/*
* V9FS FID Management
*
+ * 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
#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 <asm/semaphore.h>
#include <net/9p/9p.h>
#include <net/9p/client.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
*
*/
-int v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid)
+void v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid)
{
- struct v9fs_dentry *dent;
+ spin_lock(&dentry->d_lock);
+ hlist_add_head(&fid->dlist, (struct hlist_head *)&dentry->d_fsdata);
+ spin_unlock(&dentry->d_lock);
+}
- P9_DPRINTK(P9_DEBUG_VFS, "fid %d dentry %s\n",
- fid->fid, dentry->d_iname);
+/**
+ * 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
+ *
+ */
- dent = dentry->d_fsdata;
- if (!dent) {
- dent = kmalloc(sizeof(struct v9fs_dentry), GFP_KERNEL);
- if (!dent)
- return -ENOMEM;
+static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any)
+{
+ struct p9_fid *fid, *ret;
- spin_lock_init(&dent->lock);
- INIT_LIST_HEAD(&dent->fidlist);
- dentry->d_fsdata = dent;
+ 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;
+ struct hlist_node *n;
+ spin_lock(&dentry->d_lock);
+ hlist_for_each_entry(fid, n, h, dlist) {
+ if (any || uid_eq(fid->uid, uid)) {
+ ret = fid;
+ break;
+ }
+ }
+ spin_unlock(&dentry->d_lock);
}
- spin_lock(&dent->lock);
- list_add(&fid->dlist, &dent->fidlist);
- spin_unlock(&dent->lock);
-
- return 0;
+ return ret;
}
-/**
- * v9fs_fid_lookup - return a locked fid from a dentry
- * @dentry: dentry to look for fid in
- *
- * find a fid in the dentry, obtain its semaphore and return a reference to it.
- * code calling lookup is responsible for releasing lock
- *
- * TODO: only match fids that have the same uid as current user
- *
+/*
+ * We need to hold v9ses->rename_sem as long as we hold references
+ * to returned path array. Array element contain pointers to
+ * dentry names.
*/
-
-struct p9_fid *v9fs_fid_lookup(struct dentry *dentry)
+static int build_path_from_dentry(struct v9fs_session_info *v9ses,
+ struct dentry *dentry, char ***names)
{
- struct v9fs_dentry *dent;
- struct p9_fid *fid;
+ int n = 0, i;
+ char **wnames;
+ struct dentry *ds;
- P9_DPRINTK(P9_DEBUG_VFS, " dentry: %s (%p)\n", dentry->d_iname, dentry);
- dent = dentry->d_fsdata;
- if (dent)
- fid = list_entry(dent->fidlist.next, struct p9_fid, dlist);
- else
- fid = ERR_PTR(-EBADF);
+ for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent)
+ n++;
- P9_DPRINTK(P9_DEBUG_VFS, " fid: %p\n", fid);
- return fid;
+ 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;
}
-struct p9_fid *v9fs_fid_lookup_remove(struct dentry *dentry)
+static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry,
+ kuid_t uid, int any)
{
- struct p9_fid *fid;
- struct v9fs_dentry *dent;
+ struct dentry *ds;
+ char **wnames, *uname;
+ int i, n, l, clone, access;
+ struct v9fs_session_info *v9ses;
+ struct p9_fid *fid, *old_fid = NULL;
- dent = dentry->d_fsdata;
- fid = v9fs_fid_lookup(dentry);
- if (!IS_ERR(fid)) {
- spin_lock(&dent->lock);
- list_del(&fid->dlist);
- spin_unlock(&dent->lock);
+ 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;
}
+ 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);
+ }
+ /* 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;
+ }
+ old_fid = fid;
+ i += l;
+ clone = 0;
+ }
+ kfree(wnames);
+fid_out:
+ if (!IS_ERR(fid))
+ v9fs_fid_add(dentry, fid);
+err_out:
+ up_read(&v9ses->rename_sem);
return fid;
}
-
/**
- * v9fs_fid_clone - lookup the fid for a dentry, clone a private copy and
- * release it
+ * v9fs_fid_lookup - lookup for a fid, try to walk if not found
* @dentry: dentry to look for fid in
*
- * find a fid in the dentry and then clone to a new private fid
- *
- * TODO: only match fids that have the same uid as current user
- *
+ * 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 p9_fid *v9fs_fid_lookup(struct dentry *dentry)
+{
+ kuid_t uid;
+ int any, access;
+ struct v9fs_session_info *v9ses;
+
+ 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);
+}
+
struct p9_fid *v9fs_fid_clone(struct dentry *dentry)
{
- struct p9_fid *ofid, *fid;
+ struct p9_fid *fid, *ret;
- P9_DPRINTK(P9_DEBUG_VFS, " dentry: %s (%p)\n", dentry->d_iname, dentry);
- ofid = v9fs_fid_lookup(dentry);
- if (IS_ERR(ofid))
- return ofid;
+ fid = v9fs_fid_lookup(dentry);
+ if (IS_ERR(fid))
+ return fid;
+
+ ret = p9_client_walk(fid, 0, NULL, 1);
+ return ret;
+}
+
+static struct p9_fid *v9fs_fid_clone_with_uid(struct dentry *dentry, kuid_t uid)
+{
+ struct p9_fid *fid, *ret;
+
+ fid = v9fs_fid_lookup_with_uid(dentry, uid, 0);
+ if (IS_ERR(fid))
+ return fid;
- fid = p9_client_walk(ofid, 0, NULL, 1);
+ 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;
}
projects / linux-3.10.git / blobdiff