[PATCH 1/3] f2fs: fix missing kmem_cache_free

[PATCH 1/3] f2fs: fix missing kmem_cache_free

[Jaegeuk Kim]

This patch fixes missing kmem_cache_free when handling errors.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 fs/f2fs/node.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index b1466cf..c59341d 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -158,7 +158,7 @@ retry:
 		head->entry_cnt = 0;
 
 		if (radix_tree_insert(&nm_i->nat_set_root, set, head)) {
-			cond_resched();
+			kmem_cache_free(nat_entry_set_slab, head);
 			goto retry;
 		}
 	}
-- 
2.1.1

[PATCH 2/3] f2fs: use rw_semaphore for nat entry lock

[Jaegeuk Kim]

Previoulsy, we used rwlock for nat_entry lock.
But, now we have a lot of complex operations in set_node_addr.
(e.g., allocating kernel memories, handling radix_trees, and so on)

So, this patches tries to change spinlock to rw_semaphore to give CPUs to other
threads.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 fs/f2fs/f2fs.h |  2 +-
 fs/f2fs/node.c | 52 ++++++++++++++++++++++++++--------------------------
 2 files changed, 27 insertions(+), 27 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index d042813..c873140 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -332,7 +332,7 @@ struct f2fs_nm_info {
 	/* NAT cache management */
 	struct radix_tree_root nat_root;/* root of the nat entry cache */
 	struct radix_tree_root nat_set_root;/* root of the nat set cache */
-	rwlock_t nat_tree_lock;		/* protect nat_tree_lock */
+	struct rw_semaphore nat_tree_lock;	/* protect nat_tree_lock */
 	struct list_head nat_entries;	/* cached nat entry list (clean) */
 	unsigned int nat_cnt;		/* the # of cached nat entries */
 	unsigned int dirty_nat_cnt;	/* total num of nat entries in set */
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index c59341d..b47555f 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -196,11 +196,11 @@ bool is_checkpointed_node(struct f2fs_sb_info *sbi, nid_t nid)
 	struct nat_entry *e;
 	bool is_cp = true;
 
-	read_lock(&nm_i->nat_tree_lock);
+	down_read(&nm_i->nat_tree_lock);
 	e = __lookup_nat_cache(nm_i, nid);
 	if (e && !get_nat_flag(e, IS_CHECKPOINTED))
 		is_cp = false;
-	read_unlock(&nm_i->nat_tree_lock);
+	up_read(&nm_i->nat_tree_lock);
 	return is_cp;
 }
 
@@ -210,11 +210,11 @@ bool has_fsynced_inode(struct f2fs_sb_info *sbi, nid_t ino)
 	struct nat_entry *e;
 	bool fsynced = false;
 
-	read_lock(&nm_i->nat_tree_lock);
+	down_read(&nm_i->nat_tree_lock);
 	e = __lookup_nat_cache(nm_i, ino);
 	if (e && get_nat_flag(e, HAS_FSYNCED_INODE))
 		fsynced = true;
-	read_unlock(&nm_i->nat_tree_lock);
+	up_read(&nm_i->nat_tree_lock);
 	return fsynced;
 }
 
@@ -224,13 +224,13 @@ bool need_inode_block_update(struct f2fs_sb_info *sbi, nid_t ino)
 	struct nat_entry *e;
 	bool need_update = true;
 
-	read_lock(&nm_i->nat_tree_lock);
+	down_read(&nm_i->nat_tree_lock);
 	e = __lookup_nat_cache(nm_i, ino);
 	if (e && get_nat_flag(e, HAS_LAST_FSYNC) &&
 			(get_nat_flag(e, IS_CHECKPOINTED) ||
 			 get_nat_flag(e, HAS_FSYNCED_INODE)))
 		need_update = false;
-	read_unlock(&nm_i->nat_tree_lock);
+	up_read(&nm_i->nat_tree_lock);
 	return need_update;
 }
 
@@ -258,17 +258,17 @@ static void cache_nat_entry(struct f2fs_nm_info *nm_i, nid_t nid,
 {
 	struct nat_entry *e;
 retry:
-	write_lock(&nm_i->nat_tree_lock);
+	down_write(&nm_i->nat_tree_lock);
 	e = __lookup_nat_cache(nm_i, nid);
 	if (!e) {
 		e = grab_nat_entry(nm_i, nid);
 		if (!e) {
-			write_unlock(&nm_i->nat_tree_lock);
+			up_write(&nm_i->nat_tree_lock);
 			goto retry;
 		}
 		node_info_from_raw_nat(&e->ni, ne);
 	}
-	write_unlock(&nm_i->nat_tree_lock);
+	up_write(&nm_i->nat_tree_lock);
 }
 
 static void set_node_addr(struct f2fs_sb_info *sbi, struct node_info *ni,
@@ -277,12 +277,12 @@ static void set_node_addr(struct f2fs_sb_info *sbi, struct node_info *ni,
 	struct f2fs_nm_info *nm_i = NM_I(sbi);
 	struct nat_entry *e;
 retry:
-	write_lock(&nm_i->nat_tree_lock);
+	down_write(&nm_i->nat_tree_lock);
 	e = __lookup_nat_cache(nm_i, ni->nid);
 	if (!e) {
 		e = grab_nat_entry(nm_i, ni->nid);
 		if (!e) {
-			write_unlock(&nm_i->nat_tree_lock);
+			up_write(&nm_i->nat_tree_lock);
 			goto retry;
 		}
 		e->ni = *ni;
@@ -326,7 +326,7 @@ retry:
 			set_nat_flag(e, HAS_FSYNCED_INODE, true);
 		set_nat_flag(e, HAS_LAST_FSYNC, fsync_done);
 	}
-	write_unlock(&nm_i->nat_tree_lock);
+	up_write(&nm_i->nat_tree_lock);
 }
 
 int try_to_free_nats(struct f2fs_sb_info *sbi, int nr_shrink)
@@ -336,7 +336,7 @@ int try_to_free_nats(struct f2fs_sb_info *sbi, int nr_shrink)
 	if (available_free_memory(sbi, NAT_ENTRIES))
 		return 0;
 
-	write_lock(&nm_i->nat_tree_lock);
+	down_write(&nm_i->nat_tree_lock);
 	while (nr_shrink && !list_empty(&nm_i->nat_entries)) {
 		struct nat_entry *ne;
 		ne = list_first_entry(&nm_i->nat_entries,
@@ -344,7 +344,7 @@ int try_to_free_nats(struct f2fs_sb_info *sbi, int nr_shrink)
 		__del_from_nat_cache(nm_i, ne);
 		nr_shrink--;
 	}
-	write_unlock(&nm_i->nat_tree_lock);
+	up_write(&nm_i->nat_tree_lock);
 	return nr_shrink;
 }
 
@@ -367,14 +367,14 @@ void get_node_info(struct f2fs_sb_info *sbi, nid_t nid, struct node_info *ni)
 	ni->nid = nid;
 
 	/* Check nat cache */
-	read_lock(&nm_i->nat_tree_lock);
+	down_read(&nm_i->nat_tree_lock);
 	e = __lookup_nat_cache(nm_i, nid);
 	if (e) {
 		ni->ino = nat_get_ino(e);
 		ni->blk_addr = nat_get_blkaddr(e);
 		ni->version = nat_get_version(e);
 	}
-	read_unlock(&nm_i->nat_tree_lock);
+	up_read(&nm_i->nat_tree_lock);
 	if (e)
 		return;
 
@@ -1432,13 +1432,13 @@ static int add_free_nid(struct f2fs_sb_info *sbi, nid_t nid, bool build)
 
 	if (build) {
 		/* do not add allocated nids */
-		read_lock(&nm_i->nat_tree_lock);
+		down_read(&nm_i->nat_tree_lock);
 		ne = __lookup_nat_cache(nm_i, nid);
 		if (ne &&
 			(!get_nat_flag(ne, IS_CHECKPOINTED) ||
 				nat_get_blkaddr(ne) != NULL_ADDR))
 			allocated = true;
-		read_unlock(&nm_i->nat_tree_lock);
+		up_read(&nm_i->nat_tree_lock);
 		if (allocated)
 			return 0;
 	}
@@ -1827,20 +1827,20 @@ static void remove_nats_in_journal(struct f2fs_sb_info *sbi)
 
 		raw_ne = nat_in_journal(sum, i);
 retry:
-		write_lock(&nm_i->nat_tree_lock);
+		down_write(&nm_i->nat_tree_lock);
 		ne = __lookup_nat_cache(nm_i, nid);
 		if (ne)
 			goto found;
 
 		ne = grab_nat_entry(nm_i, nid);
 		if (!ne) {
-			write_unlock(&nm_i->nat_tree_lock);
+			up_write(&nm_i->nat_tree_lock);
 			goto retry;
 		}
 		node_info_from_raw_nat(&ne->ni, &raw_ne);
 found:
 		__set_nat_cache_dirty(nm_i, ne);
-		write_unlock(&nm_i->nat_tree_lock);
+		up_write(&nm_i->nat_tree_lock);
 	}
 	update_nats_in_cursum(sum, -i);
 	mutex_unlock(&curseg->curseg_mutex);
@@ -1911,10 +1911,10 @@ static void __flush_nat_entry_set(struct f2fs_sb_info *sbi,
 		}
 		raw_nat_from_node_info(raw_ne, &ne->ni);
 
-		write_lock(&NM_I(sbi)->nat_tree_lock);
+		down_write(&NM_I(sbi)->nat_tree_lock);
 		nat_reset_flag(ne);
 		__clear_nat_cache_dirty(NM_I(sbi), ne);
-		write_unlock(&NM_I(sbi)->nat_tree_lock);
+		up_write(&NM_I(sbi)->nat_tree_lock);
 
 		if (nat_get_blkaddr(ne) == NULL_ADDR)
 			add_free_nid(sbi, nid, false);
@@ -2000,7 +2000,7 @@ static int init_node_manager(struct f2fs_sb_info *sbi)
 
 	mutex_init(&nm_i->build_lock);
 	spin_lock_init(&nm_i->free_nid_list_lock);
-	rwlock_init(&nm_i->nat_tree_lock);
+	init_rwsem(&nm_i->nat_tree_lock);
 
 	nm_i->next_scan_nid = le32_to_cpu(sbi->ckpt->next_free_nid);
 	nm_i->bitmap_size = __bitmap_size(sbi, NAT_BITMAP);
@@ -2056,7 +2056,7 @@ void destroy_node_manager(struct f2fs_sb_info *sbi)
 	spin_unlock(&nm_i->free_nid_list_lock);
 
 	/* destroy nat cache */
-	write_lock(&nm_i->nat_tree_lock);
+	down_write(&nm_i->nat_tree_lock);
 	while ((found = __gang_lookup_nat_cache(nm_i,
 					nid, NATVEC_SIZE, natvec))) {
 		unsigned idx;
@@ -2065,7 +2065,7 @@ void destroy_node_manager(struct f2fs_sb_info *sbi)
 			__del_from_nat_cache(nm_i, natvec[idx]);
 	}
 	f2fs_bug_on(sbi, nm_i->nat_cnt);
-	write_unlock(&nm_i->nat_tree_lock);
+	up_write(&nm_i->nat_tree_lock);
 
 	kfree(nm_i->nat_bitmap);
 	sbi->nm_info = NULL;
-- 
2.1.1


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[PATCH 3/3] f2fs: call radix_tree_preload before radix_tree_insert

[Jaegeuk Kim]

This patch tries to fix:

 BUG: using smp_processor_id() in preemptible [00000000] code: f2fs_gc-254:0/384
  (radix_tree_node_alloc+0x14/0x74) from [<c033d8a0>] (radix_tree_insert+0x110/0x200)
  (radix_tree_insert+0x110/0x200) from [<c02e8264>] (gc_data_segment+0x340/0x52c)
  (gc_data_segment+0x340/0x52c) from [<c02e8658>] (f2fs_gc+0x208/0x400)
  (f2fs_gc+0x208/0x400) from [<c02e8a98>] (gc_thread_func+0x248/0x28c)
  (gc_thread_func+0x248/0x28c) from [<c0139944>] (kthread+0xa0/0xac)
  (kthread+0xa0/0xac) from [<c0105ef8>] (ret_from_fork+0x14/0x3c)

The reason is that f2fs calls radix_tree_insert under enabled preemption.
So, before calling it, we need to call radix_tree_preload.

Otherwise, we should use _GFP_WAIT for the radix tree, and use mutex or
semaphore to cover the radix tree operations.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 fs/f2fs/checkpoint.c | 8 ++++++++
 fs/f2fs/gc.c         | 6 ++----
 fs/f2fs/node.c       | 6 +++---
 3 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 20a917b..6a81b73 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -304,6 +304,11 @@ static void __add_ino_entry(struct f2fs_sb_info *sbi, nid_t ino, int type)
 	struct inode_management *im = &sbi->im[type];
 	struct ino_entry *e;
 retry:
+	if (radix_tree_preload(GFP_NOFS)) {
+		cond_resched();
+		goto retry;
+	}
+
 	spin_lock(&im->ino_lock);
 
 	e = radix_tree_lookup(&im->ino_root, ino);
@@ -311,11 +316,13 @@ retry:
 		e = kmem_cache_alloc(ino_entry_slab, GFP_ATOMIC);
 		if (!e) {
 			spin_unlock(&im->ino_lock);
+			radix_tree_preload_end();
 			goto retry;
 		}
 		if (radix_tree_insert(&im->ino_root, ino, e)) {
 			spin_unlock(&im->ino_lock);
 			kmem_cache_free(ino_entry_slab, e);
+			radix_tree_preload_end();
 			goto retry;
 		}
 		memset(e, 0, sizeof(struct ino_entry));
@@ -326,6 +333,7 @@ retry:
 			im->ino_num++;
 	}
 	spin_unlock(&im->ino_lock);
+	radix_tree_preload_end();
 }
 
 static void __remove_ino_entry(struct f2fs_sb_info *sbi, nid_t ino, int type)
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index a1af74f..2c58c58 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -351,7 +351,6 @@ static struct inode *find_gc_inode(struct gc_inode_list *gc_list, nid_t ino)
 static void add_gc_inode(struct gc_inode_list *gc_list, struct inode *inode)
 {
 	struct inode_entry *new_ie;
-	int ret;
 
 	if (inode == find_gc_inode(gc_list, inode->i_ino)) {
 		iput(inode);
@@ -361,8 +360,7 @@ retry:
 	new_ie = f2fs_kmem_cache_alloc(winode_slab, GFP_NOFS);
 	new_ie->inode = inode;
 
-	ret = radix_tree_insert(&gc_list->iroot, inode->i_ino, new_ie);
-	if (ret) {
+	if (radix_tree_insert(&gc_list->iroot, inode->i_ino, new_ie)) {
 		kmem_cache_free(winode_slab, new_ie);
 		goto retry;
 	}
@@ -703,7 +701,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi)
 	struct cp_control cpc;
 	struct gc_inode_list gc_list = {
 		.ilist = LIST_HEAD_INIT(gc_list.ilist),
-		.iroot = RADIX_TREE_INIT(GFP_ATOMIC),
+		.iroot = RADIX_TREE_INIT(GFP_NOFS),
 	};
 
 	cpc.reason = test_opt(sbi, FASTBOOT) ? CP_UMOUNT : CP_SYNC;
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index b47555f..fa115d0 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1992,10 +1992,10 @@ static int init_node_manager(struct f2fs_sb_info *sbi)
 	nm_i->nat_cnt = 0;
 	nm_i->ram_thresh = DEF_RAM_THRESHOLD;
 
-	INIT_RADIX_TREE(&nm_i->free_nid_root, GFP_ATOMIC);
+	INIT_RADIX_TREE(&nm_i->free_nid_root, GFP_NOIO);
 	INIT_LIST_HEAD(&nm_i->free_nid_list);
-	INIT_RADIX_TREE(&nm_i->nat_root, GFP_ATOMIC);
-	INIT_RADIX_TREE(&nm_i->nat_set_root, GFP_ATOMIC);
+	INIT_RADIX_TREE(&nm_i->nat_root, GFP_NOIO);
+	INIT_RADIX_TREE(&nm_i->nat_set_root, GFP_NOIO);
 	INIT_LIST_HEAD(&nm_i->nat_entries);
 
 	mutex_init(&nm_i->build_lock);
-- 
2.1.1

Re: [PATCH 1/3] f2fs: fix missing kmem_cache_free

[Gu Zheng]

Hi Jaegeuk, 
On 12/05/2014 08:49 AM, Jaegeuk Kim wrote:

> This patch fixes missing kmem_cache_free when handling errors.
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> ---
>  fs/f2fs/node.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> index b1466cf..c59341d 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -158,7 +158,7 @@ retry:
>  		head->entry_cnt = 0;
>  
>  		if (radix_tree_insert(&nm_i->nat_set_root, set, head)) {
> -			cond_resched();
> +			kmem_cache_free(nat_entry_set_slab, head);

Why not reuse the allocated entry?
This routine is under nat_tree_lock, so the free_old->research->alloc_new
is needless, because no other ones can race with us.

>  			goto retry;

And radix_tree_insert can only fail -ENOMEM here, IMO, the in-time retry step
makes very little sense here. How about retaining the "cond_resched()" and retry
insert later?

If I misread something, please correct me.:)

Thanks,
Gu

>  		}
>  	}

Re: [PATCH 1/3] f2fs: fix missing kmem_cache_free

[Jaegeuk Kim]

Hi Gu,

On Fri, Dec 05, 2014 at 11:34:49AM +0800, Gu Zheng wrote:
> Hi Jaegeuk, 
> On 12/05/2014 08:49 AM, Jaegeuk Kim wrote:
> 
> > This patch fixes missing kmem_cache_free when handling errors.
> > 
> > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> > ---
> >  fs/f2fs/node.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> > index b1466cf..c59341d 100644
> > --- a/fs/f2fs/node.c
> > +++ b/fs/f2fs/node.c
> > @@ -158,7 +158,7 @@ retry:
> >  		head->entry_cnt = 0;
> >  
> >  		if (radix_tree_insert(&nm_i->nat_set_root, set, head)) {
> > -			cond_resched();
> > +			kmem_cache_free(nat_entry_set_slab, head);
> 
> Why not reuse the allocated entry?
> This routine is under nat_tree_lock, so the free_old->research->alloc_new
> is needless, because no other ones can race with us.

IMO, this issue is quite different one that you're mentioning.
This patch just fixes a missing kfree.

> 
> >  			goto retry;
> 
> And radix_tree_insert can only fail -ENOMEM here, IMO, the in-time retry step
> makes very little sense here. How about retaining the "cond_resched()" and retry
> insert later?

I think the following patches related to radix_tree_preload that I submitted
would address that.
But, still it seems that I need to review the retrial paths again.

Thanks,

> 
> If I misread something, please correct me.:)
> 
> Thanks,
> Gu
> 
> >  		}
> >  	}