Hi Miao, Anand, (2014/07/03 19:22), Miao Xie wrote: > From: Anand Jain <[email protected]> > > device_list_add() is called when user runs btrfs dev scan, which would add > any btrfs device into the btrfs_fs_devices list.
Reviewed-by: Satoru Takeuchi <[email protected]> Thanks, Satoru > > Now think of a mounted btrfs. And a new device which contains the a SB > from the mounted btrfs devices. > > In this situation when user runs btrfs dev scan, the current code would > just replace existing device with the new device. > > Which is to note that old device is neither closed nor gracefully > removed from the btrfs. > > The FS is still operational with the old bdev however the device name > is the btrfs_device is new which is provided by the btrfs dev scan. > > reproducer: > > devmgt[1] detach /dev/sdc > > replace the missing disk /dev/sdc > > btrfs rep start -f 1 /dev/sde /btrfs > Label: none uuid: 5dc0aaf4-4683-4050-b2d6-5ebe5f5cd120 > Total devices 2 FS bytes used 32.00KiB > devid 1 size 958.94MiB used 115.88MiB path /dev/sde > devid 2 size 958.94MiB used 103.88MiB path /dev/sdd > > make /dev/sdc to reappear > > devmgt attach host2 > > btrfs dev scan > > btrfs fi show -m > Label: none uuid: 5dc0aaf4-4683-4050-b2d6-5ebe5f5cd120^M > Total devices 2 FS bytes used 32.00KiB^M > devid 1 size 958.94MiB used 115.88MiB path /dev/sdc <- Wrong. > devid 2 size 958.94MiB used 103.88MiB path /dev/sdd > > since /dev/sdc has been replaced with /dev/sde, the /dev/sdc shouldn't be > part of the btrfs-fsid when it reappears. If user want it to be part of it > then sys admin should be using btrfs device add instead. > > [1] github.com/anajain/devmgt.git > > Signed-off-by: Anand Jain <[email protected]> > Signed-off-by: Wang Shilong <[email protected]> > Signed-off-by: Miao Xie <[email protected]> > --- > Changelog v3->v4: > - Fix the over-80-charactor problem > --- > fs/btrfs/volumes.c | 27 +++++++++++++++++++++++++++ > 1 file changed, 27 insertions(+) > > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c > index a9c11a0..16e71a1 100644 > --- a/fs/btrfs/volumes.c > +++ b/fs/btrfs/volumes.c > @@ -508,6 +508,33 @@ 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)) { > + /* > + * When FS is already mounted. > + * 1. If you are here and if the device->name is NULL that > + * means this device was missing at time of FS mount. > + * 2. If you are here and if the device->name is different > + * from 'path' that means either > + * a. The same device disappeared and reappeared with > + * different name. or > + * b. The missing-disk-which-was-replaced, has > + * reappeared now. > + * > + * We must allow 1 and 2a above. But 2b would be a spurious > + * and unintentional. > + * > + * Further in case of 1 and 2a above, the disk at 'path' > + * would have missed some transaction when it was away and > + * in case of 2a the stale bdev has to be updated as well. > + * 2b must not be allowed at all time. > + */ > + > + /* > + * As of now don't allow update to btrfs_fs_device through > + * the btrfs dev scan cli, after FS has been mounted. > + */ > + if (fs_devices->opened) > + return -EBUSY; > + > name = rcu_string_strdup(path, GFP_NOFS); > if (!name) > return -ENOMEM; > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
