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
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1083,6 +1083,9 @@
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
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -28,7 +28,9 @@
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
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -320,6 +320,9 @@
/** 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
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -531,6 +531,8 @@
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 @@
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
--- a/include/linux/fuse.h
+++ b/include/linux/fuse.h
@@ -101,6 +101,7 @@
#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