After dev replace, we should not select the superblock of the
replaced dev. Otherwise, all the superblokcs will be overwritten
by this invalid superblock.
To prevent this case, let btrfs-select-super check the first
superblock on the selected dev. If the magic doesn't match,
then the dev is a replaced dev and error message will show up.
Signed-off-by: Gui Hecheng <guihc.fnst@xxxxxxxxxxxxxx>
---
btrfs-select-super.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/btrfs-select-super.c b/btrfs-select-super.c
index d7cd187..cba3414 100644
--- a/btrfs-select-super.c
+++ b/btrfs-select-super.c
@@ -45,6 +45,9 @@ int main(int ac, char **av)
int ret;
u64 num = 0;
u64 bytenr = 0;
+ int fd;
+ u8 buf[BTRFS_SUPER_INFO_SIZE];
+ struct btrfs_super_block *sb = (struct btrfs_super_block *)buf;
while(1) {
int c;
@@ -86,6 +89,26 @@ int main(int ac, char **av)
return -EBUSY;
}
+ /*
+ * After dev replace, the first super block of replaced dev will be cleared,
+ * don't select that dev.
+ */
+ fd = open(av[optind], O_RDONLY, 0666);
+ if (fd < 0)
+ return -errno;
+
+ ret = pread64(fd, buf, sizeof(buf), BTRFS_SUPER_INFO_OFFSET);
+ if (ret < sizeof(buf)) {
+ close(fd);
+ return -errno;
+ }
+
+ if (sb->magic != cpu_to_le64(BTRFS_MAGIC)) {
+ fprintf(stderr, "Cannot select an invalid super block.\n");
+ close(fd);
+ return 1;
+ }
+
root = open_ctree(av[optind], bytenr, 1);
if (!root) {
--
1.8.1.4
--
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