mirror of https://gitee.com/openkylin/linux.git
iov_iter: make iterator callbacks use base and len instead of iovec
Iterator macros used to provide the arguments for step callbacks in a structure matching the flavour - iovec for ITER_IOVEC, kvec for ITER_KVEC and bio_vec for ITER_BVEC. That already broke down for ITER_XARRAY (bio_vec there); now that we are using kvec callback for bvec and xarray cases, we are always passing a pointer + length (void __user * + size_t for ITER_IOVEC callback, void * + size_t for everything else). Note that the original reason for bio_vec (page + offset + len) in case of ITER_BVEC used to be that we did *not* want to kmap a page when all we wanted was e.g. to find the alignment of its subrange. Now all such users are gone and the ones that are left want the page mapped anyway for actually copying the data. So in all cases we have pointer + length, and there's no good reason for keeping those in struct iovec or struct kvec - we can just pass them to callback separately. Again, less boilerplate in callbacks... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro
parent
622838f3fd
commit
7baa509900
150
lib/iov_iter.c
150
lib/iov_iter.c
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@ -17,56 +17,56 @@
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#define PIPE_PARANOIA /* for now */
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/* covers iovec and kvec alike */
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#define iterate_iovec(i, n, __v, __off, __p, skip, STEP) { \
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size_t __off = 0; \
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#define iterate_iovec(i, n, base, len, off, __p, skip, STEP) { \
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size_t off = 0; \
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do { \
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__v.iov_len = min(n, __p->iov_len - skip); \
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if (likely(__v.iov_len)) { \
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__v.iov_base = __p->iov_base + skip; \
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__v.iov_len -= (STEP); \
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__off += __v.iov_len; \
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skip += __v.iov_len; \
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n -= __v.iov_len; \
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len = min(n, __p->iov_len - skip); \
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if (likely(len)) { \
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base = __p->iov_base + skip; \
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len -= (STEP); \
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off += len; \
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skip += len; \
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n -= len; \
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if (skip < __p->iov_len) \
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break; \
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} \
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__p++; \
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skip = 0; \
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} while (n); \
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n = __off; \
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n = off; \
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}
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#define iterate_bvec(i, n, __v, __off, p, skip, STEP) { \
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size_t __off = 0; \
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#define iterate_bvec(i, n, base, len, off, p, skip, STEP) { \
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size_t off = 0; \
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while (n) { \
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unsigned offset = p->bv_offset + skip; \
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unsigned left; \
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void *kaddr = kmap_local_page(p->bv_page + \
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offset / PAGE_SIZE); \
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__v.iov_base = kaddr + offset % PAGE_SIZE; \
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__v.iov_len = min(min(n, p->bv_len - skip), \
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base = kaddr + offset % PAGE_SIZE; \
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len = min(min(n, p->bv_len - skip), \
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(size_t)(PAGE_SIZE - offset % PAGE_SIZE)); \
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left = (STEP); \
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kunmap_local(kaddr); \
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__v.iov_len -= left; \
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__off += __v.iov_len; \
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skip += __v.iov_len; \
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len -= left; \
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off += len; \
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skip += len; \
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if (skip == p->bv_len) { \
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skip = 0; \
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p++; \
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} \
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n -= __v.iov_len; \
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n -= len; \
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if (left) \
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break; \
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} \
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n = __off; \
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n = off; \
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}
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#define iterate_xarray(i, n, __v, __off, skip, STEP) { \
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#define iterate_xarray(i, n, base, len, __off, skip, STEP) { \
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__label__ __out; \
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size_t __off = 0; \
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struct page *head = NULL; \
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size_t seg, offset; \
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size_t offset; \
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loff_t start = i->xarray_start + skip; \
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pgoff_t index = start >> PAGE_SHIFT; \
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int j; \
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@ -86,14 +86,14 @@
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j < thp_nr_pages(head); j++) { \
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void *kaddr = kmap_local_page(head + j); \
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offset = (start + __off) % PAGE_SIZE; \
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__v.iov_base = kaddr + offset; \
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seg = PAGE_SIZE - offset; \
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__v.iov_len = min(n, seg); \
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base = kaddr + offset; \
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len = PAGE_SIZE - offset; \
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len = min(n, len); \
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left = (STEP); \
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kunmap_local(kaddr); \
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__v.iov_len -= left; \
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__off += __v.iov_len; \
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n -= __v.iov_len; \
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len -= left; \
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__off += len; \
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n -= len; \
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if (left || n == 0) \
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goto __out; \
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} \
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@ -104,39 +104,47 @@ __out: \
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n = __off; \
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}
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#define __iterate_and_advance(i, n, v, off, I, K) { \
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#define __iterate_and_advance(i, n, base, len, off, I, K) { \
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if (unlikely(i->count < n)) \
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n = i->count; \
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if (likely(n)) { \
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size_t skip = i->iov_offset; \
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if (likely(iter_is_iovec(i))) { \
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const struct iovec *iov = i->iov; \
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struct iovec v; \
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iterate_iovec(i, n, v, off, iov, skip, (I)) \
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void __user *base; \
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size_t len; \
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iterate_iovec(i, n, base, len, off, \
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iov, skip, (I)) \
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i->nr_segs -= iov - i->iov; \
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i->iov = iov; \
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} else if (iov_iter_is_bvec(i)) { \
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const struct bio_vec *bvec = i->bvec; \
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struct kvec v; \
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iterate_bvec(i, n, v, off, bvec, skip, (K)) \
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void *base; \
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size_t len; \
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iterate_bvec(i, n, base, len, off, \
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bvec, skip, (K)) \
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i->nr_segs -= bvec - i->bvec; \
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i->bvec = bvec; \
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} else if (iov_iter_is_kvec(i)) { \
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const struct kvec *kvec = i->kvec; \
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struct kvec v; \
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iterate_iovec(i, n, v, off, kvec, skip, (K)) \
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void *base; \
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size_t len; \
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iterate_iovec(i, n, base, len, off, \
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kvec, skip, (K)) \
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i->nr_segs -= kvec - i->kvec; \
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i->kvec = kvec; \
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} else if (iov_iter_is_xarray(i)) { \
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struct kvec v; \
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iterate_xarray(i, n, v, off, skip, (K)) \
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void *base; \
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size_t len; \
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iterate_xarray(i, n, base, len, off, \
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skip, (K)) \
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} \
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i->count -= n; \
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i->iov_offset = skip; \
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} \
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}
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#define iterate_and_advance(i, n, v, off, I, K) \
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__iterate_and_advance(i, n, v, off, I, ((void)(K),0))
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#define iterate_and_advance(i, n, base, len, off, I, K) \
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__iterate_and_advance(i, n, base, len, off, I, ((void)(K),0))
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static int copyout(void __user *to, const void *from, size_t n)
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{
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@ -613,9 +621,9 @@ size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
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return copy_pipe_to_iter(addr, bytes, i);
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if (iter_is_iovec(i))
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might_fault();
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iterate_and_advance(i, bytes, v, off,
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copyout(v.iov_base, addr + off, v.iov_len),
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memcpy(v.iov_base, addr + off, v.iov_len)
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iterate_and_advance(i, bytes, base, len, off,
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copyout(base, addr + off, len),
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memcpy(base, addr + off, len)
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)
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return bytes;
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@ -708,9 +716,9 @@ size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
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return copy_mc_pipe_to_iter(addr, bytes, i);
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if (iter_is_iovec(i))
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might_fault();
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__iterate_and_advance(i, bytes, v, off,
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copyout_mc(v.iov_base, addr + off, v.iov_len),
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copy_mc_to_kernel(v.iov_base, addr + off, v.iov_len)
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__iterate_and_advance(i, bytes, base, len, off,
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copyout_mc(base, addr + off, len),
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copy_mc_to_kernel(base, addr + off, len)
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)
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return bytes;
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@ -726,9 +734,9 @@ size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
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}
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if (iter_is_iovec(i))
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might_fault();
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iterate_and_advance(i, bytes, v, off,
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copyin(addr + off, v.iov_base, v.iov_len),
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memcpy(addr + off, v.iov_base, v.iov_len)
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iterate_and_advance(i, bytes, base, len, off,
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copyin(addr + off, base, len),
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memcpy(addr + off, base, len)
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)
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return bytes;
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@ -741,10 +749,9 @@ size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
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WARN_ON(1);
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return 0;
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}
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iterate_and_advance(i, bytes, v, off,
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__copy_from_user_inatomic_nocache(addr + off,
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v.iov_base, v.iov_len),
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memcpy(addr + off, v.iov_base, v.iov_len)
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iterate_and_advance(i, bytes, base, len, off,
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__copy_from_user_inatomic_nocache(addr + off, base, len),
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memcpy(addr + off, base, len)
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)
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return bytes;
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@ -772,9 +779,9 @@ size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
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WARN_ON(1);
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return 0;
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}
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iterate_and_advance(i, bytes, v, off,
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__copy_from_user_flushcache(addr + off, v.iov_base, v.iov_len),
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memcpy_flushcache(addr + off, v.iov_base, v.iov_len)
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iterate_and_advance(i, bytes, base, len, off,
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__copy_from_user_flushcache(addr + off, base, len),
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memcpy_flushcache(addr + off, base, len)
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)
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return bytes;
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@ -903,9 +910,9 @@ size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
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{
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if (unlikely(iov_iter_is_pipe(i)))
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return pipe_zero(bytes, i);
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iterate_and_advance(i, bytes, v, count,
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clear_user(v.iov_base, v.iov_len),
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memset(v.iov_base, 0, v.iov_len)
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iterate_and_advance(i, bytes, base, len, count,
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clear_user(base, len),
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memset(base, 0, len)
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)
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return bytes;
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@ -925,9 +932,9 @@ size_t copy_page_from_iter_atomic(struct page *page, unsigned offset, size_t byt
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WARN_ON(1);
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return 0;
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}
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iterate_and_advance(i, bytes, v, off,
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copyin(p + off, v.iov_base, v.iov_len),
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memcpy(p + off, v.iov_base, v.iov_len)
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iterate_and_advance(i, bytes, base, len, off,
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copyin(p + off, base, len),
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memcpy(p + off, base, len)
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)
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kunmap_atomic(kaddr);
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return bytes;
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@ -1654,16 +1661,13 @@ size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum,
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WARN_ON(1);
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return 0;
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}
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iterate_and_advance(i, bytes, v, off, ({
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next = csum_and_copy_from_user(v.iov_base,
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addr + off,
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v.iov_len);
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iterate_and_advance(i, bytes, base, len, off, ({
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next = csum_and_copy_from_user(base, addr + off, len);
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if (next)
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sum = csum_block_add(sum, next, off);
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next ? 0 : v.iov_len;
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next ? 0 : len;
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}), ({
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sum = csum_and_memcpy(addr + off, v.iov_base, v.iov_len,
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sum, off);
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sum = csum_and_memcpy(addr + off, base, len, sum, off);
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})
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)
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*csum = sum;
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@ -1685,17 +1689,13 @@ size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *_csstate,
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WARN_ON(1); /* for now */
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return 0;
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}
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iterate_and_advance(i, bytes, v, off, ({
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next = csum_and_copy_to_user(addr + off,
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v.iov_base,
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v.iov_len);
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iterate_and_advance(i, bytes, base, len, off, ({
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next = csum_and_copy_to_user(addr + off, base, len);
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if (next)
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sum = csum_block_add(sum, next, off);
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next ? 0 : v.iov_len;
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next ? 0 : len;
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}), ({
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sum = csum_and_memcpy(v.iov_base,
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addr + off,
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v.iov_len, sum, off);
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sum = csum_and_memcpy(base, addr + off, len, sum, off);
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})
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)
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csstate->csum = csum_shift(sum, csstate->off);
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