Hi Jeffle,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on dhowells-fs/fscache-next]
[cannot apply to xiang-erofs/dev-test ceph-client/for-linus linus/master v5.16-rc7 next-20211224]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Jeffle-Xu/fscache-erofs-fscache-based-demand-read-semantics/20211227-205742
base:   https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git fscache-next
config: x86_64-randconfig-a014-20211227 (https://download.01.org/0day-ci/archive/20211228/202112280132.0kJ8Vjql-lkp@intel.com/config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/0day-ci/linux/commit/c3453b91df3b4e89c3336453437f761d6cb6bca3
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Jeffle-Xu/fscache-erofs-fscache-based-demand-read-semantics/20211227-205742
        git checkout c3453b91df3b4e89c3336453437f761d6cb6bca3
        # save the config file to linux build tree
        mkdir build_dir
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   vmlinux.o: warning: objtool: do_machine_check()+0x89f: call to queue_task_work() leaves .noinstr.text section
   vmlinux.o: warning: objtool: enter_from_user_mode()+0x4e: call to on_thread_stack() leaves .noinstr.text section
   vmlinux.o: warning: objtool: syscall_enter_from_user_mode()+0x59: call to on_thread_stack() leaves .noinstr.text section
   vmlinux.o: warning: objtool: syscall_enter_from_user_mode_prepare()+0x4e: call to on_thread_stack() leaves .noinstr.text section
   vmlinux.o: warning: objtool: irqentry_enter_from_user_mode()+0x4e: call to on_thread_stack() leaves .noinstr.text section
   ld: fs/erofs/fscache.o: in function `erofs_issue_op':
   fs/erofs/fscache.c:27: undefined reference to `netfs_subreq_terminated'
   ld: fs/erofs/fscache.o: in function `erofs_readpage_from_fscache':
>> fs/erofs/fscache.c:59: undefined reference to `netfs_readpage'


vim +59 fs/erofs/fscache.c

    35	
    36	struct page *erofs_readpage_from_fscache(struct erofs_cookie_ctx *ctx,
    37						 pgoff_t index)
    38	{
    39		struct folio *folio;
    40		struct page *page;
    41		struct super_block *sb = ctx->inode->i_sb;
    42		int ret;
    43	
    44		page = find_or_create_page(ctx->inode->i_mapping, index, GFP_KERNEL);
    45		if (unlikely(!page)) {
    46			erofs_err(sb, "failed to allocate page");
    47			return ERR_PTR(-ENOMEM);
    48		}
    49	
    50		/* The content is already buffered in the address space */
    51		if (PageUptodate(page)) {
    52			unlock_page(page);
    53			return page;
    54		}
    55	
    56		/* Or a new page cache is created, then read the content from fscache */
    57		folio = page_folio(page);
    58	
  > 59		ret = netfs_readpage(NULL, folio, &erofs_req_ops, ctx->cookie);
    60		if (unlikely(ret || !PageUptodate(page))) {
    61			erofs_err(sb, "failed to read from fscache");
    62			return ERR_PTR(-EINVAL);
    63		}
    64	
    65		return page;
    66	}
    67	

---
0-DAY CI Kernel Test Service, Intel Corporation
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