[PATCH] FUSE - read-only operations

This patch adds the read-only filesystem operations of FUSE.

This contains the following files:

 o dir.c
    - directory, symlink and file-inode operations

The following operations are added:

 o lookup
 o getattr
 o readlink
 o follow_link
 o directory open
 o readdir
 o directory release
 o permission
 o dentry revalidate
 o statfs
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/fuse/Makefile

@@ -4,4 +4,4 @@
 
 obj-$(CONFIG_FUSE_FS) += fuse.o
 
-fuse-objs := dev.o inode.o
+fuse-objs := dev.o dir.o inode.o

fs/fuse/dev.c

@@ -691,6 +691,13 @@ static struct fuse_req *request_find(struct fuse_conn *fc, u64 unique)
 	return NULL;
 }
 
+/* fget() needs to be done in this context */
+static void process_getdir(struct fuse_req *req)
+{
+	struct fuse_getdir_out_i *arg = req->out.args[0].value;
+	arg->file = fget(arg->fd);
+}
+
 static int copy_out_args(struct fuse_copy_state *cs, struct fuse_out *out,
 			 unsigned nbytes)
 {
@@ -770,6 +777,8 @@ static ssize_t fuse_dev_writev(struct file *file, const struct iovec *iov,
 	if (!err) {
 		if (req->interrupted)
 			err = -ENOENT;
+		else if (req->in.h.opcode == FUSE_GETDIR && !oh.error)
+			process_getdir(req);
 	} else if (!req->interrupted)
 		req->out.h.error = -EIO;
 	request_end(fc, req);

fs/fuse/fuse_i.h

@@ -30,6 +30,9 @@ struct fuse_inode {
 	 * and kernel */
 	u64 nodeid;
 
+	/** The request used for sending the FORGET message */
+	struct fuse_req *forget_req;
+
 	/** Time in jiffies until the file attributes are valid */
 	unsigned long i_time;
 };
@@ -129,6 +132,7 @@ struct fuse_req {
 
 	/** Data for asynchronous requests */
 	union {
+		struct fuse_forget_in forget_in;
 		struct fuse_init_in_out init_in_out;
 	} misc;
 
@@ -197,6 +201,11 @@ struct fuse_conn {
 	struct backing_dev_info bdi;
 };
 
+struct fuse_getdir_out_i {
+	int fd;
+	void *file; /* Used by kernel only */
+};
+
 static inline struct fuse_conn **get_fuse_conn_super_p(struct super_block *sb)
 {
 	return (struct fuse_conn **) &sb->s_fs_info;
@@ -239,6 +248,38 @@ extern struct file_operations fuse_dev_operations;
  */
 extern spinlock_t fuse_lock;
 
+/**
+ * Get a filled in inode
+ */
+struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid,
+			int generation, struct fuse_attr *attr, int version);
+
+/**
+ * Send FORGET command
+ */
+void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
+		      unsigned long nodeid, int version);
+
+/**
+ * Initialise inode operations on regular files and special files
+ */
+void fuse_init_common(struct inode *inode);
+
+/**
+ * Initialise inode and file operations on a directory
+ */
+void fuse_init_dir(struct inode *inode);
+
+/**
+ * Initialise inode operations on a symlink
+ */
+void fuse_init_symlink(struct inode *inode);
+
+/**
+ * Change attributes of an inode
+ */
+void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr);
+
 /**
  * Check if the connection can be released, and if yes, then free the
  * connection structure
@@ -306,6 +347,16 @@ void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req);
  */
 void request_send_background(struct fuse_conn *fc, struct fuse_req *req);
 
+/**
+ * Get the attributes of a file
+ */
+int fuse_do_getattr(struct inode *inode);
+
+/**
+ * Invalidate inode attributes
+ */
+void fuse_invalidate_attr(struct inode *inode);
+
 /**
  * Send the INIT message
  */

fs/fuse/inode.c

@@ -51,12 +51,20 @@ static struct inode *fuse_alloc_inode(struct super_block *sb)
 	fi = get_fuse_inode(inode);
 	fi->i_time = jiffies - 1;
 	fi->nodeid = 0;
+	fi->forget_req = fuse_request_alloc();
+	if (!fi->forget_req) {
+		kmem_cache_free(fuse_inode_cachep, inode);
+		return NULL;
+	}
 
 	return inode;
 }
 
 static void fuse_destroy_inode(struct inode *inode)
 {
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	if (fi->forget_req)
+		fuse_request_free(fi->forget_req);
 	kmem_cache_free(fuse_inode_cachep, inode);
 }
 
@@ -65,8 +73,27 @@ static void fuse_read_inode(struct inode *inode)
 	/* No op */
 }
 
+void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
+		      unsigned long nodeid, int version)
+{
+	struct fuse_forget_in *inarg = &req->misc.forget_in;
+	inarg->version = version;
+	req->in.h.opcode = FUSE_FORGET;
+	req->in.h.nodeid = nodeid;
+	req->in.numargs = 1;
+	req->in.args[0].size = sizeof(struct fuse_forget_in);
+	req->in.args[0].value = inarg;
+	request_send_noreply(fc, req);
+}
+
 static void fuse_clear_inode(struct inode *inode)
 {
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	if (fc) {
+		struct fuse_inode *fi = get_fuse_inode(inode);
+		fuse_send_forget(fc, fi->forget_req, fi->nodeid, inode->i_version);
+		fi->forget_req = NULL;
+	}
 }
 
 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr)
@@ -94,6 +121,22 @@ static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)
 {
 	inode->i_mode = attr->mode & S_IFMT;
 	i_size_write(inode, attr->size);
+	if (S_ISREG(inode->i_mode)) {
+		fuse_init_common(inode);
+	} else if (S_ISDIR(inode->i_mode))
+		fuse_init_dir(inode);
+	else if (S_ISLNK(inode->i_mode))
+		fuse_init_symlink(inode);
+	else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
+		 S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
+		fuse_init_common(inode);
+		init_special_inode(inode, inode->i_mode,
+				   new_decode_dev(attr->rdev));
+	} else {
+		/* Don't let user create weird files */
+		inode->i_mode = S_IFREG;
+		fuse_init_common(inode);
+	}
 }
 
 static int fuse_inode_eq(struct inode *inode, void *_nodeidp)
@@ -158,6 +201,43 @@ static void fuse_put_super(struct super_block *sb)
 	spin_unlock(&fuse_lock);
 }
 
+static void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatfs *attr)
+{
+	stbuf->f_type    = FUSE_SUPER_MAGIC;
+	stbuf->f_bsize   = attr->bsize;
+	stbuf->f_blocks  = attr->blocks;
+	stbuf->f_bfree   = attr->bfree;
+	stbuf->f_bavail  = attr->bavail;
+	stbuf->f_files   = attr->files;
+	stbuf->f_ffree   = attr->ffree;
+	stbuf->f_namelen = attr->namelen;
+	/* fsid is left zero */
+}
+
+static int fuse_statfs(struct super_block *sb, struct kstatfs *buf)
+{
+	struct fuse_conn *fc = get_fuse_conn_super(sb);
+	struct fuse_req *req;
+	struct fuse_statfs_out outarg;
+	int err;
+
+        req = fuse_get_request(fc);
+	if (!req)
+		return -ERESTARTSYS;
+
+	req->in.numargs = 0;
+	req->in.h.opcode = FUSE_STATFS;
+	req->out.numargs = 1;
+	req->out.args[0].size = sizeof(outarg);
+	req->out.args[0].value = &outarg;
+	request_send(fc, req);
+	err = req->out.h.error;
+	if (!err)
+		convert_fuse_statfs(buf, &outarg.st);
+	fuse_put_request(fc, req);
+	return err;
+}
+
 enum {
 	OPT_FD,
 	OPT_ROOTMODE,
@@ -318,6 +398,7 @@ static struct super_operations fuse_super_operations = {
 	.read_inode	= fuse_read_inode,
 	.clear_inode	= fuse_clear_inode,
 	.put_super	= fuse_put_super,
+	.statfs		= fuse_statfs,
 	.show_options	= fuse_show_options,
 };
 

include/linux/fuse.h

@@ -42,13 +42,61 @@ struct fuse_attr {
 	__u32	rdev;
 };
 
+struct fuse_kstatfs {
+	__u64	blocks;
+	__u64	bfree;
+	__u64	bavail;
+	__u64	files;
+	__u64	ffree;
+	__u32	bsize;
+	__u32	namelen;
+};
+
 enum fuse_opcode {
+	FUSE_LOOKUP	   = 1,
+	FUSE_FORGET	   = 2,  /* no reply */
+	FUSE_GETATTR	   = 3,
+	FUSE_READLINK	   = 5,
+	FUSE_GETDIR	   = 7,
+	FUSE_STATFS	   = 17,
 	FUSE_INIT          = 26
 };
 
 /* Conservative buffer size for the client */
 #define FUSE_MAX_IN 8192
 
+#define FUSE_NAME_MAX 1024
+
+struct fuse_entry_out {
+	__u64	nodeid;		/* Inode ID */
+	__u64	generation;	/* Inode generation: nodeid:gen must
+				   be unique for the fs's lifetime */
+	__u64	entry_valid;	/* Cache timeout for the name */
+	__u64	attr_valid;	/* Cache timeout for the attributes */
+	__u32	entry_valid_nsec;
+	__u32	attr_valid_nsec;
+	struct fuse_attr attr;
+};
+
+struct fuse_forget_in {
+	__u64	version;
+};
+
+struct fuse_attr_out {
+	__u64	attr_valid;	/* Cache timeout for the attributes */
+	__u32	attr_valid_nsec;
+	__u32	dummy;
+	struct fuse_attr attr;
+};
+
+struct fuse_getdir_out {
+	__u32	fd;
+};
+
+struct fuse_statfs_out {
+	struct fuse_kstatfs st;
+};
+
 struct fuse_init_in_out {
 	__u32	major;
 	__u32	minor;
@@ -70,3 +118,15 @@ struct fuse_out_header {
 	__u64	unique;
 };
 
+struct fuse_dirent {
+	__u64	ino;
+	__u64	off;
+	__u32	namelen;
+	__u32	type;
+	char name[0];
+};
+
+#define FUSE_NAME_OFFSET ((unsigned) ((struct fuse_dirent *) 0)->name)
+#define FUSE_DIRENT_ALIGN(x) (((x) + sizeof(__u64) - 1) & ~(sizeof(__u64) - 1))
+#define FUSE_DIRENT_SIZE(d) \
+	FUSE_DIRENT_ALIGN(FUSE_NAME_OFFSET + (d)->namelen)