[PATCH V3 12/23] xfs_db: Add support to read from external log device

[Chandan Babu R <chandan.babu@xxxxxxxxxx>]

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.

Signed-off-by: Chandan Babu R <chandan.babu@xxxxxxxxxx>
---
 db/io.c | 56 +++++++++++++++++++++++++++++++++++++++++++-------------
 db/io.h |  2 ++
 2 files changed, 45 insertions(+), 13 deletions(-)

diff --git a/db/io.c b/db/io.c
index 3d257236..5ccfe3b5 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;
 	}
@@ -589,6 +590,35 @@ set_cur(
 		ring_add();
 }
 
+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 c29a7488..bd86c31f 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);
-- 
2.39.1