On 04/10/2014 03:30 PM, Qu Wenruo wrote:
'btrfs scan' uses libblkid to scan devices by default, and libblkid uses
cache to reduce the probe.
But if operations below is done in less than 2 seconds(BLKID_PROBE_MIN),
'btrfs scan' will still use the uncorrect cache and scan on the deleted device.
Great thanks for looking into this.
Anand
0. /dev/sda[1-4] mounted on /mnt using single data/metadata
1. btrfs dev scan
2. btrfs dev del /dev/sda3 /mnt
3. btrfs dev scan
Since the cache made by step 1 is still validated, step 3 will use the
cache and consider /dev/sda3 as a btrfs filesystem and try to scan it.
But the superblock(at least the first one) is wiped and failed to scan,
a error message, which can be avoided and is unneeded, is output.
This patch will force scan_for_btrfs() not to use cache to avoid the
problem.
Reported-by: Tsutomu Itoh <t-i...@jp.fujitsu.com>
Singed-off-by: Qu Wenruo <quwen...@cn.fujitsu.com>
---
utils.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/utils.c b/utils.c
index 0bfb9d9..1cd1d28 100644
--- a/utils.c
+++ b/utils.c
@@ -2057,7 +2057,8 @@ int btrfs_scan_lblkid(int update_kernel)
blkid_cache cache = NULL;
char path[PATH_MAX];
- if (blkid_get_cache(&cache, 0) < 0) {
+ /* No to use libblkid cache to avoid old data */
+ if (blkid_get_cache(&cache, "/dev/null") < 0) {
printf("ERROR: lblkid cache get failed\n");
return 1;
}
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