On Sun, May 24, 2015 at 11:01:56PM +0800, Kinglong Mee wrote: > If there are some mount points(not exported for nfs) under pseudo root, > after client's operation of those entry under the root, anyone *can't* > unmount those mount points until export cache expired. Thanks for the update, apologies for the delayed response. > > # cat /etc/exports > /nfs/xfs *(rw,insecure,no_subtree_check,no_root_squash) > /nfs/pnfs *(rw,insecure,no_subtree_check,no_root_squash) > # ll /nfs/ > total 0 > drwxr-xr-x. 3 root root 84 Apr 21 22:27 pnfs > drwxr-xr-x. 3 root root 84 Apr 21 22:27 test > drwxr-xr-x. 2 root root 6 Apr 20 22:01 xfs > # mount /dev/sde /nfs/test > # df > Filesystem 1K-blocks Used Available Use% Mounted on > ...... > /dev/sdd 1038336 32944 1005392 4% /nfs/pnfs > /dev/sdc 10475520 32928 10442592 1% /nfs/xfs > /dev/sde 999320 1284 929224 1% /nfs/test > # mount -t nfs 127.0.0.1:/nfs/ /mnt > # ll /mnt/*/ > /mnt/pnfs/: > total 0 > -rw-r--r--. 1 root root 0 Apr 21 22:23 attr > drwxr-xr-x. 2 root root 6 Apr 21 22:19 tmp > > /mnt/xfs/: > total 0 > # umount /nfs/test/ > umount: /nfs/test/: target is busy > (In some cases useful info about processes that > use the device is found by lsof(8) or fuser(1).) > > I don't think that's user expect, they want umount /nfs/test/. > > It's caused by exports cache of nfsd holds the reference of > the path (here is /nfs/test/), so, it can't be umounted. > > v1 --> v2, > 1. Adds an option named "allow_umount" for exports allowing user > un-mounting the filesystem where nfsd exports base on. I don't think allow_umount is a useful option. I'd rather just make the code behave like allow_umount was on all the time. The fact is nobody could ever *depend* on umount to fail on an exported filesystem anyway. I do think we might want a stronger "allow_umount" option that actually revokes locks and such as necessary. I just don't see the need for this in between case. --b. > 2. New helpers path_get_pin/path_put_unpin for path pin. > 3. Update exports according to the "allow_umount" option. > > Kinglong Mee (5): > fs_pin: Fix uninitialized value in fs_pin > fs_pin: Export functions for specific filesystem > path: New helpers path_get_pin/path_put_unpin for path pin > sunrpc: New helper cache_force_expire for cache cleanup > nfsd: Allows user un-mounting filesystem where nfsd exports base on > > fs/fs_pin.c | 3 +++ > fs/namei.c | 26 ++++++++++++++++++++ > fs/nfsd/export.c | 52 ++++++++++++++++++++++++++++++++-------- > fs/nfsd/export.h | 11 ++++++++- > include/linux/fs_pin.h | 6 +++++ > include/linux/path.h | 4 ++++ > include/linux/sunrpc/cache.h | 11 +++++++++ > include/uapi/linux/nfsd/export.h | 3 ++- > 8 files changed, 104 insertions(+), 12 deletions(-) > > -- > 2.4.1 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
