ashmem: switch to ->read_iter

And use the proper VFS helper for using the backing file.

Also make sure we hold ashmem_lock while updating f_pos to make sure that
it's not racy.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c
index 6ba270e0494ddc689eb7be7a12eecc819bc1ac7b..0f695df14c9d8f0a5c0a95ea8c28dc075c2aa36c 100644 (file)
--- a/drivers/staging/android/ashmem.c
+++ b/drivers/staging/android/ashmem.c
@@ -294,19 +294,9 @@ static int ashmem_release(struct inode *ignored, struct file *file)
        return 0;
 }
 
-/**
- * ashmem_read() - Reads a set of bytes from an Ashmem-enabled file
- * @file:         The associated backing file.
- * @buf:          The buffer of data being written to
- * @len:          The number of bytes being read
- * @pos:          The position of the first byte to read.
- *
- * Return: 0 if successful, or another return code if not.
- */
-static ssize_t ashmem_read(struct file *file, char __user *buf,
-                          size_t len, loff_t *pos)
+static ssize_t ashmem_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 {
-       struct ashmem_area *asma = file->private_data;
+       struct ashmem_area *asma = iocb->ki_filp->private_data;
        int ret = 0;
 
        mutex_lock(&ashmem_mutex);
@@ -320,20 +310,17 @@ static ssize_t ashmem_read(struct file *file, char __user *buf,
                goto out_unlock;
        }
 
-       mutex_unlock(&ashmem_mutex);
-
        /*
         * asma and asma->file are used outside the lock here.  We assume
         * once asma->file is set it will never be changed, and will not
         * be destroyed until all references to the file are dropped and
         * ashmem_release is called.
         */
-       ret = __vfs_read(asma->file, buf, len, pos);
-       if (ret >= 0)
-               /** Update backing file pos, since f_ops->read() doesn't */
-               asma->file->f_pos = *pos;
-       return ret;
-
+       mutex_unlock(&ashmem_mutex);
+       ret = vfs_iter_read(asma->file, iter, &iocb->ki_pos, 0);
+       mutex_lock(&ashmem_mutex);
+       if (ret > 0)
+               asma->file->f_pos = iocb->ki_pos;
 out_unlock:
        mutex_unlock(&ashmem_mutex);
        return ret;
@@ -834,7 +821,7 @@ static const struct file_operations ashmem_fops = {
        .owner = THIS_MODULE,
        .open = ashmem_open,
        .release = ashmem_release,
-       .read = ashmem_read,
+       .read_iter = ashmem_read_iter,
        .llseek = ashmem_llseek,
        .mmap = ashmem_mmap,
        .unlocked_ioctl = ashmem_ioctl,