Commit 886a3911 authored by Al Viro's avatar Al Viro
Browse files

new primitive: iov_iter_alignment() 



returns the value aligned as badly as the worst remaining segment
in iov_iter is.  Use instead of open-coded equivalents.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 26978b8b

drivers/staging/lustre/lustre/llite/rw26.c

+2 −5
Original line number Diff line number Diff line
@@ -391,11 +391,8 @@ static ssize_t ll_direct_IO_26(int rw, struct kiocb *iocb, 
	       MAX_DIO_SIZE >> PAGE_CACHE_SHIFT);



	/* Check that all user buffers are aligned as well */

	for (seg = 0; seg < iter->nr_segs; seg++) {

		if (((unsigned long)iter->iov[seg].iov_base & ~CFS_PAGE_MASK) ||

		    (iter->iov[seg].iov_len & ~CFS_PAGE_MASK))

	if (iov_iter_alignment(iter) & ~CFS_PAGE_MASK)

		return -EINVAL;

	}



	env = cl_env_get(&refcheck);

	LASSERT(!IS_ERR(env));

fs/direct-io.c

+5 −22
Original line number Diff line number Diff line
@@ -1112,19 +1112,18 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, 
	dio_submit_t submit_io,	int flags)

{

	int seg;

	size_t size;

	unsigned long addr;

	unsigned i_blkbits = ACCESS_ONCE(inode->i_blkbits);

	unsigned blkbits = i_blkbits;

	unsigned blocksize_mask = (1 << blkbits) - 1;

	ssize_t retval = -EINVAL;

	loff_t end = offset;

	loff_t end = offset + iov_iter_count(iter);

	struct dio *dio;

	struct dio_submit sdio = { 0, };

	unsigned long user_addr;

	size_t bytes;

	struct buffer_head map_bh = { 0, };

	struct blk_plug plug;

	unsigned long align = offset | iov_iter_alignment(iter);



	if (rw & WRITE)

		rw = WRITE_ODIRECT;
@@ -1134,32 +1133,16 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, 
	 * the early prefetch in the caller enough time.

	 */



	if (offset & blocksize_mask) {

	if (align & blocksize_mask) {

		if (bdev)

			blkbits = blksize_bits(bdev_logical_block_size(bdev));

		blocksize_mask = (1 << blkbits) - 1;

		if (offset & blocksize_mask)

		if (align & blocksize_mask)

			goto out;

	}



	/* Check the memory alignment.  Blocks cannot straddle pages */

	for (seg = 0; seg < iter->nr_segs; seg++) {

		addr = (unsigned long)iter->iov[seg].iov_base;

		size = iter->iov[seg].iov_len;

		end += size;

		if (unlikely((addr & blocksize_mask) ||

			     (size & blocksize_mask))) {

			if (bdev)

				blkbits = blksize_bits(

					 bdev_logical_block_size(bdev));

			blocksize_mask = (1 << blkbits) - 1;

			if ((addr & blocksize_mask) || (size & blocksize_mask))

				goto out;

		}

	}



	/* watch out for a 0 len io from a tricksy fs */

	if (rw == READ && end == offset)

	if (rw == READ && !iov_iter_count(iter))

		return 0;



	dio = kmem_cache_alloc(dio_cache, GFP_KERNEL);

include/linux/uio.h

+2 −0
Original line number Diff line number Diff line
@@ -67,6 +67,7 @@ int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes); 
size_t iov_iter_single_seg_count(const struct iov_iter *i);

size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,

			 struct iov_iter *i);

unsigned long iov_iter_alignment(const struct iov_iter *i);



static inline void iov_iter_init(struct iov_iter *i,

			const struct iovec *iov, unsigned long nr_segs,
@@ -88,4 +89,5 @@ static inline size_t iov_iter_count(struct iov_iter *i) 
int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len);

int memcpy_toiovec(struct iovec *iov, unsigned char *kdata, int len);





#endif

mm/iov_iter.c

+25 −0
Original line number Diff line number Diff line
@@ -195,3 +195,28 @@ size_t iov_iter_single_seg_count(const struct iov_iter *i) 
		return min(i->count, iov->iov_len - i->iov_offset);

}

EXPORT_SYMBOL(iov_iter_single_seg_count);



unsigned long iov_iter_alignment(const struct iov_iter *i)

{

	const struct iovec *iov = i->iov;

	unsigned long res;

	size_t size = i->count;

	size_t n;



	if (!size)

		return 0;



	res = (unsigned long)iov->iov_base + i->iov_offset;

	n = iov->iov_len - i->iov_offset;

	if (n >= size)

		return res | size;

	size -= n;

	res |= n;

	while (size > (++iov)->iov_len) {

		res |= (unsigned long)iov->iov_base | iov->iov_len;

		size -= iov->iov_len;

	}

	res |= (unsigned long)iov->iov_base | size;

	return res;

}

EXPORT_SYMBOL(iov_iter_alignment);