Commit 3d14ec1f authored by David Howells's avatar David Howells
Browse files

iov_iter: Four fixes for ITER_XARRAY 



Fix four things[1] in the patch that adds ITER_XARRAY[2]:

 (1) Remove the address_space struct predeclaration.  This is a holdover
     from when it was ITER_MAPPING.

 (2) Fix _copy_mc_to_iter() so that the xarray segment updates count and
     iov_offset in the iterator before returning.

 (3) Fix iov_iter_alignment() to not loop in the xarray case.  Because the
     middle pages are all whole pages, only the end pages need be
     considered - and this can be reduced to just looking at the start
     position in the xarray and the iteration size.

 (4) Fix iov_iter_advance() to limit the size of the advance to no more
     than the remaining iteration size.

Reported-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Reviewed-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Tested-by: default avatarJeff Layton <jlayton@redhat.com>
Tested-by: default avatarDave Wysochanski <dwysocha@redhat.com>
Link: https://lore.kernel.org/r/YIVrJT8GwLI0Wlgx@zeniv-ca.linux.org.uk [1]
Link: https://lore.kernel.org/r/161918448151.3145707.11541538916600921083.stgit@warthog.procyon.org.uk [2]
parent 26aaeffc

include/linux/uio.h

+0 −1
Original line number Diff line number Diff line
@@ -10,7 +10,6 @@ 
#include <uapi/linux/uio.h>



struct page;

struct address_space;

struct pipe_inode_info;



struct kvec {

lib/iov_iter.c

+5 −0
Original line number Diff line number Diff line
@@ -791,6 +791,8 @@ size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i) 
			curr_addr = (unsigned long) from;

			bytes = curr_addr - s_addr - rem;

			rcu_read_unlock();

			i->iov_offset += bytes;

			i->count -= bytes;

			return bytes;

		}

		})
@@ -1147,6 +1149,7 @@ void iov_iter_advance(struct iov_iter *i, size_t size) 
		return;

	}

	if (unlikely(iov_iter_is_xarray(i))) {

		size = min(size, i->count);

		i->iov_offset += size;

		i->count -= size;

		return;
@@ -1346,6 +1349,8 @@ unsigned long iov_iter_alignment(const struct iov_iter *i) 
			return size | i->iov_offset;

		return size;

	}

	if (unlikely(iov_iter_is_xarray(i)))

		return (i->xarray_start + i->iov_offset) | i->count;

	iterate_all_kinds(i, size, v,

		(res |= (unsigned long)v.iov_base | v.iov_len, 0),

		res |= v.bv_offset | v.bv_len,