fuse: add atomic open+truncate support

This patch allows fuse filesystems to implement open(..., O_TRUNC) as a single
request, instead of separate truncate and open requests.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 537d38b..052327b 100644 (file)
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1083,6 +1083,9 @@ static int fuse_do_setattr(struct dentry *entry, struct iattr *attr,
                        return err;
        }
 
+       if ((attr->ia_valid & ATTR_OPEN) && fc->atomic_o_trunc)
+               return 0;
+
        if (attr->ia_valid & ATTR_SIZE) {
                unsigned long limit;
                if (IS_SWAPFILE(inode))

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 4a28c3d..6726378 100644 (file)
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -28,7 +28,9 @@ static int fuse_send_open(struct inode *inode, struct file *file, int isdir,
                return PTR_ERR(req);
 
        memset(&inarg, 0, sizeof(inarg));
-       inarg.flags = file->f_flags & ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
+       inarg.flags = file->f_flags & ~(O_CREAT | O_EXCL | O_NOCTTY);
+       if (!fc->atomic_o_trunc)
+               inarg.flags &= ~O_TRUNC;
        req->in.h.opcode = isdir ? FUSE_OPENDIR : FUSE_OPEN;
        req->in.h.nodeid = get_node_id(inode);
        req->in.numargs = 1;

diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index ffbcada..b24fc9b 100644 (file)
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -320,6 +320,9 @@ struct fuse_conn {
        /** Do readpages asynchronously?  Only set in INIT */
        unsigned async_read : 1;
 
+       /** Do not send separate SETATTR request before open(O_TRUNC)  */
+       unsigned atomic_o_trunc : 1;
+
        /*
         * The following bitfields are only for optimization purposes
         * and hence races in setting them will not cause malfunction

diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 6ef3973..3c13981 100644 (file)
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -531,6 +531,8 @@ static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
                                fc->async_read = 1;
                        if (!(arg->flags & FUSE_POSIX_LOCKS))
                                fc->no_lock = 1;
+                       if (arg->flags & FUSE_ATOMIC_O_TRUNC)
+                               fc->atomic_o_trunc = 1;
                } else {
                        ra_pages = fc->max_read / PAGE_CACHE_SIZE;
                        fc->no_lock = 1;
@@ -553,7 +555,8 @@ static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)
        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 | FUSE_POSIX_LOCKS | FUSE_FILE_OPS;
+       arg->flags |= FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_FILE_OPS |
+               FUSE_ATOMIC_O_TRUNC;
        req->in.h.opcode = FUSE_INIT;
        req->in.numargs = 1;
        req->in.args[0].size = sizeof(*arg);

diff --git a/include/linux/fuse.h b/include/linux/fuse.h
index 43a77d7..4360470 100644 (file)
--- a/include/linux/fuse.h
+++ b/include/linux/fuse.h
@@ -101,6 +101,7 @@ struct fuse_file_lock {
 #define FUSE_ASYNC_READ                (1 << 0)
 #define FUSE_POSIX_LOCKS       (1 << 1)
 #define FUSE_FILE_OPS          (1 << 2)
+#define FUSE_ATOMIC_O_TRUNC    (1 << 3)
 
 /**
  * Release flags