f2fs: don't cache nat entry if out of memory

If we run out of memory, in cache_nat_entry, it's better to avoid loop
for allocating memory to cache nat entry, so in low memory scenario, for
read path of node block, I expect this can avoid unneeded latency.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index b9078fd..03a1f90 100644 (file)
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -245,12 +245,24 @@ bool need_inode_block_update(struct f2fs_sb_info *sbi, nid_t ino)
        return need_update;
 }
 
-static struct nat_entry *grab_nat_entry(struct f2fs_nm_info *nm_i, nid_t nid)
+static struct nat_entry *grab_nat_entry(struct f2fs_nm_info *nm_i, nid_t nid,
+                                                               bool no_fail)
 {
        struct nat_entry *new;
 
-       new = f2fs_kmem_cache_alloc(nat_entry_slab, GFP_NOFS);
-       f2fs_radix_tree_insert(&nm_i->nat_root, nid, new);
+       if (no_fail) {
+               new = f2fs_kmem_cache_alloc(nat_entry_slab, GFP_NOFS);
+               f2fs_radix_tree_insert(&nm_i->nat_root, nid, new);
+       } else {
+               new = kmem_cache_alloc(nat_entry_slab, GFP_NOFS);
+               if (!new)
+                       return NULL;
+               if (radix_tree_insert(&nm_i->nat_root, nid, new)) {
+                       kmem_cache_free(nat_entry_slab, new);
+                       return NULL;
+               }
+       }
+
        memset(new, 0, sizeof(struct nat_entry));
        nat_set_nid(new, nid);
        nat_reset_flag(new);
@@ -267,8 +279,9 @@ static void cache_nat_entry(struct f2fs_sb_info *sbi, nid_t nid,
 
        e = __lookup_nat_cache(nm_i, nid);
        if (!e) {
-               e = grab_nat_entry(nm_i, nid);
-               node_info_from_raw_nat(&e->ni, ne);
+               e = grab_nat_entry(nm_i, nid, false);
+               if (e)
+                       node_info_from_raw_nat(&e->ni, ne);
        } else {
                f2fs_bug_on(sbi, nat_get_ino(e) != le32_to_cpu(ne->ino) ||
                                nat_get_blkaddr(e) !=
@@ -286,7 +299,7 @@ static void set_node_addr(struct f2fs_sb_info *sbi, struct node_info *ni,
        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);
+               e = grab_nat_entry(nm_i, ni->nid, true);
                copy_node_info(&e->ni, ni);
                f2fs_bug_on(sbi, ni->blk_addr == NEW_ADDR);
        } else if (new_blkaddr == NEW_ADDR) {
@@ -2152,7 +2165,7 @@ static void remove_nats_in_journal(struct f2fs_sb_info *sbi)
 
                ne = __lookup_nat_cache(nm_i, nid);
                if (!ne) {
-                       ne = grab_nat_entry(nm_i, nid);
+                       ne = grab_nat_entry(nm_i, nid, true);
                        node_info_from_raw_nat(&ne->ni, &raw_ne);
                }