fuse: update mtime on open(O_TRUNC) in atomic_o_trunc mode

In case of fc->atomic_o_trunc is set, fuse does nothing in
fuse_do_setattr() while handling open(O_TRUNC). Hence, i_mtime must be
updated explicitly in fuse_finish_open(). The patch also adds extra locking
encompassing open(O_TRUNC) operation to avoid races between the truncation
and updating i_mtime.

Signed-off-by: Maxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 7ae1e69..e68d8c3 100644 (file)
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -223,6 +223,8 @@ void fuse_finish_open(struct inode *inode, struct file *file)
                i_size_write(inode, 0);
                spin_unlock(&fc->lock);
                fuse_invalidate_attr(inode);
+               if (fc->writeback_cache)
+                       file_update_time(file);
        }
        if ((file->f_mode & FMODE_WRITE) && fc->writeback_cache)
                fuse_link_write_file(file);
@@ -232,18 +234,26 @@ int fuse_open_common(struct inode *inode, struct file *file, bool isdir)
 {
        struct fuse_conn *fc = get_fuse_conn(inode);
        int err;
+       bool lock_inode = (file->f_flags & O_TRUNC) &&
+                         fc->atomic_o_trunc &&
+                         fc->writeback_cache;
 
        err = generic_file_open(inode, file);
        if (err)
                return err;
 
+       if (lock_inode)
+               mutex_lock(&inode->i_mutex);
+
        err = fuse_do_open(fc, get_node_id(inode), file, isdir);
-       if (err)
-               return err;
 
-       fuse_finish_open(inode, file);
+       if (!err)
+               fuse_finish_open(inode, file);
 
-       return 0;
+       if (lock_inode)
+               mutex_unlock(&inode->i_mutex);
+
+       return err;
 }
 
 static void fuse_prepare_release(struct fuse_file *ff, int flags, int opcode)