On 01/03/2019 12:00 AM, David Sterba wrote:
On Wed, Jan 02, 2019 at 01:49:31PM +0800, Anand Jain wrote:
Support for a new command 'btrfs dev forget [dev]' is proposed here
to undo the effects of 'btrfs dev scan [dev]'. For this purpose
this patch proposes to use ioctl #5 as it was empty.
IOW(BTRFS_IOCTL_MAGIC, 5, ..)
This patch adds new ioctl BTRFS_IOC_FORGET_DEV which can be sent from
the /dev/btrfs-control to forget one or all devices, (devices which are
not mounted) from the btrfs kernel.
The argument it takes is struct btrfs_ioctl_vol_args, and ::name can be
set to specify the device path. And all unmounted devices can be removed
from the kernel if no device path is provided.
Again, the devices are removed only if the relevant fsid aren't mounted.
This new cli can provide..
. Release of unwanted btrfs_fs_devices and btrfs_devices memory if the
device is not going to be mounted.
. Ability to mount the device in degraded mode when one of the other
device is corrupted like in split brain raid1.
. Running test cases which requires btrfs.ko-reload if the rootfs
is btrfs.
Signed-off-by: Anand Jain <anand.j...@oracle.com>
Reviewed-by: Nikolay Borisov <nbori...@suse.com>
---
v11->v12: fix coding style add spacing before after ":".
v1->v11: Pls ref to the cover-letter. (sorry about that).
fs/btrfs/super.c | 3 +++
fs/btrfs/volumes.c | 9 +++++++++
fs/btrfs/volumes.h | 1 +
include/uapi/linux/btrfs.h | 2 ++
4 files changed, 15 insertions(+)
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index d3c6bbc0aa3a..eba2966913ae 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -2247,6 +2247,9 @@ static long btrfs_control_ioctl(struct file *file,
unsigned int cmd,
ret = PTR_ERR_OR_ZERO(device);
mutex_unlock(&uuid_mutex);
break;
+ case BTRFS_IOC_FORGET_DEV:
+ ret = btrfs_forget_devices(vol->name);
+ break;
case BTRFS_IOC_DEVICES_READY:
mutex_lock(&uuid_mutex);
device = btrfs_scan_one_device(vol->name, FMODE_READ,
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 8e36cbb355df..48415a9edd46 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1397,6 +1397,15 @@ static int btrfs_read_disk_super(struct block_device
*bdev, u64 bytenr,
return 0;
}
+int btrfs_forget_devices(const char *path)
+{
+ mutex_lock(&uuid_mutex);
+ btrfs_free_stale_devices(strlen(path) ? path : NULL, NULL);
+ mutex_unlock(&uuid_mutex);
+
+ return 0;
I think this should reflect the status of the operation. The ioctl
caller has no information about success/error. Eg. an invalid device
path passed could return -ENOENT, 0 if it was released and 1 if not.
In case of all devices, it's probably ok to return 0.
OK. v13 will return error if the given device is not found,
and I find ENXIO is more suitable (instead of ENOENT).
If you disagree pls can you make the changes as in [1]
when integrating. I have tested with both.
--------
[1]
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 2ab42bfe5d3c..e04784c64a98 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -763,7 +763,7 @@ static int btrfs_free_stale_devices(const char *path,
int ret;
if (path)
- ret = -ENXIO;
+ ret = -ENOENT;
else
ret = 0;
----------------
Thanks, Anand
