btrfs: add extra error messages to cover non-ENOMEM errors from device_add_list()
[BUG]
When test case btrfs/219 (aka, mount a registered device but with a lower
generation) failed, there is not any useful information for the end user
to find out what's going wrong.
The mount failure just looks like this:
# mount -o loop /tmp/219.img2 /mnt/btrfs/
mount: /mnt/btrfs: mount(2) system call failed: File exists.
dmesg(1) may have more information after failed mount system call.
While the dmesg contains nothing but the loop device change:
loop1: detected capacity change from 0 to 524288
[CAUSE]
In device_list_add() we have a lot of extra checks to reject invalid
cases.
That function also contains the regular device scan result like the
following prompt:
BTRFS: device fsid 6222333e-f9f1-47e6-b306-55ddd4dcaef4 devid 1 transid 8 /dev/loop0 scanned by systemd-udevd (3027)
But unfortunately not all errors have their own error messages, thus if
we hit something wrong in device_add_list(), there may be no error
messages at all.
[FIX]
Add errors message for all non-ENOMEM errors.
For ENOMEM, I'd say we're in a much worse situation, and there should be
some OOM messages way before our call sites.
CC: stable@vger.kernel.org # 6.0+
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index aa25fa3..bf0deca 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -768,8 +768,11 @@ static noinline struct btrfs_device *device_list_add(const char *path,
BTRFS_SUPER_FLAG_CHANGING_FSID_V2);
error = lookup_bdev(path, &path_devt);
- if (error)
+ if (error) {
+ btrfs_err(NULL, "failed to lookup block device for path %s: %d",
+ path, error);
return ERR_PTR(error);
+ }
if (fsid_change_in_progress) {
if (!has_metadata_uuid)
@@ -836,6 +839,9 @@ static noinline struct btrfs_device *device_list_add(const char *path,
unsigned int nofs_flag;
if (fs_devices->opened) {
+ btrfs_err(NULL,
+ "device %s belongs to fsid %pU, and the fs is already mounted",
+ path, fs_devices->fsid);
mutex_unlock(&fs_devices->device_list_mutex);
return ERR_PTR(-EBUSY);
}
@@ -905,6 +911,9 @@ static noinline struct btrfs_device *device_list_add(const char *path,
* generation are equal.
*/
mutex_unlock(&fs_devices->device_list_mutex);
+ btrfs_err(NULL,
+"device %s already registered with a higher generation, found %llu expect %llu",
+ path, found_transid, device->generation);
return ERR_PTR(-EEXIST);
}
