Bunch of unrelated fixes

- polling fix for trans fd that ought to have been fixed otherwise back
 in March, but apparently came back somewhere else...
 - USB transport buffer overflow fix
 - Some dentry lifetime rework to handle metadata update for currently
 opened files in uncached mode, or inode type change in cached mode
 - a double-put on invalid flush found by syzbot
 - and finally /sys/fs/9p/caches not advancing buffer and overwriting
 itself for large contents
 
 Thanks to everyone involved!
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Merge tag '9p-for-6.18-rc1' of https://github.com/martinetd/linux

Pull 9p updates from Dominique Martinet:
 "A bunch of unrelated fixes:

   - polling fix for trans fd that ought to have been fixed otherwise
     back in March, but apparently came back somewhere else...

   - USB transport buffer overflow fix

   - Some dentry lifetime rework to handle metadata update for currently
     opened files in uncached mode, or inode type change in cached mode

   - a double-put on invalid flush found by syzbot

   - and finally /sys/fs/9p/caches not advancing buffer and overwriting
     itself for large contents

  Thanks to everyone involved!"

* tag '9p-for-6.18-rc1' of https://github.com/martinetd/linux:
  9p: sysfs_init: don't hardcode error to ENOMEM
  9p: fix /sys/fs/9p/caches overwriting itself
  9p: clean up comment typos
  9p/trans_fd: p9_fd_request: kick rx thread if EPOLLIN
  net/9p: fix double req put in p9_fd_cancelled
  net/9p: Fix buffer overflow in USB transport layer
  fs/9p: Add p9_debug(VFS) in d_revalidate
  fs/9p: Invalidate dentry if inode type change detected in cached mode
  fs/9p: Refresh metadata in d_revalidate for uncached mode too

fs/9p/v9fs.c

@@ -438,8 +438,7 @@ struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses,
 		v9ses->flags &= ~V9FS_ACCESS_MASK;
 		v9ses->flags |= V9FS_ACCESS_USER;
 	}
-	/*FIXME !! */
-	/* for legacy mode, fall back to V9FS_ACCESS_ANY */
+	/* FIXME: for legacy mode, fall back to V9FS_ACCESS_ANY */
 	if (!(v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses)) &&
 		((v9ses->flags&V9FS_ACCESS_MASK) == V9FS_ACCESS_USER)) {
 
@@ -450,7 +449,7 @@ struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses,
 	if (!v9fs_proto_dotl(v9ses) ||
 		!((v9ses->flags & V9FS_ACCESS_MASK) == V9FS_ACCESS_CLIENT)) {
 		/*
-		 * We support ACL checks on clinet only if the protocol is
+		 * We support ACL checks on client only if the protocol is
 		 * 9P2000.L and access is V9FS_ACCESS_CLIENT.
 		 */
 		v9ses->flags &= ~V9FS_ACL_MASK;
@@ -561,7 +560,7 @@ static ssize_t caches_show(struct kobject *kobj,
 	spin_lock(&v9fs_sessionlist_lock);
 	list_for_each_entry(v9ses, &v9fs_sessionlist, slist) {
 		if (v9ses->cachetag) {
-			n = snprintf(buf, limit, "%s\n", v9ses->cachetag);
+			n = snprintf(buf + count, limit, "%s\n", v9ses->cachetag);
 			if (n < 0) {
 				count = n;
 				break;
@@ -597,13 +596,16 @@ static const struct attribute_group v9fs_attr_group = {
 
 static int __init v9fs_sysfs_init(void)
 {
+	int ret;
+
 	v9fs_kobj = kobject_create_and_add("9p", fs_kobj);
 	if (!v9fs_kobj)
 		return -ENOMEM;
 
-	if (sysfs_create_group(v9fs_kobj, &v9fs_attr_group)) {
+	ret = sysfs_create_group(v9fs_kobj, &v9fs_attr_group);
+	if (ret) {
 		kobject_put(v9fs_kobj);
-		return -ENOMEM;
+		return ret;
 	}
 
 	return 0;
@@ -669,7 +671,7 @@ static int __init init_v9fs(void)
 	int err;
 
 	pr_info("Installing v9fs 9p2000 file system support\n");
-	/* TODO: Setup list of registered trasnport modules */
+	/* TODO: Setup list of registered transport modules */
 
 	err = v9fs_init_inode_cache();
 	if (err < 0) {

fs/9p/vfs_dentry.c

@@ -66,6 +66,7 @@ static int __v9fs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
 	struct p9_fid *fid;
 	struct inode *inode;
 	struct v9fs_inode *v9inode;
+	unsigned int cached;
 
 	if (flags & LOOKUP_RCU)
 		return -ECHILD;
@@ -75,13 +76,22 @@ static int __v9fs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
 		goto out_valid;
 
 	v9inode = V9FS_I(inode);
-	if (v9inode->cache_validity & V9FS_INO_INVALID_ATTR) {
+	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
+
+	cached = v9ses->cache & (CACHE_META | CACHE_LOOSE);
+
+	if (!cached || v9inode->cache_validity & V9FS_INO_INVALID_ATTR) {
 		int retval;
 		struct v9fs_session_info *v9ses;
 
 		fid = v9fs_fid_lookup(dentry);
-		if (IS_ERR(fid))
+		if (IS_ERR(fid)) {
+			p9_debug(
+				P9_DEBUG_VFS,
+				"v9fs_fid_lookup: dentry = %pd (%p), got error %pe\n",
+				dentry, dentry, fid);
 			return PTR_ERR(fid);
+		}
 
 		v9ses = v9fs_inode2v9ses(inode);
 		if (v9fs_proto_dotl(v9ses))
@@ -90,12 +100,25 @@ static int __v9fs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
 			retval = v9fs_refresh_inode(fid, inode);
 		p9_fid_put(fid);
 
-		if (retval == -ENOENT)
+		if (retval == -ENOENT) {
+			p9_debug(P9_DEBUG_VFS, "dentry: %pd (%p) invalidated due to ENOENT\n",
+				 dentry, dentry);
 			return 0;
-		if (retval < 0)
+		}
+		if (v9inode->cache_validity & V9FS_INO_INVALID_ATTR) {
+			p9_debug(P9_DEBUG_VFS, "dentry: %pd (%p) invalidated due to type change\n",
+				 dentry, dentry);
+			return 0;
+		}
+		if (retval < 0) {
+			p9_debug(P9_DEBUG_VFS,
+				"refresh inode: dentry = %pd (%p), got error %pe\n",
+				dentry, dentry, ERR_PTR(retval));
 			return retval;
 		}
+	}
 out_valid:
+	p9_debug(P9_DEBUG_VFS, "dentry: %pd (%p) is valid\n", dentry, dentry);
 	return 1;
 }
 
@@ -127,6 +150,8 @@ const struct dentry_operations v9fs_cached_dentry_operations = {
 };
 
 const struct dentry_operations v9fs_dentry_operations = {
+	.d_revalidate = v9fs_lookup_revalidate,
+	.d_weak_revalidate = __v9fs_lookup_revalidate,
 	.d_release = v9fs_dentry_release,
 	.d_unalias_trylock = v9fs_dentry_unalias_trylock,
 	.d_unalias_unlock = v9fs_dentry_unalias_unlock,

fs/9p/vfs_inode.c

@@ -1339,8 +1339,14 @@ int v9fs_refresh_inode(struct p9_fid *fid, struct inode *inode)
 	 * Don't update inode if the file type is different
 	 */
 	umode = p9mode2unixmode(v9ses, st, &rdev);
-	if (inode_wrong_type(inode, umode))
+	if (inode_wrong_type(inode, umode)) {
+		/*
+		 * Do this as a way of letting the caller know the inode should not
+		 * be reused
+		 */
+		v9fs_invalidate_inode_attr(inode);
 		goto out;
+	}
 
 	/*
 	 * We don't want to refresh inode->i_size,

fs/9p/vfs_inode_dotl.c

@@ -897,8 +897,14 @@ int v9fs_refresh_inode_dotl(struct p9_fid *fid, struct inode *inode)
 	/*
 	 * Don't update inode if the file type is different
 	 */
-	if (inode_wrong_type(inode, st->st_mode))
+	if (inode_wrong_type(inode, st->st_mode)) {
+		/*
+		 * Do this as a way of letting the caller know the inode should not
+		 * be reused
+		 */
+		v9fs_invalidate_inode_attr(inode);
 		goto out;
+	}
 
 	/*
 	 * We don't want to refresh inode->i_size,

net/9p/trans_fd.c

@@ -666,7 +666,6 @@ static void p9_poll_mux(struct p9_conn *m)
 
 static int p9_fd_request(struct p9_client *client, struct p9_req_t *req)
 {
-	__poll_t n;
 	int err;
 	struct p9_trans_fd *ts = client->trans;
 	struct p9_conn *m = &ts->conn;
@@ -686,13 +685,7 @@ static int p9_fd_request(struct p9_client *client, struct p9_req_t *req)
 	list_add_tail(&req->req_list, &m->unsent_req_list);
 	spin_unlock(&m->req_lock);
 
-	if (test_and_clear_bit(Wpending, &m->wsched))
-		n = EPOLLOUT;
-	else
-		n = p9_fd_poll(m->client, NULL, NULL);
-
-	if (n & EPOLLOUT && !test_and_set_bit(Wworksched, &m->wsched))
-		schedule_work(&m->wq);
+	p9_poll_mux(m);
 
 	return 0;
 }
@@ -726,10 +719,10 @@ static int p9_fd_cancelled(struct p9_client *client, struct p9_req_t *req)
 	p9_debug(P9_DEBUG_TRANS, "client %p req %p\n", client, req);
 
 	spin_lock(&m->req_lock);
-	/* Ignore cancelled request if message has been received
-	 * before lock.
+	/* Ignore cancelled request if status changed since the request was
+	 * processed in p9_client_flush()
 	*/
-	if (req->status == REQ_STATUS_RCVD) {
+	if (req->status != REQ_STATUS_SENT) {
 		spin_unlock(&m->req_lock);
 		return 0;
 	}

net/9p/trans_usbg.c

@@ -231,6 +231,8 @@ static void usb9pfs_rx_complete(struct usb_ep *ep, struct usb_request *req)
 	struct f_usb9pfs *usb9pfs = ep->driver_data;
 	struct usb_composite_dev *cdev = usb9pfs->function.config->cdev;
 	struct p9_req_t *p9_rx_req;
+	unsigned int req_size = req->actual;
+	int status = REQ_STATUS_RCVD;
 
 	if (req->status) {
 		dev_err(&cdev->gadget->dev, "%s usb9pfs complete --> %d, %d/%d\n",
@@ -242,11 +244,19 @@ static void usb9pfs_rx_complete(struct usb_ep *ep, struct usb_request *req)
 	if (!p9_rx_req)
 		return;
 
-	memcpy(p9_rx_req->rc.sdata, req->buf, req->actual);
+	if (req_size > p9_rx_req->rc.capacity) {
+		dev_err(&cdev->gadget->dev,
+			"%s received data size %u exceeds buffer capacity %zu\n",
+			ep->name, req_size, p9_rx_req->rc.capacity);
+		req_size = 0;
+		status = REQ_STATUS_ERROR;
+	}
 
-	p9_rx_req->rc.size = req->actual;
+	memcpy(p9_rx_req->rc.sdata, req->buf, req_size);
 
-	p9_client_cb(usb9pfs->client, p9_rx_req, REQ_STATUS_RCVD);
+	p9_rx_req->rc.size = req_size;
+
+	p9_client_cb(usb9pfs->client, p9_rx_req, status);
 	p9_req_put(usb9pfs->client, p9_rx_req);
 
 	complete(&usb9pfs->received);