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>

1 files changed, 14 insertions, 4 deletions

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 7ae1e6972caa..e68d8c3f063a 100644
--- 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)