// SPDX-License-Identifier: GPL-2.0 /* * Copyright (c) 2016-present, Facebook, Inc. * All rights reserved. * */ #include <linux/bio.h> #include <linux/bitmap.h> #include <linux/err.h> #include <linux/init.h> #include <linux/kernel.h> #include <linux/mm.h> #include <linux/sched/mm.h> #include <linux/pagemap.h> #include <linux/refcount.h> #include <linux/sched.h> #include <linux/slab.h> #include <linux/zstd.h> #include "misc.h" #include "compression.h" #include "ctree.h" #define ZSTD_BTRFS_MAX_WINDOWLOG 17 #define ZSTD_BTRFS_MAX_INPUT (1 << ZSTD_BTRFS_MAX_WINDOWLOG) #define ZSTD_BTRFS_DEFAULT_LEVEL 3 #define ZSTD_BTRFS_MAX_LEVEL 15 /* 307s to avoid pathologically clashing with transaction commit */ #define ZSTD_BTRFS_RECLAIM_JIFFIES (307 * HZ) static ZSTD_parameters zstd_get_btrfs_parameters(unsigned int level, size_t src_len) { ZSTD_parameters params = ZSTD_getParams(level, src_len, 0); if (params.cParams.windowLog > ZSTD_BTRFS_MAX_WINDOWLOG) params.cParams.windowLog = ZSTD_BTRFS_MAX_WINDOWLOG; WARN_ON(src_len > ZSTD_BTRFS_MAX_INPUT); return params; } struct workspace { void *mem; size_t size; char *buf; unsigned int level; unsigned int req_level; unsigned long last_used; /* jiffies */ struct list_head list; struct list_head lru_list; ZSTD_inBuffer in_buf; ZSTD_outBuffer out_buf; }; /* * Zstd Workspace Management * * Zstd workspaces have different memory requirements depending on the level. * The zstd workspaces are managed by having individual lists for each level * and a global lru. Forward progress is maintained by protecting a max level * workspace. * * Getting a workspace is done by using the bitmap to identify the levels that * have available workspaces and scans up. This lets us recycle higher level * workspaces because of the monotonic memory guarantee. A workspace's * last_used is only updated if it is being used by the corresponding memory * level. Putting a workspace involves adding it back to the appropriate places * and adding it back to the lru if necessary. * * A timer is used to reclaim workspaces if they have not been used for * ZSTD_BTRFS_RECLAIM_JIFFIES. This helps keep only active workspaces around. * The upper bound is provided by the workqueue limit which is 2 (percpu limit). */ struct zstd_workspace_manager { const struct btrfs_compress_op *ops; spinlock_t lock; struct list_head lru_list; struct list_head idle_ws[ZSTD_BTRFS_MAX_LEVEL]; unsigned long active_map; wait_queue_head_t wait; struct timer_list timer; }; static struct zstd_workspace_manager wsm; static size_t zstd_ws_mem_sizes[ZSTD_BTRFS_MAX_LEVEL]; static inline struct workspace *list_to_workspace(struct list_head *list) { return container_of(list, struct workspace, list); } void zstd_free_workspace(struct list_head *ws); struct list_head *zstd_alloc_workspace(unsigned int level); /* * zstd_reclaim_timer_fn - reclaim timer * @t: timer * * This scans the lru_list and attempts to reclaim any workspace that hasn't * been used for ZSTD_BTRFS_RECLAIM_JIFFIES. */ static void zstd_reclaim_timer_fn(struct timer_list *timer) { unsigned long reclaim_threshold = jiffies - ZSTD_BTRFS_RECLAIM_JIFFIES; struct list_head *pos, *next; spin_lock_bh(&wsm.lock); if (list_empty(&wsm.lru_list)) { spin_unlock_bh(&wsm.lock); return; } list_for_each_prev_safe(pos, next, &wsm.lru_list) { struct workspace *victim = container_of(pos, struct workspace, lru_list); unsigned int level; if (time_after(victim->last_used, reclaim_threshold)) break; /* workspace is in use */ if (victim->req_level) continue; level = victim->level; list_del(&victim->lru_list); list_del(&victim->list); zstd_free_workspace(&victim->list); if (list_empty(&wsm.idle_ws[level - 1])) clear_bit(level - 1, &wsm.active_map); } if (!list_empty(&wsm.lru_list)) mod_timer(&wsm.timer, jiffies + ZSTD_BTRFS_RECLAIM_JIFFIES); spin_unlock_bh(&wsm.lock); } /* * zstd_calc_ws_mem_sizes - calculate monotonic memory bounds * * It is possible based on the level configurations that a higher level * workspace uses less memory than a lower level workspace. In order to reuse * workspaces, this must be made a monotonic relationship. This precomputes * the required memory for each level and enforces the monotonicity between * level and memory required. */ static void zstd_calc_ws_mem_sizes(void) { size_t max_size = 0; unsigned int level; for (level = 1; level <= ZSTD_BTRFS_MAX_LEVEL; level++) { ZSTD_parameters params = zstd_get_btrfs_parameters(level, ZSTD_BTRFS_MAX_INPUT); size_t level_size = max_t(size_t, ZSTD_CStreamWorkspaceBound(params.cParams), ZSTD_DStreamWorkspaceBound(ZSTD_BTRFS_MAX_INPUT)); max_size = max_t(size_t, max_size, level_size); zstd_ws_mem_sizes[level - 1] = max_size; } } void zstd_init_workspace_manager(void) { struct list_head *ws; int i; zstd_calc_ws_mem_sizes(); wsm.ops = &btrfs_zstd_compress; spin_lock_init(&wsm.lock); init_waitqueue_head(&wsm.wait); timer_setup(&wsm.timer, zstd_reclaim_timer_fn, 0); INIT_LIST_HEAD(&wsm.lru_list); for (i = 0; i < ZSTD_BTRFS_MAX_LEVEL; i++) INIT_LIST_HEAD(&wsm.idle_ws[i]); ws = zstd_alloc_workspace(ZSTD_BTRFS_MAX_LEVEL); if (IS_ERR(ws)) { pr_warn( "BTRFS: cannot preallocate zstd compression workspace\n"); } else { set_bit(ZSTD_BTRFS_MAX_LEVEL - 1, &wsm.active_map); list_add(ws, &wsm.idle_ws[ZSTD_BTRFS_MAX_LEVEL - 1]); } } void zstd_cleanup_workspace_manager(void) { struct workspace *workspace; int i; spin_lock_bh(&wsm.lock); for (i = 0; i < ZSTD_BTRFS_MAX_LEVEL; i++) { while (!list_empty(&wsm.idle_ws[i])) { workspace = container_of(wsm.idle_ws[i].next, struct workspace, list); list_del(&workspace->list); list_del(&workspace->lru_list); zstd_free_workspace(&workspace->list); } } spin_unlock_bh(&wsm.lock); del_timer_sync(&wsm.timer); } /* * zstd_find_workspace - find workspace * @level: compression level * * This iterates over the set bits in the active_map beginning at the requested * compression level. This lets us utilize already allocated workspaces before * allocating a new one. If the workspace is of a larger size, it is used, but * the place in the lru_list and last_used times are not updated. This is to * offer the opportunity to reclaim the workspace in favor of allocating an * appropriately sized one in the future. */ static struct list_head *zstd_find_workspace(unsigned int level) { struct list_head *ws; struct workspace *workspace; int i = level - 1; spin_lock_bh(&wsm.lock); for_each_set_bit_from(i, &wsm.active_map, ZSTD_BTRFS_MAX_LEVEL) { if (!list_empty(&wsm.idle_ws[i])) { ws = wsm.idle_ws[i].next; workspace = list_to_workspace(ws); list_del_init(ws); /* keep its place if it's a lower level using this */ workspace->req_level = level; if (level == workspace->level) list_del(&workspace->lru_list); if (list_empty(&wsm.idle_ws[i])) clear_bit(i, &wsm.active_map); spin_unlock_bh(&wsm.lock); return ws; } } spin_unlock_bh(&wsm.lock); return NULL; } /* * zstd_get_workspace - zstd's get_workspace * @level: compression level * * If @level is 0, then any compression level can be used. Therefore, we begin * scanning from 1. We first scan through possible workspaces and then after * attempt to allocate a new workspace. If we fail to allocate one due to * memory pressure, go to sleep waiting for the max level workspace to free up. */ struct list_head *zstd_get_workspace(unsigned int level) { struct list_head *ws; unsigned int nofs_flag; /* level == 0 means we can use any workspace */ if (!level) level = 1; again: ws = zstd_find_workspace(level); if (ws) return ws; nofs_flag = memalloc_nofs_save(); ws = zstd_alloc_workspace(level); memalloc_nofs_restore(nofs_flag); if (IS_ERR(ws)) { DEFINE_WAIT(wait); prepare_to_wait(&wsm.wait, &wait, TASK_UNINTERRUPTIBLE); schedule(); finish_wait(&wsm.wait, &wait); goto again; } return ws; } /* * zstd_put_workspace - zstd put_workspace * @ws: list_head for the workspace * * When putting back a workspace, we only need to update the LRU if we are of * the requested compression level. Here is where we continue to protect the * max level workspace or update last_used accordingly. If the reclaim timer * isn't set, it is also set here. Only the max level workspace tries and wakes * up waiting workspaces. */ void zstd_put_workspace(struct list_head *ws) { struct workspace *workspace = list_to_workspace(ws); spin_lock_bh(&wsm.lock); /* A node is only taken off the lru if we are the corresponding level */ if (workspace->req_level == workspace->level) { /* Hide a max level workspace from reclaim */ if (list_empty(&wsm.idle_ws[ZSTD_BTRFS_MAX_LEVEL - 1])) { INIT_LIST_HEAD(&workspace->lru_list); } else { workspace->last_used = jiffies; list_add(&workspace->lru_list, &wsm.lru_list); if (!timer_pending(&wsm.timer)) mod_timer(&wsm.timer, jiffies + ZSTD_BTRFS_RECLAIM_JIFFIES); } } set_bit(workspace->level - 1, &wsm.active_map); list_add(&workspace->list, &wsm.idle_ws[workspace->level - 1]); workspace->req_level = 0; spin_unlock_bh(&wsm.lock); if (workspace->level == ZSTD_BTRFS_MAX_LEVEL) cond_wake_up(&wsm.wait); } void zstd_free_workspace(struct list_head *ws) { struct workspace *workspace = list_entry(ws, struct workspace, list); kvfree(workspace->mem); kfree(workspace->buf); kfree(workspace); } struct list_head *zstd_alloc_workspace(unsigned int level) { struct workspace *workspace; workspace = kzalloc(sizeof(*workspace), GFP_KERNEL); if (!workspace) return ERR_PTR(-ENOMEM); workspace->size = zstd_ws_mem_sizes[level - 1]; workspace->level = level; workspace->req_level = level; workspace->last_used = jiffies; workspace->mem = kvmalloc(workspace->size, GFP_KERNEL); workspace->buf = kmalloc(PAGE_SIZE, GFP_KERNEL); if (!workspace->mem || !workspace->buf) goto fail; INIT_LIST_HEAD(&workspace->list); INIT_LIST_HEAD(&workspace->lru_list); return &workspace->list; fail: zstd_free_workspace(&workspace->list); return ERR_PTR(-ENOMEM); } int zstd_compress_pages(struct list_head *ws, struct address_space *mapping, u64 start, struct page **pages, unsigned long *out_pages, unsigned long *total_in, unsigned long *total_out) { struct workspace *workspace = list_entry(ws, struct workspace, list); ZSTD_CStream *stream; int ret = 0; int nr_pages = 0; struct page *in_page = NULL; /* The current page to read */ struct page *out_page = NULL; /* The current page to write to */ unsigned long tot_in = 0; unsigned long tot_out = 0; unsigned long len = *total_out; const unsigned long nr_dest_pages = *out_pages; unsigned long max_out = nr_dest_pages * PAGE_SIZE; ZSTD_parameters params = zstd_get_btrfs_parameters(workspace->req_level, len); *out_pages = 0; *total_out = 0; *total_in = 0; /* Initialize the stream */ stream = ZSTD_initCStream(params, len, workspace->mem, workspace->size); if (!stream) { pr_warn("BTRFS: ZSTD_initCStream failed\n"); ret = -EIO; goto out; } /* map in the first page of input data */ in_page = find_get_page(mapping, start >> PAGE_SHIFT); workspace->in_buf.src = kmap(in_page); workspace->in_buf.pos = 0; workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE); /* Allocate and map in the output buffer */ out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); if (out_page == NULL) { ret = -ENOMEM; goto out; } pages[nr_pages++] = out_page; workspace->out_buf.dst = kmap(out_page); workspace->out_buf.pos = 0; workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE); while (1) { size_t ret2; ret2 = ZSTD_compressStream(stream, &workspace->out_buf, &workspace->in_buf); if (ZSTD_isError(ret2)) { pr_debug("BTRFS: ZSTD_compressStream returned %d\n", ZSTD_getErrorCode(ret2)); ret = -EIO; goto out; } /* Check to see if we are making it bigger */ if (tot_in + workspace->in_buf.pos > 8192 && tot_in + workspace->in_buf.pos < tot_out + workspace->out_buf.pos) { ret = -E2BIG; goto out; } /* We've reached the end of our output range */ if (workspace->out_buf.pos >= max_out) { tot_out += workspace->out_buf.pos; ret = -E2BIG; goto out; } /* Check if we need more output space */ if (workspace->out_buf.pos == workspace->out_buf.size) { tot_out += PAGE_SIZE; max_out -= PAGE_SIZE; kunmap(out_page); if (nr_pages == nr_dest_pages) { out_page = NULL; ret = -E2BIG; goto out; } out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); if (out_page == NULL) { ret = -ENOMEM; goto out; } pages[nr_pages++] = out_page; workspace->out_buf.dst = kmap(out_page); workspace->out_buf.pos = 0; workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE); } /* We've reached the end of the input */ if (workspace->in_buf.pos >= len) { tot_in += workspace->in_buf.pos; break; } /* Check if we need more input */ if (workspace->in_buf.pos == workspace->in_buf.size) { tot_in += PAGE_SIZE; kunmap(in_page); put_page(in_page); start += PAGE_SIZE; len -= PAGE_SIZE; in_page = find_get_page(mapping, start >> PAGE_SHIFT); workspace->in_buf.src = kmap(in_page); workspace->in_buf.pos = 0; workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE); } } while (1) { size_t ret2; ret2 = ZSTD_endStream(stream, &workspace->out_buf); if (ZSTD_isError(ret2)) { pr_debug("BTRFS: ZSTD_endStream returned %d\n", ZSTD_getErrorCode(ret2)); ret = -EIO; goto out; } if (ret2 == 0) { tot_out += workspace->out_buf.pos; break; } if (workspace->out_buf.pos >= max_out) { tot_out += workspace->out_buf.pos; ret = -E2BIG; goto out; } tot_out += PAGE_SIZE; max_out -= PAGE_SIZE; kunmap(out_page); if (nr_pages == nr_dest_pages) { out_page = NULL; ret = -E2BIG; goto out; } out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); if (out_page == NULL) { ret = -ENOMEM; goto out; } pages[nr_pages++] = out_page; workspace->out_buf.dst = kmap(out_page); workspace->out_buf.pos = 0; workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE); } if (tot_out >= tot_in) { ret = -E2BIG; goto out; } ret = 0; *total_in = tot_in; *total_out = tot_out; out: *out_pages = nr_pages; /* Cleanup */ if (in_page) { kunmap(in_page); put_page(in_page); } if (out_page) kunmap(out_page); return ret; } int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb) { struct workspace *workspace = list_entry(ws, struct workspace, list); struct page **pages_in = cb->compressed_pages; u64 disk_start = cb->start; struct bio *orig_bio = cb->orig_bio; size_t srclen = cb->compressed_len; ZSTD_DStream *stream; int ret = 0; unsigned long page_in_index = 0; unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE); unsigned long buf_start; unsigned long total_out = 0; stream = ZSTD_initDStream( ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size); if (!stream) { pr_debug("BTRFS: ZSTD_initDStream failed\n"); ret = -EIO; goto done; } workspace->in_buf.src = kmap(pages_in[page_in_index]); workspace->in_buf.pos = 0; workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE); workspace->out_buf.dst = workspace->buf; workspace->out_buf.pos = 0; workspace->out_buf.size = PAGE_SIZE; while (1) { size_t ret2; ret2 = ZSTD_decompressStream(stream, &workspace->out_buf, &workspace->in_buf); if (ZSTD_isError(ret2)) { pr_debug("BTRFS: ZSTD_decompressStream returned %d\n", ZSTD_getErrorCode(ret2)); ret = -EIO; goto done; } buf_start = total_out; total_out += workspace->out_buf.pos; workspace->out_buf.pos = 0; ret = btrfs_decompress_buf2page(workspace->out_buf.dst, buf_start, total_out, disk_start, orig_bio); if (ret == 0) break; if (workspace->in_buf.pos >= srclen) break; /* Check if we've hit the end of a frame */ if (ret2 == 0) break; if (workspace->in_buf.pos == workspace->in_buf.size) { kunmap(pages_in[page_in_index++]); if (page_in_index >= total_pages_in) { workspace->in_buf.src = NULL; ret = -EIO; goto done; } srclen -= PAGE_SIZE; workspace->in_buf.src = kmap(pages_in[page_in_index]); workspace->in_buf.pos = 0; workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE); } } ret = 0; zero_fill_bio(orig_bio); done: if (workspace->in_buf.src) kunmap(pages_in[page_in_index]); return ret; } int zstd_decompress(struct list_head *ws, unsigned char *data_in, struct page *dest_page, unsigned long start_byte, size_t srclen, size_t destlen) { struct workspace *workspace = list_entry(ws, struct workspace, list); ZSTD_DStream *stream; int ret = 0; size_t ret2; unsigned long total_out = 0; unsigned long pg_offset = 0; char *kaddr; stream = ZSTD_initDStream( ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size); if (!stream) { pr_warn("BTRFS: ZSTD_initDStream failed\n"); ret = -EIO; goto finish; } destlen = min_t(size_t, destlen, PAGE_SIZE); workspace->in_buf.src = data_in; workspace->in_buf.pos = 0; workspace->in_buf.size = srclen; workspace->out_buf.dst = workspace->buf; workspace->out_buf.pos = 0; workspace->out_buf.size = PAGE_SIZE; ret2 = 1; while (pg_offset < destlen && workspace->in_buf.pos < workspace->in_buf.size) { unsigned long buf_start; unsigned long buf_offset; unsigned long bytes; /* Check if the frame is over and we still need more input */ if (ret2 == 0) { pr_debug("BTRFS: ZSTD_decompressStream ended early\n"); ret = -EIO; goto finish; } ret2 = ZSTD_decompressStream(stream, &workspace->out_buf, &workspace->in_buf); if (ZSTD_isError(ret2)) { pr_debug("BTRFS: ZSTD_decompressStream returned %d\n", ZSTD_getErrorCode(ret2)); ret = -EIO; goto finish; } buf_start = total_out; total_out += workspace->out_buf.pos; workspace->out_buf.pos = 0; if (total_out <= start_byte) continue; if (total_out > start_byte && buf_start < start_byte) buf_offset = start_byte - buf_start; else buf_offset = 0; bytes = min_t(unsigned long, destlen - pg_offset, workspace->out_buf.size - buf_offset); kaddr = kmap_atomic(dest_page); memcpy(kaddr + pg_offset, workspace->out_buf.dst + buf_offset, bytes); kunmap_atomic(kaddr); pg_offset += bytes; } ret = 0; finish: if (pg_offset < destlen) { kaddr = kmap_atomic(dest_page); memset(kaddr + pg_offset, 0, destlen - pg_offset); kunmap_atomic(kaddr); } return ret; } const struct btrfs_compress_op btrfs_zstd_compress = { /* ZSTD uses own workspace manager */ .workspace_manager = NULL, .max_level = ZSTD_BTRFS_MAX_LEVEL, .default_level = ZSTD_BTRFS_DEFAULT_LEVEL, };