Re: [PATCH 2/3] quota: Support using the page cache for quota files

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

Hi "Matthew,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on tytso-ext4/dev]
[also build test WARNING on jack-fs/for_next linus/master v5.19-rc1 next-20220603]
[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/intel-lab-lkp/linux/commits/Matthew-Wilcox-Oracle/Cache-quota-files-in-the-page-cache/20220606-021629
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git dev
config: mips-mtx1_defconfig (https://download.01.org/0day-ci/archive/20220606/202206061045.oKwjpuXb-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project b92436efcb7813fc481b30f2593a4907568d917a)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install mips cross compiling tool for clang build
        # apt-get install binutils-mipsel-linux-gnu
        # https://github.com/intel-lab-lkp/linux/commit/a7ff347e002ef476c8c116f30858f83529638a9b
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Matthew-Wilcox-Oracle/Cache-quota-files-in-the-page-cache/20220606-021629
        git checkout a7ff347e002ef476c8c116f30858f83529638a9b
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=mips SHELL=/bin/bash fs/quota/

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

All warnings (new ones prefixed by >>):

>> fs/quota/dquot.c:2184:19: warning: comparison of distinct pointer types ('typeof (toread) *' (aka 'unsigned int *') and 'typeof (((1UL) << 12) - ((unsigned long)(pos) & ~(~((1 << 12) - 1)))) *' (aka 'unsigned long *')) [-Wcompare-distinct-pointer-types]
                   size_t tocopy = min(toread, PAGE_SIZE - offset_in_page(pos));
                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/minmax.h:45:19: note: expanded from macro 'min'
   #define min(x, y)       __careful_cmp(x, y, <)
                           ^~~~~~~~~~~~~~~~~~~~~~
   include/linux/minmax.h:36:24: note: expanded from macro '__careful_cmp'
           __builtin_choose_expr(__safe_cmp(x, y), \
                                 ^~~~~~~~~~~~~~~~
   include/linux/minmax.h:26:4: note: expanded from macro '__safe_cmp'
                   (__typecheck(x, y) && __no_side_effects(x, y))
                    ^~~~~~~~~~~~~~~~~
   include/linux/minmax.h:20:28: note: expanded from macro '__typecheck'
           (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
                      ~~~~~~~~~~~~~~ ^  ~~~~~~~~~~~~~~
   1 warning generated.


vim +2184 fs/quota/dquot.c

  2165	
  2166	ssize_t generic_quota_read(struct super_block *sb, int type, char *data,
  2167				      size_t len, loff_t pos)
  2168	{
  2169		struct inode *inode = sb_dqopt(sb)->files[type];
  2170		struct address_space *mapping = inode->i_mapping;
  2171		size_t toread;
  2172		pgoff_t index;
  2173		loff_t i_size = i_size_read(inode);
  2174	
  2175		if (pos > i_size)
  2176			return 0;
  2177		if (pos + len > i_size)
  2178			len = i_size - pos;
  2179		toread = len;
  2180		index = pos / PAGE_SIZE;
  2181	
  2182		while (toread > 0) {
  2183			struct folio *folio = read_mapping_folio(mapping, index, NULL);
> 2184			size_t tocopy = min(toread, PAGE_SIZE - offset_in_page(pos));
  2185			void *src;
  2186	
  2187			if (folio == ERR_PTR(-ENOMEM)) {
  2188				memalloc_retry_wait(GFP_NOFS);
  2189				continue;
  2190			} else if (IS_ERR(folio))
  2191				return PTR_ERR(folio);
  2192	
  2193			src = kmap_local_folio(folio, offset_in_folio(folio, pos));
  2194			memcpy(data, src, tocopy);
  2195			kunmap_local(src);
  2196			folio_put(folio);
  2197	
  2198			toread -= tocopy;
  2199			data += tocopy;
  2200			pos += tocopy;
  2201			index++;
  2202		}
  2203		return len;
  2204	}
  2205	EXPORT_SYMBOL(generic_quota_read);
  2206	

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