Re: [PATCH] buffer: Associate the meta bio with blkg from buffer page

[kernel test robot <lkp@intel.com>]

Hi Haifeng,

kernel test robot noticed the following build errors:

[auto build test ERROR on brauner-vfs/vfs.all]
[also build test ERROR on linus/master v6.11-rc5 next-20240829]
[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#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Haifeng-Xu/buffer-Associate-the-meta-bio-with-blkg-from-buffer-page/20240828-113409
base:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git vfs.all
patch link:    https://lore.kernel.org/r/20240828033224.146584-1-haifeng.xu%40shopee.com
patch subject: [PATCH] buffer: Associate the meta bio with blkg from buffer page
config: alpha-defconfig (https://download.01.org/0day-ci/archive/20240830/202408300007.m9sHEOXo-lkp@intel.com/config)
compiler: alpha-linux-gcc (GCC) 13.3.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240830/202408300007.m9sHEOXo-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202408300007.m9sHEOXo-lkp@intel.com/

All errors (new ones prefixed by >>):

   fs/buffer.c: In function 'submit_bh_wbc':
   fs/buffer.c:2826:29: error: implicit declaration of function 'mem_cgroup_css_from_folio'; did you mean 'mem_cgroup_from_obj'? [-Werror=implicit-function-declaration]
    2826 |                 memcg_css = mem_cgroup_css_from_folio(folio);
         |                             ^~~~~~~~~~~~~~~~~~~~~~~~~
         |                             mem_cgroup_from_obj
   fs/buffer.c:2826:27: warning: assignment to 'struct cgroup_subsys_state *' from 'int' makes pointer from integer without a cast [-Wint-conversion]
    2826 |                 memcg_css = mem_cgroup_css_from_folio(folio);
         |                           ^
>> fs/buffer.c:2827:21: error: implicit declaration of function 'cgroup_subsys_on_dfl' [-Werror=implicit-function-declaration]
    2827 |                 if (cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
         |                     ^~~~~~~~~~~~~~~~~~~~
>> fs/buffer.c:2827:42: error: 'memory_cgrp_subsys' undeclared (first use in this function)
    2827 |                 if (cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
         |                                          ^~~~~~~~~~~~~~~~~~
   fs/buffer.c:2827:42: note: each undeclared identifier is reported only once for each function it appears in
   fs/buffer.c:2828:42: error: 'io_cgrp_subsys' undeclared (first use in this function)
    2828 |                     cgroup_subsys_on_dfl(io_cgrp_subsys)) {
         |                                          ^~~~~~~~~~~~~~
>> fs/buffer.c:2829:37: error: implicit declaration of function 'cgroup_e_css'; did you mean 'cgroup_exit'? [-Werror=implicit-function-declaration]
    2829 |                         blkcg_css = cgroup_e_css(memcg_css->cgroup, &io_cgrp_subsys);
         |                                     ^~~~~~~~~~~~
         |                                     cgroup_exit
>> fs/buffer.c:2829:59: error: invalid use of undefined type 'struct cgroup_subsys_state'
    2829 |                         blkcg_css = cgroup_e_css(memcg_css->cgroup, &io_cgrp_subsys);
         |                                                           ^~
   cc1: some warnings being treated as errors


vim +/cgroup_subsys_on_dfl +2827 fs/buffer.c

  2778	
  2779	static void submit_bh_wbc(blk_opf_t opf, struct buffer_head *bh,
  2780				  enum rw_hint write_hint,
  2781				  struct writeback_control *wbc)
  2782	{
  2783		const enum req_op op = opf & REQ_OP_MASK;
  2784		struct bio *bio;
  2785	
  2786		BUG_ON(!buffer_locked(bh));
  2787		BUG_ON(!buffer_mapped(bh));
  2788		BUG_ON(!bh->b_end_io);
  2789		BUG_ON(buffer_delay(bh));
  2790		BUG_ON(buffer_unwritten(bh));
  2791	
  2792		/*
  2793		 * Only clear out a write error when rewriting
  2794		 */
  2795		if (test_set_buffer_req(bh) && (op == REQ_OP_WRITE))
  2796			clear_buffer_write_io_error(bh);
  2797	
  2798		if (buffer_meta(bh))
  2799			opf |= REQ_META;
  2800		if (buffer_prio(bh))
  2801			opf |= REQ_PRIO;
  2802	
  2803		bio = bio_alloc(bh->b_bdev, 1, opf, GFP_NOIO);
  2804	
  2805		fscrypt_set_bio_crypt_ctx_bh(bio, bh, GFP_NOIO);
  2806	
  2807		bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
  2808		bio->bi_write_hint = write_hint;
  2809	
  2810		__bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh));
  2811	
  2812		bio->bi_end_io = end_bio_bh_io_sync;
  2813		bio->bi_private = bh;
  2814	
  2815		/* Take care of bh's that straddle the end of the device */
  2816		guard_bio_eod(bio);
  2817	
  2818		if (wbc) {
  2819			wbc_init_bio(wbc, bio);
  2820			wbc_account_cgroup_owner(wbc, bh->b_page, bh->b_size);
  2821		} else if (buffer_meta(bh)) {
  2822			struct folio *folio;
  2823			struct cgroup_subsys_state *memcg_css, *blkcg_css;
  2824	
  2825			folio = page_folio(bh->b_page);
  2826			memcg_css = mem_cgroup_css_from_folio(folio);
> 2827			if (cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
  2828			    cgroup_subsys_on_dfl(io_cgrp_subsys)) {
> 2829				blkcg_css = cgroup_e_css(memcg_css->cgroup, &io_cgrp_subsys);
  2830				bio_associate_blkg_from_css(bio, blkcg_css);
  2831			}
  2832		}
  2833	
  2834		submit_bio(bio);
  2835	}
  2836	

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