f2fs: fix to account total free nid correctly
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, reuse nm_i::available_nids for accounting free nids
and make nid allocation and counting being atomical during node creation.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index ae758e8..1693d4c 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -512,7 +512,7 @@
struct f2fs_nm_info {
block_t nat_blkaddr; /* base disk address of NAT */
nid_t max_nid; /* maximum possible node ids */
- nid_t available_nids; /* maximum available node ids */
+ nid_t available_nids; /* # of available node ids */
nid_t next_scan_nid; /* the next nid to be scanned */
unsigned int ram_thresh; /* control the memory footprint */
unsigned int ra_nid_pages; /* # of nid pages to be readaheaded */