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

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

[cgel.zte]

From: Changcheng Deng <deng.changcheng@zte.com.cn>

Use min() in order to make code cleaner.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Changcheng Deng <deng.changcheng@zte.com.cn>
---
 fs/ext4/super.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 5ec5a1c3b364..d0c50e0e787d 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -6922,8 +6922,7 @@ static ssize_t ext4_quota_read(struct super_block *sb, int type, char *data,
 		len = i_size-off;
 	toread = len;
 	while (toread > 0) {
-		tocopy = sb->s_blocksize - offset < toread ?
-				sb->s_blocksize - offset : toread;
+		tocopy = min(sb->s_blocksize - offset, toread);
 		bh = ext4_bread(NULL, inode, blk, 0);
 		if (IS_ERR(bh))
 			return PTR_ERR(bh);
-- 
2.25.1

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

[kernel test robot]

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	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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

[kernel test robot]

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-20211217]
[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: arc-randconfig-s032-20211218 (https://download.01.org/0day-ci/archive/20211219/202112190602.FX1i96n9-lkp@intel.com/config)
compiler: arc-elf-gcc (GCC) 11.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # apt-get install sparse
        # sparse version: v0.6.4-dirty
        # 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=gcc-11.2.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=arc SHELL=/bin/bash drivers/iio/accel/ fs/ext4/

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


sparse warnings: (new ones prefixed by >>)
>> fs/ext4/super.c:6926:26: sparse: sparse: incompatible types in comparison expression (different type sizes):
>> fs/ext4/super.c:6926:26: sparse:    unsigned long *
>> fs/ext4/super.c:6926:26: sparse:    unsigned int *
   fs/ext4/super.c:2643:46: sparse: sparse: incorrect type in argument 1 (different address spaces) @@     expected void const *objp @@     got char [noderef] __rcu * @@
   fs/ext4/super.c:2643:46: sparse:     expected void const *objp
   fs/ext4/super.c:2643:46: sparse:     got char [noderef] __rcu *
   fs/ext4/super.c:2698:51: sparse: sparse: incorrect type in argument 1 (different address spaces) @@     expected char const *cs @@     got char [noderef] __rcu * @@
   fs/ext4/super.c:2698:51: sparse:     expected char const *cs
   fs/ext4/super.c:2698:51: sparse:     got char [noderef] __rcu *
   fs/ext4/super.c:993:6: sparse: sparse: context imbalance in '__ext4_grp_locked_error' - different lock contexts for basic block
   fs/ext4/super.c:3321:9: sparse: sparse: context imbalance in 'ext4_check_descriptors' - different lock contexts for basic block

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	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org