[PATCH] xfs_db: new -FF option help to continue the command without verify

[Zorro Lang <zlang@redhat.com>]

When I try to do below steps(a V5 xfs on $fsile):

  # xfs_db -x -c "sb 0" -c "write features_ro_compat 4096" $fsfile
  # xfs_db -x -c "sb 0" -c "write features_ro_compat 0" $fsfile
  # xfs_db -c "sb 0" -c p $fsfile

The step#2 and #3 all failed, as:

  Superblock has unknown read-only compatible features (0x1000) enable

When the "sb" command try to verify the superblock, it find a bad
features_ro_compat number then end the xfs_db process.

Even"-F" option can't help more. So we need a "super force" mode
which can ignore all "verify" failures, continue the command running.

Signed-off-by: Zorro Lang <zlang@redhat.com>
---

Hi,

I don't know if my patch is good or not, but I think the "--forceforce"
option is needed for xfs_db. As above example:

  # xfs_db -x -c "sb 0" -c "write features_ro_compat 4096" $fsfile
  # xfs_db -x -c "sb 0" -c "write features_ro_compat 0" $fsfile
  # xfs_db -c "sb 0" -c p $fsfile

If we break the superblock, at least xfs_db should help to print the
superblock info. And as a xfs debugger, xfs_db should can ignore
unexpected errors to continue the "expert" command which an expert
want to do.

That's my personal opinion, so if I'm wrong, feel free to correct me:)

Thanks,
Zorro

 db/init.c         |  6 +++++-
 db/io.c           | 21 ++++++++++++++++++++-
 db/io.h           |  2 ++
 man/man8/xfs_db.8 |  4 ++++
 4 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/db/init.c b/db/init.c
index c0472c8..690e6ea 100644
--- a/db/init.c
+++ b/db/init.c
@@ -29,6 +29,7 @@
 #include "malloc.h"
 #include "type.h"
 
+int			xfs_skip_verify = 0;
 static char		**cmdline;
 static int		ncmdline;
 char			*fsdevice;
@@ -75,7 +76,7 @@ init(
 			x.disfile = 1;
 			break;
 		case 'F':
-			force = 1;
+			force++;
 			break;
 		case 'i':
 			x.isreadonly = (LIBXFS_ISREADONLY|LIBXFS_ISINACTIVE);
@@ -105,6 +106,9 @@ init(
 		/*NOTREACHED*/
 	}
 
+	if (force > 1)
+		xfs_skip_verify = 1;
+
 	fsdevice = argv[optind];
 	if (!x.disfile)
 		x.volname = fsdevice;
diff --git a/db/io.c b/db/io.c
index 91cab12..897388d 100644
--- a/db/io.c
+++ b/db/io.c
@@ -41,6 +41,16 @@ static void     back_help(void);
 static int      ring_f(int argc, char **argv);
 static void     ring_help(void);
 
+/*
+ * If xfs_skip_verify is true, use this dummy xfs_buf_ops structure
+ * to instead of the real xfs_buf_ops in set_cur()
+ */
+static const struct xfs_buf_ops xfs_dummy_buf_ops = {
+        .name = "dummy",
+        .verify_read = xfs_dummy_verify,
+        .verify_write = xfs_dummy_verify,
+};
+
 static const cmdinfo_t	pop_cmd =
 	{ "pop", NULL, pop_f, 0, 0, 0, NULL,
 	  N_("pop location from the stack"), pop_help };
@@ -503,7 +513,16 @@ set_cur(
 	xfs_ino_t	dirino;
 	xfs_ino_t	ino;
 	__uint16_t	mode;
-	const struct xfs_buf_ops *ops = t ? t->bops : NULL;
+	const struct xfs_buf_ops *ops = NULL;
+
+	if (t) {
+		if (xfs_skip_verify) {
+			ops = &xfs_dummy_buf_ops;
+		} else {
+			ops = t->bops;
+		}
+	} else
+		ops = NULL;
 
 	if (iocur_sp < 0) {
 		dbprintf(_("set_cur no stack element to set\n"));
diff --git a/db/io.h b/db/io.h
index c69e9ce..eb64638 100644
--- a/db/io.h
+++ b/db/io.h
@@ -16,6 +16,8 @@
  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
+extern int xfs_skip_verify;
+
 struct typ;
 
 #define	BBMAP_SIZE		(XFS_MAX_BLOCKSIZE / BBSIZE)
diff --git a/man/man8/xfs_db.8 b/man/man8/xfs_db.8
index ff8f862..c52a5bf 100644
--- a/man/man8/xfs_db.8
+++ b/man/man8/xfs_db.8
@@ -57,6 +57,10 @@ Specifies that we want to continue even if the superblock magic is not
 correct.  For use in
 .BR xfs_metadump .
 .TP
+.B \-FF
+The "force force" mode. Skip all read/write verify to continue the command,
+even if it'll cause something be broken.
+.TP
 .B \-i
 Allows execution on a mounted filesystem, provided it is mounted read-only.
 Useful for shell scripts
-- 
2.7.4

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