);
diff --git a/db/metadump.c b/db/metadump.c
index 81023cf178..f9c82148e7 100644
--- a/db/metadump.c
+++ b/db/metadump.c
@@ -38,7 +38,7 @@ static void	metadump_help(void);
 
 static const cmdinfo_t	metadump_cmd =
 	{ "metadump", NULL, metadump_f, 0, -1, 0,
-		N_("[-a] [-e] [-g] [-m max_extent] [-w] [-o] filename"),
+		N_("[-a] [-e] [-g] [-m max_extent] [-w] [-o] [-v 1|2] filename"),
 		N_("dump metadata to a file"), metadump_help };
 
 struct metadump_ops {
@@ -75,6 +75,7 @@ static struct metadump {
 	bool			zero_stale_data;
 	bool			progress_since_warning;
 	bool			dirty_log;
+	bool			external_log;
 	bool			stdout_metadump;
 	xfs_ino_t		cur_ino;
 	/* Metadump file */
@@ -108,6 +109,7 @@ metadump_help(void)
 "   -g -- Display dump progress\n"
 "   -m -- Specify max extent size in blocks to copy (default = %d blocks)\n"
 "   -o -- Don't obfuscate names and extended attributes\n"
+"   -v -- Metadump version to be used\n"
 "   -w -- Show warnings of bad metadata information\n"
 "\n"), DEFAULT_MAX_EXT_SIZE);
 }
@@ -2589,8 +2591,20 @@ copy_log(void)
 		print_progress("Copying log");
 
 	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 (metadump.external_log) {
+		ASSERT(mp->m_sb.sb_logstart == 0);
+		set_log_cur(&typtab[TYP_LOG],
+				XFS_FSB_TO_DADDR(mp, mp->m_sb.sb_logstart),
+				mp->m_sb.sb_logblocks * blkbb, DB_RING_IGN,
+				NULL);
+	} else {
+		ASSERT(mp->m_sb.sb_logstart != 0);
+		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 == NULL) {
 		pop_cur();
 		print_warning("cannot read log");
@@ -2751,6 +2765,8 @@ init_metadump_v2(void)
 		compat_flags |= XFS_MD2_COMPAT_FULLBLOCKS;
 	if (metadump.dirty_log)
 		compat_flags |= XFS_MD2_COMPAT_DIRTYLOG;
+	if (metadump.external_log)
+		compat_flags |= XFS_MD2_COMPAT_EXTERNALLOG;
 
 	xmh.xmh_compat_flags = cpu_to_be32(compat_flags);
 
@@ -2811,6 +2827,7 @@ metadump_f(
 	int		outfd = -1;
 	int		ret;
 	char		*p;
+	bool		version_opt_set = false;
 
 	exitcode = 1;
 
@@ -2822,6 +2839,7 @@ metadump_f(
 	metadump.obfuscate = true;
 	metadump.zero_stale_data = true;
 	metadump.dirty_log = false;
+	metadump.external_log = false;
 
 	if (mp->m_sb.sb_magicnum != XFS_SB_MAGIC) {
 		print_warning("bad superblock magic number %x, giving up",
@@ -2839,7 +2857,7 @@ metadump_f(
 		return 0;
 	}
 
-	while ((c = getopt(argc, argv, "aegm:ow")) != EOF) {
+	while ((c = getopt(argc, argv, "aegm:ov:w")) != EOF) {
 		switch (c) {
 			case 'a':
 				metadump.zero_stale_data = false;
@@ -2863,6 +2881,17 @@ metadump_f(
 			case 'o':
 				metadump.obfuscate = false;
 				break;
+			case 'v':
+				metadump.version = (int)strtol(optarg, &p, 0);
+				if (*p != '\0' ||
+				    (metadump.version != 1 &&
+						metadump.version != 2)) {
+					print_warning("bad metadump version: %s",
+						optarg);
+					return 0;
+				}
+				version_opt_set = true;
+				break;
 			case 'w':
 				metadump.show_warnings = true;
 				break;
@@ -2877,12 +2906,42 @@ metadump_f(
 		return 0;
 	}
 
-	/* If we'll copy the log, see if the log is dirty */
-	if (mp->m_sb.sb_logstart) {
+	if (mp->m_logdev_targp->bt_bdev != mp->m_ddev_targp->bt_bdev)
+		metadump.external_log = true;
+
+	if (metadump.external_log && !version_opt_set)
+		metadump.version = 2;
+
+	if (metadump.version == 2 && mp->m_sb.sb_logstart == 0 &&
+	    !metadump.external_log) {
+		print_warning("external log device not loaded, use -l");
+		return 1;
+	}
+
+	/*
+	 * If we'll copy the log, see if the log is dirty.
+	 *
+	 * Metadump v1 does not support dumping the contents of an external
+	 * log. Hence we skip the dirty log check.
+	 */
+	if (!(metadump.version == 1 && metadump.external_log)) {
 		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 (metadump.external_log) {
+			ASSERT(mp->m_sb.sb_logstart == 0);
+			set_log_cur(&typtab[TYP_LOG],
+					XFS_FSB_TO_DADDR(mp,
+							mp->m_sb.sb_logstart),
+					mp->m_sb.sb_logblocks * blkbb,
+					DB_RING_IGN, NULL);
+		} else {
+			ASSERT(mp->m_sb.sb_logstart != 0);
+			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;
 
@@ -2958,8 +3017,8 @@ metadump_f(
 	if (!exitcode)
 		exitcode = !copy_sb_inodes();
 
-	/* copy log if it's internal */
-	if ((mp->m_sb.sb_logstart != 0) && !exitcode)
+	/* copy log */
+	if (!exitcode && !(metadump.version == 1 && metadump.external_log))
 		exitcode = !copy_log();
 
 	/* write the remaining index */
diff --git a/db/xfs_metadump.sh b/db/xfs_metadump.sh
index 9852a5bc2b..9e8f86e53e 100755
--- a/db/xfs_metadump.sh
+++ b/db/xfs_metadump.sh
@@ -8,7 +8,7 @@ OPTS=" "
 DBOPTS=" "
 USAGE="Usage: xfs_metadump [-aefFogwV] [-m max_extents] [-l logdev] source target"
 
-while getopts "aefgl:m:owFV" c
+while getopts "aefgl:m:owFv:V" c
 do
 	case $c in
 	a)	OPTS=$OPTS"-a ";;
@@ -20,6 +20,7 @@ do
 	f)	DBOPTS=$DBOPTS" -f";;
 	l)	DBOPTS=$DBOPTS" -l "$OPTARG" ";;
 	F)	DBOPTS=$DBOPTS" -F";;
+	v)	OPTS=$OPTS"-v "$OPTARG" ";;
 	V)	xfs_db -p xfs_metadump -V
 		status=$?
 		exit $status
diff --git a/man/man8/xfs_metadump.8 b/man/man8/xfs_metadump.8
index c0e79d7799..1732012cd0 100644
--- a/man/man8/xfs_metadump.8
+++ b/man/man8/xfs_metadump.8
@@ -11,6 +11,9 @@ xfs_metadump \- copy XFS filesystem metadata to a file
 ] [
 .B \-l
 .I logdev
+] [
+.B \-v
+.I version
 ]
 .I source
 .I target
@@ -74,6 +77,12 @@ metadata such as filenames is not considered sensitive.  If obfuscation
 is required on a metadump with a dirty log, please inform the recipient
 of the metadump image about this situation.
 .PP
+The contents of an external log device can be dumped only when using the v2
+format.
+Metadump in v2 format can be generated by passing the "-v 2" option.
+Metadump in v2 format is generated by default if the filesystem has an
+external log and the metadump version to use is not explicitly mentioned.
+.PP
 .B xfs_metadump
 should not be used for any purposes other than for debugging and reporting
 filesystem problems. The most common usage scenario for this tool is when
@@ -134,6 +143,11 @@ this value.  The default size is 2097151 blocks.
 .B \-o
 Disables obfuscation of file names and extended attributes.
 .TP
+.B \-v
+The format of the metadump file to be produced.
+Valid values are 1 and 2.
+The default metadump format is 1.
+.TP
 .B \-w
 Prints warnings of inconsistent metadata encountered to stderr. Bad metadata
 is still copied.