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

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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: David 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: Christian Brauner <brauner@kernel.org>
This commit is contained in:
David Howells 2023-09-25 13:03:05 +01:00 committed by Christian Brauner
parent f1982740f5
commit c9eec08bac
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
1 changed files with 23 additions and 12 deletions
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33
lib/iov_iter.c
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@ -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;