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Date:   Mon, 24 Aug 2020 15:15:30 +0300
From:   Dan Carpenter <>
To:     Ritesh Harjani <>,
Cc:,,,, Dan Williams <>,
        Anju T Sudhakar <>,,,
        Ritesh Harjani <>
Subject: Re: [PATCHv2 1/3] ext4: Refactor ext4_overwrite_io() to take
 ext4_map_blocks as argument

Hi Ritesh,

I love your patch! Perhaps something to improve:

[auto build test WARNING on v5.9-rc1]
[cannot apply to ext4/dev next-20200821]
[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]

base:    9123e3a74ec7b934a4a099e98af6a61c2f80bbf5
config: i386-randconfig-m021-20200822 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <>
Reported-by: Dan Carpenter <>

New smatch warnings:
fs/ext4/file.c:194 ext4_overwrite_io() warn: should '(map->m_lblk + map->m_len) << blkbits' be a 64 bit type?

Old smatch warnings:
include/linux/fs.h:867 i_size_write() warn: statement has no effect 31
fs/ext4/file.c:585 ext4_dio_write_iter() warn: inconsistent returns 'inode->i_rwsem'.

git remote add linux-review
git fetch --no-tags linux-review Ritesh-Harjani/Optimize-ext4-DAX-overwrites/20200822-193615
git checkout 5d171d1d87ee0aca0a992b6843d154b41466e5e5
vim +194 fs/ext4/file.c

e9e3bcecf44c04 Eric Sandeen   2011-02-12  189  
213bcd9ccbf04b Jan Kara       2016-11-20  190  /* Is IO overwriting allocated and initialized blocks? */
5d171d1d87ee0a Ritesh Harjani 2020-08-22  191  static bool ext4_overwrite_io(struct inode *inode, struct ext4_map_blocks *map)
213bcd9ccbf04b Jan Kara       2016-11-20  192  {
213bcd9ccbf04b Jan Kara       2016-11-20  193  	unsigned int blkbits = inode->i_blkbits;
5d171d1d87ee0a Ritesh Harjani 2020-08-22 @194  	loff_t end = (map->m_lblk + map->m_len) << blkbits;
potential shift wrap?

5d171d1d87ee0a Ritesh Harjani 2020-08-22  195  	int err, blklen = map->m_len;
213bcd9ccbf04b Jan Kara       2016-11-20  196  
5d171d1d87ee0a Ritesh Harjani 2020-08-22  197  	if (end > i_size_read(inode))
213bcd9ccbf04b Jan Kara       2016-11-20  198  		return false;
213bcd9ccbf04b Jan Kara       2016-11-20  199  
5d171d1d87ee0a Ritesh Harjani 2020-08-22  200  	err = ext4_map_blocks(NULL, inode, map, 0);
213bcd9ccbf04b Jan Kara       2016-11-20  201  	/*
213bcd9ccbf04b Jan Kara       2016-11-20  202  	 * 'err==len' means that all of the blocks have been preallocated,
213bcd9ccbf04b Jan Kara       2016-11-20  203  	 * regardless of whether they have been initialized or not. To exclude
213bcd9ccbf04b Jan Kara       2016-11-20  204  	 * unwritten extents, we need to check m_flags.
213bcd9ccbf04b Jan Kara       2016-11-20  205  	 */
5d171d1d87ee0a Ritesh Harjani 2020-08-22  206  	return err == blklen && (map->m_flags & EXT4_MAP_MAPPED);
213bcd9ccbf04b Jan Kara       2016-11-20  207  }
213bcd9ccbf04b Jan Kara       2016-11-20  208  

0-DAY CI Kernel Test Service, Intel Corporation

Download attachment ".config.gz" of type "application/gzip" (35937 bytes)

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