2 files changed, 27 insertions, 3 deletions

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 1e941b3f2453..537d38bee13c 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1014,6 +1014,20 @@ static int fuse_dir_fsync(struct file *file, struct dentry *de, int datasync)
         return file ? fuse_fsync_common(file, de, datasync, 1) : 0;
 }
 
+static bool update_mtime(unsigned ivalid)
+{
+        /* Always update if mtime is explicitly set  */
+        if (ivalid & ATTR_MTIME_SET)
+                return true;
+
+        /* If it's an open(O_TRUNC) or an ftruncate(), don't update */
+        if ((ivalid & ATTR_SIZE) && (ivalid & (ATTR_OPEN | ATTR_FILE)))
+                return false;
+
+        /* In all other cases update */
+        return true;
+}
+
 static void iattr_to_fattr(struct iattr *iattr, struct fuse_setattr_in *arg)
 {
         unsigned ivalid = iattr->ia_valid;
@@ -1026,11 +1040,19 @@ static void iattr_to_fattr(struct iattr *iattr, struct fuse_setattr_in *arg)
                 arg->valid |= FATTR_GID,    arg->gid = iattr->ia_gid;
         if (ivalid & ATTR_SIZE)
                 arg->valid |= FATTR_SIZE,   arg->size = iattr->ia_size;
-        /* You can only _set_ these together (they may change by themselves) */
-        if ((ivalid & (ATTR_ATIME | ATTR_MTIME)) == (ATTR_ATIME | ATTR_MTIME)) {
-                arg->valid |= FATTR_ATIME | FATTR_MTIME;
+        if (ivalid & ATTR_ATIME) {
+                arg->valid |= FATTR_ATIME;
                 arg->atime = iattr->ia_atime.tv_sec;
+                arg->atimensec = iattr->ia_atime.tv_nsec;
+                if (!(ivalid & ATTR_ATIME_SET))
+                        arg->valid |= FATTR_ATIME_NOW;
+        }
+        if ((ivalid & ATTR_MTIME) && update_mtime(ivalid)) {
+                arg->valid |= FATTR_MTIME;
                 arg->mtime = iattr->ia_mtime.tv_sec;
+                arg->mtimensec = iattr->ia_mtime.tv_nsec;
+                if (!(ivalid & ATTR_MTIME_SET))
+                        arg->valid |= FATTR_MTIME_NOW;
         }
 }
 
diff --git a/include/linux/fuse.h b/include/linux/fuse.h
index a50d0d9ac7ae..43a77d73349c 100644
--- a/include/linux/fuse.h
+++ b/include/linux/fuse.h
@@ -83,6 +83,8 @@ struct fuse_file_lock {
 #define FATTR_ATIME     (1 << 4)
 #define FATTR_MTIME     (1 << 5)
 #define FATTR_FH        (1 << 6)
+#define FATTR_ATIME_NOW (1 << 7)
+#define FATTR_MTIME_NOW (1 << 8)
 
 /**
  * Flags returned by the OPEN request