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ecf3d1f1aa
The following set of operations on a NFS client and server will cause
server# mkdir a
client# cd a
server# mv a a.bak
client# sleep 30 # (or whatever the dir attrcache timeout is)
client# stat .
stat: cannot stat `.': Stale NFS file handle
Obviously, we should not be getting an ESTALE error back there since the
inode still exists on the server. The problem is that the lookup code
will call d_revalidate on the dentry that "." refers to, because NFS has
FS_REVAL_DOT set.
nfs_lookup_revalidate will see that the parent directory has changed and
will try to reverify the dentry by redoing a LOOKUP. That of course
fails, so the lookup code returns ESTALE.
The problem here is that d_revalidate is really a bad fit for this case.
What we really want to know at this point is whether the inode is still
good or not, but we don't really care what name it goes by or whether
the dcache is still valid.
Add a new d_op->d_weak_revalidate operation and have complete_walk call
that instead of d_revalidate. The intent there is to allow for a
"weaker" d_revalidate that just checks to see whether the inode is still
good. This is also gives us an opportunity to kill off the FS_REVAL_DOT
special casing.
[AV: changed method name, added note in porting, fixed confusion re
having it possibly called from RCU mode (it won't be)]
Cc: NeilBrown <neilb@suse.de>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
149 lines
3.5 KiB
C
149 lines
3.5 KiB
C
/*
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* linux/fs/9p/vfs_dentry.c
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*
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* This file contians vfs dentry ops for the 9P2000 protocol.
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*
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* Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
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* Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to:
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* Free Software Foundation
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* 51 Franklin Street, Fifth Floor
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* Boston, MA 02111-1301 USA
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*
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*/
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#include <linux/module.h>
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#include <linux/errno.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/pagemap.h>
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#include <linux/stat.h>
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#include <linux/string.h>
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#include <linux/inet.h>
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#include <linux/namei.h>
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#include <linux/idr.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <net/9p/9p.h>
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#include <net/9p/client.h>
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#include "v9fs.h"
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#include "v9fs_vfs.h"
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#include "fid.h"
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/**
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* v9fs_dentry_delete - called when dentry refcount equals 0
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* @dentry: dentry in question
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*
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* By returning 1 here we should remove cacheing of unused
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* dentry components.
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*
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*/
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static int v9fs_dentry_delete(const struct dentry *dentry)
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{
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p9_debug(P9_DEBUG_VFS, " dentry: %s (%p)\n",
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dentry->d_name.name, dentry);
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return 1;
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}
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/**
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* v9fs_cached_dentry_delete - called when dentry refcount equals 0
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* @dentry: dentry in question
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*
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*/
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static int v9fs_cached_dentry_delete(const struct dentry *dentry)
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{
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p9_debug(P9_DEBUG_VFS, " dentry: %s (%p)\n",
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dentry->d_name.name, dentry);
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/* Don't cache negative dentries */
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if (!dentry->d_inode)
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return 1;
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return 0;
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}
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/**
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* v9fs_dentry_release - called when dentry is going to be freed
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* @dentry: dentry that is being release
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*
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*/
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static void v9fs_dentry_release(struct dentry *dentry)
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{
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struct v9fs_dentry *dent;
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struct p9_fid *temp, *current_fid;
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p9_debug(P9_DEBUG_VFS, " dentry: %s (%p)\n",
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dentry->d_name.name, dentry);
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dent = dentry->d_fsdata;
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if (dent) {
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list_for_each_entry_safe(current_fid, temp, &dent->fidlist,
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dlist) {
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p9_client_clunk(current_fid);
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}
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kfree(dent);
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dentry->d_fsdata = NULL;
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}
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}
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static int v9fs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
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{
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struct p9_fid *fid;
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struct inode *inode;
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struct v9fs_inode *v9inode;
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if (flags & LOOKUP_RCU)
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return -ECHILD;
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inode = dentry->d_inode;
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if (!inode)
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goto out_valid;
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v9inode = V9FS_I(inode);
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if (v9inode->cache_validity & V9FS_INO_INVALID_ATTR) {
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int retval;
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struct v9fs_session_info *v9ses;
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fid = v9fs_fid_lookup(dentry);
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if (IS_ERR(fid))
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return PTR_ERR(fid);
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v9ses = v9fs_inode2v9ses(inode);
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if (v9fs_proto_dotl(v9ses))
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retval = v9fs_refresh_inode_dotl(fid, inode);
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else
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retval = v9fs_refresh_inode(fid, inode);
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if (retval == -ENOENT)
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return 0;
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if (retval < 0)
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return retval;
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}
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out_valid:
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return 1;
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}
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const struct dentry_operations v9fs_cached_dentry_operations = {
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.d_revalidate = v9fs_lookup_revalidate,
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.d_weak_revalidate = v9fs_lookup_revalidate,
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.d_delete = v9fs_cached_dentry_delete,
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.d_release = v9fs_dentry_release,
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};
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const struct dentry_operations v9fs_dentry_operations = {
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.d_delete = v9fs_dentry_delete,
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.d_release = v9fs_dentry_release,
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};
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