Unionfs: implement splice_read/write methods directly

Must implement splice_read/write directly, using VFS helpers, because we can
no longer rely on generic_file_splice_read/write: they need
address_space_operations implemented, which we no longer have.

Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>

diff --git a/fs/unionfs/file.c b/fs/unionfs/file.c
index ee8dd6f63554377c477c90a45746a68aa6e3f454..6141efc6cccead018c7f0ff735445891b2c7acaf 100644 (file)
--- a/fs/unionfs/file.c
+++ b/fs/unionfs/file.c
@@ -173,6 +173,66 @@ out:
        return err;
 }
 
+static ssize_t unionfs_splice_read(struct file *file, loff_t *ppos,
+                                  struct pipe_inode_info *pipe, size_t len,
+                                  unsigned int flags)
+{
+       ssize_t err;
+       struct file *lower_file;
+       struct dentry *dentry = file->f_path.dentry;
+
+       unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_PARENT);
+       unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
+       err = unionfs_file_revalidate(file, false);
+       if (unlikely(err))
+               goto out;
+
+       lower_file = unionfs_lower_file(file);
+       err = vfs_splice_to(lower_file, ppos, pipe, len, flags);
+       /* update our inode atime upon a successful lower splice-read */
+       if (err >= 0) {
+               fsstack_copy_attr_atime(dentry->d_inode,
+                                       lower_file->f_path.dentry->d_inode);
+               unionfs_check_file(file);
+       }
+
+out:
+       unionfs_unlock_dentry(dentry);
+       unionfs_read_unlock(dentry->d_sb);
+       return err;
+}
+
+static ssize_t unionfs_splice_write(struct pipe_inode_info *pipe,
+                                   struct file *file, loff_t *ppos,
+                                   size_t len, unsigned int flags)
+{
+       ssize_t err = 0;
+       struct file *lower_file;
+       struct dentry *dentry = file->f_path.dentry;
+
+       unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_PARENT);
+       unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
+       err = unionfs_file_revalidate(file, true);
+       if (unlikely(err))
+               goto out;
+
+       lower_file = unionfs_lower_file(file);
+       err = vfs_splice_from(pipe, lower_file, ppos, len, flags);
+       /* update our inode times+sizes upon a successful lower write */
+       if (err >= 0) {
+               fsstack_copy_inode_size(dentry->d_inode,
+                                       lower_file->f_path.dentry->d_inode);
+               fsstack_copy_attr_times(dentry->d_inode,
+                                       lower_file->f_path.dentry->d_inode);
+               unionfs_check_file(file);
+       }
+
+out:
+       unionfs_unlock_dentry(dentry);
+       unionfs_read_unlock(dentry->d_sb);
+       return err;
+}
+
 struct file_operations unionfs_main_fops = {
        .llseek         = generic_file_llseek,
        .read           = do_sync_read,
@@ -188,4 +248,6 @@ struct file_operations unionfs_main_fops = {
        .fsync          = unionfs_fsync,
        .fasync         = unionfs_fasync,
        .sendfile       = generic_file_sendfile,
+       .splice_read    = unionfs_splice_read,
+       .splice_write   = unionfs_splice_write,
 };