/* * CDDL HEADER START * * The contents of this file are subject to the terms of the * Common Development and Distribution License (the "License"). * You may not use this file except in compliance with the License. * * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE * or http://www.opensolaris.org/os/licensing. * See the License for the specific language governing permissions * and limitations under the License. * * When distributing Covered Code, include this CDDL HEADER in each * file and include the License file at usr/src/OPENSOLARIS.LICENSE. * If applicable, add the following below this CDDL HEADER, with the * fields enclosed by brackets "[]" replaced with your own identifying * information: Portions Copyright [yyyy] [name of copyright owner] * * CDDL HEADER END */ /* * Copyright (c) 2014 by Chunwei Chen. All rights reserved. * Copyright (c) 2019 by Delphix. All rights reserved. */ /* * ARC buffer data (ABD). * * ABDs are an abstract data structure for the ARC which can use two * different ways of storing the underlying data: * * (a) Linear buffer. In this case, all the data in the ABD is stored in one * contiguous buffer in memory (from a zio_[data_]buf_* kmem cache). * * +-------------------+ * | ABD (linear) | * | abd_flags = ... | * | abd_size = ... | +--------------------------------+ * | abd_buf ------------->| raw buffer of size abd_size | * +-------------------+ +--------------------------------+ * no abd_chunks * * (b) Scattered buffer. In this case, the data in the ABD is split into * equal-sized chunks (from the abd_chunk_cache kmem_cache), with pointers * to the chunks recorded in an array at the end of the ABD structure. * * +-------------------+ * | ABD (scattered) | * | abd_flags = ... | * | abd_size = ... | * | abd_offset = 0 | +-----------+ * | abd_chunks[0] ----------------------------->| chunk 0 | * | abd_chunks[1] ---------------------+ +-----------+ * | ... | | +-----------+ * | abd_chunks[N-1] ---------+ +------->| chunk 1 | * +-------------------+ | +-----------+ * | ... * | +-----------+ * +----------------->| chunk N-1 | * +-----------+ * * In addition to directly allocating a linear or scattered ABD, it is also * possible to create an ABD by requesting the "sub-ABD" starting at an offset * within an existing ABD. In linear buffers this is simple (set abd_buf of * the new ABD to the starting point within the original raw buffer), but * scattered ABDs are a little more complex. The new ABD makes a copy of the * relevant abd_chunks pointers (but not the underlying data). However, to * provide arbitrary rather than only chunk-aligned starting offsets, it also * tracks an abd_offset field which represents the starting point of the data * within the first chunk in abd_chunks. For both linear and scattered ABDs, * creating an offset ABD marks the original ABD as the offset's parent, and the * original ABD's abd_children refcount is incremented. This data allows us to * ensure the root ABD isn't deleted before its children. * * Most consumers should never need to know what type of ABD they're using -- * the ABD public API ensures that it's possible to transparently switch from * using a linear ABD to a scattered one when doing so would be beneficial. * * If you need to use the data within an ABD directly, if you know it's linear * (because you allocated it) you can use abd_to_buf() to access the underlying * raw buffer. Otherwise, you should use one of the abd_borrow_buf* functions * which will allocate a raw buffer if necessary. Use the abd_return_buf* * functions to return any raw buffers that are no longer necessary when you're * done using them. * * There are a variety of ABD APIs that implement basic buffer operations: * compare, copy, read, write, and fill with zeroes. If you need a custom * function which progressively accesses the whole ABD, use the abd_iterate_* * functions. * * It is possible to make all ABDs linear by setting zfs_abd_scatter_enabled to * B_FALSE. */ #include #include #include #include #include /* see block comment above for description */ int zfs_abd_scatter_enabled = B_TRUE; boolean_t abd_is_linear(abd_t *abd) { return ((abd->abd_flags & ABD_FLAG_LINEAR) != 0 ? B_TRUE : B_FALSE); } boolean_t abd_is_linear_page(abd_t *abd) { return ((abd->abd_flags & ABD_FLAG_LINEAR_PAGE) != 0 ? B_TRUE : B_FALSE); } void abd_verify(abd_t *abd) { ASSERT3U(abd->abd_size, >, 0); ASSERT3U(abd->abd_size, <=, SPA_MAXBLOCKSIZE); ASSERT3U(abd->abd_flags, ==, abd->abd_flags & (ABD_FLAG_LINEAR | ABD_FLAG_OWNER | ABD_FLAG_META | ABD_FLAG_MULTI_ZONE | ABD_FLAG_MULTI_CHUNK | ABD_FLAG_LINEAR_PAGE)); IMPLY(abd->abd_parent != NULL, !(abd->abd_flags & ABD_FLAG_OWNER)); IMPLY(abd->abd_flags & ABD_FLAG_META, abd->abd_flags & ABD_FLAG_OWNER); if (abd_is_linear(abd)) { ASSERT3P(ABD_LINEAR_BUF(abd), !=, NULL); } else { abd_verify_scatter(abd); } } uint_t abd_get_size(abd_t *abd) { abd_verify(abd); return (abd->abd_size); } /* * Allocate an ABD, along with its own underlying data buffers. Use this if you * don't care whether the ABD is linear or not. */ abd_t * abd_alloc(size_t size, boolean_t is_metadata) { if (!zfs_abd_scatter_enabled || abd_size_alloc_linear(size)) return (abd_alloc_linear(size, is_metadata)); VERIFY3U(size, <=, SPA_MAXBLOCKSIZE); abd_t *abd = abd_alloc_struct(size); abd->abd_flags = ABD_FLAG_OWNER; abd->abd_u.abd_scatter.abd_offset = 0; abd_alloc_chunks(abd, size); if (is_metadata) { abd->abd_flags |= ABD_FLAG_META; } abd->abd_size = size; abd->abd_parent = NULL; zfs_refcount_create(&abd->abd_children); abd_update_scatter_stats(abd, ABDSTAT_INCR); return (abd); } static void abd_free_scatter(abd_t *abd) { abd_free_chunks(abd); zfs_refcount_destroy(&abd->abd_children); abd_update_scatter_stats(abd, ABDSTAT_DECR); abd_free_struct(abd); } /* * Free an ABD allocated from abd_get_offset() or abd_get_from_buf(). Will not * free the underlying scatterlist or buffer. */ void abd_put(abd_t *abd) { if (abd == NULL) return; abd_verify(abd); ASSERT(!(abd->abd_flags & ABD_FLAG_OWNER)); if (abd->abd_parent != NULL) { (void) zfs_refcount_remove_many(&abd->abd_parent->abd_children, abd->abd_size, abd); } zfs_refcount_destroy(&abd->abd_children); abd_free_struct(abd); } /* * Allocate an ABD that must be linear, along with its own underlying data * buffer. Only use this when it would be very annoying to write your ABD * consumer with a scattered ABD. */ abd_t * abd_alloc_linear(size_t size, boolean_t is_metadata) { abd_t *abd = abd_alloc_struct(0); VERIFY3U(size, <=, SPA_MAXBLOCKSIZE); abd->abd_flags = ABD_FLAG_LINEAR | ABD_FLAG_OWNER; if (is_metadata) { abd->abd_flags |= ABD_FLAG_META; } abd->abd_size = size; abd->abd_parent = NULL; zfs_refcount_create(&abd->abd_children); if (is_metadata) { ABD_LINEAR_BUF(abd) = zio_buf_alloc(size); } else { ABD_LINEAR_BUF(abd) = zio_data_buf_alloc(size); } abd_update_linear_stats(abd, ABDSTAT_INCR); return (abd); } static void abd_free_linear(abd_t *abd) { if (abd_is_linear_page(abd)) { abd_free_linear_page(abd); return; } if (abd->abd_flags & ABD_FLAG_META) { zio_buf_free(ABD_LINEAR_BUF(abd), abd->abd_size); } else { zio_data_buf_free(ABD_LINEAR_BUF(abd), abd->abd_size); } zfs_refcount_destroy(&abd->abd_children); abd_update_linear_stats(abd, ABDSTAT_DECR); abd_free_struct(abd); } /* * Free an ABD. Only use this on ABDs allocated with abd_alloc() or * abd_alloc_linear(). */ void abd_free(abd_t *abd) { if (abd == NULL) return; abd_verify(abd); ASSERT3P(abd->abd_parent, ==, NULL); ASSERT(abd->abd_flags & ABD_FLAG_OWNER); if (abd_is_linear(abd)) abd_free_linear(abd); else abd_free_scatter(abd); } /* * Allocate an ABD of the same format (same metadata flag, same scatterize * setting) as another ABD. */ abd_t * abd_alloc_sametype(abd_t *sabd, size_t size) { boolean_t is_metadata = (sabd->abd_flags & ABD_FLAG_META) != 0; if (abd_is_linear(sabd) && !abd_is_linear_page(sabd)) { return (abd_alloc_linear(size, is_metadata)); } else { return (abd_alloc(size, is_metadata)); } } /* * Allocate a new ABD to point to offset off of sabd. It shares the underlying * buffer data with sabd. Use abd_put() to free. sabd must not be freed while * any derived ABDs exist. */ static abd_t * abd_get_offset_impl(abd_t *sabd, size_t off, size_t size) { abd_t *abd = NULL; abd_verify(sabd); ASSERT3U(off, <=, sabd->abd_size); if (abd_is_linear(sabd)) { abd = abd_alloc_struct(0); /* * Even if this buf is filesystem metadata, we only track that * if we own the underlying data buffer, which is not true in * this case. Therefore, we don't ever use ABD_FLAG_META here. */ abd->abd_flags = ABD_FLAG_LINEAR; ABD_LINEAR_BUF(abd) = (char *)ABD_LINEAR_BUF(sabd) + off; } else { abd = abd_get_offset_scatter(sabd, off); } abd->abd_size = size; abd->abd_parent = sabd; zfs_refcount_create(&abd->abd_children); (void) zfs_refcount_add_many(&sabd->abd_children, abd->abd_size, abd); return (abd); } abd_t * abd_get_offset(abd_t *sabd, size_t off) { size_t size = sabd->abd_size > off ? sabd->abd_size - off : 0; VERIFY3U(size, >, 0); return (abd_get_offset_impl(sabd, off, size)); } abd_t * abd_get_offset_size(abd_t *sabd, size_t off, size_t size) { ASSERT3U(off + size, <=, sabd->abd_size); return (abd_get_offset_impl(sabd, off, size)); } /* * Allocate a linear ABD structure for buf. You must free this with abd_put() * since the resulting ABD doesn't own its own buffer. */ abd_t * abd_get_from_buf(void *buf, size_t size) { abd_t *abd = abd_alloc_struct(0); VERIFY3U(size, <=, SPA_MAXBLOCKSIZE); /* * Even if this buf is filesystem metadata, we only track that if we * own the underlying data buffer, which is not true in this case. * Therefore, we don't ever use ABD_FLAG_META here. */ abd->abd_flags = ABD_FLAG_LINEAR; abd->abd_size = size; abd->abd_parent = NULL; zfs_refcount_create(&abd->abd_children); ABD_LINEAR_BUF(abd) = buf; return (abd); } /* * Get the raw buffer associated with a linear ABD. */ void * abd_to_buf(abd_t *abd) { ASSERT(abd_is_linear(abd)); abd_verify(abd); return (ABD_LINEAR_BUF(abd)); } /* * Borrow a raw buffer from an ABD without copying the contents of the ABD * into the buffer. If the ABD is scattered, this will allocate a raw buffer * whose contents are undefined. To copy over the existing data in the ABD, use * abd_borrow_buf_copy() instead. */ void * abd_borrow_buf(abd_t *abd, size_t n) { void *buf; abd_verify(abd); ASSERT3U(abd->abd_size, >=, n); if (abd_is_linear(abd)) { buf = abd_to_buf(abd); } else { buf = zio_buf_alloc(n); } (void) zfs_refcount_add_many(&abd->abd_children, n, buf); return (buf); } void * abd_borrow_buf_copy(abd_t *abd, size_t n) { void *buf = abd_borrow_buf(abd, n); if (!abd_is_linear(abd)) { abd_copy_to_buf(buf, abd, n); } return (buf); } /* * Return a borrowed raw buffer to an ABD. If the ABD is scattered, this will * not change the contents of the ABD and will ASSERT that you didn't modify * the buffer since it was borrowed. If you want any changes you made to buf to * be copied back to abd, use abd_return_buf_copy() instead. */ void abd_return_buf(abd_t *abd, void *buf, size_t n) { abd_verify(abd); ASSERT3U(abd->abd_size, >=, n); if (abd_is_linear(abd)) { ASSERT3P(buf, ==, abd_to_buf(abd)); } else { ASSERT0(abd_cmp_buf(abd, buf, n)); zio_buf_free(buf, n); } (void) zfs_refcount_remove_many(&abd->abd_children, n, buf); } void abd_return_buf_copy(abd_t *abd, void *buf, size_t n) { if (!abd_is_linear(abd)) { abd_copy_from_buf(abd, buf, n); } abd_return_buf(abd, buf, n); } void abd_release_ownership_of_buf(abd_t *abd) { ASSERT(abd_is_linear(abd)); ASSERT(abd->abd_flags & ABD_FLAG_OWNER); /* * abd_free() needs to handle LINEAR_PAGE ABD's specially. * Since that flag does not survive the * abd_release_ownership_of_buf() -> abd_get_from_buf() -> * abd_take_ownership_of_buf() sequence, we don't allow releasing * these "linear but not zio_[data_]buf_alloc()'ed" ABD's. */ ASSERT(!abd_is_linear_page(abd)); abd_verify(abd); abd->abd_flags &= ~ABD_FLAG_OWNER; /* Disable this flag since we no longer own the data buffer */ abd->abd_flags &= ~ABD_FLAG_META; abd_update_linear_stats(abd, ABDSTAT_DECR); } /* * Give this ABD ownership of the buffer that it's storing. Can only be used on * linear ABDs which were allocated via abd_get_from_buf(), or ones allocated * with abd_alloc_linear() which subsequently released ownership of their buf * with abd_release_ownership_of_buf(). */ void abd_take_ownership_of_buf(abd_t *abd, boolean_t is_metadata) { ASSERT(abd_is_linear(abd)); ASSERT(!(abd->abd_flags & ABD_FLAG_OWNER)); abd_verify(abd); abd->abd_flags |= ABD_FLAG_OWNER; if (is_metadata) { abd->abd_flags |= ABD_FLAG_META; } abd_update_linear_stats(abd, ABDSTAT_INCR); } int abd_iterate_func(abd_t *abd, size_t off, size_t size, abd_iter_func_t *func, void *private) { int ret = 0; struct abd_iter aiter; abd_verify(abd); ASSERT3U(off + size, <=, abd->abd_size); abd_iter_init(&aiter, abd); abd_iter_advance(&aiter, off); while (size > 0) { abd_iter_map(&aiter); size_t len = MIN(aiter.iter_mapsize, size); ASSERT3U(len, >, 0); ret = func(aiter.iter_mapaddr, len, private); abd_iter_unmap(&aiter); if (ret != 0) break; size -= len; abd_iter_advance(&aiter, len); } return (ret); } struct buf_arg { void *arg_buf; }; static int abd_copy_to_buf_off_cb(void *buf, size_t size, void *private) { struct buf_arg *ba_ptr = private; (void) memcpy(ba_ptr->arg_buf, buf, size); ba_ptr->arg_buf = (char *)ba_ptr->arg_buf + size; return (0); } /* * Copy abd to buf. (off is the offset in abd.) */ void abd_copy_to_buf_off(void *buf, abd_t *abd, size_t off, size_t size) { struct buf_arg ba_ptr = { buf }; (void) abd_iterate_func(abd, off, size, abd_copy_to_buf_off_cb, &ba_ptr); } static int abd_cmp_buf_off_cb(void *buf, size_t size, void *private) { int ret; struct buf_arg *ba_ptr = private; ret = memcmp(buf, ba_ptr->arg_buf, size); ba_ptr->arg_buf = (char *)ba_ptr->arg_buf + size; return (ret); } /* * Compare the contents of abd to buf. (off is the offset in abd.) */ int abd_cmp_buf_off(abd_t *abd, const void *buf, size_t off, size_t size) { struct buf_arg ba_ptr = { (void *) buf }; return (abd_iterate_func(abd, off, size, abd_cmp_buf_off_cb, &ba_ptr)); } static int abd_copy_from_buf_off_cb(void *buf, size_t size, void *private) { struct buf_arg *ba_ptr = private; (void) memcpy(buf, ba_ptr->arg_buf, size); ba_ptr->arg_buf = (char *)ba_ptr->arg_buf + size; return (0); } /* * Copy from buf to abd. (off is the offset in abd.) */ void abd_copy_from_buf_off(abd_t *abd, const void *buf, size_t off, size_t size) { struct buf_arg ba_ptr = { (void *) buf }; (void) abd_iterate_func(abd, off, size, abd_copy_from_buf_off_cb, &ba_ptr); } /*ARGSUSED*/ static int abd_zero_off_cb(void *buf, size_t size, void *private) { (void) memset(buf, 0, size); return (0); } /* * Zero out the abd from a particular offset to the end. */ void abd_zero_off(abd_t *abd, size_t off, size_t size) { (void) abd_iterate_func(abd, off, size, abd_zero_off_cb, NULL); } /* * Iterate over two ABDs and call func incrementally on the two ABDs' data in * equal-sized chunks (passed to func as raw buffers). func could be called many * times during this iteration. */ int abd_iterate_func2(abd_t *dabd, abd_t *sabd, size_t doff, size_t soff, size_t size, abd_iter_func2_t *func, void *private) { int ret = 0; struct abd_iter daiter, saiter; abd_verify(dabd); abd_verify(sabd); ASSERT3U(doff + size, <=, dabd->abd_size); ASSERT3U(soff + size, <=, sabd->abd_size); abd_iter_init(&daiter, dabd); abd_iter_init(&saiter, sabd); abd_iter_advance(&daiter, doff); abd_iter_advance(&saiter, soff); while (size > 0) { abd_iter_map(&daiter); abd_iter_map(&saiter); size_t dlen = MIN(daiter.iter_mapsize, size); size_t slen = MIN(saiter.iter_mapsize, size); size_t len = MIN(dlen, slen); ASSERT(dlen > 0 || slen > 0); ret = func(daiter.iter_mapaddr, saiter.iter_mapaddr, len, private); abd_iter_unmap(&saiter); abd_iter_unmap(&daiter); if (ret != 0) break; size -= len; abd_iter_advance(&daiter, len); abd_iter_advance(&saiter, len); } return (ret); } /*ARGSUSED*/ static int abd_copy_off_cb(void *dbuf, void *sbuf, size_t size, void *private) { (void) memcpy(dbuf, sbuf, size); return (0); } /* * Copy from sabd to dabd starting from soff and doff. */ void abd_copy_off(abd_t *dabd, abd_t *sabd, size_t doff, size_t soff, size_t size) { (void) abd_iterate_func2(dabd, sabd, doff, soff, size, abd_copy_off_cb, NULL); } /*ARGSUSED*/ static int abd_cmp_cb(void *bufa, void *bufb, size_t size, void *private) { return (memcmp(bufa, bufb, size)); } /* * Compares the contents of two ABDs. */ int abd_cmp(abd_t *dabd, abd_t *sabd) { ASSERT3U(dabd->abd_size, ==, sabd->abd_size); return (abd_iterate_func2(dabd, sabd, 0, 0, dabd->abd_size, abd_cmp_cb, NULL)); } /* * Iterate over code ABDs and a data ABD and call @func_raidz_gen. * * @cabds parity ABDs, must have equal size * @dabd data ABD. Can be NULL (in this case @dsize = 0) * @func_raidz_gen should be implemented so that its behaviour * is the same when taking linear and when taking scatter */ void abd_raidz_gen_iterate(abd_t **cabds, abd_t *dabd, ssize_t csize, ssize_t dsize, const unsigned parity, void (*func_raidz_gen)(void **, const void *, size_t, size_t)) { int i; ssize_t len, dlen; struct abd_iter caiters[3]; struct abd_iter daiter = {0}; void *caddrs[3]; unsigned long flags __maybe_unused = 0; ASSERT3U(parity, <=, 3); for (i = 0; i < parity; i++) abd_iter_init(&caiters[i], cabds[i]); if (dabd) abd_iter_init(&daiter, dabd); ASSERT3S(dsize, >=, 0); abd_enter_critical(flags); while (csize > 0) { len = csize; if (dabd && dsize > 0) abd_iter_map(&daiter); for (i = 0; i < parity; i++) { abd_iter_map(&caiters[i]); caddrs[i] = caiters[i].iter_mapaddr; } switch (parity) { case 3: len = MIN(caiters[2].iter_mapsize, len); /* falls through */ case 2: len = MIN(caiters[1].iter_mapsize, len); /* falls through */ case 1: len = MIN(caiters[0].iter_mapsize, len); } /* must be progressive */ ASSERT3S(len, >, 0); if (dabd && dsize > 0) { /* this needs precise iter.length */ len = MIN(daiter.iter_mapsize, len); dlen = len; } else dlen = 0; /* must be progressive */ ASSERT3S(len, >, 0); /* * The iterated function likely will not do well if each * segment except the last one is not multiple of 512 (raidz). */ ASSERT3U(((uint64_t)len & 511ULL), ==, 0); func_raidz_gen(caddrs, daiter.iter_mapaddr, len, dlen); for (i = parity-1; i >= 0; i--) { abd_iter_unmap(&caiters[i]); abd_iter_advance(&caiters[i], len); } if (dabd && dsize > 0) { abd_iter_unmap(&daiter); abd_iter_advance(&daiter, dlen); dsize -= dlen; } csize -= len; ASSERT3S(dsize, >=, 0); ASSERT3S(csize, >=, 0); } abd_exit_critical(flags); } /* * Iterate over code ABDs and data reconstruction target ABDs and call * @func_raidz_rec. Function maps at most 6 pages atomically. * * @cabds parity ABDs, must have equal size * @tabds rec target ABDs, at most 3 * @tsize size of data target columns * @func_raidz_rec expects syndrome data in target columns. Function * reconstructs data and overwrites target columns. */ void abd_raidz_rec_iterate(abd_t **cabds, abd_t **tabds, ssize_t tsize, const unsigned parity, void (*func_raidz_rec)(void **t, const size_t tsize, void **c, const unsigned *mul), const unsigned *mul) { int i; ssize_t len; struct abd_iter citers[3]; struct abd_iter xiters[3]; void *caddrs[3], *xaddrs[3]; unsigned long flags __maybe_unused = 0; ASSERT3U(parity, <=, 3); for (i = 0; i < parity; i++) { abd_iter_init(&citers[i], cabds[i]); abd_iter_init(&xiters[i], tabds[i]); } abd_enter_critical(flags); while (tsize > 0) { for (i = 0; i < parity; i++) { abd_iter_map(&citers[i]); abd_iter_map(&xiters[i]); caddrs[i] = citers[i].iter_mapaddr; xaddrs[i] = xiters[i].iter_mapaddr; } len = tsize; switch (parity) { case 3: len = MIN(xiters[2].iter_mapsize, len); len = MIN(citers[2].iter_mapsize, len); /* falls through */ case 2: len = MIN(xiters[1].iter_mapsize, len); len = MIN(citers[1].iter_mapsize, len); /* falls through */ case 1: len = MIN(xiters[0].iter_mapsize, len); len = MIN(citers[0].iter_mapsize, len); } /* must be progressive */ ASSERT3S(len, >, 0); /* * The iterated function likely will not do well if each * segment except the last one is not multiple of 512 (raidz). */ ASSERT3U(((uint64_t)len & 511ULL), ==, 0); func_raidz_rec(xaddrs, len, caddrs, mul); for (i = parity-1; i >= 0; i--) { abd_iter_unmap(&xiters[i]); abd_iter_unmap(&citers[i]); abd_iter_advance(&xiters[i], len); abd_iter_advance(&citers[i], len); } tsize -= len; ASSERT3S(tsize, >=, 0); } abd_exit_critical(flags); }