On 12.12.19 г. 13:01 ч., damenly.su@xxxxxxxxx wrote:
> From: Su Yue <Damenly_Su@xxxxxxx>
>
> The parameter @metadata_fsid of fs_id() is not NULL while scanned device
> has metadata_uuid but not changing. Obviously, the cases handling part
> in fs_id() is for this situation. Move the logic into new function
> find_fsid_changing_metadata_uuid().
I think the following changelog might sound better.
metadata_fsid parameter of find_fsid is non-null in once specific case
in device_list_add. Factor the code out of find_fsid to a dedicated
function to improve readability.
>
> Signed-off-by: Su Yue <Damenly_Su@xxxxxxx>
> ---
> fs/btrfs/volumes.c | 78 ++++++++++++++++++++++++----------------------
> 1 file changed, 41 insertions(+), 37 deletions(-)
>
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 9efa4123c335..b08b06a89a77 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -438,40 +438,6 @@ static noinline struct btrfs_fs_devices *find_fsid(
>
> ASSERT(fsid);
>
> - if (metadata_fsid) {
> - /*
> - * Handle scanned device having completed its fsid change but
> - * belonging to a fs_devices that was created by first scanning
> - * a device which didn't have its fsid/metadata_uuid changed
> - * at all and the CHANGING_FSID_V2 flag set.
> - */
> - list_for_each_entry(fs_devices, &fs_uuids, fs_list) {
> - if (fs_devices->fsid_change &&
> - memcmp(metadata_fsid, fs_devices->fsid,
> - BTRFS_FSID_SIZE) == 0 &&
> - memcmp(fs_devices->fsid, fs_devices->metadata_uuid,
> - BTRFS_FSID_SIZE) == 0) {
> - return fs_devices;
> - }
> - }
> - /*
> - * Handle scanned device having completed its fsid change but
> - * belonging to a fs_devices that was created by a device that
> - * has an outdated pair of fsid/metadata_uuid and
> - * CHANGING_FSID_V2 flag set.
> - */
> - list_for_each_entry(fs_devices, &fs_uuids, fs_list) {
> - if (fs_devices->fsid_change &&
> - memcmp(fs_devices->metadata_uuid,
> - fs_devices->fsid, BTRFS_FSID_SIZE) != 0 &&
> - memcmp(metadata_fsid, fs_devices->metadata_uuid,
> - BTRFS_FSID_SIZE) == 0) {
> - return fs_devices;
> - }
> - }
> - }
> -
> - /* Handle non-split brain cases */
> list_for_each_entry(fs_devices, &fs_uuids, fs_list) {
> if (metadata_fsid) {
> if (memcmp(fsid, fs_devices->fsid, BTRFS_FSID_SIZE) == 0
> @@ -712,6 +678,46 @@ static struct btrfs_fs_devices *find_fsid_changed(
>
> return NULL;
> }
> +
> +static struct btrfs_fs_devices *find_fsid_changing_metada_uuid(
That function name is long (and contains a typo). More like something like:
find_fsid_with_metadata_uuid.
> + struct btrfs_super_block *disk_super)
> +{
> + struct btrfs_fs_devices *fs_devices;
> +
> + /*
> + * Handle scanned device having completed its fsid change but
> + * belonging to a fs_devices that was created by first scanning
> + * a device which didn't have its fsid/metadata_uuid changed
> + * at all and the CHANGING_FSID_V2 flag set.
> + */
> + list_for_each_entry(fs_devices, &fs_uuids, fs_list) {
> + if (fs_devices->fsid_change &&
> + memcmp(disk_super->metadata_uuid, fs_devices->fsid,
> + BTRFS_FSID_SIZE) == 0 &&
> + memcmp(fs_devices->fsid, fs_devices->metadata_uuid,
> + BTRFS_FSID_SIZE) == 0) {
> + return fs_devices;
> + }
> + }
> + /*
> + * Handle scanned device having completed its fsid change but
> + * belonging to a fs_devices that was created by a device that
> + * has an outdated pair of fsid/metadata_uuid and
> + * CHANGING_FSID_V2 flag set.
> + */
> + list_for_each_entry(fs_devices, &fs_uuids, fs_list) {
> + if (fs_devices->fsid_change &&
> + memcmp(fs_devices->metadata_uuid,
> + fs_devices->fsid, BTRFS_FSID_SIZE) != 0 &&
> + memcmp(disk_super->metadata_uuid, fs_devices->metadata_uuid,
> + BTRFS_FSID_SIZE) == 0) {
> + return fs_devices;
> + }
> + }
> +
> + return find_fsid(disk_super->fsid, disk_super->metadata_uuid);
> +}
> +
> /*
> * Add new device to list of registered devices
> *
> @@ -751,13 +757,11 @@ static noinline struct btrfs_device *device_list_add(const char *path,
> fs_devices = find_fsid_changed(disk_super);
> }
> } else if (has_metadata_uuid) {
> - fs_devices = find_fsid(disk_super->fsid,
> - disk_super->metadata_uuid);
> + fs_devices = find_fsid_changing_metada_uuid(disk_super);
> } else {
> fs_devices = find_fsid(disk_super->fsid, NULL);
> }
>
> -
> if (!fs_devices) {
> if (has_metadata_uuid)
> fs_devices = alloc_fs_devices(disk_super->fsid,
>
