Hi all, It may trigger hungtask in ENOSPC case with fsstress, please ignore this patch before an update.
Thanks, On 2017/9/26 19:22, Chao Yu wrote: > Previously, there is no restrict order among free nid allocators, if > there are no free nids being cached in memory, previous allocator will > try to load them by scanning NAT pages, but after that, these newly > loaded free nids could be grabbed by later allocators, result in long > delay of previous allocator during nid allocation. > > This patch tries to refactor alloc_nid flow to serialize allocators. > > Signed-off-by: Chao Yu <[email protected]> > --- > fs/f2fs/f2fs.h | 3 ++- > fs/f2fs/node.c | 63 > ++++++++++++++++++++++++++++++++++++++++++++-------------- > 2 files changed, 50 insertions(+), 16 deletions(-) > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > index 8fdae8ec0377..96366a141f68 100644 > --- a/fs/f2fs/f2fs.h > +++ b/fs/f2fs/f2fs.h > @@ -721,7 +721,8 @@ struct f2fs_nm_info { > struct list_head nid_list[MAX_NID_LIST];/* lists for free nids */ > unsigned int nid_cnt[MAX_NID_LIST]; /* the number of free node id */ > spinlock_t nid_list_lock; /* protect nid lists ops */ > - struct mutex build_lock; /* lock for build free nids */ > + struct semaphore build_lock; /* lock for build free nids */ > + atomic_t allocator; /* # of free nid allocators */ > unsigned char (*free_nid_bitmap)[NAT_ENTRY_BITMAP_SIZE]; > unsigned char *nat_block_bitmap; > unsigned short *free_nid_count; /* free nid count of NAT block */ > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c > index bfeaa0124670..e1bd6ff383df 100644 > --- a/fs/f2fs/node.c > +++ b/fs/f2fs/node.c > @@ -2041,9 +2041,9 @@ static void __build_free_nids(struct f2fs_sb_info *sbi, > bool sync, bool mount) > > void build_free_nids(struct f2fs_sb_info *sbi, bool sync, bool mount) > { > - mutex_lock(&NM_I(sbi)->build_lock); > + down(&NM_I(sbi)->build_lock); > __build_free_nids(sbi, sync, mount); > - mutex_unlock(&NM_I(sbi)->build_lock); > + up(&NM_I(sbi)->build_lock); > } > > /* > @@ -2055,22 +2055,30 @@ bool alloc_nid(struct f2fs_sb_info *sbi, nid_t *nid) > { > struct f2fs_nm_info *nm_i = NM_I(sbi); > struct free_nid *i = NULL; > + bool alloc_failed = false, lock_build = false, ret = false; > + > + spin_lock(&nm_i->nid_list_lock); > retry: > #ifdef CONFIG_F2FS_FAULT_INJECTION > if (time_to_inject(sbi, FAULT_ALLOC_NID)) { > f2fs_show_injection_info(FAULT_ALLOC_NID); > - return false; > + goto out; > } > #endif > - spin_lock(&nm_i->nid_list_lock); > > - if (unlikely(nm_i->available_nids == 0)) { > - spin_unlock(&nm_i->nid_list_lock); > - return false; > - } > + if (unlikely(nm_i->available_nids == 0)) > + goto out; > > /* We should not use stale free nids created by build_free_nids */ > - if (nm_i->nid_cnt[FREE_NID_LIST] && !on_build_free_nids(nm_i)) { > + if (nm_i->nid_cnt[FREE_NID_LIST] > atomic_read(&nm_i->allocator)) { > + > + if (!lock_build) { > + if (!down_trylock(&nm_i->build_lock)) > + lock_build = true; > + else > + goto build; > + } > + > f2fs_bug_on(sbi, list_empty(&nm_i->nid_list[FREE_NID_LIST])); > i = list_first_entry(&nm_i->nid_list[FREE_NID_LIST], > struct free_nid, list); > @@ -2083,14 +2091,38 @@ bool alloc_nid(struct f2fs_sb_info *sbi, nid_t *nid) > > update_free_nid_bitmap(sbi, *nid, false, false); > > - spin_unlock(&nm_i->nid_list_lock); > - return true; > + ret = true; > + goto out; > + } > +build: > + if (!alloc_failed) { > + alloc_failed = true; > + atomic_inc(&nm_i->allocator); > } > spin_unlock(&nm_i->nid_list_lock); > > + if (lock_build) { > + lock_build = false; > + up(&nm_i->build_lock); > + } > + > /* Let's scan nat pages and its caches to get free nids */ > - build_free_nids(sbi, true, false); > + down(&nm_i->build_lock); > + lock_build = true; > + > + if (nm_i->nid_cnt[FREE_NID_LIST] < atomic_read(&nm_i->allocator)) > + __build_free_nids(sbi, true, false); > + > + spin_lock(&nm_i->nid_list_lock); > goto retry; > + > +out: > + if (alloc_failed) > + atomic_dec(&nm_i->allocator); > + spin_unlock(&nm_i->nid_list_lock); > + if (lock_build) > + up(&nm_i->build_lock); > + return ret; > } > > /* > @@ -2154,7 +2186,7 @@ int try_to_free_nids(struct f2fs_sb_info *sbi, int > nr_shrink) > if (nm_i->nid_cnt[FREE_NID_LIST] <= MAX_FREE_NIDS) > return 0; > > - if (!mutex_trylock(&nm_i->build_lock)) > + if (!down_trylock(&nm_i->build_lock)) > return 0; > > spin_lock(&nm_i->nid_list_lock); > @@ -2169,7 +2201,7 @@ int try_to_free_nids(struct f2fs_sb_info *sbi, int > nr_shrink) > nr_shrink--; > } > spin_unlock(&nm_i->nid_list_lock); > - mutex_unlock(&nm_i->build_lock); > + up(&nm_i->build_lock); > > return nr - nr_shrink; > } > @@ -2656,7 +2688,8 @@ static int init_node_manager(struct f2fs_sb_info *sbi) > INIT_RADIX_TREE(&nm_i->nat_set_root, GFP_NOIO); > INIT_LIST_HEAD(&nm_i->nat_entries); > > - mutex_init(&nm_i->build_lock); > + sema_init(&nm_i->build_lock, 1); > + atomic_set(&nm_i->allocator, 0); > spin_lock_init(&nm_i->nid_list_lock); > init_rwsem(&nm_i->nat_tree_lock); > >
