/* * fs/f2fs/gc.c * * Copyright (c) 2012 Samsung Electronics Co., Ltd. * http://www.samsung.com/ * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <linux/fs.h> #include <linux/module.h> #include <linux/backing-dev.h> #include <linux/proc_fs.h> #include <linux/init.h> #include <linux/f2fs_fs.h> #include <linux/kthread.h> #include <linux/delay.h> #include <linux/freezer.h> #include <linux/blkdev.h> #include "f2fs.h" #include "node.h" #include "segment.h" #include "gc.h" static struct kmem_cache *winode_slab; static int gc_thread_func(void *data) { struct f2fs_sb_info *sbi = data; wait_queue_head_t *wq = &sbi->gc_thread->gc_wait_queue_head; long wait_ms; wait_ms = GC_THREAD_MIN_SLEEP_TIME; do { if (try_to_freeze()) continue; else wait_event_interruptible_timeout(*wq, kthread_should_stop(), msecs_to_jiffies(wait_ms)); if (kthread_should_stop()) break; f2fs_balance_fs(sbi); if (!test_opt(sbi, BG_GC)) continue; /* * [GC triggering condition] * 0. GC is not conducted currently. * 1. There are enough dirty segments. * 2. IO subsystem is idle by checking the # of writeback pages. * 3. IO subsystem is idle by checking the # of requests in * bdev's request list. * * Note) We have to avoid triggering GCs too much frequently. * Because it is possible that some segments can be * invalidated soon after by user update or deletion. * So, I'd like to wait some time to collect dirty segments. */ if (!mutex_trylock(&sbi->gc_mutex)) continue; if (!is_idle(sbi)) { wait_ms = increase_sleep_time(wait_ms); mutex_unlock(&sbi->gc_mutex); continue; } if (has_enough_invalid_blocks(sbi)) wait_ms = decrease_sleep_time(wait_ms); else wait_ms = increase_sleep_time(wait_ms); sbi->bg_gc++; if (f2fs_gc(sbi) == GC_NONE) wait_ms = GC_THREAD_NOGC_SLEEP_TIME; else if (wait_ms == GC_THREAD_NOGC_SLEEP_TIME) wait_ms = GC_THREAD_MAX_SLEEP_TIME; } while (!kthread_should_stop()); return 0; } int start_gc_thread(struct f2fs_sb_info *sbi) { struct f2fs_gc_kthread *gc_th; gc_th = kmalloc(sizeof(struct f2fs_gc_kthread), GFP_KERNEL); if (!gc_th) return -ENOMEM; sbi->gc_thread = gc_th; init_waitqueue_head(&sbi->gc_thread->gc_wait_queue_head); sbi->gc_thread->f2fs_gc_task = kthread_run(gc_thread_func, sbi, GC_THREAD_NAME); if (IS_ERR(gc_th->f2fs_gc_task)) { kfree(gc_th); return -ENOMEM; } return 0; } void stop_gc_thread(struct f2fs_sb_info *sbi) { struct f2fs_gc_kthread *gc_th = sbi->gc_thread; if (!gc_th) return; kthread_stop(gc_th->f2fs_gc_task); kfree(gc_th); sbi->gc_thread = NULL; } static int select_gc_type(int gc_type) { return (gc_type == BG_GC) ? GC_CB : GC_GREEDY; } static void select_policy(struct f2fs_sb_info *sbi, int gc_type, int type, struct victim_sel_policy *p) { struct dirty_seglist_info *dirty_i = DIRTY_I(sbi); if (p->alloc_mode) { p->gc_mode = GC_GREEDY; p->dirty_segmap = dirty_i->dirty_segmap[type]; p->ofs_unit = 1; } else { p->gc_mode = select_gc_type(gc_type); p->dirty_segmap = dirty_i->dirty_segmap[DIRTY]; p->ofs_unit = sbi->segs_per_sec; } p->offset = sbi->last_victim[p->gc_mode]; } static unsigned int get_max_cost(struct f2fs_sb_info *sbi, struct victim_sel_policy *p) { if (p->gc_mode == GC_GREEDY) return (1 << sbi->log_blocks_per_seg) * p->ofs_unit; else if (p->gc_mode == GC_CB) return UINT_MAX; else /* No other gc_mode */ return 0; } static unsigned int check_bg_victims(struct f2fs_sb_info *sbi) { struct dirty_seglist_info *dirty_i = DIRTY_I(sbi); unsigned int segno; /* * If the gc_type is FG_GC, we can select victim segments * selected by background GC before. * Those segments guarantee they have small valid blocks. */ segno = find_next_bit(dirty_i->victim_segmap[BG_GC], TOTAL_SEGS(sbi), 0); if (segno < TOTAL_SEGS(sbi)) { clear_bit(segno, dirty_i->victim_segmap[BG_GC]); return segno; } return NULL_SEGNO; } static unsigned int get_cb_cost(struct f2fs_sb_info *sbi, unsigned int segno) { struct sit_info *sit_i = SIT_I(sbi); unsigned int secno = GET_SECNO(sbi, segno); unsigned int start = secno * sbi->segs_per_sec; unsigned long long mtime = 0; unsigned int vblocks; unsigned char age = 0; unsigned char u; unsigned int i; for (i = 0; i < sbi->segs_per_sec; i++) mtime += get_seg_entry(sbi, start + i)->mtime; vblocks = get_valid_blocks(sbi, segno, sbi->segs_per_sec); mtime = div_u64(mtime, sbi->segs_per_sec); vblocks = div_u64(vblocks, sbi->segs_per_sec); u = (vblocks * 100) >> sbi->log_blocks_per_seg; /* Handle if the system time is changed by user */ if (mtime < sit_i->min_mtime) sit_i->min_mtime = mtime; if (mtime > sit_i->max_mtime) sit_i->max_mtime = mtime; if (sit_i->max_mtime != sit_i->min_mtime) age = 100 - div64_u64(100 * (mtime - sit_i->min_mtime), sit_i->max_mtime - sit_i->min_mtime); return UINT_MAX - ((100 * (100 - u) * age) / (100 + u)); } static unsigned int get_gc_cost(struct f2fs_sb_info *sbi, unsigned int segno, struct victim_sel_policy *p) { if (p->alloc_mode == SSR) return get_seg_entry(sbi, segno)->ckpt_valid_blocks; /* alloc_mode == LFS */ if (p->gc_mode == GC_GREEDY) return get_valid_blocks(sbi, segno, sbi->segs_per_sec); else return get_cb_cost(sbi, segno); } /* * This function is called from two pathes. * One is garbage collection and the other is SSR segment selection. * When it is called during GC, it just gets a victim segment * and it does not remove it from dirty seglist. * When it is called from SSR segment selection, it finds a segment * which has minimum valid blocks and removes it from dirty seglist. */ static int get_victim_by_default(struct f2fs_sb_info *sbi, unsigned int *result, int gc_type, int type, char alloc_mode) { struct dirty_seglist_info *dirty_i = DIRTY_I(sbi); struct victim_sel_policy p; unsigned int segno; int nsearched = 0; p.alloc_mode = alloc_mode; select_policy(sbi, gc_type, type, &p); p.min_segno = NULL_SEGNO; p.min_cost = get_max_cost(sbi, &p); mutex_lock(&dirty_i->seglist_lock); if (p.alloc_mode == LFS && gc_type == FG_GC) { p.min_segno = check_bg_victims(sbi); if (p.min_segno != NULL_SEGNO) goto got_it; } while (1) { unsigned long cost; segno = find_next_bit(p.dirty_segmap, TOTAL_SEGS(sbi), p.offset); if (segno >= TOTAL_SEGS(sbi)) { if (sbi->last_victim[p.gc_mode]) { sbi->last_victim[p.gc_mode] = 0; p.offset = 0; continue; } break; } p.offset = ((segno / p.ofs_unit) * p.ofs_unit) + p.ofs_unit; if (test_bit(segno, dirty_i->victim_segmap[FG_GC])) continue; if (gc_type == BG_GC && test_bit(segno, dirty_i->victim_segmap[BG_GC])) continue; if (IS_CURSEC(sbi, GET_SECNO(sbi, segno))) continue; cost = get_gc_cost(sbi, segno, &p); if (p.min_cost > cost) { p.min_segno = segno; p.min_cost = cost; } if (cost == get_max_cost(sbi, &p)) continue; if (nsearched++ >= MAX_VICTIM_SEARCH) { sbi->last_victim[p.gc_mode] = segno; break; } } got_it: if (p.min_segno != NULL_SEGNO) { *result = (p.min_segno / p.ofs_unit) * p.ofs_unit; if (p.alloc_mode == LFS) { int i; for (i = 0; i < p.ofs_unit; i++) set_bit(*result + i, dirty_i->victim_segmap[gc_type]); } } mutex_unlock(&dirty_i->seglist_lock); return (p.min_segno == NULL_SEGNO) ? 0 : 1; } static const struct victim_selection default_v_ops = { .get_victim = get_victim_by_default, }; static struct inode *find_gc_inode(nid_t ino, struct list_head *ilist) { struct list_head *this; struct inode_entry *ie; list_for_each(this, ilist) { ie = list_entry(this, struct inode_entry, list); if (ie->inode->i_ino == ino) return ie->inode; } return NULL; } static void add_gc_inode(struct inode *inode, struct list_head *ilist) { struct list_head *this; struct inode_entry *new_ie, *ie; list_for_each(this, ilist) { ie = list_entry(this, struct inode_entry, list); if (ie->inode == inode) { iput(inode); return; } } repeat: new_ie = kmem_cache_alloc(winode_slab, GFP_NOFS); if (!new_ie) { cond_resched(); goto repeat; } new_ie->inode = inode; list_add_tail(&new_ie->list, ilist); } static void put_gc_inode(struct list_head *ilist) { struct inode_entry *ie, *next_ie; list_for_each_entry_safe(ie, next_ie, ilist, list) { iput(ie->inode); list_del(&ie->list); kmem_cache_free(winode_slab, ie); } } static int check_valid_map(struct f2fs_sb_info *sbi, unsigned int segno, int offset) { struct sit_info *sit_i = SIT_I(sbi); struct seg_entry *sentry; int ret; mutex_lock(&sit_i->sentry_lock); sentry = get_seg_entry(sbi, segno); ret = f2fs_test_bit(offset, sentry->cur_valid_map); mutex_unlock(&sit_i->sentry_lock); return ret ? GC_OK : GC_NEXT; } /* * This function compares node address got in summary with that in NAT. * On validity, copy that node with cold status, otherwise (invalid node) * ignore that. */ static int gc_node_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum, unsigned int segno, int gc_type) { bool initial = true; struct f2fs_summary *entry; int off; next_step: entry = sum; for (off = 0; off < sbi->blocks_per_seg; off++, entry++) { nid_t nid = le32_to_cpu(entry->nid); struct page *node_page; int err; /* * It makes sure that free segments are able to write * all the dirty node pages before CP after this CP. * So let's check the space of dirty node pages. */ if (should_do_checkpoint(sbi)) { mutex_lock(&sbi->cp_mutex); block_operations(sbi); return GC_BLOCKED; } err = check_valid_map(sbi, segno, off); if (err == GC_NEXT) continue; if (initial) { ra_node_page(sbi, nid); continue; } node_page = get_node_page(sbi, nid); if (IS_ERR(node_page)) continue; /* set page dirty and write it */ if (!PageWriteback(node_page)) set_page_dirty(node_page); f2fs_put_page(node_page, 1); stat_inc_node_blk_count(sbi, 1); } if (initial) { initial = false; goto next_step; } if (gc_type == FG_GC) { struct writeback_control wbc = { .sync_mode = WB_SYNC_ALL, .nr_to_write = LONG_MAX, .for_reclaim = 0, }; sync_node_pages(sbi, 0, &wbc); } return GC_DONE; } /* * Calculate start block index indicating the given node offset. * Be careful, caller should give this node offset only indicating direct node * blocks. If any node offsets, which point the other types of node blocks such * as indirect or double indirect node blocks, are given, it must be a caller's * bug. */ block_t start_bidx_of_node(unsigned int node_ofs) { unsigned int indirect_blks = 2 * NIDS_PER_BLOCK + 4; unsigned int bidx; if (node_ofs == 0) return 0; if (node_ofs <= 2) { bidx = node_ofs - 1; } else if (node_ofs <= indirect_blks) { int dec = (node_ofs - 4) / (NIDS_PER_BLOCK + 1); bidx = node_ofs - 2 - dec; } else { int dec = (node_ofs - indirect_blks - 3) / (NIDS_PER_BLOCK + 1); bidx = node_ofs - 5 - dec; } return bidx * ADDRS_PER_BLOCK + ADDRS_PER_INODE; } static int check_dnode(struct f2fs_sb_info *sbi, struct f2fs_summary *sum, struct node_info *dni, block_t blkaddr, unsigned int *nofs) { struct page *node_page; nid_t nid; unsigned int ofs_in_node; block_t source_blkaddr; nid = le32_to_cpu(sum->nid); ofs_in_node = le16_to_cpu(sum->ofs_in_node); node_page = get_node_page(sbi, nid); if (IS_ERR(node_page)) return GC_NEXT; get_node_info(sbi, nid, dni); if (sum->version != dni->version) { f2fs_put_page(node_page, 1); return GC_NEXT; } *nofs = ofs_of_node(node_page); source_blkaddr = datablock_addr(node_page, ofs_in_node); f2fs_put_page(node_page, 1); if (source_blkaddr != blkaddr) return GC_NEXT; return GC_OK; } static void move_data_page(struct inode *inode, struct page *page, int gc_type) { if (page->mapping != inode->i_mapping) goto out; if (inode != page->mapping->host) goto out; if (PageWriteback(page)) goto out; if (gc_type == BG_GC) { set_page_dirty(page); set_cold_data(page); } else { struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb); mutex_lock_op(sbi, DATA_WRITE); if (clear_page_dirty_for_io(page) && S_ISDIR(inode->i_mode)) { dec_page_count(sbi, F2FS_DIRTY_DENTS); inode_dec_dirty_dents(inode); } set_cold_data(page); do_write_data_page(page); mutex_unlock_op(sbi, DATA_WRITE); clear_cold_data(page); } out: f2fs_put_page(page, 1); } /* * This function tries to get parent node of victim data block, and identifies * data block validity. If the block is valid, copy that with cold status and * modify parent node. * If the parent node is not valid or the data block address is different, * the victim data block is ignored. */ static int gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum, struct list_head *ilist, unsigned int segno, int gc_type) { struct super_block *sb = sbi->sb; struct f2fs_summary *entry; block_t start_addr; int err, off; int phase = 0; start_addr = START_BLOCK(sbi, segno); next_step: entry = sum; for (off = 0; off < sbi->blocks_per_seg; off++, entry++) { struct page *data_page; struct inode *inode; struct node_info dni; /* dnode info for the data */ unsigned int ofs_in_node, nofs; block_t start_bidx; /* * It makes sure that free segments are able to write * all the dirty node pages before CP after this CP. * So let's check the space of dirty node pages. */ if (should_do_checkpoint(sbi)) { mutex_lock(&sbi->cp_mutex); block_operations(sbi); err = GC_BLOCKED; goto stop; } err = check_valid_map(sbi, segno, off); if (err == GC_NEXT) continue; if (phase == 0) { ra_node_page(sbi, le32_to_cpu(entry->nid)); continue; } /* Get an inode by ino with checking validity */ err = check_dnode(sbi, entry, &dni, start_addr + off, &nofs); if (err == GC_NEXT) continue; if (phase == 1) { ra_node_page(sbi, dni.ino); continue; } start_bidx = start_bidx_of_node(nofs); ofs_in_node = le16_to_cpu(entry->ofs_in_node); if (phase == 2) { inode = f2fs_iget_nowait(sb, dni.ino); if (IS_ERR(inode)) continue; data_page = find_data_page(inode, start_bidx + ofs_in_node); if (IS_ERR(data_page)) goto next_iput; f2fs_put_page(data_page, 0); add_gc_inode(inode, ilist); } else { inode = find_gc_inode(dni.ino, ilist); if (inode) { data_page = get_lock_data_page(inode, start_bidx + ofs_in_node); if (IS_ERR(data_page)) continue; move_data_page(inode, data_page, gc_type); stat_inc_data_blk_count(sbi, 1); } } continue; next_iput: iput(inode); } if (++phase < 4) goto next_step; err = GC_DONE; stop: if (gc_type == FG_GC) f2fs_submit_bio(sbi, DATA, true); return err; } static int __get_victim(struct f2fs_sb_info *sbi, unsigned int *victim, int gc_type, int type) { struct sit_info *sit_i = SIT_I(sbi); int ret; mutex_lock(&sit_i->sentry_lock); ret = DIRTY_I(sbi)->v_ops->get_victim(sbi, victim, gc_type, type, LFS); mutex_unlock(&sit_i->sentry_lock); return ret; } static int do_garbage_collect(struct f2fs_sb_info *sbi, unsigned int segno, struct list_head *ilist, int gc_type) { struct page *sum_page; struct f2fs_summary_block *sum; int ret = GC_DONE; /* read segment summary of victim */ sum_page = get_sum_page(sbi, segno); if (IS_ERR(sum_page)) return GC_ERROR; /* * CP needs to lock sum_page. In this time, we don't need * to lock this page, because this summary page is not gone anywhere. * Also, this page is not gonna be updated before GC is done. */ unlock_page(sum_page); sum = page_address(sum_page); switch (GET_SUM_TYPE((&sum->footer))) { case SUM_TYPE_NODE: ret = gc_node_segment(sbi, sum->entries, segno, gc_type); break; case SUM_TYPE_DATA: ret = gc_data_segment(sbi, sum->entries, ilist, segno, gc_type); break; } stat_inc_seg_count(sbi, GET_SUM_TYPE((&sum->footer))); stat_inc_call_count(sbi->stat_info); f2fs_put_page(sum_page, 0); return ret; } int f2fs_gc(struct f2fs_sb_info *sbi) { struct list_head ilist; unsigned int segno, i; int gc_type = BG_GC; int gc_status = GC_NONE; INIT_LIST_HEAD(&ilist); gc_more: if (!(sbi->sb->s_flags & MS_ACTIVE)) goto stop; if (has_not_enough_free_secs(sbi)) gc_type = FG_GC; if (!__get_victim(sbi, &segno, gc_type, NO_CHECK_TYPE)) goto stop; for (i = 0; i < sbi->segs_per_sec; i++) { /* * do_garbage_collect will give us three gc_status: * GC_ERROR, GC_DONE, and GC_BLOCKED. * If GC is finished uncleanly, we have to return * the victim to dirty segment list. */ gc_status = do_garbage_collect(sbi, segno + i, &ilist, gc_type); if (gc_status != GC_DONE) break; } if (has_not_enough_free_secs(sbi)) { write_checkpoint(sbi, (gc_status == GC_BLOCKED), false); if (has_not_enough_free_secs(sbi)) goto gc_more; } stop: mutex_unlock(&sbi->gc_mutex); put_gc_inode(&ilist); return gc_status; } void build_gc_manager(struct f2fs_sb_info *sbi) { DIRTY_I(sbi)->v_ops = &default_v_ops; } int __init create_gc_caches(void) { winode_slab = f2fs_kmem_cache_create("f2fs_gc_inodes", sizeof(struct inode_entry), NULL); if (!winode_slab) return -ENOMEM; return 0; } void destroy_gc_caches(void) { kmem_cache_destroy(winode_slab); }