1 files changed, 228 insertions, 174 deletions

diff --git a/fs/9p/fid.c b/fs/9p/fid.c
index eda449778fa..d51ec9fafcc 100644
--- a/fs/9p/fid.c
+++ b/fs/9p/fid.c
@@ -1,12 +1,12 @@
 /*
  * V9FS FID Management
  *
- *  Copyright (C) 2005 by Eric Van Hensbergen <ericvh@gmail.com>
+ *  Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
+ *  Copyright (C) 2005, 2006 by Eric Van Hensbergen <ericvh@gmail.com>
  *
  *  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.
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
  *
  *  This program is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ -21,232 +21,286 @@
  *
  */
 
-#include <linux/config.h>
 #include <linux/module.h>
 #include <linux/errno.h>
 #include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
 #include <linux/idr.h>
+#include <net/9p/9p.h>
+#include <net/9p/client.h>
 
-#include "debug.h"
 #include "v9fs.h"
-#include "9p.h"
 #include "v9fs_vfs.h"
 #include "fid.h"
 
 /**
- * v9fs_fid_insert - add a fid to a dentry
+ * v9fs_fid_add - add a fid to a dentry
+ * @dentry: dentry that the fid is being added to
  * @fid: fid to add
- * @dentry: dentry that it is being added to
  *
  */
 
-static int v9fs_fid_insert(struct v9fs_fid *fid, struct dentry *dentry)
+static inline void __add_fid(struct dentry *dentry, struct p9_fid *fid)
 {
-	struct list_head *fid_list = (struct list_head *)dentry->d_fsdata;
-	dprintk(DEBUG_9P, "fid %d (%p) dentry %s (%p)\n", fid->fid, fid,
-		dentry->d_iname, dentry);
-	if (dentry->d_fsdata == NULL) {
-		dentry->d_fsdata =
-		    kmalloc(sizeof(struct list_head), GFP_KERNEL);
-		if (dentry->d_fsdata == NULL) {
-			dprintk(DEBUG_ERROR, "Out of memory\n");
-			return -ENOMEM;
-		}
-		fid_list = (struct list_head *)dentry->d_fsdata;
-		INIT_LIST_HEAD(fid_list);	/* Initialize list head */
-	}
+	hlist_add_head(&fid->dlist, (struct hlist_head *)&dentry->d_fsdata);
+}
 
-	fid->uid = current->uid;
-	fid->pid = current->pid;
-	list_add(&fid->list, fid_list);
-	return 0;
+void v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid)
+{
+	spin_lock(&dentry->d_lock);
+	__add_fid(dentry, fid);
+	spin_unlock(&dentry->d_lock);
 }
 
 /**
- * v9fs_fid_create - allocate a FID structure
- * @dentry - dentry to link newly created fid to
+ * v9fs_fid_find - retrieve a fid that belongs to the specified uid
+ * @dentry: dentry to look for fid in
+ * @uid: return fid that belongs to the specified user
+ * @any: if non-zero, return any fid associated with the dentry
  *
  */
 
-struct v9fs_fid *v9fs_fid_create(struct dentry *dentry,
-	struct v9fs_session_info *v9ses, int fid, int create)
+static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any)
 {
-	struct v9fs_fid *new;
-
-	dprintk(DEBUG_9P, "fid create dentry %p, fid %d, create %d\n",
-		dentry, fid, create);
+	struct p9_fid *fid, *ret;
 
-	new = kmalloc(sizeof(struct v9fs_fid), GFP_KERNEL);
-	if (new == NULL) {
-		dprintk(DEBUG_ERROR, "Out of Memory\n");
-		return ERR_PTR(-ENOMEM);
+	p9_debug(P9_DEBUG_VFS, " dentry: %s (%p) uid %d any %d\n",
+		 dentry->d_name.name, dentry, from_kuid(&init_user_ns, uid),
+		 any);
+	ret = NULL;
+	/* we'll recheck under lock if there's anything to look in */
+	if (dentry->d_fsdata) {
+		struct hlist_head *h = (struct hlist_head *)&dentry->d_fsdata;
+		spin_lock(&dentry->d_lock);
+		hlist_for_each_entry(fid, h, dlist) {
+			if (any || uid_eq(fid->uid, uid)) {
+				ret = fid;
+				break;
+			}
+		}
+		spin_unlock(&dentry->d_lock);
 	}
 
-	new->fid = fid;
-	new->v9ses = v9ses;
-	new->fidopen = 0;
-	new->fidcreate = create;
-	new->fidclunked = 0;
-	new->iounit = 0;
-	new->rdir_pos = 0;
-	new->rdir_fcall = NULL;
-
-	if (v9fs_fid_insert(new, dentry) == 0)
-		return new;
-	else {
-		dprintk(DEBUG_ERROR, "Problems inserting to dentry\n");
-		kfree(new);
-		return NULL;
-	}
+	return ret;
 }
 
-/**
- * v9fs_fid_destroy - deallocate a FID structure
- * @fid: fid to destroy
- *
+/*
+ * We need to hold v9ses->rename_sem as long as we hold references
+ * to returned path array. Array element contain pointers to
+ * dentry names.
  */
-
-void v9fs_fid_destroy(struct v9fs_fid *fid)
+static int build_path_from_dentry(struct v9fs_session_info *v9ses,
+				  struct dentry *dentry, char ***names)
 {
-	list_del(&fid->list);
-	kfree(fid);
+	int n = 0, i;
+	char **wnames;
+	struct dentry *ds;
+
+	for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent)
+		n++;
+
+	wnames = kmalloc(sizeof(char *) * n, GFP_KERNEL);
+	if (!wnames)
+		goto err_out;
+
+	for (ds = dentry, i = (n-1); i >= 0; i--, ds = ds->d_parent)
+		wnames[i] = (char  *)ds->d_name.name;
+
+	*names = wnames;
+	return n;
+err_out:
+	return -ENOMEM;
 }
 
-/**
- * v9fs_fid_walk_up - walks from the process current directory
- * 	up to the specified dentry.
- */
-static struct v9fs_fid *v9fs_fid_walk_up(struct dentry *dentry)
+static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry,
+					       kuid_t uid, int any)
 {
-	int fidnum, cfidnum, err;
-	struct v9fs_fid *cfid;
-	struct dentry *cde;
+	struct dentry *ds;
+	char **wnames, *uname;
+	int i, n, l, clone, access;
 	struct v9fs_session_info *v9ses;
-
-	v9ses = v9fs_inode2v9ses(current->fs->pwd->d_inode);
-	cfid = v9fs_fid_lookup(current->fs->pwd);
-	if (cfid == NULL) {
-		dprintk(DEBUG_ERROR, "process cwd doesn't have a fid\n");
-		return ERR_PTR(-ENOENT);
+	struct p9_fid *fid, *old_fid = NULL;
+
+	v9ses = v9fs_dentry2v9ses(dentry);
+	access = v9ses->flags & V9FS_ACCESS_MASK;
+	fid = v9fs_fid_find(dentry, uid, any);
+	if (fid)
+		return fid;
+	/*
+	 * we don't have a matching fid. To do a TWALK we need
+	 * parent fid. We need to prevent rename when we want to
+	 * look at the parent.
+	 */
+	down_read(&v9ses->rename_sem);
+	ds = dentry->d_parent;
+	fid = v9fs_fid_find(ds, uid, any);
+	if (fid) {
+		/* Found the parent fid do a lookup with that */
+		fid = p9_client_walk(fid, 1, (char **)&dentry->d_name.name, 1);
+		goto fid_out;
 	}
-
-	cfidnum = cfid->fid;
-	cde = current->fs->pwd;
-	/* TODO: take advantage of multiwalk */
-
-	fidnum = v9fs_get_idpool(&v9ses->fidpool);
-	if (fidnum < 0) {
-		dprintk(DEBUG_ERROR, "could not get a new fid num\n");
-		err = -ENOENT;
-		goto clunk_fid;
+	up_read(&v9ses->rename_sem);
+
+	/* start from the root and try to do a lookup */
+	fid = v9fs_fid_find(dentry->d_sb->s_root, uid, any);
+	if (!fid) {
+		/* the user is not attached to the fs yet */
+		if (access == V9FS_ACCESS_SINGLE)
+			return ERR_PTR(-EPERM);
+
+		if (v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses))
+				uname = NULL;
+		else
+			uname = v9ses->uname;
+
+		fid = p9_client_attach(v9ses->clnt, NULL, uname, uid,
+				       v9ses->aname);
+		if (IS_ERR(fid))
+			return fid;
+
+		v9fs_fid_add(dentry->d_sb->s_root, fid);
 	}
-
-	while (cde != dentry) {
-		if (cde == cde->d_parent) {
-			dprintk(DEBUG_ERROR, "can't find dentry\n");
-			err = -ENOENT;
-			goto clunk_fid;
+	/* If we are root ourself just return that */
+	if (dentry->d_sb->s_root == dentry)
+		return fid;
+	/*
+	 * Do a multipath walk with attached root.
+	 * When walking parent we need to make sure we
+	 * don't have a parallel rename happening
+	 */
+	down_read(&v9ses->rename_sem);
+	n  = build_path_from_dentry(v9ses, dentry, &wnames);
+	if (n < 0) {
+		fid = ERR_PTR(n);
+		goto err_out;
+	}
+	clone = 1;
+	i = 0;
+	while (i < n) {
+		l = min(n - i, P9_MAXWELEM);
+		/*
+		 * We need to hold rename lock when doing a multipath
+		 * walk to ensure none of the patch component change
+		 */
+		fid = p9_client_walk(fid, l, &wnames[i], clone);
+		if (IS_ERR(fid)) {
+			if (old_fid) {
+				/*
+				 * If we fail, clunk fid which are mapping
+				 * to path component and not the last component
+				 * of the path.
+				 */
+				p9_client_clunk(old_fid);
+			}
+			kfree(wnames);
+			goto err_out;
 		}
-
-		err = v9fs_t_walk(v9ses, cfidnum, fidnum, "..", NULL);
-		if (err < 0) {
-			dprintk(DEBUG_ERROR, "problem walking to parent\n");
-			goto clunk_fid;
+		old_fid = fid;
+		i += l;
+		clone = 0;
+	}
+	kfree(wnames);
+fid_out:
+	if (!IS_ERR(fid)) {
+		spin_lock(&dentry->d_lock);
+		if (d_unhashed(dentry)) {
+			spin_unlock(&dentry->d_lock);
+			p9_client_clunk(fid);
+			fid = ERR_PTR(-ENOENT);
+		} else {
+			__add_fid(dentry, fid);
+			spin_unlock(&dentry->d_lock);
 		}
-
-		cfidnum = fidnum;
-		cde = cde->d_parent;
 	}
-
-	return v9fs_fid_create(dentry, v9ses, fidnum, 0);
-
-clunk_fid:
-	v9fs_t_clunk(v9ses, fidnum);
-	return ERR_PTR(err);
+err_out:
+	up_read(&v9ses->rename_sem);
+	return fid;
 }
 
 /**
- * v9fs_fid_lookup - retrieve the right fid from a  particular dentry
+ * v9fs_fid_lookup - lookup for a fid, try to walk if not found
  * @dentry: dentry to look for fid in
- * @type: intent of lookup (operation or traversal)
- *
- * search list of fids associated with a dentry for a fid with a matching
- * thread id or uid.  If that fails, look up the dentry's parents to see if you
- * can find a matching fid.
  *
+ * Look for a fid in the specified dentry for the current user.
+ * If no fid is found, try to create one walking from a fid from the parent
+ * dentry (if it has one), or the root dentry. If the user haven't accessed
+ * the fs yet, attach now and walk from the root.
  */
 
-struct v9fs_fid *v9fs_fid_lookup(struct dentry *dentry)
+struct p9_fid *v9fs_fid_lookup(struct dentry *dentry)
 {
-	struct list_head *fid_list = (struct list_head *)dentry->d_fsdata;
-	struct v9fs_fid *current_fid = NULL;
-	struct v9fs_fid *temp = NULL;
-	struct v9fs_fid *return_fid = NULL;
-
-	dprintk(DEBUG_9P, " dentry: %s (%p)\n", dentry->d_iname, dentry);
-
-	if (fid_list) {
-		list_for_each_entry_safe(current_fid, temp, fid_list, list) {
-			if (!current_fid->fidcreate) {
-				return_fid = current_fid;
-				break;
-			}
-		}
-
-		if (!return_fid)
-			return_fid = current_fid;
-	}
+	kuid_t uid;
+	int  any, access;
+	struct v9fs_session_info *v9ses;
 
-	/* we are at the root but didn't match */
-	if ((!return_fid) && (dentry->d_parent == dentry)) {
-		/* TODO: clone attach with new uid */
-		return_fid = current_fid;
+	v9ses = v9fs_dentry2v9ses(dentry);
+	access = v9ses->flags & V9FS_ACCESS_MASK;
+	switch (access) {
+	case V9FS_ACCESS_SINGLE:
+	case V9FS_ACCESS_USER:
+	case V9FS_ACCESS_CLIENT:
+		uid = current_fsuid();
+		any = 0;
+		break;
+
+	case V9FS_ACCESS_ANY:
+		uid = v9ses->uid;
+		any = 1;
+		break;
+
+	default:
+		uid = INVALID_UID;
+		any = 0;
+		break;
 	}
+	return v9fs_fid_lookup_with_uid(dentry, uid, any);
+}
 
-	if (!return_fid) {
-		struct dentry *par = current->fs->pwd->d_parent;
-		int count = 1;
-		while (par != NULL) {
-			if (par == dentry)
-				break;
-			count++;
-			if (par == par->d_parent) {
-				dprintk(DEBUG_ERROR,
-					"got to root without finding dentry\n");
-				break;
-			}
-			par = par->d_parent;
-		}
+struct p9_fid *v9fs_fid_clone(struct dentry *dentry)
+{
+	struct p9_fid *fid, *ret;
 
-/* XXX - there may be some duplication we can get rid of */
-		if (par == dentry) {
-			return_fid = v9fs_fid_walk_up(dentry);
-			if (IS_ERR(return_fid))
-				return_fid = NULL;
-		}
-	}
+	fid = v9fs_fid_lookup(dentry);
+	if (IS_ERR(fid))
+		return fid;
 
-	return return_fid;
+	ret = p9_client_walk(fid, 0, NULL, 1);
+	return ret;
 }
 
-struct v9fs_fid *v9fs_fid_get_created(struct dentry *dentry)
+static struct p9_fid *v9fs_fid_clone_with_uid(struct dentry *dentry, kuid_t uid)
 {
-	struct list_head *fid_list;
-	struct v9fs_fid *fid, *ftmp, *ret;
+	struct p9_fid *fid, *ret;
 
-	dprintk(DEBUG_9P, " dentry: %s (%p)\n", dentry->d_iname, dentry);
-	fid_list = (struct list_head *)dentry->d_fsdata;
-	ret = NULL;
-	if (fid_list) {
-		list_for_each_entry_safe(fid, ftmp, fid_list, list) {
-			if (fid->fidcreate && fid->pid == current->pid) {
-				list_del(&fid->list);
-				ret = fid;
-				break;
-			}
-		}
-	}
+	fid = v9fs_fid_lookup_with_uid(dentry, uid, 0);
+	if (IS_ERR(fid))
+		return fid;
 
-	dprintk(DEBUG_9P, "return %p\n", ret);
+	ret = p9_client_walk(fid, 0, NULL, 1);
 	return ret;
 }
+
+struct p9_fid *v9fs_writeback_fid(struct dentry *dentry)
+{
+	int err;
+	struct p9_fid *fid;
+
+	fid = v9fs_fid_clone_with_uid(dentry, GLOBAL_ROOT_UID);
+	if (IS_ERR(fid))
+		goto error_out;
+	/*
+	 * writeback fid will only be used to write back the
+	 * dirty pages. We always request for the open fid in read-write
+	 * mode so that a partial page write which result in page
+	 * read can work.
+	 */
+	err = p9_client_open(fid, O_RDWR);
+	if (err < 0) {
+		p9_client_clunk(fid);
+		fid = ERR_PTR(err);
+		goto error_out;
+	}
+error_out:
+	return fid;
+}