f2fs: avoid race in between GC and block exchange
During block exchange in {insert,collapse,move}_range, page-block mapping
is unstable due to mapping moving or recovery, so there should be no
concurrent cache read operation rely on such mapping, nor cache write
operation to mess up block exchange.
So this patch let background GC be aware of that.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index ff8f001..5d5bba4 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -832,10 +832,17 @@ static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
continue;
}
+ if (!down_write_trylock(
+ &F2FS_I(inode)->dio_rwsem[WRITE])) {
+ iput(inode);
+ continue;
+ }
+
start_bidx = start_bidx_of_node(nofs, inode);
data_page = get_read_data_page(inode,
start_bidx + ofs_in_node, REQ_RAHEAD,
true);
+ up_write(&F2FS_I(inode)->dio_rwsem[WRITE]);
if (IS_ERR(data_page)) {
iput(inode);
continue;