9p-for-5.17-rc1: fixes, split 9p_net_fd, new reviewer

- fix possible uninitialized memory usage for setattr
 - fix fscache reading hole in a file just after it's been grown
 - split net/9p/trans_fd.c in its own module like other transports
   that module defaults to 9P_NET and is autoloaded if required so
   users should not be impacted
 - add Christian Schoenebeck to 9p reviewers
 - some more trivial cleanup
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Merge tag '9p-for-5.17-rc1' of git://github.com/martinetd/linux

Pull 9p updates from Dominique Martinet:
 "Fixes, split 9p_net_fd, and new reviewer:

   - fix possible uninitialized memory usage for setattr

   - fix fscache reading hole in a file just after it's been grown

   - split net/9p/trans_fd.c in its own module like other transports.

     The new transport module defaults to 9P_NET and is autoloaded if
     required so users should not be impacted

   - add Christian Schoenebeck to 9p reviewers

   - some more trivial cleanup"

* tag '9p-for-5.17-rc1' of git://github.com/martinetd/linux:
  9p: fix enodata when reading growing file
  net/9p: show error message if user 'msize' cannot be satisfied
  MAINTAINERS: 9p: add Christian Schoenebeck as reviewer
  9p: only copy valid iattrs in 9P2000.L setattr implementation
  9p: Use BUG_ON instead of if condition followed by BUG.
  net/p9: load default transports
  9p/xen: autoload when xenbus service is available
  9p/trans_fd: split into dedicated module
  fs: 9p: remove unneeded variable
  9p/trans_virtio: Fix typo in the comment for p9_virtio_create()

MAINTAINERS

@@ -226,6 +226,7 @@ F:	drivers/net/ethernet/8390/
 M:	Eric Van Hensbergen <ericvh@gmail.com>
 M:	Latchesar Ionkov <lucho@ionkov.net>
 M:	Dominique Martinet <asmadeus@codewreck.org>
+R:	Christian Schoenebeck <linux_oss@crudebyte.com>
 L:	v9fs-developer@lists.sourceforge.net
 S:	Maintained
 W:	http://swik.net/v9fs

fs/9p/vfs_addr.c

@@ -43,6 +43,11 @@ static void v9fs_req_issue_op(struct netfs_read_subrequest *subreq)
 	iov_iter_xarray(&to, READ, &rreq->mapping->i_pages, pos, len);
 
 	total = p9_client_read(fid, pos, &to, &err);
+
+	/* if we just extended the file size, any portion not in
+	 * cache won't be on server and is zeroes */
+	__set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
+
 	netfs_subreq_terminated(subreq, err ?: total, false);
 }
 

fs/9p/vfs_file.c

@@ -115,7 +115,6 @@ out_error:
 
 static int v9fs_file_lock(struct file *filp, int cmd, struct file_lock *fl)
 {
-	int res = 0;
 	struct inode *inode = file_inode(filp);
 
 	p9_debug(P9_DEBUG_VFS, "filp: %p lock: %p\n", filp, fl);
@@ -125,7 +124,7 @@ static int v9fs_file_lock(struct file *filp, int cmd, struct file_lock *fl)
 		invalidate_mapping_pages(&inode->i_data, 0, -1);
 	}
 
-	return res;
+	return 0;
 }
 
 static int v9fs_file_do_lock(struct file *filp, int cmd, struct file_lock *fl)
@@ -140,8 +139,7 @@ static int v9fs_file_do_lock(struct file *filp, int cmd, struct file_lock *fl)
 	fid = filp->private_data;
 	BUG_ON(fid == NULL);
 
-	if ((fl->fl_flags & FL_POSIX) != FL_POSIX)
-		BUG();
+	BUG_ON((fl->fl_flags & FL_POSIX) != FL_POSIX);
 
 	res = locks_lock_file_wait(filp, fl);
 	if (res < 0)

fs/9p/vfs_inode_dotl.c

@@ -552,7 +552,10 @@ int v9fs_vfs_setattr_dotl(struct user_namespace *mnt_userns,
 {
 	int retval, use_dentry = 0;
 	struct p9_fid *fid = NULL;
-	struct p9_iattr_dotl p9attr;
+	struct p9_iattr_dotl p9attr = {
+		.uid = INVALID_UID,
+		.gid = INVALID_GID,
+	};
 	struct inode *inode = d_inode(dentry);
 
 	p9_debug(P9_DEBUG_VFS, "\n");
@@ -562,14 +565,22 @@ int v9fs_vfs_setattr_dotl(struct user_namespace *mnt_userns,
 		return retval;
 
 	p9attr.valid = v9fs_mapped_iattr_valid(iattr->ia_valid);
-	p9attr.mode = iattr->ia_mode;
-	p9attr.uid = iattr->ia_uid;
-	p9attr.gid = iattr->ia_gid;
-	p9attr.size = iattr->ia_size;
-	p9attr.atime_sec = iattr->ia_atime.tv_sec;
-	p9attr.atime_nsec = iattr->ia_atime.tv_nsec;
-	p9attr.mtime_sec = iattr->ia_mtime.tv_sec;
-	p9attr.mtime_nsec = iattr->ia_mtime.tv_nsec;
+	if (iattr->ia_valid & ATTR_MODE)
+		p9attr.mode = iattr->ia_mode;
+	if (iattr->ia_valid & ATTR_UID)
+		p9attr.uid = iattr->ia_uid;
+	if (iattr->ia_valid & ATTR_GID)
+		p9attr.gid = iattr->ia_gid;
+	if (iattr->ia_valid & ATTR_SIZE)
+		p9attr.size = iattr->ia_size;
+	if (iattr->ia_valid & ATTR_ATIME_SET) {
+		p9attr.atime_sec = iattr->ia_atime.tv_sec;
+		p9attr.atime_nsec = iattr->ia_atime.tv_nsec;
+	}
+	if (iattr->ia_valid & ATTR_MTIME_SET) {
+		p9attr.mtime_sec = iattr->ia_mtime.tv_sec;
+		p9attr.mtime_nsec = iattr->ia_mtime.tv_nsec;
+	}
 
 	if (iattr->ia_valid & ATTR_FILE) {
 		fid = iattr->ia_file->private_data;

include/net/9p/9p.h

@@ -551,6 +551,4 @@ struct p9_fcall {
 int p9_errstr2errno(char *errstr, int len);
 
 int p9_error_init(void);
-int p9_trans_fd_init(void);
-void p9_trans_fd_exit(void);
 #endif /* NET_9P_H */

include/net/9p/transport.h

@@ -54,7 +54,7 @@ struct p9_trans_module {
 
 void v9fs_register_trans(struct p9_trans_module *m);
 void v9fs_unregister_trans(struct p9_trans_module *m);
-struct p9_trans_module *v9fs_get_trans_by_name(char *s);
+struct p9_trans_module *v9fs_get_trans_by_name(const char *s);
 struct p9_trans_module *v9fs_get_default_trans(void);
 void v9fs_put_trans(struct p9_trans_module *m);
 

net/9p/Kconfig

@@ -15,6 +15,13 @@ menuconfig NET_9P
 
 if NET_9P
 
+config NET_9P_FD
+	default NET_9P
+	tristate "9P FD Transport"
+	help
+	  This builds support for transports over TCP, Unix sockets and
+	  filedescriptors.
+
 config NET_9P_VIRTIO
 	depends on VIRTIO
 	tristate "9P Virtio Transport"

net/9p/Makefile

@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_NET_9P) := 9pnet.o
+obj-$(CONFIG_NET_9P_FD) += 9pnet_fd.o
 obj-$(CONFIG_NET_9P_XEN) += 9pnet_xen.o
 obj-$(CONFIG_NET_9P_VIRTIO) += 9pnet_virtio.o
 obj-$(CONFIG_NET_9P_RDMA) += 9pnet_rdma.o
@@ -9,9 +10,11 @@ obj-$(CONFIG_NET_9P_RDMA) += 9pnet_rdma.o
 	client.o \
 	error.o \
 	protocol.o \
-	trans_fd.o \
 	trans_common.o \
 
+9pnet_fd-objs := \
+	trans_fd.o \
+
 9pnet_virtio-objs := \
 	trans_virtio.o \
 

net/9p/client.c

@@ -1038,8 +1038,13 @@ struct p9_client *p9_client_create(const char *dev_name, char *options)
 	if (err)
 		goto put_trans;
 
-	if (clnt->msize > clnt->trans_mod->maxsize)
+	if (clnt->msize > clnt->trans_mod->maxsize) {
 		clnt->msize = clnt->trans_mod->maxsize;
+		pr_info("Limiting 'msize' to %d as this is the maximum "
+			"supported by transport %s\n",
+			clnt->msize, clnt->trans_mod->name
+		);
+	}
 
 	if (clnt->msize < 4096) {
 		p9_debug(P9_DEBUG_ERROR,

net/9p/mod.c

@@ -83,7 +83,7 @@ void v9fs_unregister_trans(struct p9_trans_module *m)
 }
 EXPORT_SYMBOL(v9fs_unregister_trans);
 
-static struct p9_trans_module *_p9_get_trans_by_name(char *s)
+static struct p9_trans_module *_p9_get_trans_by_name(const char *s)
 {
 	struct p9_trans_module *t, *found = NULL;
 
@@ -106,7 +106,7 @@ static struct p9_trans_module *_p9_get_trans_by_name(char *s)
  * @s: string identifying transport
  *
  */
-struct p9_trans_module *v9fs_get_trans_by_name(char *s)
+struct p9_trans_module *v9fs_get_trans_by_name(const char *s)
 {
 	struct p9_trans_module *found = NULL;
 
@@ -123,6 +123,10 @@ struct p9_trans_module *v9fs_get_trans_by_name(char *s)
 }
 EXPORT_SYMBOL(v9fs_get_trans_by_name);
 
+static const char * const v9fs_default_transports[] = {
+	"virtio", "tcp", "fd", "unix", "xen", "rdma",
+};
+
 /**
  * v9fs_get_default_trans - get the default transport
  *
@@ -131,6 +135,7 @@ EXPORT_SYMBOL(v9fs_get_trans_by_name);
 struct p9_trans_module *v9fs_get_default_trans(void)
 {
 	struct p9_trans_module *t, *found = NULL;
+	int i;
 
 	spin_lock(&v9fs_trans_lock);
 
@@ -148,6 +153,10 @@ struct p9_trans_module *v9fs_get_default_trans(void)
 			}
 
 	spin_unlock(&v9fs_trans_lock);
+
+	for (i = 0; !found && i < ARRAY_SIZE(v9fs_default_transports); i++)
+		found = v9fs_get_trans_by_name(v9fs_default_transports[i]);
+
 	return found;
 }
 EXPORT_SYMBOL(v9fs_get_default_trans);
@@ -177,7 +186,6 @@ static int __init init_p9(void)
 
 	p9_error_init();
 	pr_info("Installing 9P2000 support\n");
-	p9_trans_fd_init();
 
 	return ret;
 }
@@ -191,7 +199,6 @@ static void __exit exit_p9(void)
 {
 	pr_info("Unloading 9P2000 support\n");
 
-	p9_trans_fd_exit();
 	p9_client_exit();
 }
 

net/9p/trans_fd.c

@@ -1090,6 +1090,7 @@ static struct p9_trans_module p9_tcp_trans = {
 	.show_options = p9_fd_show_options,
 	.owner = THIS_MODULE,
 };
+MODULE_ALIAS_9P("tcp");
 
 static struct p9_trans_module p9_unix_trans = {
 	.name = "unix",
@@ -1103,6 +1104,7 @@ static struct p9_trans_module p9_unix_trans = {
 	.show_options = p9_fd_show_options,
 	.owner = THIS_MODULE,
 };
+MODULE_ALIAS_9P("unix");
 
 static struct p9_trans_module p9_fd_trans = {
 	.name = "fd",
@@ -1116,6 +1118,7 @@ static struct p9_trans_module p9_fd_trans = {
 	.show_options = p9_fd_show_options,
 	.owner = THIS_MODULE,
 };
+MODULE_ALIAS_9P("fd");
 
 /**
  * p9_poll_workfn - poll worker thread
@@ -1149,7 +1152,7 @@ static void p9_poll_workfn(struct work_struct *work)
 	p9_debug(P9_DEBUG_TRANS, "finish\n");
 }
 
-int p9_trans_fd_init(void)
+static int __init p9_trans_fd_init(void)
 {
 	v9fs_register_trans(&p9_tcp_trans);
 	v9fs_register_trans(&p9_unix_trans);
@@ -1158,10 +1161,17 @@ int p9_trans_fd_init(void)
 	return 0;
 }
 
-void p9_trans_fd_exit(void)
+static void __exit p9_trans_fd_exit(void)
 {
 	flush_work(&p9_poll_work);
 	v9fs_unregister_trans(&p9_tcp_trans);
 	v9fs_unregister_trans(&p9_unix_trans);
 	v9fs_unregister_trans(&p9_fd_trans);
 }
+
+module_init(p9_trans_fd_init);
+module_exit(p9_trans_fd_exit);
+
+MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
+MODULE_DESCRIPTION("Filedescriptor Transport for 9P");
+MODULE_LICENSE("GPL");

net/9p/trans_virtio.c

@@ -648,7 +648,7 @@ fail:
  * @args: args passed from sys_mount() for per-transport options (unused)
  *
  * This sets up a transport channel for 9p communication.  Right now
- * we only match the first available channel, but eventually we couldlook up
+ * we only match the first available channel, but eventually we could look up
  * alternate channels by matching devname versus a virtio_config entry.
  * We use a simple reference count mechanism to ensure that only a single
  * mount has a channel open at a time.

net/9p/trans_xen.c

@@ -538,6 +538,7 @@ static void p9_trans_xen_exit(void)
 }
 module_exit(p9_trans_xen_exit);
 
+MODULE_ALIAS("xen:9pfs");
 MODULE_AUTHOR("Stefano Stabellini <stefano@aporeto.com>");
 MODULE_DESCRIPTION("Xen Transport for 9P");
 MODULE_LICENSE("GPL");