fs/9p: Add OS dependent open flags in 9p protocol

Some of the flags are OS/arch dependent we add a 9p
protocol value which maps to asm-generic/fcntl.h values in Linux
Based on the original patch from Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

fs/9p/v9fs_vfs.h

@@ -83,4 +83,6 @@ static inline void v9fs_invalidate_inode_attr(struct inode *inode)
 	v9inode->cache_validity |= V9FS_INO_INVALID_ATTR;
 	return;
 }
+
+int v9fs_open_to_dotl_flags(int flags);
 #endif

fs/9p/vfs_file.c

@@ -65,7 +65,7 @@ int v9fs_file_open(struct inode *inode, struct file *file)
 	v9inode = V9FS_I(inode);
 	v9ses = v9fs_inode2v9ses(inode);
 	if (v9fs_proto_dotl(v9ses))
-		omode = file->f_flags;
+		omode = v9fs_open_to_dotl_flags(file->f_flags);
 	else
 		omode = v9fs_uflags2omode(file->f_flags,
 					v9fs_proto_dotu(v9ses));

fs/9p/vfs_inode.c

@@ -552,6 +552,19 @@ v9fs_inode_from_fid(struct v9fs_session_info *v9ses, struct p9_fid *fid,
 	return inode;
 }
 
+/**
+ * v9fs_at_to_dotl_flags- convert Linux specific AT flags to
+ * plan 9 AT flag.
+ * @flags: flags to convert
+ */
+static int v9fs_at_to_dotl_flags(int flags)
+{
+	int rflags = 0;
+	if (flags & AT_REMOVEDIR)
+		rflags |= P9_DOTL_AT_REMOVEDIR;
+	return rflags;
+}
+
 /**
  * v9fs_remove - helper function to remove files and directories
  * @dir: directory inode that is being deleted
@@ -579,7 +592,8 @@ static int v9fs_remove(struct inode *dir, struct dentry *dentry, int flags)
 		return retval;
 	}
 	if (v9fs_proto_dotl(v9ses))
-		retval = p9_client_unlinkat(dfid, dentry->d_name.name, flags);
+		retval = p9_client_unlinkat(dfid, dentry->d_name.name,
+					    v9fs_at_to_dotl_flags(flags));
 	if (retval == -EOPNOTSUPP) {
 		/* Try the one based on path */
 		v9fid = v9fs_fid_clone(dentry);

fs/9p/vfs_inode_dotl.c

@@ -191,6 +191,58 @@ v9fs_inode_from_fid_dotl(struct v9fs_session_info *v9ses, struct p9_fid *fid,
 	return inode;
 }
 
+struct dotl_openflag_map {
+	int open_flag;
+	int dotl_flag;
+};
+
+static int v9fs_mapped_dotl_flags(int flags)
+{
+	int i;
+	int rflags = 0;
+	struct dotl_openflag_map dotl_oflag_map[] = {
+		{ O_CREAT,	P9_DOTL_CREATE },
+		{ O_EXCL,	P9_DOTL_EXCL },
+		{ O_NOCTTY,	P9_DOTL_NOCTTY },
+		{ O_TRUNC,	P9_DOTL_TRUNC },
+		{ O_APPEND,	P9_DOTL_APPEND },
+		{ O_NONBLOCK,	P9_DOTL_NONBLOCK },
+		{ O_DSYNC,	P9_DOTL_DSYNC },
+		{ FASYNC,	P9_DOTL_FASYNC },
+		{ O_DIRECT,	P9_DOTL_DIRECT },
+		{ O_LARGEFILE,	P9_DOTL_LARGEFILE },
+		{ O_DIRECTORY,	P9_DOTL_DIRECTORY },
+		{ O_NOFOLLOW,	P9_DOTL_NOFOLLOW },
+		{ O_NOATIME,	P9_DOTL_NOATIME },
+		{ O_CLOEXEC,	P9_DOTL_CLOEXEC },
+		{ O_SYNC,	P9_DOTL_SYNC},
+	};
+	for (i = 0; i < ARRAY_SIZE(dotl_oflag_map); i++) {
+		if (flags & dotl_oflag_map[i].open_flag)
+			rflags |= dotl_oflag_map[i].dotl_flag;
+	}
+	return rflags;
+}
+
+/**
+ * v9fs_open_to_dotl_flags- convert Linux specific open flags to
+ * plan 9 open flag.
+ * @flags: flags to convert
+ */
+int v9fs_open_to_dotl_flags(int flags)
+{
+	int rflags = 0;
+
+	/*
+	 * We have same bits for P9_DOTL_READONLY, P9_DOTL_WRONLY
+	 * and P9_DOTL_NOACCESS
+	 */
+	rflags |= flags & O_ACCMODE;
+	rflags |= v9fs_mapped_dotl_flags(flags);
+
+	return rflags;
+}
+
 /**
  * v9fs_vfs_create_dotl - VFS hook to create files for 9P2000.L protocol.
  * @dir: directory inode that is being created
@@ -259,7 +311,8 @@ v9fs_vfs_create_dotl(struct inode *dir, struct dentry *dentry, int omode,
 			   "Failed to get acl values in creat %d\n", err);
 		goto error;
 	}
-	err = p9_client_create_dotl(ofid, name, flags, mode, gid, &qid);
+	err = p9_client_create_dotl(ofid, name, v9fs_open_to_dotl_flags(flags),
+				    mode, gid, &qid);
 	if (err < 0) {
 		P9_DPRINTK(P9_DEBUG_VFS,
 				"p9_client_open_dotl failed in creat %d\n",

include/net/9p/9p.h

@@ -288,6 +288,30 @@ enum p9_perm_t {
 	P9_DMSETVTX = 0x00010000,
 };
 
+/* 9p2000.L open flags */
+#define P9_DOTL_RDONLY        00000000
+#define P9_DOTL_WRONLY        00000001
+#define P9_DOTL_RDWR          00000002
+#define P9_DOTL_NOACCESS      00000003
+#define P9_DOTL_CREATE        00000100
+#define P9_DOTL_EXCL          00000200
+#define P9_DOTL_NOCTTY        00000400
+#define P9_DOTL_TRUNC         00001000
+#define P9_DOTL_APPEND        00002000
+#define P9_DOTL_NONBLOCK      00004000
+#define P9_DOTL_DSYNC         00010000
+#define P9_DOTL_FASYNC        00020000
+#define P9_DOTL_DIRECT        00040000
+#define P9_DOTL_LARGEFILE     00100000
+#define P9_DOTL_DIRECTORY     00200000
+#define P9_DOTL_NOFOLLOW      00400000
+#define P9_DOTL_NOATIME       01000000
+#define P9_DOTL_CLOEXEC       02000000
+#define P9_DOTL_SYNC          04000000
+
+/* 9p2000.L at flags */
+#define P9_DOTL_AT_REMOVEDIR		0x200
+
 /**
  * enum p9_qid_t - QID types
  * @P9_QTDIR: directory