[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>

5 files changed, 555 insertions, 1 deletions

diff --git a/fs/fuse/Makefile b/fs/fuse/Makefile
index 21021c356481..c34e268a0ed3 100644
--- a/fs/fuse/Makefile
+++ b/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
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 9aaf10a6588f..e8f3170946f1 100644
--- a/fs/fuse/dev.c
+++ b/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);
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;
+}
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 50ad6a0c39bf..8d91e1492f96 100644
--- a/fs/fuse/fuse_i.h
+++ b/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;
@@ -240,6 +249,38 @@ 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
  */
@@ -307,6 +348,16 @@ 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
  */
 void fuse_send_init(struct fuse_conn *fc);
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 33fad334ba70..41498a1952a0 100644
--- a/fs/fuse/inode.c
+++ b/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,
 };