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Commit c3a69024 authored Oct 10, 2016 by Al Viro

fix ITER_PIPE interaction with direct_IO



by making sure we call iov_iter_advance() on original
iov_iter even if direct_IO (done on its copy) has returned 0.
It's a no-op for old iov_iter flavours and does the right thing
(== truncation of the stuff we'd allocated, but not filled) in
ITER_PIPE case.  Failures (e.g. -EIO) get caught and dealt with
by cleanup in generic_file_read_iter().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

parent a949e639

fs/splice.c

+3 −9

Original line number	Diff line number	Diff line
		@@ -315,15 +315,9 @@ ssize_t generic_file_splice_read(struct file in, loff_t ppos,
		*ppos = kiocb.ki_pos;
		file_accessed(in);
		} else if (ret < 0) {
		if (WARN_ON(to.idx != idx \|\| to.iov_offset)) {
		/*
		* a bogus ->read_iter() has copied something and still
		* returned an error instead of a short read.
		*/
		to.idx = idx;
		to.iov_offset = 0;
		iov_iter_advance(&to, 0); /* to free what was emitted */
		}
		/*
		* callers of ->splice_read() expect -EAGAIN on
		* "can't put anything in there", rather than -EFAULT.

fs/xfs/xfs_file.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -317,7 +317,7 @@ xfs_file_dio_aio_read(
		data = *to;
		ret = __blockdev_direct_IO(iocb, inode, target->bt_bdev, &data,
		xfs_get_blocks_direct, NULL, NULL, 0);
		if (ret > 0) {
		if (ret >= 0) {
		iocb->ki_pos += ret;
		iov_iter_advance(to, ret);
		}

mm/filemap.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1920,7 +1920,7 @@ generic_file_read_iter(struct kiocb iocb, struct iov_iter iter)
		retval = mapping->a_ops->direct_IO(iocb, &data);
		}

		if (retval > 0) {
		if (retval >= 0) {
		iocb->ki_pos += retval;
		iov_iter_advance(iter, retval);
		}