Commit cfe057f7 authored by Al Viro's avatar Al Viro Committed by Al Viro
Browse files

iomap_dio_actor(): fix iov_iter bugs 



1) Ignoring return value from iov_iter_zero() is wrong
for iovec-backed case as well as for pipes - it can fail.

2) Failure to fault destination pages in 25Mb into a 50Mb iovec
should not act as if nothing in the area had been read, nevermind
that the first 25Mb might have *already* been read by that point.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 8ececffa

fs/iomap.c

+15 −9
Original line number Diff line number Diff line
@@ -848,6 +848,7 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length, 
	struct bio *bio;

	bool need_zeroout = false;

	int nr_pages, ret;

	size_t copied = 0;



	if ((pos | length | align) & ((1 << blkbits) - 1))

		return -EINVAL;
@@ -859,7 +860,7 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length, 
		/*FALLTHRU*/

	case IOMAP_UNWRITTEN:

		if (!(dio->flags & IOMAP_DIO_WRITE)) {

			iov_iter_zero(length, dio->submit.iter);

			length = iov_iter_zero(length, dio->submit.iter);

			dio->size += length;

			return length;

		}
@@ -896,8 +897,11 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length, 
	}



	do {

		if (dio->error)

		size_t n;

		if (dio->error) {

			iov_iter_revert(dio->submit.iter, copied);

			return 0;

		}



		bio = bio_alloc(GFP_KERNEL, nr_pages);

		bio_set_dev(bio, iomap->bdev);
@@ -910,20 +914,24 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length, 
		ret = bio_iov_iter_get_pages(bio, &iter);

		if (unlikely(ret)) {

			bio_put(bio);

			return ret;

			return copied ? copied : ret;

		}



		n = bio->bi_iter.bi_size;

		if (dio->flags & IOMAP_DIO_WRITE) {

			bio_set_op_attrs(bio, REQ_OP_WRITE, REQ_SYNC | REQ_IDLE);

			task_io_account_write(bio->bi_iter.bi_size);

			task_io_account_write(n);

		} else {

			bio_set_op_attrs(bio, REQ_OP_READ, 0);

			if (dio->flags & IOMAP_DIO_DIRTY)

				bio_set_pages_dirty(bio);

		}



		dio->size += bio->bi_iter.bi_size;

		pos += bio->bi_iter.bi_size;

		iov_iter_advance(dio->submit.iter, n);



		dio->size += n;

		pos += n;

		copied += n;



		nr_pages = iov_iter_npages(&iter, BIO_MAX_PAGES);
@@ -939,9 +947,7 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length, 
		if (pad)

			iomap_dio_zero(dio, iomap, pos, fs_block_size - pad);

	}



	iov_iter_advance(dio->submit.iter, length);

	return length;

	return copied;

}



ssize_t

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