| Message ID | 1408158488-4316-2-git-send-email-anand.jain@oracle.com (mailing list archive) |
|---|---|
| State | Under Review |
| Headers | show |
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index da73ab3..05dd88b 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2725,7 +2725,7 @@ static long btrfs_ioctl_fs_info(struct btrfs_root *root, void __user *arg) return -ENOMEM; mutex_lock(&fs_devices->device_list_mutex); - fi_args->num_devices = fs_devices->num_devices; + fi_args->num_devices = fs_devices->total_devices; memcpy(&fi_args->fsid, root->fs_info->fsid, sizeof(fi_args->fsid)); list_for_each_entry_safe(device, next, &fs_devices->devices, dev_list) {
ioctl BTRFS_IOC_FS_INFO return num_devices which does _not_ include seed device, But the following ioctl BTRFS_IOC_DEV_INFO counts and gets seed disk when probed. So in the userland we hit a count-slot missmatch bug.. get_fs_info() :: BUG_ON(ndevs >= fi_args->num_devices); which hits this bug when we have mounted a seed device. So to fix this problem here in this patch ioctl BTRFS_IOC_FS_INFO will provide total_devices instead of num_devices. This would fix the problem partly. Partly because ealier num_devices included the replacing device but now total_device does not include the replacing device. Getting a count which includes a transient device is rather too in efficient/wrong indeed, because there can be a race condition where in the time between ioctl BTRFS_IOC_FS_INFO to BTRFS_IOC_DEV_INFO the replace device operation might have been completed. So to fix this problem its better that user land btrfs-progs probes replacing device (at devid 0) separately. v2: Agree with Wang's comment. Its better to show seed disks under the sprout fs, so that user can establish mapping of seed to sprout devices. So here I am making BTRFS_IOC_FS_INFO to return the total_devices which would count the seed devices (but not the replacing device). A btrfs-progs patch will separately probe for devid 0 (which is a replacing transient device when present). v1: This patch will make BTRFS_IOC_DEV_INFO ioctl to provide disks only of the FSID being probed (seed disks are under different FSID). which means when seed is still not deleted from the sprout the btrfs filesystem show command will show disks them under their respective FSIDs Signed-off-by: Anand Jain <anand.jain@oracle.com> --- fs/btrfs/ioctl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)