Qu, Kindly note, device->generation is not updated when user scan the device for the first time. I have sent out patch: [PATCH 2/2] btrfs: check generation as replace duplicates devid+uuid Please feel free to add your Signed-off-by, if you think so. review comments are appreciated as usual. Thanks, Anand On 10/06/2014 16:53, Qu Wenruo wrote:
Since btrfs currently use dulicated dev uuid when doing device replace, the following problem will happen: 1) mount with device A missing using degraded mode. 2) replace device A with device B. 3) device A reappears. 4) umount btrfs fs. 5) mount btrfs fs. After step 5), btrfs will still use device A even device B has a larger generation. The patch will judge generation when difference device with same dev uuid. And the patch should be applied after Anand's patch: https://patchwork.kernel.org/patch/4309651/ Cc: Anand Jain <Anand.Jain@xxxxxxxxxx> Signed-off-by: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx> --- fs/btrfs/volumes.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 0a5017a..07f0cf7 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -508,7 +508,8 @@ static noinline int device_list_add(const char *path, ret = 1; device->fs_devices = fs_devices; - } else if (!device->name || strcmp(device->name->str, path)) { + } else if (!device->name || (strcmp(device->name->str, path) && + found_transid > device->generation)) { /* * When FS is already mounted. * 1. If you are here and if the device->name is NULL that means
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