Unverified Commit c9eec08b authored by David Howells's avatar David Howells Committed by Christian Brauner
Browse files

iov_iter: Don't deal with iter->copy_mc in memcpy_from_iter_mc() 



iter->copy_mc is only used with a bvec iterator and only by
dump_emit_page() in fs/coredump.c so rather than handle this in
memcpy_from_iter_mc() where it is checked repeatedly by _copy_from_iter()
and copy_page_from_iter_atomic(),

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20230925120309.1731676-9-dhowells@redhat.com


cc: Alexander Viro <viro@zeniv.linux.org.uk>
cc: Jens Axboe <axboe@kernel.dk>
cc: Christoph Hellwig <hch@lst.de>
cc: Christian Brauner <christian@brauner.io>
cc: Matthew Wilcox <willy@infradead.org>
cc: Linus Torvalds <torvalds@linux-foundation.org>
cc: David Laight <David.Laight@ACULAB.COM>
cc: linux-block@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent f1982740

lib/iov_iter.c

+23 −12
Original line number Diff line number Diff line
@@ -253,14 +253,29 @@ size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i) 
EXPORT_SYMBOL_GPL(_copy_mc_to_iter);

#endif /* CONFIG_ARCH_HAS_COPY_MC */



static size_t memcpy_from_iter_mc(void *iter_from, size_t progress,

static __always_inline

size_t memcpy_from_iter_mc(void *iter_from, size_t progress,

			   size_t len, void *to, void *priv2)

{

	struct iov_iter *iter = priv2;



	if (iov_iter_is_copy_mc(iter))

	return copy_mc_to_kernel(to + progress, iter_from, len);

	return memcpy_from_iter(iter_from, progress, len, to, priv2);

}



static size_t __copy_from_iter_mc(void *addr, size_t bytes, struct iov_iter *i)

{

	if (unlikely(i->count < bytes))

		bytes = i->count;

	if (unlikely(!bytes))

		return 0;

	return iterate_bvec(i, bytes, addr, NULL, memcpy_from_iter_mc);

}



static __always_inline

size_t __copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)

{

	if (unlikely(iov_iter_is_copy_mc(i)))

		return __copy_from_iter_mc(addr, bytes, i);

	return iterate_and_advance(i, bytes, addr,

				   copy_from_user_iter, memcpy_from_iter);

}



size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
@@ -270,9 +285,7 @@ size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i) 


	if (user_backed_iter(i))

		might_fault();

	return iterate_and_advance2(i, bytes, addr, i,

				    copy_from_user_iter,

				    memcpy_from_iter_mc);

	return __copy_from_iter(addr, bytes, i);

}

EXPORT_SYMBOL(_copy_from_iter);
@@ -493,9 +506,7 @@ size_t copy_page_from_iter_atomic(struct page *page, size_t offset, 
		}



		p = kmap_atomic(page) + offset;

		n = iterate_and_advance2(i, n, p, i,

					 copy_from_user_iter,

					 memcpy_from_iter_mc);

		n = __copy_from_iter(p, n, i);

		kunmap_atomic(p);

		copied += n;

		offset += n;