f2fs: fix race between write_checkpoint and write_begin (2866fb16) · Commits · 戴 / test

The following race could lead to inconsistent SIT bitmap: Task A Task B ====== ====== f2fs_write_checkpoint block_operations f2fs_lock_all down_write(node_change) down_write(node_write) ... sync ... up_write(node_change) f2fs_file_write_iter set_inode_flag(FI_NO_PREALLOC) ...... f2fs_write_begin(index=0, has inline data) prepare_write_begin __do_map_lock(AIO) => down_read(node_change) f2fs_convert_inline_page => update SIT __do_map_lock(AIO) => up_read(node_change) f2fs_flush_sit_entries <= inconsistent SIT finish write checkpoint sudden-power-off If SPO occurs after checkpoint is finished, SIT bitmap will be set incorrectly. Signed-off-by:

Sheng Yong <shengyong1@huawei.com> Reviewed-by:

Chao Yu <yuchao0@huawei.com> Signed-off-by:

Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/data.c

+10 −2

Original line number	Diff line number	Diff line
		@@ -2322,6 +2322,7 @@ static int prepare_write_begin(struct f2fs_sb_info *sbi,
		bool locked = false;
		struct extent_info ei = {0,0,0};
		int err = 0;
		int flag;

		/*
		* we already allocated all the blocks, so we don't need to get
		@@ -2331,9 +2332,15 @@ static int prepare_write_begin(struct f2fs_sb_info *sbi,
		!is_inode_flag_set(inode, FI_NO_PREALLOC))
		return 0;

		/* f2fs_lock_op avoids race between write CP and convert_inline_page */
		if (f2fs_has_inline_data(inode) && pos + len > MAX_INLINE_DATA(inode))
		flag = F2FS_GET_BLOCK_DEFAULT;
		else
		flag = F2FS_GET_BLOCK_PRE_AIO;

		if (f2fs_has_inline_data(inode) \|\|
		(pos & PAGE_MASK) >= i_size_read(inode)) {
		__do_map_lock(sbi, F2FS_GET_BLOCK_PRE_AIO, true);
		__do_map_lock(sbi, flag, true);
		locked = true;
		}
		restart:
		@@ -2371,6 +2378,7 @@ restart:
		f2fs_put_dnode(&dn);
		__do_map_lock(sbi, F2FS_GET_BLOCK_PRE_AIO,
		true);
		WARN_ON(flag != F2FS_GET_BLOCK_PRE_AIO);
		locked = true;
		goto restart;
		}
		@@ -2384,7 +2392,7 @@ out:
		f2fs_put_dnode(&dn);
		unlock_out:
		if (locked)
		__do_map_lock(sbi, F2FS_GET_BLOCK_PRE_AIO, false);
		__do_map_lock(sbi, flag, false);
		return err;
		}

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