[PATCH V2 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 | 57 ++++++++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 44 insertions(+), 13 deletions(-)

diff --git a/db/io.c b/db/io.c
index 3d257236..a6feaba3 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 +590,36 @@ 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)
+{
+	struct xfs_buftarg	*btargp = mp->m_ddev_targp;
+
+	if (mp->m_logdev_targp->bt_bdev != mp->m_ddev_targp->bt_bdev) {
+		ASSERT(mp->m_sb.sb_logstart == 0);
+		btargp = mp->m_logdev_targp;
+	}
+
+	__set_cur(btargp, type, blknum, len, ring_flag, bbmap);
+}
+
+
 void
 set_iocur_type(
 	const typ_t	*type)
-- 
2.39.1