Qu Wenruo
2014-Apr-10 07:30 UTC
[PATCH] btrfs-progs: Force 'btrfs dev scan' not using old libblkid cache
'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@jp.fujitsu.com> Singed-off-by: Qu Wenruo <quwenruo@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; } -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html