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authorSteve Dickson <SteveD@redhat.com>2009-09-09 14:58:22 -0400
committerJ. Bruce Fields <bfields@citi.umich.edu>2009-12-15 14:00:40 -0500
commiteb4c86c6a5adec423c9e615d4937fdddd06a16c5 (patch)
tree50aee7013c9ca92cce9828268af4ee3d220a416c /fs/nfsd
parent12045a6ee9908b38b6d286530c7d816e39071346 (diff)
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nfsd: introduce export flag for v4 pseudoroot
NFSv4 differs from v2 and v3 in that it presents a single unified filesystem tree, whereas v2 and v3 exported multiple filesystem (whose roots could be found using a separate mount protocol). Our original NFSv4 server implementation asked the administrator to designate a single filesystem as the NFSv4 root, then to mount filesystems they wished to export underneath. (Often using bind mounts of already-existing filesystems.) This was conceptually simple, and allowed easy implementation, but created a serious obstacle to upgrading between v2/v3: since the paths to v4 filesystems were different, administrators would have to adjust all the paths in client-side mount commands when switching to v4. Various workarounds are possible. For example, the administrator could export "/" and designate it as the v4 root. However, the security risks of that approach are obvious, and in any case we shouldn't be requiring the administrator to take extra steps to fix this problem; instead, the server should present consistent paths across different versions by default. These patches take a modified version of that approach: we provide a new export option which exports only a subset of a filesystem. With this flag, it becomes safe for mountd to export "/" by default, with no need for additional configuration. We begin just by defining the new flag. Signed-off-by: Steve Dickson <steved@redhat.com> Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Diffstat (limited to 'fs/nfsd')
-rw-r--r--fs/nfsd/export.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
index cb3dae2..c64d55f 100644
--- a/fs/nfsd/export.c
+++ b/fs/nfsd/export.c
@@ -1425,6 +1425,7 @@ static struct flags {
{ NFSEXP_CROSSMOUNT, {"crossmnt", ""}},
{ NFSEXP_NOSUBTREECHECK, {"no_subtree_check", ""}},
{ NFSEXP_NOAUTHNLM, {"insecure_locks", ""}},
+ { NFSEXP_V4ROOT, {"v4root", ""}},
#ifdef MSNFS
{ NFSEXP_MSNFS, {"msnfs", ""}},
#endif