(I am unable to reproduce the issue, tried to go back with progs versions
but still the same. So as of now this code remains untested, suggest to
wait till we have a reproducible test case).
Here is a test case which says it all..
mkfs.xfs -f $DEV
mkfs.btrfs -f $DEV
mount $DEV $MNT
mount: /dev/vdiskc: more filesystems detected. This should not happen,
use -t <type> to explicitly specify the filesystem type or
use wipefs(8) to clean up the device.
mount: you must specify the filesystem type
with this patch btrfs_prepare_device() also wipes old FS if any,
btrfs_prepare_device() is called after we have verified that
user has provided -f option.
v2: to satisfy the backward compatibility issue, replace
blkid_do_wipe() with local wipe function.
Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxx>
---
utils.c | 38 ++++++++++++++++++++++++++++++++++++++
1 file changed, 38 insertions(+)
diff --git a/utils.c b/utils.c
index fb78dd6..5f21737 100644
--- a/utils.c
+++ b/utils.c
@@ -680,6 +680,42 @@ int btrfs_add_to_fsid(struct btrfs_trans_handle *trans,
return 0;
}
+static void btrfs_wipe_existing_sb(int fd)
+{
+ const char *off = NULL;
+ size_t len = 0;
+ loff_t offset;
+ char buf[BUFSIZ];
+ int rc = 0;
+ blkid_probe pr = NULL;
+
+ pr = blkid_new_probe();
+ if (!pr)
+ return;
+
+ if (blkid_probe_set_device(pr, fd, 0, 0))
+ goto out;
+
+ rc = blkid_probe_lookup_value(pr, "SBMAGIC_OFFSET", &off, NULL);
+ if (!rc)
+ rc = blkid_probe_lookup_value(pr, "SBMAGIC", NULL, &len);
+
+ if (rc || len == 0 || off == NULL)
+ goto out;
+
+ offset = strtoll(off, NULL, 10);
+ if (len > sizeof(buf))
+ len = sizeof(buf);
+
+ memset(buf, 0, len);
+ rc = pwrite(fd, buf, len, offset);
+ fsync(fd);
+
+out:
+ blkid_free_probe(pr);
+ return;
+}
+
int btrfs_prepare_device(int fd, char *file, int zero_end, u64 *block_count_ret,
u64 max_block_count, int *mixed, int discard)
{
@@ -731,6 +767,8 @@ int btrfs_prepare_device(int fd, char *file, int zero_end, u64 *block_count_ret,
return 1;
}
+ btrfs_wipe_existing_sb(fd);
+
*block_count_ret = block_count;
return 0;
}
--
2.0.0.153.g79dcccc
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