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Diffstat (limited to 'Documentation/filesystems/aufs/design/07export.txt')
| -rw-r--r-- | Documentation/filesystems/aufs/design/07export.txt | 58 |
1 files changed, 0 insertions, 58 deletions
diff --git a/Documentation/filesystems/aufs/design/07export.txt b/Documentation/filesystems/aufs/design/07export.txt deleted file mode 100644 index b25dd950c..000000000 --- a/Documentation/filesystems/aufs/design/07export.txt +++ /dev/null @@ -1,58 +0,0 @@ - -# Copyright (C) 2005-2015 Junjiro R. Okajima -# -# This program is free software; you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation; either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program. If not, see <http://www.gnu.org/licenses/>. - -Export Aufs via NFS ----------------------------------------------------------------------- -Here is an approach. -- like xino/xib, add a new file 'xigen' which stores aufs inode - generation. -- iget_locked(): initialize aufs inode generation for a new inode, and - store it in xigen file. -- destroy_inode(): increment aufs inode generation and store it in xigen - file. it is necessary even if it is not unlinked, because any data of - inode may be changed by UDBA. -- encode_fh(): for a root dir, simply return FILEID_ROOT. otherwise - build file handle by - + branch id (4 bytes) - + superblock generation (4 bytes) - + inode number (4 or 8 bytes) - + parent dir inode number (4 or 8 bytes) - + inode generation (4 bytes)) - + return value of exportfs_encode_fh() for the parent on a branch (4 - bytes) - + file handle for a branch (by exportfs_encode_fh()) -- fh_to_dentry(): - + find the index of a branch from its id in handle, and check it is - still exist in aufs. - + 1st level: get the inode number from handle and search it in cache. - + 2nd level: if not found in cache, get the parent inode number from - the handle and search it in cache. and then open the found parent - dir, find the matching inode number by vfs_readdir() and get its - name, and call lookup_one_len() for the target dentry. - + 3rd level: if the parent dir is not cached, call - exportfs_decode_fh() for a branch and get the parent on a branch, - build a pathname of it, convert it a pathname in aufs, call - path_lookup(). now aufs gets a parent dir dentry, then handle it as - the 2nd level. - + to open the dir, aufs needs struct vfsmount. aufs keeps vfsmount - for every branch, but not itself. to get this, (currently) aufs - searches in current->nsproxy->mnt_ns list. it may not be a good - idea, but I didn't get other approach. - + test the generation of the gotten inode. -- every inode operation: they may get EBUSY due to UDBA. in this case, - convert it into ESTALE for NFSD. -- readdir(): call lockdep_on/off() because filldir in NFSD calls - lookup_one_len(), vfs_getattr(), encode_fh() and others. |