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SubjectRe: [f2fs-dev] [PATCH] f2fs: fix to account total free nid correctly
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On 2016/11/15 4:45, Jaegeuk Kim wrote:
> On Mon, Nov 14, 2016 at 07:24:56PM +0800, 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
>> and do nid allocation atomically during node creation.
>
> How about using nm_i::avaiable_nids for this?
> It seems that we don't need both of variables at the same time.
>
> Thanks,
>
>>
>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>> ---
>> fs/f2fs/f2fs.h | 1 +
>> fs/f2fs/node.c | 19 +++++++++++++++----
>> 2 files changed, 16 insertions(+), 4 deletions(-)
>>
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index 6de1fbf..9de6f20 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -551,6 +551,7 @@ struct f2fs_nm_info {
>> struct radix_tree_root free_nid_root;/* root of the free_nid cache */
>> 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 */
>> + unsigned int free_nid_cnt; /* the number of total free nid */
>> spinlock_t nid_list_lock; /* protect nid lists ops */
>> struct mutex build_lock; /* lock for build free nids */
>>
>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>> index d58438f..e412d0e 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->free_nid_cnt == 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->free_nid_cnt--;
>> 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->free_nid_cnt++;
>> +
>> 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)->free_nid_cnt++;
Hi all,
Here, we should consider clean NULL_ADDR nat entry in journal.

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index dcfab29..b22ecb0 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -158,6 +158,13 @@ static void __set_nat_cache_dirty(struct f2fs_nm_info *nm_i,
if (get_nat_flag(ne, IS_DIRTY))
return;

+ if (ne->ni.blk_addr == NULL_ADDR) {
+ spin_lock(&nm_i->free_nid_list_lock);
+ nm_i->available_nids--;
+ spin_unlock(&nm_i->free_nid_list_lock);
+ }
+
+

Thanks.

>> + spin_unlock(&NM_I(sbi)->nid_list_lock);
>> + }
>> }
>>
>> if (to_journal)
>> @@ -2302,6 +2312,7 @@ static int init_node_manager(struct f2fs_sb_info *sbi)
>> nm_i->nid_cnt[FREE_NID_LIST] = 0;
>> nm_i->nid_cnt[ALLOC_NID_LIST] = 0;
>> nm_i->nat_cnt = 0;
>> + nm_i->free_nid_cnt = nm_i->available_nids - sbi->total_valid_node_count;
>> nm_i->ram_thresh = DEF_RAM_THRESHOLD;
>> nm_i->ra_nid_pages = DEF_RA_NID_PAGES;
>> nm_i->dirty_nats_ratio = DEF_DIRTY_NAT_RATIO_THRESHOLD;
>> --
>> 2.8.2.311.gee88674
>
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