f2fs: use __GFP_NOFAIL to avoid infinite loop

__GFP_NOFAIL can avoid retrying the whole path of kmem_cache_alloc and
bio_alloc.
And, it also fixes the use cases of GFP_ATOMIC correctly.
Suggested-by: NChao Yu <chao2.yu@samsung.com>
Reviewed-by: NChao Yu <chao2.yu@samsung.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/checkpoint.c

@@ -336,26 +336,18 @@ const struct address_space_operations f2fs_meta_aops = {
 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;
+	struct ino_entry *e, *tmp;
+
+	tmp = f2fs_kmem_cache_alloc(ino_entry_slab, GFP_NOFS);
 retry:
-	if (radix_tree_preload(GFP_NOFS)) {
-		cond_resched();
-		goto retry;
-	}
+	radix_tree_preload(GFP_NOFS | __GFP_NOFAIL);
 
 	spin_lock(&im->ino_lock);
-
 	e = radix_tree_lookup(&im->ino_root, ino);
 	if (!e) {
-		e = kmem_cache_alloc(ino_entry_slab, GFP_ATOMIC);
-		if (!e) {
-			spin_unlock(&im->ino_lock);
-			radix_tree_preload_end();
-			goto retry;
-		}
+		e = tmp;
 		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;
 		}
@@ -368,6 +360,9 @@ static void __add_ino_entry(struct f2fs_sb_info *sbi, nid_t ino, int type)
 	}
 	spin_unlock(&im->ino_lock);
 	radix_tree_preload_end();
+
+	if (e != tmp)
+		kmem_cache_free(ino_entry_slab, tmp);
 }
 
 static void __remove_ino_entry(struct f2fs_sb_info *sbi, nid_t ino, int type)

fs/f2fs/f2fs.h

@@ -1252,13 +1252,10 @@ static inline void *f2fs_kmem_cache_alloc(struct kmem_cache *cachep,
 						gfp_t flags)
 {
 	void *entry;
-retry:
-	entry = kmem_cache_alloc(cachep, flags);
-	if (!entry) {
-		cond_resched();
-		goto retry;
-	}
 
+	entry = kmem_cache_alloc(cachep, flags);
+	if (!entry)
+		entry = kmem_cache_alloc(cachep, flags | __GFP_NOFAIL);
 	return entry;
 }
 
@@ -1267,12 +1264,9 @@ static inline struct bio *f2fs_bio_alloc(int npages)
 	struct bio *bio;
 
 	/* No failure on bio allocation */
-retry:
 	bio = bio_alloc(GFP_NOIO, npages);
-	if (!bio) {
-		cond_resched();
-		goto retry;
-	}
+	if (!bio)
+		bio = bio_alloc(GFP_NOIO | __GFP_NOFAIL, npages);
 	return bio;
 }
 

fs/f2fs/node.c

@@ -159,7 +159,7 @@ static void __set_nat_cache_dirty(struct f2fs_nm_info *nm_i,
 
 	head = radix_tree_lookup(&nm_i->nat_set_root, set);
 	if (!head) {
-		head = f2fs_kmem_cache_alloc(nat_entry_set_slab, GFP_ATOMIC);
+		head = f2fs_kmem_cache_alloc(nat_entry_set_slab, GFP_NOFS);
 
 		INIT_LIST_HEAD(&head->entry_list);
 		INIT_LIST_HEAD(&head->set_list);
@@ -246,7 +246,7 @@ static struct nat_entry *grab_nat_entry(struct f2fs_nm_info *nm_i, nid_t nid)
 {
 	struct nat_entry *new;
 
-	new = f2fs_kmem_cache_alloc(nat_entry_slab, GFP_ATOMIC);
+	new = f2fs_kmem_cache_alloc(nat_entry_slab, GFP_NOFS);
 	f2fs_radix_tree_insert(&nm_i->nat_root, nid, new);
 	memset(new, 0, sizeof(struct nat_entry));
 	nat_set_nid(new, nid);

fs/f2fs/segment.c

@@ -1753,7 +1753,7 @@ static struct page *get_next_sit_page(struct f2fs_sb_info *sbi,
 static struct sit_entry_set *grab_sit_entry_set(void)
 {
 	struct sit_entry_set *ses =
-			f2fs_kmem_cache_alloc(sit_entry_set_slab, GFP_ATOMIC);
+			f2fs_kmem_cache_alloc(sit_entry_set_slab, GFP_NOFS);
 
 	ses->entry_cnt = 0;
 	INIT_LIST_HEAD(&ses->set_list);