Author: rmacklem
Date: Wed Jan 1 22:43:16 2014
New Revision: 260173
URL: http://svnweb.freebsd.org/changeset/base/260173
Log:
MFC: r259845
An intermittent problem with NFSv4 exporting of ZFS snapshots was
reported to the freebsd-fs mailing list. I believe the problem was
caused by the Readdir operation using VFS_VGET() for a snapshot file entry
instead of VOP_LOOKUP(). This would not occur for NFSv3, since it
will do a VFS_VGET() of "." which fails with ENOTSUPP at the beginning
of the directory, whereas NFSv4 does not check "." or "..". This
patch adds a call to VFS_VGET() for the directory being read to check
for ENOTSUPP.
I also observed that the mount_on_fileid and fsid attributes were
not correct at the snapshot's auto mountpoints when looking at packet
traces for the Readdir. This patch fixes the attributes by doing a check
for different v_mount structure, even if the vnode v_mountedhere is not
set.
Modified:
stable/9/sys/fs/nfsserver/nfs_nfsdport.c
Directory Properties:
stable/9/sys/ (props changed)
stable/9/sys/fs/ (props changed)
Modified: stable/9/sys/fs/nfsserver/nfs_nfsdport.c
==============================================================================
--- stable/9/sys/fs/nfsserver/nfs_nfsdport.c Wed Jan 1 22:35:11 2014
(r260172)
+++ stable/9/sys/fs/nfsserver/nfs_nfsdport.c Wed Jan 1 22:43:16 2014
(r260173)
@@ -1985,6 +1985,27 @@ again:
}
/*
+ * Check to see if entries in this directory can be safely acquired
+ * via VFS_VGET() or if a switch to VOP_LOOKUP() is required.
+ * ZFS snapshot directories need VOP_LOOKUP(), so that any
+ * automount of the snapshot directory that is required will
+ * be done.
+ * This needs to be done here for NFSv4, since NFSv4 never does
+ * a VFS_VGET() for "." or "..".
+ */
+ if (not_zfs == 0) {
+ r = VFS_VGET(mp, at.na_fileid, LK_SHARED, &nvp);
+ if (r == EOPNOTSUPP) {
+ usevget = 0;
+ cn.cn_nameiop = LOOKUP;
+ cn.cn_lkflags = LK_SHARED | LK_RETRY;
+ cn.cn_cred = nd->nd_cred;
+ cn.cn_thread = p;
+ } else if (r == 0)
+ vput(nvp);
+ }
+
+ /*
* Save this position, in case there is an error before one entry
* is created.
*/
@@ -2122,6 +2143,22 @@ again:
if (!r)
r = nfsvno_getattr(nvp, nvap,
nd->nd_cred, p, 1);
+ if (r == 0 && not_zfs == 0 &&
+ nfsrv_enable_crossmntpt != 0 &&
+ (nd->nd_flag & ND_NFSV4) != 0 &&
+ nvp->v_type == VDIR &&
+ vp->v_mount != nvp->v_mount) {
+ /*
+ * For a ZFS snapshot, there is a
+ * pseudo mount that does not set
+ * v_mountedhere, so it needs to
+ * be detected via a different
+ * mount structure.
+ */
+ at_root = 1;
+ if (new_mp == mp)
+ new_mp = nvp->v_mount;
+ }
}
} else {
nvp = NULL;
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