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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: 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>
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@ -253,14 +253,29 @@ size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
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EXPORT_SYMBOL_GPL(_copy_mc_to_iter);
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#endif /* CONFIG_ARCH_HAS_COPY_MC */
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static size_t memcpy_from_iter_mc(void *iter_from, size_t progress,
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static __always_inline
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size_t memcpy_from_iter_mc(void *iter_from, size_t progress,
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size_t len, void *to, void *priv2)
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{
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struct iov_iter *iter = priv2;
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if (iov_iter_is_copy_mc(iter))
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return copy_mc_to_kernel(to + progress, iter_from, len);
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return memcpy_from_iter(iter_from, progress, len, to, priv2);
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}
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static size_t __copy_from_iter_mc(void *addr, size_t bytes, struct iov_iter *i)
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{
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if (unlikely(i->count < bytes))
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bytes = i->count;
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if (unlikely(!bytes))
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return 0;
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return iterate_bvec(i, bytes, addr, NULL, memcpy_from_iter_mc);
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}
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static __always_inline
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size_t __copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
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{
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if (unlikely(iov_iter_is_copy_mc(i)))
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return __copy_from_iter_mc(addr, bytes, i);
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return iterate_and_advance(i, bytes, addr,
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copy_from_user_iter, memcpy_from_iter);
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}
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size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
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@ -270,9 +285,7 @@ size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
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if (user_backed_iter(i))
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might_fault();
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return iterate_and_advance2(i, bytes, addr, i,
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copy_from_user_iter,
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memcpy_from_iter_mc);
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return __copy_from_iter(addr, bytes, i);
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}
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EXPORT_SYMBOL(_copy_from_iter);
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@ -493,9 +506,7 @@ size_t copy_page_from_iter_atomic(struct page *page, size_t offset,
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}
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p = kmap_atomic(page) + offset;
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n = iterate_and_advance2(i, n, p, i,
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copy_from_user_iter,
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memcpy_from_iter_mc);
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n = __copy_from_iter(p, n, i);
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kunmap_atomic(p);
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copied += n;
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offset += n;
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