From: Jaegeuk Kim Date: Thu, 25 Apr 2013 07:05:51 +0000 (+0900) Subject: f2fs: enhance alloc_nid and build_free_nids flows X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=55008d845d233396ed374473da4613cee691aa03;p=openwrt%2Fstaging%2Fblogic.git f2fs: enhance alloc_nid and build_free_nids flows In order to avoid build_free_nid lock contention, let's change the order of function calls as follows. At first, check whether there is enough free nids. - If available, just get a free nid with spin_lock without any overhead. - Otherwise, conduct build_free_nids. : scan nat pages, journal nat entries, and nat cache entries. We should consider carefullly not to serve free nids intermediately made by build_free_nids. We can get stable free nids only after build_free_nids is done. Reviewed-by: Namjae Jeon Signed-off-by: Jaegeuk Kim --- diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 6283c8d77c2e..20aab02f2a42 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -190,7 +190,6 @@ static inline void set_raw_extent(struct extent_info *ext, struct f2fs_nm_info { block_t nat_blkaddr; /* base disk address of NAT */ nid_t max_nid; /* maximum possible node ids */ - nid_t init_scan_nid; /* the first nid to be scanned */ nid_t next_scan_nid; /* the next nid to be scanned */ /* NAT cache management */ @@ -360,6 +359,7 @@ struct f2fs_sb_info { struct mutex writepages; /* mutex for writepages() */ unsigned char next_lock_num; /* round-robin global locks */ int por_doing; /* recovery is doing or not */ + int on_build_free_nids; /* build_free_nids is doing */ /* for orphan inode management */ struct list_head orphan_inode_list; /* orphan inode list */ diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c index c8f48d436487..aede91071f71 100644 --- a/fs/f2fs/node.c +++ b/fs/f2fs/node.c @@ -1309,14 +1309,14 @@ static void build_free_nids(struct f2fs_sb_info *sbi) struct f2fs_nm_info *nm_i = NM_I(sbi); struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA); struct f2fs_summary_block *sum = curseg->sum_blk; - nid_t nid = 0; - bool is_cycled = false; - int fcnt = 0; - int i; + int fcnt = 0, i = 0; + nid_t nid = nm_i->next_scan_nid; - nid = nm_i->next_scan_nid; - nm_i->init_scan_nid = nid; + /* Enough entries */ + if (nm_i->fcnt > NAT_ENTRY_PER_BLOCK) + return; + /* readahead nat pages to be scanned */ ra_nat_pages(sbi, nid); while (1) { @@ -1326,19 +1326,15 @@ static void build_free_nids(struct f2fs_sb_info *sbi) f2fs_put_page(page, 1); nid += (NAT_ENTRY_PER_BLOCK - (nid % NAT_ENTRY_PER_BLOCK)); - - if (nid >= nm_i->max_nid) { + if (nid >= nm_i->max_nid) nid = 0; - is_cycled = true; - } - if (fcnt > MAX_FREE_NIDS) - break; - if (is_cycled && nm_i->init_scan_nid <= nid) + + if (i++ == FREE_NID_PAGES) break; } - /* go to the next nat page in order to reuse free nids first */ - nm_i->next_scan_nid = nm_i->init_scan_nid + NAT_ENTRY_PER_BLOCK; + /* go to the next free nat pages to find free nids abundantly */ + nm_i->next_scan_nid = nid; /* find free nids from current sum_pages */ mutex_lock(&curseg->curseg_mutex); @@ -1375,41 +1371,36 @@ bool alloc_nid(struct f2fs_sb_info *sbi, nid_t *nid) struct free_nid *i = NULL; struct list_head *this; retry: - mutex_lock(&nm_i->build_lock); - if (!nm_i->fcnt) { - /* scan NAT in order to build free nid list */ - build_free_nids(sbi); - if (!nm_i->fcnt) { - mutex_unlock(&nm_i->build_lock); - return false; - } - } - mutex_unlock(&nm_i->build_lock); + if (sbi->total_valid_node_count + 1 >= nm_i->max_nid) + return false; - /* - * We check fcnt again since previous check is racy as - * we didn't hold free_nid_list_lock. So other thread - * could consume all of free nids. - */ spin_lock(&nm_i->free_nid_list_lock); - if (!nm_i->fcnt) { - spin_unlock(&nm_i->free_nid_list_lock); - goto retry; - } - BUG_ON(list_empty(&nm_i->free_nid_list)); - list_for_each(this, &nm_i->free_nid_list) { - i = list_entry(this, struct free_nid, list); - if (i->state == NID_NEW) - break; - } + /* We should not use stale free nids created by build_free_nids */ + if (nm_i->fcnt && !sbi->on_build_free_nids) { + BUG_ON(list_empty(&nm_i->free_nid_list)); + list_for_each(this, &nm_i->free_nid_list) { + i = list_entry(this, struct free_nid, list); + if (i->state == NID_NEW) + break; + } - BUG_ON(i->state != NID_NEW); - *nid = i->nid; - i->state = NID_ALLOC; - nm_i->fcnt--; + BUG_ON(i->state != NID_NEW); + *nid = i->nid; + i->state = NID_ALLOC; + nm_i->fcnt--; + spin_unlock(&nm_i->free_nid_list_lock); + return true; + } spin_unlock(&nm_i->free_nid_list_lock); - return true; + + /* Let's scan nat pages and its caches to get free nids */ + mutex_lock(&nm_i->build_lock); + sbi->on_build_free_nids = 1; + build_free_nids(sbi); + sbi->on_build_free_nids = 0; + mutex_unlock(&nm_i->build_lock); + goto retry; } /* @@ -1696,7 +1687,6 @@ static int init_node_manager(struct f2fs_sb_info *sbi) spin_lock_init(&nm_i->free_nid_list_lock); rwlock_init(&nm_i->nat_tree_lock); - nm_i->init_scan_nid = le32_to_cpu(sbi->ckpt->next_free_nid); nm_i->next_scan_nid = le32_to_cpu(sbi->ckpt->next_free_nid); nm_i->bitmap_size = __bitmap_size(sbi, NAT_BITMAP); version_bitmap = __bitmap_ptr(sbi, NAT_BITMAP);