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Commit 838c4f3d authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Darrick J. Wong
Browse files

iomap: move the iomap_dio_rw ->end_io callback into a structure 



Add a new iomap_dio_ops structure that for now just contains the end_io
handler.  This avoid storing the function pointer in a mutable structure,
which is a possible exploit vector for kernel code execution, and prepares
for adding a submit_io handler that btrfs needs.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
parent 6fe7b990

fs/iomap/direct-io.c

+10 −11
Original line number Diff line number Diff line
@@ -24,7 +24,7 @@ 


struct iomap_dio {

	struct kiocb		*iocb;

	iomap_dio_end_io_t	*end_io;

	const struct iomap_dio_ops *dops;

	loff_t			i_size;

	loff_t			size;

	atomic_t		ref;
@@ -72,15 +72,14 @@ static void iomap_dio_submit_bio(struct iomap_dio *dio, struct iomap *iomap, 


static ssize_t iomap_dio_complete(struct iomap_dio *dio)

{

	const struct iomap_dio_ops *dops = dio->dops;

	struct kiocb *iocb = dio->iocb;

	struct inode *inode = file_inode(iocb->ki_filp);

	loff_t offset = iocb->ki_pos;

	ssize_t ret;

	ssize_t ret = dio->error;



	if (dio->end_io)

		ret = dio->end_io(iocb, dio->size, dio->error, dio->flags);

	else

		ret = dio->error;

	if (dops && dops->end_io)

		ret = dops->end_io(iocb, dio->size, ret, dio->flags);



	if (likely(!ret)) {

		ret = dio->size;
@@ -98,9 +97,9 @@ static ssize_t iomap_dio_complete(struct iomap_dio *dio) 
	 * one is a pretty crazy thing to do, so we don't support it 100%.  If

	 * this invalidation fails, tough, the write still worked...

	 *

	 * And this page cache invalidation has to be after dio->end_io(), as

	 * some filesystems convert unwritten extents to real allocations in

	 * end_io() when necessary, otherwise a racing buffer read would cache

	 * And this page cache invalidation has to be after ->end_io(), as some

	 * filesystems convert unwritten extents to real allocations in

	 * ->end_io() when necessary, otherwise a racing buffer read would cache

	 * zeros from unwritten extents.

	 */

	if (!dio->error &&
@@ -393,7 +392,7 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length, 
 */

ssize_t

iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,

		const struct iomap_ops *ops, iomap_dio_end_io_t end_io)

		const struct iomap_ops *ops, const struct iomap_dio_ops *dops)

{

	struct address_space *mapping = iocb->ki_filp->f_mapping;

	struct inode *inode = file_inode(iocb->ki_filp);
@@ -418,7 +417,7 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, 
	atomic_set(&dio->ref, 1);

	dio->size = 0;

	dio->i_size = i_size_read(inode);

	dio->end_io = end_io;

	dio->dops = dops;

	dio->error = 0;

	dio->flags = 0;

fs/xfs/xfs_file.c

+5 −1
Original line number Diff line number Diff line
@@ -442,6 +442,10 @@ xfs_dio_write_end_io( 
	return error;

}



static const struct iomap_dio_ops xfs_dio_write_ops = {

	.end_io		= xfs_dio_write_end_io,

};



/*

 * xfs_file_dio_aio_write - handle direct IO writes

 *
@@ -542,7 +546,7 @@ xfs_file_dio_aio_write( 
	}



	trace_xfs_file_direct_write(ip, count, iocb->ki_pos);

	ret = iomap_dio_rw(iocb, from, &xfs_iomap_ops, xfs_dio_write_end_io);

	ret = iomap_dio_rw(iocb, from, &xfs_iomap_ops, &xfs_dio_write_ops);



	/*

	 * If unaligned, this is the only IO in-flight. If it has not yet

include/linux/iomap.h

+7 −3
Original line number Diff line number Diff line
@@ -188,10 +188,14 @@ sector_t iomap_bmap(struct address_space *mapping, sector_t bno, 
 */

#define IOMAP_DIO_UNWRITTEN	(1 << 0)	/* covers unwritten extent(s) */

#define IOMAP_DIO_COW		(1 << 1)	/* covers COW extent(s) */

typedef int (iomap_dio_end_io_t)(struct kiocb *iocb, ssize_t size, int error,

				 unsigned int flags);



struct iomap_dio_ops {

	int (*end_io)(struct kiocb *iocb, ssize_t size, int error,

		      unsigned flags);

};



ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,

		const struct iomap_ops *ops, iomap_dio_end_io_t end_io);

		const struct iomap_ops *ops, const struct iomap_dio_ops *dops);

int iomap_dio_iopoll(struct kiocb *kiocb, bool spin);



#ifdef CONFIG_SWAP