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Diffstat (limited to 'module/os/linux/zfs/abd.c')
-rw-r--r-- | module/os/linux/zfs/abd.c | 1638 |
1 files changed, 1638 insertions, 0 deletions
diff --git a/module/os/linux/zfs/abd.c b/module/os/linux/zfs/abd.c new file mode 100644 index 000000000..ac6b0b742 --- /dev/null +++ b/module/os/linux/zfs/abd.c @@ -0,0 +1,1638 @@ +/* + * 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 | + * +-----------+ + * + * Linear buffers act exactly like normal buffers and are always mapped into the + * kernel's virtual memory space, while scattered ABD data chunks are allocated + * as physical pages and then mapped in only while they are actually being + * accessed through one of the abd_* library functions. Using scattered ABDs + * provides several benefits: + * + * (1) They avoid use of kmem_*, preventing performance problems where running + * kmem_reap on very large memory systems never finishes and causes + * constant TLB shootdowns. + * + * (2) Fragmentation is less of an issue since when we are at the limit of + * allocatable space, we won't have to search around for a long free + * hole in the VA space for large ARC allocations. Each chunk is mapped in + * individually, so even if we are using HIGHMEM (see next point) we + * wouldn't need to worry about finding a contiguous address range. + * + * (3) If we are not using HIGHMEM, then all physical memory is always + * mapped into the kernel's address space, so we also avoid the map / + * unmap costs on each ABD access. + * + * If we are not using HIGHMEM, scattered buffers which have only one chunk + * can be treated as linear buffers, because they are contiguous in the + * kernel's virtual address space. See abd_alloc_pages() for details. + * + * It is possible to make all ABDs linear by setting zfs_abd_scatter_enabled to + * B_FALSE. + * + * 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. + */ + +#include <sys/abd.h> +#include <sys/param.h> +#include <sys/zio.h> +#include <sys/zfs_context.h> +#include <sys/zfs_znode.h> +#ifdef _KERNEL +#include <linux/scatterlist.h> +#include <linux/kmap_compat.h> +#else +#define MAX_ORDER 1 +#endif + +typedef struct abd_stats { + kstat_named_t abdstat_struct_size; + kstat_named_t abdstat_linear_cnt; + kstat_named_t abdstat_linear_data_size; + kstat_named_t abdstat_scatter_cnt; + kstat_named_t abdstat_scatter_data_size; + kstat_named_t abdstat_scatter_chunk_waste; + kstat_named_t abdstat_scatter_orders[MAX_ORDER]; + kstat_named_t abdstat_scatter_page_multi_chunk; + kstat_named_t abdstat_scatter_page_multi_zone; + kstat_named_t abdstat_scatter_page_alloc_retry; + kstat_named_t abdstat_scatter_sg_table_retry; +} abd_stats_t; + +static abd_stats_t abd_stats = { + /* Amount of memory occupied by all of the abd_t struct allocations */ + { "struct_size", KSTAT_DATA_UINT64 }, + /* + * The number of linear ABDs which are currently allocated, excluding + * ABDs which don't own their data (for instance the ones which were + * allocated through abd_get_offset() and abd_get_from_buf()). If an + * ABD takes ownership of its buf then it will become tracked. + */ + { "linear_cnt", KSTAT_DATA_UINT64 }, + /* Amount of data stored in all linear ABDs tracked by linear_cnt */ + { "linear_data_size", KSTAT_DATA_UINT64 }, + /* + * The number of scatter ABDs which are currently allocated, excluding + * ABDs which don't own their data (for instance the ones which were + * allocated through abd_get_offset()). + */ + { "scatter_cnt", KSTAT_DATA_UINT64 }, + /* Amount of data stored in all scatter ABDs tracked by scatter_cnt */ + { "scatter_data_size", KSTAT_DATA_UINT64 }, + /* + * The amount of space wasted at the end of the last chunk across all + * scatter ABDs tracked by scatter_cnt. + */ + { "scatter_chunk_waste", KSTAT_DATA_UINT64 }, + /* + * The number of compound allocations of a given order. These + * allocations are spread over all currently allocated ABDs, and + * act as a measure of memory fragmentation. + */ + { { "scatter_order_N", KSTAT_DATA_UINT64 } }, + /* + * The number of scatter ABDs which contain multiple chunks. + * ABDs are preferentially allocated from the minimum number of + * contiguous multi-page chunks, a single chunk is optimal. + */ + { "scatter_page_multi_chunk", KSTAT_DATA_UINT64 }, + /* + * The number of scatter ABDs which are split across memory zones. + * ABDs are preferentially allocated using pages from a single zone. + */ + { "scatter_page_multi_zone", KSTAT_DATA_UINT64 }, + /* + * The total number of retries encountered when attempting to + * allocate the pages to populate the scatter ABD. + */ + { "scatter_page_alloc_retry", KSTAT_DATA_UINT64 }, + /* + * The total number of retries encountered when attempting to + * allocate the sg table for an ABD. + */ + { "scatter_sg_table_retry", KSTAT_DATA_UINT64 }, +}; + +#define ABDSTAT(stat) (abd_stats.stat.value.ui64) +#define ABDSTAT_INCR(stat, val) \ + atomic_add_64(&abd_stats.stat.value.ui64, (val)) +#define ABDSTAT_BUMP(stat) ABDSTAT_INCR(stat, 1) +#define ABDSTAT_BUMPDOWN(stat) ABDSTAT_INCR(stat, -1) + +#define ABD_SCATTER(abd) (abd->abd_u.abd_scatter) +#define ABD_BUF(abd) (abd->abd_u.abd_linear.abd_buf) +#define abd_for_each_sg(abd, sg, n, i) \ + for_each_sg(ABD_SCATTER(abd).abd_sgl, sg, n, i) + +/* see block comment above for description */ +int zfs_abd_scatter_enabled = B_TRUE; +unsigned zfs_abd_scatter_max_order = MAX_ORDER - 1; + +/* + * zfs_abd_scatter_min_size is the minimum allocation size to use scatter + * ABD's. Smaller allocations will use linear ABD's which uses + * zio_[data_]buf_alloc(). + * + * Scatter ABD's use at least one page each, so sub-page allocations waste + * some space when allocated as scatter (e.g. 2KB scatter allocation wastes + * half of each page). Using linear ABD's for small allocations means that + * they will be put on slabs which contain many allocations. This can + * improve memory efficiency, but it also makes it much harder for ARC + * evictions to actually free pages, because all the buffers on one slab need + * to be freed in order for the slab (and underlying pages) to be freed. + * Typically, 512B and 1KB kmem caches have 16 buffers per slab, so it's + * possible for them to actually waste more memory than scatter (one page per + * buf = wasting 3/4 or 7/8th; one buf per slab = wasting 15/16th). + * + * Spill blocks are typically 512B and are heavily used on systems running + * selinux with the default dnode size and the `xattr=sa` property set. + * + * By default we use linear allocations for 512B and 1KB, and scatter + * allocations for larger (1.5KB and up). + */ +int zfs_abd_scatter_min_size = 512 * 3; + +static kmem_cache_t *abd_cache = NULL; +static kstat_t *abd_ksp; + +static inline size_t +abd_chunkcnt_for_bytes(size_t size) +{ + return (P2ROUNDUP(size, PAGESIZE) / PAGESIZE); +} + +#ifdef _KERNEL +/* + * Mark zfs data pages so they can be excluded from kernel crash dumps + */ +#ifdef _LP64 +#define ABD_FILE_CACHE_PAGE 0x2F5ABDF11ECAC4E + +static inline void +abd_mark_zfs_page(struct page *page) +{ + get_page(page); + SetPagePrivate(page); + set_page_private(page, ABD_FILE_CACHE_PAGE); +} + +static inline void +abd_unmark_zfs_page(struct page *page) +{ + set_page_private(page, 0UL); + ClearPagePrivate(page); + put_page(page); +} +#else +#define abd_mark_zfs_page(page) +#define abd_unmark_zfs_page(page) +#endif /* _LP64 */ + +#ifndef CONFIG_HIGHMEM + +#ifndef __GFP_RECLAIM +#define __GFP_RECLAIM __GFP_WAIT +#endif + +/* + * The goal is to minimize fragmentation by preferentially populating ABDs + * with higher order compound pages from a single zone. Allocation size is + * progressively decreased until it can be satisfied without performing + * reclaim or compaction. When necessary this function will degenerate to + * allocating individual pages and allowing reclaim to satisfy allocations. + */ +static void +abd_alloc_pages(abd_t *abd, size_t size) +{ + struct list_head pages; + struct sg_table table; + struct scatterlist *sg; + struct page *page, *tmp_page = NULL; + gfp_t gfp = __GFP_NOWARN | GFP_NOIO; + gfp_t gfp_comp = (gfp | __GFP_NORETRY | __GFP_COMP) & ~__GFP_RECLAIM; + int max_order = MIN(zfs_abd_scatter_max_order, MAX_ORDER - 1); + int nr_pages = abd_chunkcnt_for_bytes(size); + int chunks = 0, zones = 0; + size_t remaining_size; + int nid = NUMA_NO_NODE; + int alloc_pages = 0; + + INIT_LIST_HEAD(&pages); + + while (alloc_pages < nr_pages) { + unsigned chunk_pages; + int order; + + order = MIN(highbit64(nr_pages - alloc_pages) - 1, max_order); + chunk_pages = (1U << order); + + page = alloc_pages_node(nid, order ? gfp_comp : gfp, order); + if (page == NULL) { + if (order == 0) { + ABDSTAT_BUMP(abdstat_scatter_page_alloc_retry); + schedule_timeout_interruptible(1); + } else { + max_order = MAX(0, order - 1); + } + continue; + } + + list_add_tail(&page->lru, &pages); + + if ((nid != NUMA_NO_NODE) && (page_to_nid(page) != nid)) + zones++; + + nid = page_to_nid(page); + ABDSTAT_BUMP(abdstat_scatter_orders[order]); + chunks++; + alloc_pages += chunk_pages; + } + + ASSERT3S(alloc_pages, ==, nr_pages); + + while (sg_alloc_table(&table, chunks, gfp)) { + ABDSTAT_BUMP(abdstat_scatter_sg_table_retry); + schedule_timeout_interruptible(1); + } + + sg = table.sgl; + remaining_size = size; + list_for_each_entry_safe(page, tmp_page, &pages, lru) { + size_t sg_size = MIN(PAGESIZE << compound_order(page), + remaining_size); + sg_set_page(sg, page, sg_size, 0); + abd_mark_zfs_page(page); + remaining_size -= sg_size; + + sg = sg_next(sg); + list_del(&page->lru); + } + + /* + * These conditions ensure that a possible transformation to a linear + * ABD would be valid. + */ + ASSERT(!PageHighMem(sg_page(table.sgl))); + ASSERT0(ABD_SCATTER(abd).abd_offset); + + if (table.nents == 1) { + /* + * Since there is only one entry, this ABD can be represented + * as a linear buffer. All single-page (4K) ABD's can be + * represented this way. Some multi-page ABD's can also be + * represented this way, if we were able to allocate a single + * "chunk" (higher-order "page" which represents a power-of-2 + * series of physically-contiguous pages). This is often the + * case for 2-page (8K) ABD's. + * + * Representing a single-entry scatter ABD as a linear ABD + * has the performance advantage of avoiding the copy (and + * allocation) in abd_borrow_buf_copy / abd_return_buf_copy. + * A performance increase of around 5% has been observed for + * ARC-cached reads (of small blocks which can take advantage + * of this). + * + * Note that this optimization is only possible because the + * pages are always mapped into the kernel's address space. + * This is not the case for highmem pages, so the + * optimization can not be made there. + */ + abd->abd_flags |= ABD_FLAG_LINEAR; + abd->abd_flags |= ABD_FLAG_LINEAR_PAGE; + abd->abd_u.abd_linear.abd_sgl = table.sgl; + abd->abd_u.abd_linear.abd_buf = + page_address(sg_page(table.sgl)); + } else if (table.nents > 1) { + ABDSTAT_BUMP(abdstat_scatter_page_multi_chunk); + abd->abd_flags |= ABD_FLAG_MULTI_CHUNK; + + if (zones) { + ABDSTAT_BUMP(abdstat_scatter_page_multi_zone); + abd->abd_flags |= ABD_FLAG_MULTI_ZONE; + } + + ABD_SCATTER(abd).abd_sgl = table.sgl; + ABD_SCATTER(abd).abd_nents = table.nents; + } +} +#else +/* + * Allocate N individual pages to construct a scatter ABD. This function + * makes no attempt to request contiguous pages and requires the minimal + * number of kernel interfaces. It's designed for maximum compatibility. + */ +static void +abd_alloc_pages(abd_t *abd, size_t size) +{ + struct scatterlist *sg = NULL; + struct sg_table table; + struct page *page; + gfp_t gfp = __GFP_NOWARN | GFP_NOIO; + int nr_pages = abd_chunkcnt_for_bytes(size); + int i = 0; + + while (sg_alloc_table(&table, nr_pages, gfp)) { + ABDSTAT_BUMP(abdstat_scatter_sg_table_retry); + schedule_timeout_interruptible(1); + } + + ASSERT3U(table.nents, ==, nr_pages); + ABD_SCATTER(abd).abd_sgl = table.sgl; + ABD_SCATTER(abd).abd_nents = nr_pages; + + abd_for_each_sg(abd, sg, nr_pages, i) { + while ((page = __page_cache_alloc(gfp)) == NULL) { + ABDSTAT_BUMP(abdstat_scatter_page_alloc_retry); + schedule_timeout_interruptible(1); + } + + ABDSTAT_BUMP(abdstat_scatter_orders[0]); + sg_set_page(sg, page, PAGESIZE, 0); + abd_mark_zfs_page(page); + } + + if (nr_pages > 1) { + ABDSTAT_BUMP(abdstat_scatter_page_multi_chunk); + abd->abd_flags |= ABD_FLAG_MULTI_CHUNK; + } +} +#endif /* !CONFIG_HIGHMEM */ + +static void +abd_free_pages(abd_t *abd) +{ + struct scatterlist *sg = NULL; + struct sg_table table; + struct page *page; + int nr_pages = ABD_SCATTER(abd).abd_nents; + int order, i = 0; + + if (abd->abd_flags & ABD_FLAG_MULTI_ZONE) + ABDSTAT_BUMPDOWN(abdstat_scatter_page_multi_zone); + + if (abd->abd_flags & ABD_FLAG_MULTI_CHUNK) + ABDSTAT_BUMPDOWN(abdstat_scatter_page_multi_chunk); + + abd_for_each_sg(abd, sg, nr_pages, i) { + page = sg_page(sg); + abd_unmark_zfs_page(page); + order = compound_order(page); + __free_pages(page, order); + ASSERT3U(sg->length, <=, PAGE_SIZE << order); + ABDSTAT_BUMPDOWN(abdstat_scatter_orders[order]); + } + + table.sgl = ABD_SCATTER(abd).abd_sgl; + table.nents = table.orig_nents = nr_pages; + sg_free_table(&table); +} + +#else /* _KERNEL */ + +#ifndef PAGE_SHIFT +#define PAGE_SHIFT (highbit64(PAGESIZE)-1) +#endif + +struct page; + +#define zfs_kmap_atomic(chunk, km) ((void *)chunk) +#define zfs_kunmap_atomic(addr, km) do { (void)(addr); } while (0) +#define local_irq_save(flags) do { (void)(flags); } while (0) +#define local_irq_restore(flags) do { (void)(flags); } while (0) +#define nth_page(pg, i) \ + ((struct page *)((void *)(pg) + (i) * PAGESIZE)) + +struct scatterlist { + struct page *page; + int length; + int end; +}; + +static void +sg_init_table(struct scatterlist *sg, int nr) +{ + memset(sg, 0, nr * sizeof (struct scatterlist)); + sg[nr - 1].end = 1; +} + +#define for_each_sg(sgl, sg, nr, i) \ + for ((i) = 0, (sg) = (sgl); (i) < (nr); (i)++, (sg) = sg_next(sg)) + +static inline void +sg_set_page(struct scatterlist *sg, struct page *page, unsigned int len, + unsigned int offset) +{ + /* currently we don't use offset */ + ASSERT(offset == 0); + sg->page = page; + sg->length = len; +} + +static inline struct page * +sg_page(struct scatterlist *sg) +{ + return (sg->page); +} + +static inline struct scatterlist * +sg_next(struct scatterlist *sg) +{ + if (sg->end) + return (NULL); + + return (sg + 1); +} + +static void +abd_alloc_pages(abd_t *abd, size_t size) +{ + unsigned nr_pages = abd_chunkcnt_for_bytes(size); + struct scatterlist *sg; + int i; + + ABD_SCATTER(abd).abd_sgl = vmem_alloc(nr_pages * + sizeof (struct scatterlist), KM_SLEEP); + sg_init_table(ABD_SCATTER(abd).abd_sgl, nr_pages); + + abd_for_each_sg(abd, sg, nr_pages, i) { + struct page *p = umem_alloc_aligned(PAGESIZE, 64, KM_SLEEP); + sg_set_page(sg, p, PAGESIZE, 0); + } + ABD_SCATTER(abd).abd_nents = nr_pages; +} + +static void +abd_free_pages(abd_t *abd) +{ + int i, n = ABD_SCATTER(abd).abd_nents; + struct scatterlist *sg; + + abd_for_each_sg(abd, sg, n, i) { + for (int j = 0; j < sg->length; j += PAGESIZE) { + struct page *p = nth_page(sg_page(sg), j >> PAGE_SHIFT); + umem_free(p, PAGESIZE); + } + } + + vmem_free(ABD_SCATTER(abd).abd_sgl, n * sizeof (struct scatterlist)); +} + +#endif /* _KERNEL */ + +void +abd_init(void) +{ + int i; + + abd_cache = kmem_cache_create("abd_t", sizeof (abd_t), + 0, NULL, NULL, NULL, NULL, NULL, 0); + + abd_ksp = kstat_create("zfs", 0, "abdstats", "misc", KSTAT_TYPE_NAMED, + sizeof (abd_stats) / sizeof (kstat_named_t), KSTAT_FLAG_VIRTUAL); + if (abd_ksp != NULL) { + abd_ksp->ks_data = &abd_stats; + kstat_install(abd_ksp); + + for (i = 0; i < MAX_ORDER; i++) { + snprintf(abd_stats.abdstat_scatter_orders[i].name, + KSTAT_STRLEN, "scatter_order_%d", i); + abd_stats.abdstat_scatter_orders[i].data_type = + KSTAT_DATA_UINT64; + } + } +} + +void +abd_fini(void) +{ + if (abd_ksp != NULL) { + kstat_delete(abd_ksp); + abd_ksp = NULL; + } + + if (abd_cache) { + kmem_cache_destroy(abd_cache); + abd_cache = NULL; + } +} + +static inline 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->abd_u.abd_linear.abd_buf, !=, NULL); + } else { + size_t n; + int i = 0; + struct scatterlist *sg = NULL; + + ASSERT3U(ABD_SCATTER(abd).abd_nents, >, 0); + ASSERT3U(ABD_SCATTER(abd).abd_offset, <, + ABD_SCATTER(abd).abd_sgl->length); + n = ABD_SCATTER(abd).abd_nents; + abd_for_each_sg(abd, sg, n, i) { + ASSERT3P(sg_page(sg), !=, NULL); + } + } +} + +static inline abd_t * +abd_alloc_struct(void) +{ + abd_t *abd = kmem_cache_alloc(abd_cache, KM_PUSHPAGE); + + ASSERT3P(abd, !=, NULL); + ABDSTAT_INCR(abdstat_struct_size, sizeof (abd_t)); + + return (abd); +} + +static inline void +abd_free_struct(abd_t *abd) +{ + kmem_cache_free(abd_cache, abd); + ABDSTAT_INCR(abdstat_struct_size, -(int)sizeof (abd_t)); +} + +/* + * 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) +{ + /* see the comment above zfs_abd_scatter_min_size */ + if (!zfs_abd_scatter_enabled || size < zfs_abd_scatter_min_size) + return (abd_alloc_linear(size, is_metadata)); + + VERIFY3U(size, <=, SPA_MAXBLOCKSIZE); + + abd_t *abd = abd_alloc_struct(); + abd->abd_flags = ABD_FLAG_OWNER; + abd->abd_u.abd_scatter.abd_offset = 0; + abd_alloc_pages(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); + + ABDSTAT_BUMP(abdstat_scatter_cnt); + ABDSTAT_INCR(abdstat_scatter_data_size, size); + ABDSTAT_INCR(abdstat_scatter_chunk_waste, + P2ROUNDUP(size, PAGESIZE) - size); + + return (abd); +} + +static void +abd_free_scatter(abd_t *abd) +{ + abd_free_pages(abd); + + zfs_refcount_destroy(&abd->abd_children); + ABDSTAT_BUMPDOWN(abdstat_scatter_cnt); + ABDSTAT_INCR(abdstat_scatter_data_size, -(int)abd->abd_size); + ABDSTAT_INCR(abdstat_scatter_chunk_waste, + (int)abd->abd_size - (int)P2ROUNDUP(abd->abd_size, PAGESIZE)); + + 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(); + + 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->abd_u.abd_linear.abd_buf = zio_buf_alloc(size); + } else { + abd->abd_u.abd_linear.abd_buf = zio_data_buf_alloc(size); + } + + ABDSTAT_BUMP(abdstat_linear_cnt); + ABDSTAT_INCR(abdstat_linear_data_size, size); + + return (abd); +} + +static void +abd_free_linear(abd_t *abd) +{ + if (abd_is_linear_page(abd)) { + /* Transform it back into a scatter ABD for freeing */ + struct scatterlist *sg = abd->abd_u.abd_linear.abd_sgl; + abd->abd_flags &= ~ABD_FLAG_LINEAR; + abd->abd_flags &= ~ABD_FLAG_LINEAR_PAGE; + ABD_SCATTER(abd).abd_nents = 1; + ABD_SCATTER(abd).abd_offset = 0; + ABD_SCATTER(abd).abd_sgl = sg; + abd_free_scatter(abd); + return; + } + if (abd->abd_flags & ABD_FLAG_META) { + zio_buf_free(abd->abd_u.abd_linear.abd_buf, abd->abd_size); + } else { + zio_data_buf_free(abd->abd_u.abd_linear.abd_buf, abd->abd_size); + } + + zfs_refcount_destroy(&abd->abd_children); + ABDSTAT_BUMPDOWN(abdstat_linear_cnt); + ABDSTAT_INCR(abdstat_linear_data_size, -(int)abd->abd_size); + + 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) +{ + 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)); + } +} + +/* + * If we're going to use this ABD for doing I/O using the block layer, the + * consumer of the ABD data doesn't care if it's scattered or not, and we don't + * plan to store this ABD in memory for a long period of time, we should + * allocate the ABD type that requires the least data copying to do the I/O. + * + * On Illumos this is linear ABDs, however if ldi_strategy() can ever issue I/Os + * using a scatter/gather list we should switch to that and replace this call + * with vanilla abd_alloc(). + * + * On Linux the optimal thing to do would be to use abd_get_offset() and + * construct a new ABD which shares the original pages thereby eliminating + * the copy. But for the moment a new linear ABD is allocated until this + * performance optimization can be implemented. + */ +abd_t * +abd_alloc_for_io(size_t size, boolean_t is_metadata) +{ + 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 inline abd_t * +abd_get_offset_impl(abd_t *sabd, size_t off, size_t size) +{ + abd_t *abd; + + abd_verify(sabd); + ASSERT3U(off, <=, sabd->abd_size); + + if (abd_is_linear(sabd)) { + abd = abd_alloc_struct(); + + /* + * 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_u.abd_linear.abd_buf = + (char *)sabd->abd_u.abd_linear.abd_buf + off; + } else { + int i = 0; + struct scatterlist *sg = NULL; + size_t new_offset = sabd->abd_u.abd_scatter.abd_offset + off; + + abd = abd_alloc_struct(); + + /* + * 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 = 0; + + abd_for_each_sg(sabd, sg, ABD_SCATTER(sabd).abd_nents, i) { + if (new_offset < sg->length) + break; + new_offset -= sg->length; + } + + ABD_SCATTER(abd).abd_sgl = sg; + ABD_SCATTER(abd).abd_offset = new_offset; + ABD_SCATTER(abd).abd_nents = ABD_SCATTER(sabd).abd_nents - i; + } + + 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(); + + 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->abd_u.abd_linear.abd_buf = buf; + + return (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) +{ + 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); +} + +/* + * 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->abd_u.abd_linear.abd_buf); +} + +/* + * 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); +} + +/* + * 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; + } + + ABDSTAT_BUMP(abdstat_linear_cnt); + ABDSTAT_INCR(abdstat_linear_data_size, abd->abd_size); +} + +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; + + ABDSTAT_BUMPDOWN(abdstat_linear_cnt); + ABDSTAT_INCR(abdstat_linear_data_size, -(int)abd->abd_size); +} + +#ifndef HAVE_1ARG_KMAP_ATOMIC +#define NR_KM_TYPE (6) +#ifdef _KERNEL +int km_table[NR_KM_TYPE] = { + KM_USER0, + KM_USER1, + KM_BIO_SRC_IRQ, + KM_BIO_DST_IRQ, + KM_PTE0, + KM_PTE1, +}; +#endif +#endif + +struct abd_iter { + /* public interface */ + void *iter_mapaddr; /* addr corresponding to iter_pos */ + size_t iter_mapsize; /* length of data valid at mapaddr */ + + /* private */ + abd_t *iter_abd; /* ABD being iterated through */ + size_t iter_pos; + size_t iter_offset; /* offset in current sg/abd_buf, */ + /* abd_offset included */ + struct scatterlist *iter_sg; /* current sg */ +#ifndef HAVE_1ARG_KMAP_ATOMIC + int iter_km; /* KM_* for kmap_atomic */ +#endif +}; + +/* + * Initialize the abd_iter. + */ +static void +abd_iter_init(struct abd_iter *aiter, abd_t *abd, int km_type) +{ + abd_verify(abd); + aiter->iter_abd = abd; + aiter->iter_mapaddr = NULL; + aiter->iter_mapsize = 0; + aiter->iter_pos = 0; + if (abd_is_linear(abd)) { + aiter->iter_offset = 0; + aiter->iter_sg = NULL; + } else { + aiter->iter_offset = ABD_SCATTER(abd).abd_offset; + aiter->iter_sg = ABD_SCATTER(abd).abd_sgl; + } +#ifndef HAVE_1ARG_KMAP_ATOMIC + ASSERT3U(km_type, <, NR_KM_TYPE); + aiter->iter_km = km_type; +#endif +} + +/* + * Advance the iterator by a certain amount. Cannot be called when a chunk is + * in use. This can be safely called when the aiter has already exhausted, in + * which case this does nothing. + */ +static void +abd_iter_advance(struct abd_iter *aiter, size_t amount) +{ + ASSERT3P(aiter->iter_mapaddr, ==, NULL); + ASSERT0(aiter->iter_mapsize); + + /* There's nothing left to advance to, so do nothing */ + if (aiter->iter_pos == aiter->iter_abd->abd_size) + return; + + aiter->iter_pos += amount; + aiter->iter_offset += amount; + if (!abd_is_linear(aiter->iter_abd)) { + while (aiter->iter_offset >= aiter->iter_sg->length) { + aiter->iter_offset -= aiter->iter_sg->length; + aiter->iter_sg = sg_next(aiter->iter_sg); + if (aiter->iter_sg == NULL) { + ASSERT0(aiter->iter_offset); + break; + } + } + } +} + +/* + * Map the current chunk into aiter. This can be safely called when the aiter + * has already exhausted, in which case this does nothing. + */ +static void +abd_iter_map(struct abd_iter *aiter) +{ + void *paddr; + size_t offset = 0; + + ASSERT3P(aiter->iter_mapaddr, ==, NULL); + ASSERT0(aiter->iter_mapsize); + + /* There's nothing left to iterate over, so do nothing */ + if (aiter->iter_pos == aiter->iter_abd->abd_size) + return; + + if (abd_is_linear(aiter->iter_abd)) { + ASSERT3U(aiter->iter_pos, ==, aiter->iter_offset); + offset = aiter->iter_offset; + aiter->iter_mapsize = aiter->iter_abd->abd_size - offset; + paddr = aiter->iter_abd->abd_u.abd_linear.abd_buf; + } else { + offset = aiter->iter_offset; + aiter->iter_mapsize = MIN(aiter->iter_sg->length - offset, + aiter->iter_abd->abd_size - aiter->iter_pos); + + paddr = zfs_kmap_atomic(sg_page(aiter->iter_sg), + km_table[aiter->iter_km]); + } + + aiter->iter_mapaddr = (char *)paddr + offset; +} + +/* + * Unmap the current chunk from aiter. This can be safely called when the aiter + * has already exhausted, in which case this does nothing. + */ +static void +abd_iter_unmap(struct abd_iter *aiter) +{ + /* There's nothing left to unmap, so do nothing */ + if (aiter->iter_pos == aiter->iter_abd->abd_size) + return; + + if (!abd_is_linear(aiter->iter_abd)) { + /* LINTED E_FUNC_SET_NOT_USED */ + zfs_kunmap_atomic(aiter->iter_mapaddr - aiter->iter_offset, + km_table[aiter->iter_km]); + } + + ASSERT3P(aiter->iter_mapaddr, !=, NULL); + ASSERT3U(aiter->iter_mapsize, >, 0); + + aiter->iter_mapaddr = NULL; + aiter->iter_mapsize = 0; +} + +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, 0); + 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, 0); + abd_iter_init(&saiter, sabd, 1); + 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; + + ASSERT3U(parity, <=, 3); + + for (i = 0; i < parity; i++) + abd_iter_init(&caiters[i], cabds[i], i); + + if (dabd) + abd_iter_init(&daiter, dabd, i); + + ASSERT3S(dsize, >=, 0); + + local_irq_save(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); + } + local_irq_restore(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; + + ASSERT3U(parity, <=, 3); + + for (i = 0; i < parity; i++) { + abd_iter_init(&citers[i], cabds[i], 2*i); + abd_iter_init(&xiters[i], tabds[i], 2*i+1); + } + + local_irq_save(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); + } + local_irq_restore(flags); +} + +#if defined(_KERNEL) +/* + * bio_nr_pages for ABD. + * @off is the offset in @abd + */ +unsigned long +abd_nr_pages_off(abd_t *abd, unsigned int size, size_t off) +{ + unsigned long pos; + + if (abd_is_linear(abd)) + pos = (unsigned long)abd_to_buf(abd) + off; + else + pos = abd->abd_u.abd_scatter.abd_offset + off; + + return ((pos + size + PAGESIZE - 1) >> PAGE_SHIFT) - + (pos >> PAGE_SHIFT); +} + +/* + * bio_map for scatter ABD. + * @off is the offset in @abd + * Remaining IO size is returned + */ +unsigned int +abd_scatter_bio_map_off(struct bio *bio, abd_t *abd, + unsigned int io_size, size_t off) +{ + int i; + struct abd_iter aiter; + + ASSERT(!abd_is_linear(abd)); + ASSERT3U(io_size, <=, abd->abd_size - off); + + abd_iter_init(&aiter, abd, 0); + abd_iter_advance(&aiter, off); + + for (i = 0; i < bio->bi_max_vecs; i++) { + struct page *pg; + size_t len, sgoff, pgoff; + struct scatterlist *sg; + + if (io_size <= 0) + break; + + sg = aiter.iter_sg; + sgoff = aiter.iter_offset; + pgoff = sgoff & (PAGESIZE - 1); + len = MIN(io_size, PAGESIZE - pgoff); + ASSERT(len > 0); + + pg = nth_page(sg_page(sg), sgoff >> PAGE_SHIFT); + if (bio_add_page(bio, pg, len, pgoff) != len) + break; + + io_size -= len; + abd_iter_advance(&aiter, len); + } + + return (io_size); +} + +/* Tunable Parameters */ +module_param(zfs_abd_scatter_enabled, int, 0644); +MODULE_PARM_DESC(zfs_abd_scatter_enabled, + "Toggle whether ABD allocations must be linear."); +module_param(zfs_abd_scatter_min_size, int, 0644); +MODULE_PARM_DESC(zfs_abd_scatter_min_size, + "Minimum size of scatter allocations."); +/* CSTYLED */ +module_param(zfs_abd_scatter_max_order, uint, 0644); +MODULE_PARM_DESC(zfs_abd_scatter_max_order, + "Maximum order allocation used for a scatter ABD."); +#endif |