Messages in this thread | | | Subject | Re: [PATCH v2] f2fs: fix to account total free nid correctly | From | Chao Yu <> | Date | Tue, 15 Nov 2016 09:27:39 +0800 |
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On 2016/11/15 9:19, Chao Yu wrote: > Thread A Thread B Thread C > - f2fs_create > - f2fs_new_inode > - f2fs_lock_op > - alloc_nid > alloc last nid > - f2fs_unlock_op > - f2fs_create > - f2fs_new_inode > - f2fs_lock_op > - alloc_nid > as node count still not > be increased, we will > loop in alloc_nid > - f2fs_write_node_pages > - f2fs_balance_fs_bg > - f2fs_sync_fs > - write_checkpoint > - block_operations > - f2fs_lock_all > - f2fs_lock_op > > While creating new inode, we do not allocate and account nid atomically, > so that when there is almost no free nids left, we may encounter deadloop > like above stack. > > In order to avoid that, add nm_i::free_nid_cnt for accounting free nids
Forgot to adapt above comments, sorry, I will send v3.
Thanks,
> and do nid allocation atomically during node creation. > > Signed-off-by: Chao Yu <yuchao0@huawei.com> > --- > fs/f2fs/f2fs.h | 2 +- > fs/f2fs/node.c | 21 ++++++++++++++++----- > 2 files changed, 17 insertions(+), 6 deletions(-) > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > index 6de1fbf..0bba5d4 100644 > --- a/fs/f2fs/f2fs.h > +++ b/fs/f2fs/f2fs.h > @@ -533,7 +533,7 @@ enum nid_list { > struct f2fs_nm_info { > block_t nat_blkaddr; /* base disk address of NAT */ > nid_t max_nid; /* maximum possible node ids */ > - nid_t available_nids; /* maximum available node ids */ > + nid_t available_nids; /* # of available node ids */ > nid_t next_scan_nid; /* the next nid to be scanned */ > unsigned int ram_thresh; /* control the memory footprint */ > unsigned int ra_nid_pages; /* # of nid pages to be readaheaded */ > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c > index d58438f..1b5b31a 100644 > --- a/fs/f2fs/node.c > +++ b/fs/f2fs/node.c > @@ -1885,11 +1885,13 @@ bool alloc_nid(struct f2fs_sb_info *sbi, nid_t *nid) > return false; > } > #endif > - if (unlikely(sbi->total_valid_node_count + 1 > nm_i->available_nids)) > - return false; > - > spin_lock(&nm_i->nid_list_lock); > > + if (unlikely(nm_i->available_nids == 0)) { > + spin_unlock(&nm_i->nid_list_lock); > + return false; > + } > + > /* 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)) { > f2fs_bug_on(sbi, list_empty(&nm_i->nid_list[FREE_NID_LIST])); > @@ -1900,6 +1902,7 @@ bool alloc_nid(struct f2fs_sb_info *sbi, nid_t *nid) > __remove_nid_from_list(sbi, i, FREE_NID_LIST, true); > i->state = NID_ALLOC; > __insert_nid_to_list(sbi, i, ALLOC_NID_LIST, false); > + nm_i->available_nids--; > spin_unlock(&nm_i->nid_list_lock); > return true; > } > @@ -1951,6 +1954,9 @@ void alloc_nid_failed(struct f2fs_sb_info *sbi, nid_t nid) > i->state = NID_NEW; > __insert_nid_to_list(sbi, i, FREE_NID_LIST, false); > } > + > + nm_i->available_nids++; > + > spin_unlock(&nm_i->nid_list_lock); > > if (need_free) > @@ -2222,8 +2228,12 @@ static void __flush_nat_entry_set(struct f2fs_sb_info *sbi, > raw_nat_from_node_info(raw_ne, &ne->ni); > nat_reset_flag(ne); > __clear_nat_cache_dirty(NM_I(sbi), ne); > - if (nat_get_blkaddr(ne) == NULL_ADDR) > + if (nat_get_blkaddr(ne) == NULL_ADDR) { > add_free_nid(sbi, nid, false); > + spin_lock(&NM_I(sbi)->nid_list_lock); > + NM_I(sbi)->available_nids++; > + spin_unlock(&NM_I(sbi)->nid_list_lock); > + } > } > > if (to_journal) > @@ -2298,7 +2308,8 @@ static int init_node_manager(struct f2fs_sb_info *sbi) > nm_i->max_nid = NAT_ENTRY_PER_BLOCK * nat_blocks; > > /* not used nids: 0, node, meta, (and root counted as valid node) */ > - nm_i->available_nids = nm_i->max_nid - F2FS_RESERVED_NODE_NUM; > + nm_i->available_nids = nm_i->max_nid - sbi->total_valid_node_count - > + F2FS_RESERVED_NODE_NUM; > nm_i->nid_cnt[FREE_NID_LIST] = 0; > nm_i->nid_cnt[ALLOC_NID_LIST] = 0; > nm_i->nat_cnt = 0; >
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