[PATCH] fuse: add POSIX file locking support
This patch adds POSIX file locking support to the fuse interface.
This implementation doesn't keep any locking state in kernel. Unlocking on
close() is handled by the FLUSH message, which now contains the lock owner id.
Mandatory locking is not supported. The filesystem may enfoce mandatory
locking in userspace if needed.
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 1d59af3..d9a8289 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -160,6 +160,18 @@
return fuse_release_common(inode, file, 0);
}
+/*
+ * It would be nice to scramble the ID space, so that the value of the
+ * files_struct pointer is not exposed to userspace. Symmetric crypto
+ * functions are overkill, since the inverse function doesn't need to
+ * be implemented (though it does have to exist). Is there something
+ * simpler?
+ */
+static inline u64 fuse_lock_owner_id(fl_owner_t id)
+{
+ return (unsigned long) id;
+}
+
static int fuse_flush(struct file *file, fl_owner_t id)
{
struct inode *inode = file->f_dentry->d_inode;
@@ -181,11 +193,13 @@
memset(&inarg, 0, sizeof(inarg));
inarg.fh = ff->fh;
+ inarg.lock_owner = fuse_lock_owner_id(id);
req->in.h.opcode = FUSE_FLUSH;
req->in.h.nodeid = get_node_id(inode);
req->in.numargs = 1;
req->in.args[0].size = sizeof(inarg);
req->in.args[0].value = &inarg;
+ req->force = 1;
request_send(fc, req);
err = req->out.h.error;
fuse_put_request(fc, req);
@@ -604,6 +618,122 @@
return 0;
}
+static int convert_fuse_file_lock(const struct fuse_file_lock *ffl,
+ struct file_lock *fl)
+{
+ switch (ffl->type) {
+ case F_UNLCK:
+ break;
+
+ case F_RDLCK:
+ case F_WRLCK:
+ if (ffl->start > OFFSET_MAX || ffl->end > OFFSET_MAX ||
+ ffl->end < ffl->start)
+ return -EIO;
+
+ fl->fl_start = ffl->start;
+ fl->fl_end = ffl->end;
+ fl->fl_pid = ffl->pid;
+ break;
+
+ default:
+ return -EIO;
+ }
+ fl->fl_type = ffl->type;
+ return 0;
+}
+
+static void fuse_lk_fill(struct fuse_req *req, struct file *file,
+ const struct file_lock *fl, int opcode, pid_t pid)
+{
+ struct inode *inode = file->f_dentry->d_inode;
+ struct fuse_file *ff = file->private_data;
+ struct fuse_lk_in *arg = &req->misc.lk_in;
+
+ arg->fh = ff->fh;
+ arg->owner = fuse_lock_owner_id(fl->fl_owner);
+ arg->lk.start = fl->fl_start;
+ arg->lk.end = fl->fl_end;
+ arg->lk.type = fl->fl_type;
+ arg->lk.pid = pid;
+ req->in.h.opcode = opcode;
+ req->in.h.nodeid = get_node_id(inode);
+ req->in.numargs = 1;
+ req->in.args[0].size = sizeof(*arg);
+ req->in.args[0].value = arg;
+}
+
+static int fuse_getlk(struct file *file, struct file_lock *fl)
+{
+ struct inode *inode = file->f_dentry->d_inode;
+ struct fuse_conn *fc = get_fuse_conn(inode);
+ struct fuse_req *req;
+ struct fuse_lk_out outarg;
+ int err;
+
+ req = fuse_get_req(fc);
+ if (IS_ERR(req))
+ return PTR_ERR(req);
+
+ fuse_lk_fill(req, file, fl, FUSE_GETLK, 0);
+ 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;
+ fuse_put_request(fc, req);
+ if (!err)
+ err = convert_fuse_file_lock(&outarg.lk, fl);
+
+ return err;
+}
+
+static int fuse_setlk(struct file *file, struct file_lock *fl)
+{
+ struct inode *inode = file->f_dentry->d_inode;
+ struct fuse_conn *fc = get_fuse_conn(inode);
+ struct fuse_req *req;
+ int opcode = (fl->fl_flags & FL_SLEEP) ? FUSE_SETLKW : FUSE_SETLK;
+ pid_t pid = fl->fl_type != F_UNLCK ? current->tgid : 0;
+ int err;
+
+ /* Unlock on close is handled by the flush method */
+ if (fl->fl_flags & FL_CLOSE)
+ return 0;
+
+ req = fuse_get_req(fc);
+ if (IS_ERR(req))
+ return PTR_ERR(req);
+
+ fuse_lk_fill(req, file, fl, opcode, pid);
+ request_send(fc, req);
+ err = req->out.h.error;
+ fuse_put_request(fc, req);
+ return err;
+}
+
+static int fuse_file_lock(struct file *file, int cmd, struct file_lock *fl)
+{
+ struct inode *inode = file->f_dentry->d_inode;
+ struct fuse_conn *fc = get_fuse_conn(inode);
+ int err;
+
+ if (cmd == F_GETLK) {
+ if (fc->no_lock) {
+ if (!posix_test_lock(file, fl, fl))
+ fl->fl_type = F_UNLCK;
+ err = 0;
+ } else
+ err = fuse_getlk(file, fl);
+ } else {
+ if (fc->no_lock)
+ err = posix_lock_file_wait(file, fl);
+ else
+ err = fuse_setlk(file, fl);
+ }
+ return err;
+}
+
static const struct file_operations fuse_file_operations = {
.llseek = generic_file_llseek,
.read = generic_file_read,
@@ -613,6 +743,7 @@
.flush = fuse_flush,
.release = fuse_release,
.fsync = fuse_fsync,
+ .lock = fuse_file_lock,
.sendfile = generic_file_sendfile,
};
@@ -624,6 +755,7 @@
.flush = fuse_flush,
.release = fuse_release,
.fsync = fuse_fsync,
+ .lock = fuse_file_lock,
/* no mmap and sendfile */
};
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index ac12b01..eb31666 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -190,6 +190,7 @@
struct fuse_init_in init_in;
struct fuse_init_out init_out;
struct fuse_read_in read_in;
+ struct fuse_lk_in lk_in;
} misc;
/** page vector */
@@ -307,6 +308,9 @@
/** Is removexattr not implemented by fs? */
unsigned no_removexattr : 1;
+ /** Are file locking primitives not implemented by fs? */
+ unsigned no_lock : 1;
+
/** Is access not implemented by fs? */
unsigned no_access : 1;
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 13a7e8a..4128929 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -98,6 +98,14 @@
}
}
+static int fuse_remount_fs(struct super_block *sb, int *flags, char *data)
+{
+ if (*flags & MS_MANDLOCK)
+ return -EINVAL;
+
+ return 0;
+}
+
void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr)
{
if (S_ISREG(inode->i_mode) && i_size_read(inode) != attr->size)
@@ -409,6 +417,7 @@
.destroy_inode = fuse_destroy_inode,
.read_inode = fuse_read_inode,
.clear_inode = fuse_clear_inode,
+ .remount_fs = fuse_remount_fs,
.put_super = fuse_put_super,
.umount_begin = fuse_umount_begin,
.statfs = fuse_statfs,
@@ -428,8 +437,12 @@
ra_pages = arg->max_readahead / PAGE_CACHE_SIZE;
if (arg->flags & FUSE_ASYNC_READ)
fc->async_read = 1;
- } else
+ if (!(arg->flags & FUSE_POSIX_LOCKS))
+ fc->no_lock = 1;
+ } else {
ra_pages = fc->max_read / PAGE_CACHE_SIZE;
+ fc->no_lock = 1;
+ }
fc->bdi.ra_pages = min(fc->bdi.ra_pages, ra_pages);
fc->minor = arg->minor;
@@ -447,7 +460,7 @@
arg->major = FUSE_KERNEL_VERSION;
arg->minor = FUSE_KERNEL_MINOR_VERSION;
arg->max_readahead = fc->bdi.ra_pages * PAGE_CACHE_SIZE;
- arg->flags |= FUSE_ASYNC_READ;
+ arg->flags |= FUSE_ASYNC_READ | FUSE_POSIX_LOCKS;
req->in.h.opcode = FUSE_INIT;
req->in.numargs = 1;
req->in.args[0].size = sizeof(*arg);
@@ -479,6 +492,9 @@
struct fuse_req *init_req;
int err;
+ if (sb->s_flags & MS_MANDLOCK)
+ return -EINVAL;
+
if (!parse_fuse_opt((char *) data, &d))
return -EINVAL;
diff --git a/include/linux/fuse.h b/include/linux/fuse.h
index 8e43196..e7a76ec 100644
--- a/include/linux/fuse.h
+++ b/include/linux/fuse.h
@@ -1,6 +1,6 @@
/*
FUSE: Filesystem in Userspace
- Copyright (C) 2001-2005 Miklos Szeredi <miklos@szeredi.hu>
+ Copyright (C) 2001-2006 Miklos Szeredi <miklos@szeredi.hu>
This program can be distributed under the terms of the GNU GPL.
See the file COPYING.
@@ -15,7 +15,7 @@
#define FUSE_KERNEL_VERSION 7
/** Minor version number of this interface */
-#define FUSE_KERNEL_MINOR_VERSION 6
+#define FUSE_KERNEL_MINOR_VERSION 7
/** The node ID of the root inode */
#define FUSE_ROOT_ID 1
@@ -59,6 +59,13 @@
__u32 spare[6];
};
+struct fuse_file_lock {
+ __u64 start;
+ __u64 end;
+ __u32 type;
+ __u32 pid; /* tgid */
+};
+
/**
* Bitmasks for fuse_setattr_in.valid
*/
@@ -83,6 +90,7 @@
* INIT request/reply flags
*/
#define FUSE_ASYNC_READ (1 << 0)
+#define FUSE_POSIX_LOCKS (1 << 1)
enum fuse_opcode {
FUSE_LOOKUP = 1,
@@ -113,6 +121,9 @@
FUSE_READDIR = 28,
FUSE_RELEASEDIR = 29,
FUSE_FSYNCDIR = 30,
+ FUSE_GETLK = 31,
+ FUSE_SETLK = 32,
+ FUSE_SETLKW = 33,
FUSE_ACCESS = 34,
FUSE_CREATE = 35
};
@@ -200,6 +211,7 @@
__u64 fh;
__u32 flush_flags;
__u32 padding;
+ __u64 lock_owner;
};
struct fuse_read_in {
@@ -248,6 +260,16 @@
__u32 padding;
};
+struct fuse_lk_in {
+ __u64 fh;
+ __u64 owner;
+ struct fuse_file_lock lk;
+};
+
+struct fuse_lk_out {
+ struct fuse_file_lock lk;
+};
+
struct fuse_access_in {
__u32 mask;
__u32 padding;