Commit 2cbd51f1 authored by John Garry's avatar John Garry Committed by Jens Axboe
Browse files

block: Don't allow an atomic write be truncated in blkdev_write_iter() 



A write which goes past the end of the bdev in blkdev_write_iter() will
be truncated. Truncating cannot tolerated for an atomic write, so error
that condition.

Fixes: caf336f8 ("block: Add fops atomic write support")
Signed-off-by: default avatarJohn Garry <john.g.garry@oracle.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20241127092318.632790-1-john.g.garry@oracle.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 1b0cab32

block/fops.c

+4 −1
Original line number Diff line number Diff line
@@ -677,6 +677,7 @@ static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from) 
	struct file *file = iocb->ki_filp;

	struct inode *bd_inode = bdev_file_inode(file);

	struct block_device *bdev = I_BDEV(bd_inode);

	bool atomic = iocb->ki_flags & IOCB_ATOMIC;

	loff_t size = bdev_nr_bytes(bdev);

	size_t shorted = 0;

	ssize_t ret;
@@ -696,7 +697,7 @@ static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from) 
	if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)

		return -EOPNOTSUPP;



	if (iocb->ki_flags & IOCB_ATOMIC) {

	if (atomic) {

		ret = generic_atomic_write_valid(iocb, from);

		if (ret)

			return ret;
@@ -704,6 +705,8 @@ static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from) 


	size -= iocb->ki_pos;

	if (iov_iter_count(from) > size) {

		if (atomic)

			return -EINVAL;

		shorted = iov_iter_count(from) - size;

		iov_iter_truncate(from, size);

	}