From 00e23707442a75b404392cef1405ab4fd498de6b Mon Sep 17 00:00:00 2001 From: David Howells Date: Mon, 22 Oct 2018 13:07:28 +0100 Subject: iov_iter: Use accessor function Use accessor functions to access an iterator's type and direction. This allows for the possibility of using some other method of determining the type of iterator than if-chains with bitwise-AND conditions. Signed-off-by: David Howells --- lib/iov_iter.c | 56 ++++++++++++++++++++++++++++---------------------------- 1 file changed, 28 insertions(+), 28 deletions(-) (limited to 'lib') diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 8be175df3075..42d39116a556 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -558,7 +558,7 @@ static size_t copy_pipe_to_iter(const void *addr, size_t bytes, size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i) { const char *from = addr; - if (unlikely(i->type & ITER_PIPE)) + if (unlikely(iov_iter_is_pipe(i))) return copy_pipe_to_iter(addr, bytes, i); if (iter_is_iovec(i)) might_fault(); @@ -658,7 +658,7 @@ size_t _copy_to_iter_mcsafe(const void *addr, size_t bytes, struct iov_iter *i) const char *from = addr; unsigned long rem, curr_addr, s_addr = (unsigned long) addr; - if (unlikely(i->type & ITER_PIPE)) + if (unlikely(iov_iter_is_pipe(i))) return copy_pipe_to_iter_mcsafe(addr, bytes, i); if (iter_is_iovec(i)) might_fault(); @@ -692,7 +692,7 @@ EXPORT_SYMBOL_GPL(_copy_to_iter_mcsafe); size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i) { char *to = addr; - if (unlikely(i->type & ITER_PIPE)) { + if (unlikely(iov_iter_is_pipe(i))) { WARN_ON(1); return 0; } @@ -712,7 +712,7 @@ EXPORT_SYMBOL(_copy_from_iter); bool _copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i) { char *to = addr; - if (unlikely(i->type & ITER_PIPE)) { + if (unlikely(iov_iter_is_pipe(i))) { WARN_ON(1); return false; } @@ -739,7 +739,7 @@ EXPORT_SYMBOL(_copy_from_iter_full); size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i) { char *to = addr; - if (unlikely(i->type & ITER_PIPE)) { + if (unlikely(iov_iter_is_pipe(i))) { WARN_ON(1); return 0; } @@ -773,7 +773,7 @@ EXPORT_SYMBOL(_copy_from_iter_nocache); size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i) { char *to = addr; - if (unlikely(i->type & ITER_PIPE)) { + if (unlikely(iov_iter_is_pipe(i))) { WARN_ON(1); return 0; } @@ -794,7 +794,7 @@ EXPORT_SYMBOL_GPL(_copy_from_iter_flushcache); bool _copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i) { char *to = addr; - if (unlikely(i->type & ITER_PIPE)) { + if (unlikely(iov_iter_is_pipe(i))) { WARN_ON(1); return false; } @@ -836,7 +836,7 @@ size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, size_t wanted = copy_to_iter(kaddr + offset, bytes, i); kunmap_atomic(kaddr); return wanted; - } else if (likely(!(i->type & ITER_PIPE))) + } else if (likely(!iov_iter_is_pipe(i))) return copy_page_to_iter_iovec(page, offset, bytes, i); else return copy_page_to_iter_pipe(page, offset, bytes, i); @@ -848,7 +848,7 @@ size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, { if (unlikely(!page_copy_sane(page, offset, bytes))) return 0; - if (unlikely(i->type & ITER_PIPE)) { + if (unlikely(iov_iter_is_pipe(i))) { WARN_ON(1); return 0; } @@ -888,7 +888,7 @@ static size_t pipe_zero(size_t bytes, struct iov_iter *i) size_t iov_iter_zero(size_t bytes, struct iov_iter *i) { - if (unlikely(i->type & ITER_PIPE)) + if (unlikely(iov_iter_is_pipe(i))) return pipe_zero(bytes, i); iterate_and_advance(i, bytes, v, clear_user(v.iov_base, v.iov_len), @@ -908,7 +908,7 @@ size_t iov_iter_copy_from_user_atomic(struct page *page, kunmap_atomic(kaddr); return 0; } - if (unlikely(i->type & ITER_PIPE)) { + if (unlikely(iov_iter_is_pipe(i))) { kunmap_atomic(kaddr); WARN_ON(1); return 0; @@ -972,7 +972,7 @@ static void pipe_advance(struct iov_iter *i, size_t size) void iov_iter_advance(struct iov_iter *i, size_t size) { - if (unlikely(i->type & ITER_PIPE)) { + if (unlikely(iov_iter_is_pipe(i))) { pipe_advance(i, size); return; } @@ -987,7 +987,7 @@ void iov_iter_revert(struct iov_iter *i, size_t unroll) if (WARN_ON(unroll > MAX_RW_COUNT)) return; i->count += unroll; - if (unlikely(i->type & ITER_PIPE)) { + if (unlikely(iov_iter_is_pipe(i))) { struct pipe_inode_info *pipe = i->pipe; int idx = i->idx; size_t off = i->iov_offset; @@ -1016,7 +1016,7 @@ void iov_iter_revert(struct iov_iter *i, size_t unroll) return; } unroll -= i->iov_offset; - if (i->type & ITER_BVEC) { + if (iov_iter_is_bvec(i)) { const struct bio_vec *bvec = i->bvec; while (1) { size_t n = (--bvec)->bv_len; @@ -1049,11 +1049,11 @@ EXPORT_SYMBOL(iov_iter_revert); */ size_t iov_iter_single_seg_count(const struct iov_iter *i) { - if (unlikely(i->type & ITER_PIPE)) + if (unlikely(iov_iter_is_pipe(i))) return i->count; // it is a silly place, anyway if (i->nr_segs == 1) return i->count; - else if (i->type & ITER_BVEC) + else if (iov_iter_is_bvec(i)) return min(i->count, i->bvec->bv_len - i->iov_offset); else return min(i->count, i->iov->iov_len - i->iov_offset); @@ -1106,7 +1106,7 @@ unsigned long iov_iter_alignment(const struct iov_iter *i) unsigned long res = 0; size_t size = i->count; - if (unlikely(i->type & ITER_PIPE)) { + if (unlikely(iov_iter_is_pipe(i))) { if (size && i->iov_offset && allocated(&i->pipe->bufs[i->idx])) return size | i->iov_offset; return size; @@ -1125,7 +1125,7 @@ unsigned long iov_iter_gap_alignment(const struct iov_iter *i) unsigned long res = 0; size_t size = i->count; - if (unlikely(i->type & ITER_PIPE)) { + if (unlikely(iov_iter_is_pipe(i))) { WARN_ON(1); return ~0U; } @@ -1193,7 +1193,7 @@ ssize_t iov_iter_get_pages(struct iov_iter *i, if (maxsize > i->count) maxsize = i->count; - if (unlikely(i->type & ITER_PIPE)) + if (unlikely(iov_iter_is_pipe(i))) return pipe_get_pages(i, pages, maxsize, maxpages, start); iterate_all_kinds(i, maxsize, v, ({ unsigned long addr = (unsigned long)v.iov_base; @@ -1205,7 +1205,7 @@ ssize_t iov_iter_get_pages(struct iov_iter *i, len = maxpages * PAGE_SIZE; addr &= ~(PAGE_SIZE - 1); n = DIV_ROUND_UP(len, PAGE_SIZE); - res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, pages); + res = get_user_pages_fast(addr, n, iov_iter_rw(i) != WRITE, pages); if (unlikely(res < 0)) return res; return (res == n ? len : res * PAGE_SIZE) - *start; @@ -1270,7 +1270,7 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, if (maxsize > i->count) maxsize = i->count; - if (unlikely(i->type & ITER_PIPE)) + if (unlikely(iov_iter_is_pipe(i))) return pipe_get_pages_alloc(i, pages, maxsize, start); iterate_all_kinds(i, maxsize, v, ({ unsigned long addr = (unsigned long)v.iov_base; @@ -1283,7 +1283,7 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, p = get_pages_array(n); if (!p) return -ENOMEM; - res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, p); + res = get_user_pages_fast(addr, n, iov_iter_rw(i) != WRITE, p); if (unlikely(res < 0)) { kvfree(p); return res; @@ -1313,7 +1313,7 @@ size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, __wsum sum, next; size_t off = 0; sum = *csum; - if (unlikely(i->type & ITER_PIPE)) { + if (unlikely(iov_iter_is_pipe(i))) { WARN_ON(1); return 0; } @@ -1355,7 +1355,7 @@ bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum, __wsum sum, next; size_t off = 0; sum = *csum; - if (unlikely(i->type & ITER_PIPE)) { + if (unlikely(iov_iter_is_pipe(i))) { WARN_ON(1); return false; } @@ -1400,7 +1400,7 @@ size_t csum_and_copy_to_iter(const void *addr, size_t bytes, __wsum *csum, __wsum sum, next; size_t off = 0; sum = *csum; - if (unlikely(i->type & ITER_PIPE)) { + if (unlikely(iov_iter_is_pipe(i))) { WARN_ON(1); /* for now */ return 0; } @@ -1443,7 +1443,7 @@ int iov_iter_npages(const struct iov_iter *i, int maxpages) if (!size) return 0; - if (unlikely(i->type & ITER_PIPE)) { + if (unlikely(iov_iter_is_pipe(i))) { struct pipe_inode_info *pipe = i->pipe; size_t off; int idx; @@ -1481,11 +1481,11 @@ EXPORT_SYMBOL(iov_iter_npages); const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags) { *new = *old; - if (unlikely(new->type & ITER_PIPE)) { + if (unlikely(iov_iter_is_pipe(new))) { WARN_ON(1); return NULL; } - if (new->type & ITER_BVEC) + if (iov_iter_is_bvec(new)) return new->bvec = kmemdup(new->bvec, new->nr_segs * sizeof(struct bio_vec), flags); -- cgit v1.2.3 From aa563d7bca6e882ec2bdae24603c8f016401a144 Mon Sep 17 00:00:00 2001 From: David Howells Date: Sat, 20 Oct 2018 00:57:56 +0100 Subject: iov_iter: Separate type from direction and use accessor functions In the iov_iter struct, separate the iterator type from the iterator direction and use accessor functions to access them in most places. Convert a bunch of places to use switch-statements to access them rather then chains of bitwise-AND statements. This makes it easier to add further iterator types. Also, this can be more efficient as to implement a switch of small contiguous integers, the compiler can use ~50% fewer compare instructions than it has to use bitwise-and instructions. Further, cease passing the iterator type into the iterator setup function. The iterator function can set that itself. Only the direction is required. Signed-off-by: David Howells --- lib/iov_iter.c | 28 +++++++++++++++------------- 1 file changed, 15 insertions(+), 13 deletions(-) (limited to 'lib') diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 42d39116a556..c42b928b15ef 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -428,17 +428,19 @@ int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes) } EXPORT_SYMBOL(iov_iter_fault_in_readable); -void iov_iter_init(struct iov_iter *i, int direction, +void iov_iter_init(struct iov_iter *i, unsigned int direction, const struct iovec *iov, unsigned long nr_segs, size_t count) { + WARN_ON(direction & ~(READ | WRITE)); + direction &= READ | WRITE; + /* It will get better. Eventually... */ if (uaccess_kernel()) { - direction |= ITER_KVEC; - i->type = direction; + i->type = ITER_KVEC | direction; i->kvec = (struct kvec *)iov; } else { - i->type = direction; + i->type = ITER_IOVEC | direction; i->iov = iov; } i->nr_segs = nr_segs; @@ -1060,12 +1062,12 @@ size_t iov_iter_single_seg_count(const struct iov_iter *i) } EXPORT_SYMBOL(iov_iter_single_seg_count); -void iov_iter_kvec(struct iov_iter *i, int direction, +void iov_iter_kvec(struct iov_iter *i, unsigned int direction, const struct kvec *kvec, unsigned long nr_segs, size_t count) { - BUG_ON(!(direction & ITER_KVEC)); - i->type = direction; + WARN_ON(direction & ~(READ | WRITE)); + i->type = ITER_KVEC | (direction & (READ | WRITE)); i->kvec = kvec; i->nr_segs = nr_segs; i->iov_offset = 0; @@ -1073,12 +1075,12 @@ void iov_iter_kvec(struct iov_iter *i, int direction, } EXPORT_SYMBOL(iov_iter_kvec); -void iov_iter_bvec(struct iov_iter *i, int direction, +void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_vec *bvec, unsigned long nr_segs, size_t count) { - BUG_ON(!(direction & ITER_BVEC)); - i->type = direction; + WARN_ON(direction & ~(READ | WRITE)); + i->type = ITER_BVEC | (direction & (READ | WRITE)); i->bvec = bvec; i->nr_segs = nr_segs; i->iov_offset = 0; @@ -1086,13 +1088,13 @@ void iov_iter_bvec(struct iov_iter *i, int direction, } EXPORT_SYMBOL(iov_iter_bvec); -void iov_iter_pipe(struct iov_iter *i, int direction, +void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe, size_t count) { - BUG_ON(direction != ITER_PIPE); + BUG_ON(direction != READ); WARN_ON(pipe->nrbufs == pipe->buffers); - i->type = direction; + i->type = ITER_PIPE | READ; i->pipe = pipe; i->idx = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1); i->iov_offset = 0; -- cgit v1.2.3 From 9ea9ce0427aab02a2fd88fc608267cf6952119f1 Mon Sep 17 00:00:00 2001 From: David Howells Date: Sat, 20 Oct 2018 00:57:56 +0100 Subject: iov_iter: Add I/O discard iterator Add a new iterator, ITER_DISCARD, that can only be used in READ mode and just discards any data copied to it. This is useful in a network filesystem for discarding any unwanted data sent by a server. Signed-off-by: David Howells --- lib/iov_iter.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 48 insertions(+), 7 deletions(-) (limited to 'lib') diff --git a/lib/iov_iter.c b/lib/iov_iter.c index c42b928b15ef..7ebccb5c1637 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -83,6 +83,7 @@ const struct kvec *kvec; \ struct kvec v; \ iterate_kvec(i, n, v, kvec, skip, (K)) \ + } else if (unlikely(i->type & ITER_DISCARD)) { \ } else { \ const struct iovec *iov; \ struct iovec v; \ @@ -114,6 +115,8 @@ } \ i->nr_segs -= kvec - i->kvec; \ i->kvec = kvec; \ + } else if (unlikely(i->type & ITER_DISCARD)) { \ + skip += n; \ } else { \ const struct iovec *iov; \ struct iovec v; \ @@ -838,7 +841,9 @@ size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, size_t wanted = copy_to_iter(kaddr + offset, bytes, i); kunmap_atomic(kaddr); return wanted; - } else if (likely(!iov_iter_is_pipe(i))) + } else if (unlikely(iov_iter_is_discard(i))) + return bytes; + else if (likely(!iov_iter_is_pipe(i))) return copy_page_to_iter_iovec(page, offset, bytes, i); else return copy_page_to_iter_pipe(page, offset, bytes, i); @@ -850,7 +855,7 @@ size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, { if (unlikely(!page_copy_sane(page, offset, bytes))) return 0; - if (unlikely(iov_iter_is_pipe(i))) { + if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { WARN_ON(1); return 0; } @@ -910,7 +915,7 @@ size_t iov_iter_copy_from_user_atomic(struct page *page, kunmap_atomic(kaddr); return 0; } - if (unlikely(iov_iter_is_pipe(i))) { + if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { kunmap_atomic(kaddr); WARN_ON(1); return 0; @@ -978,6 +983,10 @@ void iov_iter_advance(struct iov_iter *i, size_t size) pipe_advance(i, size); return; } + if (unlikely(iov_iter_is_discard(i))) { + i->count -= size; + return; + } iterate_and_advance(i, size, v, 0, 0, 0) } EXPORT_SYMBOL(iov_iter_advance); @@ -1013,6 +1022,8 @@ void iov_iter_revert(struct iov_iter *i, size_t unroll) pipe_truncate(i); return; } + if (unlikely(iov_iter_is_discard(i))) + return; if (unroll <= i->iov_offset) { i->iov_offset -= unroll; return; @@ -1055,6 +1066,8 @@ size_t iov_iter_single_seg_count(const struct iov_iter *i) return i->count; // it is a silly place, anyway if (i->nr_segs == 1) return i->count; + if (unlikely(iov_iter_is_discard(i))) + return i->count; else if (iov_iter_is_bvec(i)) return min(i->count, i->bvec->bv_len - i->iov_offset); else @@ -1103,6 +1116,24 @@ void iov_iter_pipe(struct iov_iter *i, unsigned int direction, } EXPORT_SYMBOL(iov_iter_pipe); +/** + * iov_iter_discard - Initialise an I/O iterator that discards data + * @i: The iterator to initialise. + * @direction: The direction of the transfer. + * @count: The size of the I/O buffer in bytes. + * + * Set up an I/O iterator that just discards everything that's written to it. + * It's only available as a READ iterator. + */ +void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count) +{ + BUG_ON(direction != READ); + i->type = ITER_DISCARD | READ; + i->count = count; + i->iov_offset = 0; +} +EXPORT_SYMBOL(iov_iter_discard); + unsigned long iov_iter_alignment(const struct iov_iter *i) { unsigned long res = 0; @@ -1127,7 +1158,7 @@ unsigned long iov_iter_gap_alignment(const struct iov_iter *i) unsigned long res = 0; size_t size = i->count; - if (unlikely(iov_iter_is_pipe(i))) { + if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { WARN_ON(1); return ~0U; } @@ -1197,6 +1228,9 @@ ssize_t iov_iter_get_pages(struct iov_iter *i, if (unlikely(iov_iter_is_pipe(i))) return pipe_get_pages(i, pages, maxsize, maxpages, start); + if (unlikely(iov_iter_is_discard(i))) + return -EFAULT; + iterate_all_kinds(i, maxsize, v, ({ unsigned long addr = (unsigned long)v.iov_base; size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1)); @@ -1274,6 +1308,9 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, if (unlikely(iov_iter_is_pipe(i))) return pipe_get_pages_alloc(i, pages, maxsize, start); + if (unlikely(iov_iter_is_discard(i))) + return -EFAULT; + iterate_all_kinds(i, maxsize, v, ({ unsigned long addr = (unsigned long)v.iov_base; size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1)); @@ -1315,7 +1352,7 @@ size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, __wsum sum, next; size_t off = 0; sum = *csum; - if (unlikely(iov_iter_is_pipe(i))) { + if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { WARN_ON(1); return 0; } @@ -1357,7 +1394,7 @@ bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum, __wsum sum, next; size_t off = 0; sum = *csum; - if (unlikely(iov_iter_is_pipe(i))) { + if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { WARN_ON(1); return false; } @@ -1402,7 +1439,7 @@ size_t csum_and_copy_to_iter(const void *addr, size_t bytes, __wsum *csum, __wsum sum, next; size_t off = 0; sum = *csum; - if (unlikely(iov_iter_is_pipe(i))) { + if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { WARN_ON(1); /* for now */ return 0; } @@ -1444,6 +1481,8 @@ int iov_iter_npages(const struct iov_iter *i, int maxpages) if (!size) return 0; + if (unlikely(iov_iter_is_discard(i))) + return 0; if (unlikely(iov_iter_is_pipe(i))) { struct pipe_inode_info *pipe = i->pipe; @@ -1487,6 +1526,8 @@ const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags) WARN_ON(1); return NULL; } + if (unlikely(iov_iter_is_discard(new))) + return NULL; if (iov_iter_is_bvec(new)) return new->bvec = kmemdup(new->bvec, new->nr_segs * sizeof(struct bio_vec), -- cgit v1.2.3