[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>

1 files changed, 413 insertions, 0 deletions

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
new file mode 100644
index 000000000000..a89730e70c58
--- /dev/null
+++ b/fs/fuse/dir.c
@@ -0,0 +1,413 @@
+/*
+  FUSE: Filesystem in Userspace
+  Copyright (C) 2001-2005  Miklos Szeredi <miklos@szeredi.hu>
+
+  This program can be distributed under the terms of the GNU GPL.
+  See the file COPYING.
+*/
+
+#include "fuse_i.h"
+
+#include <linux/pagemap.h>
+#include <linux/file.h>
+#include <linux/gfp.h>
+#include <linux/sched.h>
+#include <linux/namei.h>
+
+static inline unsigned long time_to_jiffies(unsigned long sec,
+					    unsigned long nsec)
+{
+	struct timespec ts = {sec, nsec};
+	return jiffies + timespec_to_jiffies(&ts);
+}
+
+static void fuse_lookup_init(struct fuse_req *req, struct inode *dir,
+			     struct dentry *entry,
+			     struct fuse_entry_out *outarg)
+{
+	req->in.h.opcode = FUSE_LOOKUP;
+	req->in.h.nodeid = get_node_id(dir);
+	req->inode = dir;
+	req->in.numargs = 1;
+	req->in.args[0].size = entry->d_name.len + 1;
+	req->in.args[0].value = entry->d_name.name;
+	req->out.numargs = 1;
+	req->out.args[0].size = sizeof(struct fuse_entry_out);
+	req->out.args[0].value = outarg;
+}
+
+static int fuse_dentry_revalidate(struct dentry *entry, struct nameidata *nd)
+{
+	if (!entry->d_inode || is_bad_inode(entry->d_inode))
+		return 0;
+	else if (time_after(jiffies, entry->d_time)) {
+		int err;
+		int version;
+		struct fuse_entry_out outarg;
+		struct inode *inode = entry->d_inode;
+		struct fuse_inode *fi = get_fuse_inode(inode);
+		struct fuse_conn *fc = get_fuse_conn(inode);
+		struct fuse_req *req = fuse_get_request_nonint(fc);
+		if (!req)
+			return 0;
+
+		fuse_lookup_init(req, entry->d_parent->d_inode, entry, &outarg);
+		request_send_nonint(fc, req);
+		version = req->out.h.unique;
+		err = req->out.h.error;
+		fuse_put_request(fc, req);
+		if (err || outarg.nodeid != get_node_id(inode) ||
+		    (outarg.attr.mode ^ inode->i_mode) & S_IFMT)
+			return 0;
+
+		fuse_change_attributes(inode, &outarg.attr);
+		inode->i_version = version;
+		entry->d_time = time_to_jiffies(outarg.entry_valid,
+						outarg.entry_valid_nsec);
+		fi->i_time = time_to_jiffies(outarg.attr_valid,
+					     outarg.attr_valid_nsec);
+	}
+	return 1;
+}
+
+static struct dentry_operations fuse_dentry_operations = {
+	.d_revalidate	= fuse_dentry_revalidate,
+};
+
+static int fuse_lookup_iget(struct inode *dir, struct dentry *entry,
+			    struct inode **inodep)
+{
+	int err;
+	int version;
+	struct fuse_entry_out outarg;
+	struct inode *inode = NULL;
+	struct fuse_conn *fc = get_fuse_conn(dir);
+	struct fuse_req *req;
+
+	if (entry->d_name.len > FUSE_NAME_MAX)
+		return -ENAMETOOLONG;
+
+	req = fuse_get_request(fc);
+	if (!req)
+		return -ERESTARTNOINTR;
+
+	fuse_lookup_init(req, dir, entry, &outarg);
+	request_send(fc, req);
+	version = req->out.h.unique;
+	err = req->out.h.error;
+	if (!err) {
+		inode = fuse_iget(dir->i_sb, outarg.nodeid, outarg.generation,
+				  &outarg.attr, version);
+		if (!inode) {
+			fuse_send_forget(fc, req, outarg.nodeid, version);
+			return -ENOMEM;
+		}
+	}
+	fuse_put_request(fc, req);
+	if (err && err != -ENOENT)
+		return err;
+
+	if (inode) {
+		struct fuse_inode *fi = get_fuse_inode(inode);
+		entry->d_time =	time_to_jiffies(outarg.entry_valid,
+						outarg.entry_valid_nsec);
+		fi->i_time = time_to_jiffies(outarg.attr_valid,
+					     outarg.attr_valid_nsec);
+	}
+
+	entry->d_op = &fuse_dentry_operations;
+	*inodep = inode;
+	return 0;
+}
+
+int fuse_do_getattr(struct inode *inode)
+{
+	int err;
+	struct fuse_attr_out arg;
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	struct fuse_req *req = fuse_get_request(fc);
+	if (!req)
+		return -ERESTARTNOINTR;
+
+	req->in.h.opcode = FUSE_GETATTR;
+	req->in.h.nodeid = get_node_id(inode);
+	req->inode = inode;
+	req->out.numargs = 1;
+	req->out.args[0].size = sizeof(arg);
+	req->out.args[0].value = &arg;
+	request_send(fc, req);
+	err = req->out.h.error;
+	fuse_put_request(fc, req);
+	if (!err) {
+		if ((inode->i_mode ^ arg.attr.mode) & S_IFMT) {
+			make_bad_inode(inode);
+			err = -EIO;
+		} else {
+			struct fuse_inode *fi = get_fuse_inode(inode);
+			fuse_change_attributes(inode, &arg.attr);
+			fi->i_time = time_to_jiffies(arg.attr_valid,
+						     arg.attr_valid_nsec);
+		}
+	}
+	return err;
+}
+
+static int fuse_revalidate(struct dentry *entry)
+{
+	struct inode *inode = entry->d_inode;
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	struct fuse_conn *fc = get_fuse_conn(inode);
+
+	if (get_node_id(inode) == FUSE_ROOT_ID) {
+		if (current->fsuid != fc->user_id)
+			return -EACCES;
+	} else if (time_before_eq(jiffies, fi->i_time))
+		return 0;
+
+	return fuse_do_getattr(inode);
+}
+
+static int fuse_permission(struct inode *inode, int mask, struct nameidata *nd)
+{
+	struct fuse_conn *fc = get_fuse_conn(inode);
+
+	if (current->fsuid != fc->user_id)
+		return -EACCES;
+	else {
+		int mode = inode->i_mode;
+		if ((mask & MAY_WRITE) && IS_RDONLY(inode) &&
+                    (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
+                        return -EROFS;
+		if ((mask & MAY_EXEC) && !S_ISDIR(mode) && !(mode & S_IXUGO))
+			return -EACCES;
+		return 0;
+	}
+}
+
+static int parse_dirfile(char *buf, size_t nbytes, struct file *file,
+			 void *dstbuf, filldir_t filldir)
+{
+	while (nbytes >= FUSE_NAME_OFFSET) {
+		struct fuse_dirent *dirent = (struct fuse_dirent *) buf;
+		size_t reclen = FUSE_DIRENT_SIZE(dirent);
+		int over;
+		if (!dirent->namelen || dirent->namelen > FUSE_NAME_MAX)
+			return -EIO;
+		if (reclen > nbytes)
+			break;
+
+		over = filldir(dstbuf, dirent->name, dirent->namelen,
+			       file->f_pos, dirent->ino, dirent->type);
+		if (over)
+			break;
+
+		buf += reclen;
+		nbytes -= reclen;
+		file->f_pos = dirent->off;
+	}
+
+	return 0;
+}
+
+static int fuse_checkdir(struct file *cfile, struct file *file)
+{
+	struct inode *inode;
+	if (!cfile)
+		return -EIO;
+	inode = cfile->f_dentry->d_inode;
+	if (!S_ISREG(inode->i_mode)) {
+		fput(cfile);
+		return -EIO;
+	}
+
+	file->private_data = cfile;
+	return 0;
+}
+
+static int fuse_getdir(struct file *file)
+{
+	struct inode *inode = file->f_dentry->d_inode;
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	struct fuse_req *req = fuse_get_request(fc);
+	struct fuse_getdir_out_i outarg;
+	int err;
+
+	if (!req)
+		return -ERESTARTNOINTR;
+
+	req->in.h.opcode = FUSE_GETDIR;
+	req->in.h.nodeid = get_node_id(inode);
+	req->inode = inode;
+	req->out.numargs = 1;
+	req->out.args[0].size = sizeof(struct fuse_getdir_out);
+	req->out.args[0].value = &outarg;
+	request_send(fc, req);
+	err = req->out.h.error;
+	fuse_put_request(fc, req);
+	if (!err)
+		err = fuse_checkdir(outarg.file, file);
+	return err;
+}
+
+static int fuse_readdir(struct file *file, void *dstbuf, filldir_t filldir)
+{
+	struct file *cfile = file->private_data;
+	char *buf;
+	int ret;
+
+	if (!cfile) {
+		ret = fuse_getdir(file);
+		if (ret)
+			return ret;
+
+		cfile = file->private_data;
+	}
+
+	buf = (char *) __get_free_page(GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = kernel_read(cfile, file->f_pos, buf, PAGE_SIZE);
+	if (ret > 0)
+		ret = parse_dirfile(buf, ret, file, dstbuf, filldir);
+
+	free_page((unsigned long) buf);
+	return ret;
+}
+
+static char *read_link(struct dentry *dentry)
+{
+	struct inode *inode = dentry->d_inode;
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	struct fuse_req *req = fuse_get_request(fc);
+	char *link;
+
+	if (!req)
+		return ERR_PTR(-ERESTARTNOINTR);
+
+	link = (char *) __get_free_page(GFP_KERNEL);
+	if (!link) {
+		link = ERR_PTR(-ENOMEM);
+		goto out;
+	}
+	req->in.h.opcode = FUSE_READLINK;
+	req->in.h.nodeid = get_node_id(inode);
+	req->inode = inode;
+	req->out.argvar = 1;
+	req->out.numargs = 1;
+	req->out.args[0].size = PAGE_SIZE - 1;
+	req->out.args[0].value = link;
+	request_send(fc, req);
+	if (req->out.h.error) {
+		free_page((unsigned long) link);
+		link = ERR_PTR(req->out.h.error);
+	} else
+		link[req->out.args[0].size] = '\0';
+ out:
+	fuse_put_request(fc, req);
+	return link;
+}
+
+static void free_link(char *link)
+{
+	if (!IS_ERR(link))
+		free_page((unsigned long) link);
+}
+
+static void *fuse_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+	nd_set_link(nd, read_link(dentry));
+	return NULL;
+}
+
+static void fuse_put_link(struct dentry *dentry, struct nameidata *nd, void *c)
+{
+	free_link(nd_get_link(nd));
+}
+
+static int fuse_dir_open(struct inode *inode, struct file *file)
+{
+	file->private_data = NULL;
+	return 0;
+}
+
+static int fuse_dir_release(struct inode *inode, struct file *file)
+{
+	struct file *cfile = file->private_data;
+
+	if (cfile)
+		fput(cfile);
+
+	return 0;
+}
+
+static int fuse_getattr(struct vfsmount *mnt, struct dentry *entry,
+			struct kstat *stat)
+{
+	struct inode *inode = entry->d_inode;
+	int err = fuse_revalidate(entry);
+	if (!err)
+		generic_fillattr(inode, stat);
+
+	return err;
+}
+
+static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry,
+				  struct nameidata *nd)
+{
+	struct inode *inode;
+	int err = fuse_lookup_iget(dir, entry, &inode);
+	if (err)
+		return ERR_PTR(err);
+	if (inode && S_ISDIR(inode->i_mode)) {
+		/* Don't allow creating an alias to a directory  */
+		struct dentry *alias = d_find_alias(inode);
+		if (alias && !(alias->d_flags & DCACHE_DISCONNECTED)) {
+			dput(alias);
+			iput(inode);
+			return ERR_PTR(-EIO);
+		}
+	}
+	return d_splice_alias(inode, entry);
+}
+
+static struct inode_operations fuse_dir_inode_operations = {
+	.lookup		= fuse_lookup,
+	.permission	= fuse_permission,
+	.getattr	= fuse_getattr,
+};
+
+static struct file_operations fuse_dir_operations = {
+	.read		= generic_read_dir,
+	.readdir	= fuse_readdir,
+	.open		= fuse_dir_open,
+	.release	= fuse_dir_release,
+};
+
+static struct inode_operations fuse_common_inode_operations = {
+	.permission	= fuse_permission,
+	.getattr	= fuse_getattr,
+};
+
+static struct inode_operations fuse_symlink_inode_operations = {
+	.follow_link	= fuse_follow_link,
+	.put_link	= fuse_put_link,
+	.readlink	= generic_readlink,
+	.getattr	= fuse_getattr,
+};
+
+void fuse_init_common(struct inode *inode)
+{
+	inode->i_op = &fuse_common_inode_operations;
+}
+
+void fuse_init_dir(struct inode *inode)
+{
+	inode->i_op = &fuse_dir_inode_operations;
+	inode->i_fop = &fuse_dir_operations;
+}
+
+void fuse_init_symlink(struct inode *inode)
+{
+	inode->i_op = &fuse_symlink_inode_operations;
+}