Sorry for the bad title of v6, it should be v5. Please ignore the threads of v6. On 6/17/2015 3:44 PM, 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. > > # 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).) > > It's caused by exports cache of nfsd holds the reference of > the path (here is /nfs/test/), so, it can't be umounted. > > I don't think that's user expect, they want umount /nfs/test/. > Bruce think user can also umount /nfs/pnfs/ and /nfs/xfs. > > This patch site lets nfsd exports pinning to vfsmount, > not using mntget, so user can umount any exports mountpoint now. > > v3, > 1. New helpers path_get_pin/path_put_unpin for path pin. > 2. Use kzalloc for allocating memory. > > v4, Thanks for Al Viro's commets for the logic of fs_pin. > 1. add a completion for pin_kill waiting the reference is decreased to zero. > 2. add a work_struct for pin_kill decreases the reference indirectly. > 3. free svc_export/svc_expkey in pin_kill, not svc_export_put/svc_expkey_put. > 4. svc_export_put/svc_expkey_put go though pin_kill logic. > > v5, > let killing fs_pin under a reference of vfsmnt. > > Kinglong Mee (6): > fs_pin: Initialize value for fs_pin explicitly > fs_pin: Export functions for specific filesystem > fs_pin: Kill fs_pin under a reference of vfsmnt > 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 | 4 ++ > fs/namei.c | 26 ++++++++++++ > fs/namespace.c | 10 ++++- > fs/nfsd/export.c | 96 +++++++++++++++++++++++++++++++++++--------- > fs/nfsd/export.h | 18 ++++++++- > include/linux/fs_pin.h | 6 +++ > include/linux/path.h | 4 ++ > include/linux/sunrpc/cache.h | 11 +++++ > 8 files changed, 154 insertions(+), 21 deletions(-) > -- 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
