diff options
| -rw-r--r-- | fs/btrfs/super.c | 6 | ||||
| -rw-r--r-- | fs/btrfs/zstd.c | 248 |
2 files changed, 245 insertions, 9 deletions
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 9ac94c9d597d..120e4340792a 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -544,9 +544,13 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options, btrfs_clear_opt(info->mount_opt, NODATASUM); btrfs_set_fs_incompat(info, COMPRESS_LZO); no_compress = 0; - } else if (strcmp(args[0].from, "zstd") == 0) { + } else if (strncmp(args[0].from, "zstd", 4) == 0) { compress_type = "zstd"; info->compress_type = BTRFS_COMPRESS_ZSTD; + info->compress_level = + btrfs_compress_str2level( + BTRFS_COMPRESS_ZSTD, + args[0].from + 4); btrfs_set_opt(info->mount_opt, COMPRESS); btrfs_clear_opt(info->mount_opt, NODATACOW); btrfs_clear_opt(info->mount_opt, NODATASUM); diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c index 65018c401c46..3e418a3aeb11 100644 --- a/fs/btrfs/zstd.c +++ b/fs/btrfs/zstd.c @@ -6,21 +6,26 @@ */ #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 "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) @@ -37,16 +42,101 @@ 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; }; -static struct workspace_manager wsm; +/* + * 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); +} + +/* + * 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(&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); + wsm.ops->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 * @@ -76,29 +166,164 @@ static void zstd_calc_ws_mem_sizes(void) static void zstd_init_workspace_manager(void) { + struct list_head *ws; + int i; + zstd_calc_ws_mem_sizes(); - btrfs_init_workspace_manager(&wsm, &btrfs_zstd_compress); + 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 = wsm.ops->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]); + } } static void zstd_cleanup_workspace_manager(void) { - btrfs_cleanup_workspace_manager(&wsm); + struct workspace *workspace; + int i; + + del_timer(&wsm.timer); + + 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); + wsm.ops->free_workspace(&workspace->list); + } + } +} + +/* + * 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(&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(&wsm.lock); + return ws; + } + } + spin_unlock(&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. + */ static struct list_head *zstd_get_workspace(unsigned int level) { - struct list_head *ws = btrfs_get_workspace(&wsm, level); - struct workspace *workspace = list_entry(ws, struct workspace, list); + struct list_head *ws; + unsigned int nofs_flag; - workspace->req_level = level; + /* 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 = wsm.ops->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. + */ static void zstd_put_workspace(struct list_head *ws) { - btrfs_put_workspace(&wsm, ws); + struct workspace *workspace = list_to_workspace(ws); + + spin_lock(&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(&wsm.lock); + + if (workspace->level == ZSTD_BTRFS_MAX_LEVEL) + cond_wake_up(&wsm.wait); } static void zstd_free_workspace(struct list_head *ws) @@ -119,12 +344,16 @@ static struct list_head *zstd_alloc_workspace(unsigned int level) 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: @@ -478,7 +707,10 @@ finish: static unsigned int zstd_set_level(unsigned int level) { - return ZSTD_BTRFS_DEFAULT_LEVEL; + if (!level) + return ZSTD_BTRFS_DEFAULT_LEVEL; + + return min_t(unsigned int, level, ZSTD_BTRFS_MAX_LEVEL); } const struct btrfs_compress_op btrfs_zstd_compress = { |