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Subject[PATCH] f2fs: don't cache nat entry if out of memory
Date
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>
---
fs/f2fs/node.c | 27 ++++++++++++++++++++-------
1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index c1bbfdc..c1e267a 100644
--- 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);
}

--
2.8.2.311.gee88674
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