0b8dd17762
Fid management cleanup. The patch attempts to fix the races in dentry's fid management. Dentries don't keep the opened fids anymore, they are moved to the file structs. Ideally there should be no more than one fid with fidcreate equal to zero in the dentry's list of fids. v9fs_fid_create initializes the important fields (fid, fidcreated) before v9fs_fid is added to the list. v9fs_fid_lookup returns only fids that are not created by v9fs_create. v9fs_fid_get_created returns the fid created by the same process by v9fs_create (if any) and removes it from dentry's list Signed-off-by: Latchesar Ionkov <lucho@ionkov.net> Cc: Eric Van Hensbergen <ericvh@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
126 lines
3.4 KiB
C
126 lines
3.4 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 as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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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/smp_lock.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 "debug.h"
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#include "v9fs.h"
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#include "9p.h"
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#include "v9fs_vfs.h"
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#include "conv.h"
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#include "fid.h"
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/**
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* v9fs_dentry_validate - VFS dcache hook to validate cache
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* @dentry: dentry that is being validated
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* @nd: path data
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*
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* dcache really shouldn't be used for 9P2000 as at all due to
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* potential attached semantics to directory traversal (walk).
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*
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* FUTURE: look into how to use dcache to allow multi-stage
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* walks in Plan 9 & potential for better dcache operation which
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* would remain valid for Plan 9 semantics. Older versions
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* had validation via stat for those interested. However, since
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* stat has the same approximate overhead as walk there really
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* is no difference. The only improvement would be from a
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* time-decay cache like NFS has and that undermines the
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* synchronous nature of 9P2000.
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*
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*/
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static int v9fs_dentry_validate(struct dentry *dentry, struct nameidata *nd)
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{
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struct dentry *dc = current->fs->pwd;
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dprintk(DEBUG_VFS, "dentry: %s (%p)\n", dentry->d_iname, dentry);
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if (v9fs_fid_lookup(dentry)) {
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dprintk(DEBUG_VFS, "VALID\n");
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return 1;
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}
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while (dc != NULL) {
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if (dc == dentry) {
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dprintk(DEBUG_VFS, "VALID\n");
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return 1;
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}
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if (dc == dc->d_parent)
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break;
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dc = dc->d_parent;
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}
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dprintk(DEBUG_VFS, "INVALID\n");
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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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void v9fs_dentry_release(struct dentry *dentry)
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{
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dprintk(DEBUG_VFS, " dentry: %s (%p)\n", dentry->d_iname, dentry);
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if (dentry->d_fsdata != NULL) {
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struct list_head *fid_list = dentry->d_fsdata;
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struct v9fs_fid *temp = NULL;
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struct v9fs_fid *current_fid = NULL;
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struct v9fs_fcall *fcall = NULL;
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list_for_each_entry_safe(current_fid, temp, fid_list, list) {
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if (v9fs_t_clunk
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(current_fid->v9ses, current_fid->fid, &fcall))
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dprintk(DEBUG_ERROR, "clunk failed: %s\n",
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FCALL_ERROR(fcall));
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v9fs_put_idpool(current_fid->fid,
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¤t_fid->v9ses->fidpool);
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kfree(fcall);
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v9fs_fid_destroy(current_fid);
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}
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kfree(dentry->d_fsdata); /* free the list_head */
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}
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}
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struct dentry_operations v9fs_dentry_operations = {
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.d_revalidate = v9fs_dentry_validate,
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.d_release = v9fs_dentry_release,
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};
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