diff options
Diffstat (limited to 'utils.c')
| -rw-r--r-- | utils.c | 38 |
1 files changed, 38 insertions, 0 deletions
@@ -678,6 +678,42 @@ 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) { @@ -729,6 +765,8 @@ 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; } |