Re: [PATCH] ext4: use min() to make code cleaner

kernel test robot
2021-12-17T02:11:37Z

Hi,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on tytso-ext4/dev]
[also build test WARNING on v5.16-rc5 next-20211215]
[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/cgel-zte-gmail-com/ext4-use-min-to-make-code-cleaner/20211216-171213
base: https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git dev
config: hexagon-randconfig-r026-20211216 (https://download.01.org/0day-ci/archive/20211217/202112171003.SXtQAHHE-lkp@intel.com/config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project dd245bab9fbb364faa1581e4f92ba3119a872fba)
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
# https://github.com/0day-ci/linux/commit/ff519f2d7d41c154cb0d31a9aebe16ce1f6af7ed
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review cgel-zte-gmail-com/ext4-use-min-to-make-code-cleaner/20211216-171213
git checkout ff519f2d7d41c154cb0d31a9aebe16ce1f6af7ed
# save the config file to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash fs/ext4/

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

All warnings (new ones prefixed by >>):

>> fs/ext4/super.c:6926:12: warning: comparison of distinct pointer types ('typeof (sb->s_blocksize - offset) *' (aka 'unsigned long *') and 'typeof (toread) *' (aka 'unsigned int *')) [-Wcompare-distinct-pointer-types]
tocopy = min(sb->s_blocksize - offset, toread);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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)))
~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~
fs/ext4/super.c:2173:1: warning: unused function 'ctx_test_flags' [-Wunused-function]
EXT4_SET_CTX(flags);
^
fs/ext4/super.c:2168:20: note: expanded from macro 'EXT4_SET_CTX'
static inline bool ctx_test_##name(struct ext4_fs_context *ctx, int flag)\
^
<scratch space>:148:1: note: expanded from here
ctx_test_flags
^
fs/ext4/super.c:2176:1: warning: unused function 'ctx_clear_mount_flags' [-Wunused-function]
EXT4_SET_CTX(mount_flags);
^
fs/ext4/super.c:2163:20: note: expanded from macro 'EXT4_SET_CTX'
static inline void ctx_clear_##name(struct ext4_fs_context *ctx, int flag)\
^
<scratch space>:169:1: note: expanded from here
ctx_clear_mount_flags
^
fs/ext4/super.c:2176:1: warning: unused function 'ctx_test_mount_flags' [-Wunused-function]
fs/ext4/super.c:2168:20: note: expanded from macro 'EXT4_SET_CTX'
static inline bool ctx_test_##name(struct ext4_fs_context *ctx, int flag)\
^
<scratch space>:172:1: note: expanded from here
ctx_test_mount_flags
^
4 warnings generated.

vim +6926 fs/ext4/super.c

6904
6905 /* Read data from quotafile - avoid pagecache and such because we cannot afford
6906 * acquiring the locks... As quota files are never truncated and quota code
6907 * itself serializes the operations (and no one else should touch the files)
6908 * we don't have to be afraid of races */
6909 static ssize_t ext4_quota_read(struct super_block *sb, int type, char *data,
6910 size_t len, loff_t off)
6911 {
6912 struct inode *inode = sb_dqopt(sb)->files[type];
6913 ext4_lblk_t blk = off >> EXT4_BLOCK_SIZE_BITS(sb);
6914 int offset = off & (sb->s_blocksize - 1);
6915 int tocopy;
6916 size_t toread;
6917 struct buffer_head *bh;
6918 loff_t i_size = i_size_read(inode);
6919
6920 if (off > i_size)
6921 return 0;
6922 if (off+len > i_size)
6923 len = i_size-off;
6924 toread = len;
6925 while (toread > 0) {
> 6926 tocopy = min(sb->s_blocksize - offset, toread);
6927 bh = ext4_bread(NULL, inode, blk, 0);
6928 if (IS_ERR(bh))
6929 return PTR_ERR(bh);
6930 if (!bh) /* A hole? */
6931 memset(data, 0, tocopy);
6932 else
6933 memcpy(data, bh->b_data+offset, tocopy);
6934 brelse(bh);
6935 offset = 0;
6936 toread -= tocopy;
6937 data += tocopy;
6938 blk++;
6939 }
6940 return len;
6941 }
6942

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0-DAY CI Kernel Test Service, Intel Corporation