'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. 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-itoh@xxxxxxxxxxxxxx> Singed-off-by: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx> --- 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; } -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html