Re: [PATCH 1/7] fs: Introduce buffered_write_operations

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

Hi Matthew,

kernel test robot noticed the following build warnings:

[auto build test WARNING on linus/master]
[also build test WARNING on v6.10-rc1 next-20240528]
[cannot apply to tytso-ext4/dev jack-fs/for_next]
[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/Matthew-Wilcox-Oracle/fs-Introduce-buffered_write_operations/20240529-005213
base:   linus/master
patch link:    https://lore.kernel.org/r/20240528164829.2105447-2-willy%40infradead.org
patch subject: [PATCH 1/7] fs: Introduce buffered_write_operations
config: arm64-allnoconfig (https://download.01.org/0day-ci/archive/20240529/202405290745.X6owMB05-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240529/202405290745.X6owMB05-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/202405290745.X6owMB05-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> mm/filemap.c:4097: warning: Function parameter or struct member 'fsdata' not described in '__filemap_write_iter'
   mm/filemap.c:4146: warning: Function parameter or struct member 'ops' not described in 'filemap_write_iter'
>> mm/filemap.c:4146: warning: Function parameter or struct member 'fsdata' not described in 'filemap_write_iter'


vim +4097 mm/filemap.c

^1da177e4c3f41 Linus Torvalds          2005-04-16  4072  
e4dd9de3c66bc7 Jan Kara                2009-08-17  4073  /**
1e90da36c016f4 Matthew Wilcox (Oracle  2024-05-28  4074)  * __filemap_write_iter - write data to a file
e4dd9de3c66bc7 Jan Kara                2009-08-17  4075   * @iocb: IO state structure (file, offset, etc.)
8174202b34c30e Al Viro                 2014-04-03  4076   * @from: iov_iter with data to write
1e90da36c016f4 Matthew Wilcox (Oracle  2024-05-28  4077)  * @ops: How to inform the filesystem that a write is starting/finishing.
e4dd9de3c66bc7 Jan Kara                2009-08-17  4078   *
e4dd9de3c66bc7 Jan Kara                2009-08-17  4079   * This function does all the work needed for actually writing data to a
e4dd9de3c66bc7 Jan Kara                2009-08-17  4080   * file. It does all basic checks, removes SUID from the file, updates
e4dd9de3c66bc7 Jan Kara                2009-08-17  4081   * modification times and calls proper subroutines depending on whether we
e4dd9de3c66bc7 Jan Kara                2009-08-17  4082   * do direct IO or a standard buffered write.
e4dd9de3c66bc7 Jan Kara                2009-08-17  4083   *
9608703e488cf7 Jan Kara                2021-04-12  4084   * It expects i_rwsem to be grabbed unless we work on a block device or similar
e4dd9de3c66bc7 Jan Kara                2009-08-17  4085   * object which does not need locking at all.
e4dd9de3c66bc7 Jan Kara                2009-08-17  4086   *
e4dd9de3c66bc7 Jan Kara                2009-08-17  4087   * This function does *not* take care of syncing data in case of O_SYNC write.
e4dd9de3c66bc7 Jan Kara                2009-08-17  4088   * A caller has to handle it. This is mainly due to the fact that we want to
9608703e488cf7 Jan Kara                2021-04-12  4089   * avoid syncing under i_rwsem.
a862f68a8b3600 Mike Rapoport           2019-03-05  4090   *
a862f68a8b3600 Mike Rapoport           2019-03-05  4091   * Return:
a862f68a8b3600 Mike Rapoport           2019-03-05  4092   * * number of bytes written, even for truncated writes
a862f68a8b3600 Mike Rapoport           2019-03-05  4093   * * negative error code if no data has been written at all
e4dd9de3c66bc7 Jan Kara                2009-08-17  4094   */
1e90da36c016f4 Matthew Wilcox (Oracle  2024-05-28  4095) ssize_t __filemap_write_iter(struct kiocb *iocb, struct iov_iter *from,
1e90da36c016f4 Matthew Wilcox (Oracle  2024-05-28  4096) 		const struct buffered_write_operations *ops, void *fsdata)
^1da177e4c3f41 Linus Torvalds          2005-04-16 @4097  {
^1da177e4c3f41 Linus Torvalds          2005-04-16  4098  	struct file *file = iocb->ki_filp;
fb5527e68d4956 Jeff Moyer              2006-10-19  4099  	struct address_space *mapping = file->f_mapping;
^1da177e4c3f41 Linus Torvalds          2005-04-16  4100  	struct inode *inode = mapping->host;
44fff0fa08ec5a Christoph Hellwig       2023-06-01  4101  	ssize_t ret;
^1da177e4c3f41 Linus Torvalds          2005-04-16  4102  
44fff0fa08ec5a Christoph Hellwig       2023-06-01  4103  	ret = file_remove_privs(file);
44fff0fa08ec5a Christoph Hellwig       2023-06-01  4104  	if (ret)
44fff0fa08ec5a Christoph Hellwig       2023-06-01  4105  		return ret;
^1da177e4c3f41 Linus Torvalds          2005-04-16  4106  
44fff0fa08ec5a Christoph Hellwig       2023-06-01  4107  	ret = file_update_time(file);
44fff0fa08ec5a Christoph Hellwig       2023-06-01  4108  	if (ret)
44fff0fa08ec5a Christoph Hellwig       2023-06-01  4109  		return ret;
^1da177e4c3f41 Linus Torvalds          2005-04-16  4110  
2ba48ce513c4e5 Al Viro                 2015-04-09  4111  	if (iocb->ki_flags & IOCB_DIRECT) {
44fff0fa08ec5a Christoph Hellwig       2023-06-01  4112  		ret = generic_file_direct_write(iocb, from);
^1da177e4c3f41 Linus Torvalds          2005-04-16  4113  		/*
fbbbad4bc2101e Matthew Wilcox          2015-02-16  4114  		 * If the write stopped short of completing, fall back to
fbbbad4bc2101e Matthew Wilcox          2015-02-16  4115  		 * buffered writes.  Some filesystems do this for writes to
fbbbad4bc2101e Matthew Wilcox          2015-02-16  4116  		 * holes, for example.  For DAX files, a buffered write will
fbbbad4bc2101e Matthew Wilcox          2015-02-16  4117  		 * not succeed (even if it did, DAX does not handle dirty
fbbbad4bc2101e Matthew Wilcox          2015-02-16  4118  		 * page-cache pages correctly).
^1da177e4c3f41 Linus Torvalds          2005-04-16  4119  		 */
44fff0fa08ec5a Christoph Hellwig       2023-06-01  4120  		if (ret < 0 || !iov_iter_count(from) || IS_DAX(inode))
44fff0fa08ec5a Christoph Hellwig       2023-06-01  4121  			return ret;
44fff0fa08ec5a Christoph Hellwig       2023-06-01  4122  		return direct_write_fallback(iocb, from, ret,
1e90da36c016f4 Matthew Wilcox (Oracle  2024-05-28  4123) 				filemap_perform_write(iocb, from, ops, fsdata));
fb5527e68d4956 Jeff Moyer              2006-10-19  4124  	}
44fff0fa08ec5a Christoph Hellwig       2023-06-01  4125  
1e90da36c016f4 Matthew Wilcox (Oracle  2024-05-28  4126) 	return filemap_perform_write(iocb, from, ops, fsdata);
^1da177e4c3f41 Linus Torvalds          2005-04-16  4127  }
1e90da36c016f4 Matthew Wilcox (Oracle  2024-05-28  4128) EXPORT_SYMBOL(__filemap_write_iter);
^1da177e4c3f41 Linus Torvalds          2005-04-16  4129  
e4dd9de3c66bc7 Jan Kara                2009-08-17  4130  /**
1e90da36c016f4 Matthew Wilcox (Oracle  2024-05-28  4131)  * filemap_write_iter - write data to a file
e4dd9de3c66bc7 Jan Kara                2009-08-17  4132   * @iocb:	IO state structure
8174202b34c30e Al Viro                 2014-04-03  4133   * @from:	iov_iter with data to write
e4dd9de3c66bc7 Jan Kara                2009-08-17  4134   *
1e90da36c016f4 Matthew Wilcox (Oracle  2024-05-28  4135)  * This is a wrapper around __filemap_write_iter() to be used by most
e4dd9de3c66bc7 Jan Kara                2009-08-17  4136   * filesystems. It takes care of syncing the file in case of O_SYNC file
9608703e488cf7 Jan Kara                2021-04-12  4137   * and acquires i_rwsem as needed.
1e90da36c016f4 Matthew Wilcox (Oracle  2024-05-28  4138)  *
a862f68a8b3600 Mike Rapoport           2019-03-05  4139   * Return:
1e90da36c016f4 Matthew Wilcox (Oracle  2024-05-28  4140)  * * negative error code if no data has been written at all or if
a862f68a8b3600 Mike Rapoport           2019-03-05  4141   *   vfs_fsync_range() failed for a synchronous write
a862f68a8b3600 Mike Rapoport           2019-03-05  4142   * * number of bytes written, even for truncated writes
e4dd9de3c66bc7 Jan Kara                2009-08-17  4143   */
1e90da36c016f4 Matthew Wilcox (Oracle  2024-05-28  4144) ssize_t filemap_write_iter(struct kiocb *iocb, struct iov_iter *from,
1e90da36c016f4 Matthew Wilcox (Oracle  2024-05-28  4145) 		const struct buffered_write_operations *ops, void *fsdata)
^1da177e4c3f41 Linus Torvalds          2005-04-16 @4146  {
^1da177e4c3f41 Linus Torvalds          2005-04-16  4147  	struct file *file = iocb->ki_filp;
148f948ba877f4 Jan Kara                2009-08-17  4148  	struct inode *inode = file->f_mapping->host;
^1da177e4c3f41 Linus Torvalds          2005-04-16  4149  	ssize_t ret;
^1da177e4c3f41 Linus Torvalds          2005-04-16  4150  
5955102c9984fa Al Viro                 2016-01-22  4151  	inode_lock(inode);
3309dd04cbcd2c Al Viro                 2015-04-09  4152  	ret = generic_write_checks(iocb, from);
3309dd04cbcd2c Al Viro                 2015-04-09  4153  	if (ret > 0)
1e90da36c016f4 Matthew Wilcox (Oracle  2024-05-28  4154) 		ret = __filemap_write_iter(iocb, from, ops, fsdata);
5955102c9984fa Al Viro                 2016-01-22  4155  	inode_unlock(inode);
^1da177e4c3f41 Linus Torvalds          2005-04-16  4156  
e259221763a404 Christoph Hellwig       2016-04-07  4157  	if (ret > 0)
e259221763a404 Christoph Hellwig       2016-04-07  4158  		ret = generic_write_sync(iocb, ret);
^1da177e4c3f41 Linus Torvalds          2005-04-16  4159  	return ret;
^1da177e4c3f41 Linus Torvalds          2005-04-16  4160  }
1e90da36c016f4 Matthew Wilcox (Oracle  2024-05-28  4161) 

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