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>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 537d38bee13c..052327bd6c9d 100644
--- 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))