diff options
Diffstat (limited to 'fs/btrfs/zstd.c')
| -rw-r--r-- | fs/btrfs/zstd.c | 702 |
1 files changed, 702 insertions, 0 deletions
diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c new file mode 100644 index 0000000000..e7ac4ec809 --- /dev/null +++ b/fs/btrfs/zstd.c @@ -0,0 +1,702 @@ +// 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_get_params(level, src_len); + + 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_in_buffer in_buf; + zstd_out_buffer 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); + +/* + * Timer callback to free unused workspaces. + * + * @t: timer + * + * This scans the lru_list and attempts to reclaim any workspace that hasn't + * been used for ZSTD_BTRFS_RECLAIM_JIFFIES. + * + * The context is softirq and does not need the _bh locking primitives. + */ +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(&wsm.lock); + + if (list_empty(&wsm.lru_list)) { + spin_unlock(&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(&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_cstream_workspace_bound(¶ms.cParams), + zstd_dstream_workspace_bound(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 | __GFP_NOWARN); + 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_init_cstream(¶ms, len, workspace->mem, + workspace->size); + if (!stream) { + pr_warn("BTRFS: zstd_init_cstream 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_local_page(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); + if (out_page == NULL) { + ret = -ENOMEM; + goto out; + } + pages[nr_pages++] = out_page; + workspace->out_buf.dst = page_address(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_compress_stream(stream, &workspace->out_buf, + &workspace->in_buf); + if (zstd_is_error(ret2)) { + pr_debug("BTRFS: zstd_compress_stream returned %d\n", + zstd_get_error_code(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; + if (nr_pages == nr_dest_pages) { + ret = -E2BIG; + goto out; + } + out_page = alloc_page(GFP_NOFS); + if (out_page == NULL) { + ret = -ENOMEM; + goto out; + } + pages[nr_pages++] = out_page; + workspace->out_buf.dst = page_address(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_local(workspace->in_buf.src); + put_page(in_page); + start += PAGE_SIZE; + len -= PAGE_SIZE; + in_page = find_get_page(mapping, start >> PAGE_SHIFT); + workspace->in_buf.src = kmap_local_page(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_end_stream(stream, &workspace->out_buf); + if (zstd_is_error(ret2)) { + pr_debug("BTRFS: zstd_end_stream returned %d\n", + zstd_get_error_code(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; + if (nr_pages == nr_dest_pages) { + ret = -E2BIG; + goto out; + } + out_page = alloc_page(GFP_NOFS); + if (out_page == NULL) { + ret = -ENOMEM; + goto out; + } + pages[nr_pages++] = out_page; + workspace->out_buf.dst = page_address(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; + if (workspace->in_buf.src) { + kunmap_local(workspace->in_buf.src); + put_page(in_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; + 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_init_dstream( + ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size); + if (!stream) { + pr_debug("BTRFS: zstd_init_dstream failed\n"); + ret = -EIO; + goto done; + } + + workspace->in_buf.src = kmap_local_page(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_decompress_stream(stream, &workspace->out_buf, + &workspace->in_buf); + if (zstd_is_error(ret2)) { + pr_debug("BTRFS: zstd_decompress_stream returned %d\n", + zstd_get_error_code(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, + total_out - buf_start, cb, buf_start); + 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_local(workspace->in_buf.src); + 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_local_page(pages_in[page_in_index]); + workspace->in_buf.pos = 0; + workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE); + } + } + ret = 0; +done: + if (workspace->in_buf.src) + kunmap_local(workspace->in_buf.src); + return ret; +} + +int zstd_decompress(struct list_head *ws, const u8 *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; + + stream = zstd_init_dstream( + ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size); + if (!stream) { + pr_warn("BTRFS: zstd_init_dstream 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_decompress_stream ended early\n"); + ret = -EIO; + goto finish; + } + ret2 = zstd_decompress_stream(stream, &workspace->out_buf, + &workspace->in_buf); + if (zstd_is_error(ret2)) { + pr_debug("BTRFS: zstd_decompress_stream returned %d\n", + zstd_get_error_code(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); + + memcpy_to_page(dest_page, pg_offset, + workspace->out_buf.dst + buf_offset, bytes); + + pg_offset += bytes; + } + ret = 0; +finish: + if (pg_offset < destlen) { + memzero_page(dest_page, pg_offset, destlen - pg_offset); + } + 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, +}; |