Re: [RFC/PATCH 2/4] fs/mm: execute in place (3rd version)

[Suparna Bhattacharya <suparna@in.ibm.com>]

On Wed, May 25, 2005 at 10:51:17AM -0700, Badari Pulavarty wrote:
> On Tue, 2005-05-24 at 07:34, Carsten Otte wrote:
> 
> > Maintenance effort is a good point. Changes would need to be applied
> > to both versions, which don't differ too much today.
> > Embedded folks will likely figure they also need the reverse path to
> > return references (like put_xip_page()), and indication of required access
> > (read/write) to make this work with flash chips.
> > Therefore I guess those two versions to differ more in the future,
> > making it hard to think about a soloution unifying the code paths
> > in a sane way so that it will work out for flash in the end.
> > As for me, I did not find a better one than in version one/two. If you
> > figure a good one, I will be happy to work on its implementation.
> > 
> 
> Hi,
> 
> This is my crude version of the cleanup patch to reduce the 
> duplication of code.
> 
> Basically, I added __generic_file_aio_read_internal() and 
> __generic_file_aio_write_nolock_internal() to take a read/write
> handlers instead of defaulting to do_generic_file_read() or
> generic_file_buffered_write().
> 
> This way I was able to reduce 129 lines of your code. 
> This patch is on top of your current set and I haven't even
> tried compiling it. Needs cleanup.
> 
> BTW, function & variable names are too long and/or ugly & doesn't 
> make sense - need fixing.
> 
> Christoph/Suparna/Andrew, Comments ?

To get a complete picture, how did you want to handle direct io ?

Regards
Suparna

> 
> Thanks,
> Badari
> 
> 
> 
> 
> 
> 
> 

> # diffstat /tmp/xip-filemap.patch
>  filemap.c     |   27 +++++++++---
>  filemap.h     |    6 ++
>  filemap_xip.c |  129 +++-------------------------------------------------------
>  3 files changed, 35 insertions(+), 127 deletions(-)
> 
> Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
> diff -X dontdiff -Narup linux-2.6.12-rc4/mm/filemap.c linux-2.6.12-rc4.xip/mm/filemap.c
> --- linux-2.6.12-rc4/mm/filemap.c	2005-05-25 03:05:55.367260168 -0700
> +++ linux-2.6.12-rc4.xip/mm/filemap.c	2005-05-25 03:07:15.805031768 -0700
> @@ -988,8 +988,8 @@ success:
>   * that can use the page cache directly.
>   */
>  ssize_t
> -__generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
> -		unsigned long nr_segs, loff_t *ppos)
> +__generic_file_aio_read_internal(struct kiocb *iocb, const struct iovec *iov,
> +		unsigned long nr_segs, loff_t *ppos, file_read_t file_read)
>  {
>  	struct file *filp = iocb->ki_filp;
>  	ssize_t retval;
> @@ -1051,7 +1051,7 @@ __generic_file_aio_read(struct kiocb *io
>  			if (desc.count == 0)
>  				continue;
>  			desc.error = 0;
> -			do_generic_file_read(filp,ppos,&desc,file_read_actor);
> +			file_read(filp,ppos,&desc,file_read_actor);
>  			retval += desc.written;
>  			if (!retval) {
>  				retval = desc.error;
> @@ -1063,6 +1063,13 @@ out:
>  	return retval;
>  }
>  
> +ssize_t
> +__generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
> +		unsigned long nr_segs, loff_t *ppos)
> +{
> +	return __generic_file_aio_read_internal(iocb, iov, nr_segs, 
> +				ppos, do_generic_file_read);
> +}
>  EXPORT_SYMBOL(__generic_file_aio_read);
>  
>  ssize_t
> @@ -2024,8 +2031,9 @@ generic_file_buffered_write(struct kiocb
>  EXPORT_SYMBOL(generic_file_buffered_write);
>  
>  ssize_t
> -__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
> -				unsigned long nr_segs, loff_t *ppos)
> +__generic_file_aio_write_nolock_internal(struct kiocb *iocb, 
> +	const struct iovec *iov, unsigned long nr_segs, loff_t *ppos,
> +	file_write_t file_write)
>  {
>  	struct file *file = iocb->ki_filp;
>  	struct address_space * mapping = file->f_mapping;
> @@ -2093,12 +2101,19 @@ __generic_file_aio_write_nolock(struct k
>  		count -= written;
>  	}
>  
> -	written = generic_file_buffered_write(iocb, iov, nr_segs,
> +	written = file_write(iocb, iov, nr_segs,
>  			pos, ppos, count, written);
>  out:
>  	current->backing_dev_info = NULL;
>  	return written ? written : err;
>  }
> +ssize_t
> +__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
> +				unsigned long nr_segs, loff_t *ppos)
> +{
> +	return __generic_file_aio_write_nolock_internal(iocb, *iov,
> +			nr_segs, *ppos, generic_file_buffered_write);
> +}
>  EXPORT_SYMBOL(generic_file_aio_write_nolock);
>  
>  ssize_t
> diff -X dontdiff -Narup linux-2.6.12-rc4/mm/filemap.h linux-2.6.12-rc4.xip/mm/filemap.h
> --- linux-2.6.12-rc4/mm/filemap.h	2005-05-25 03:06:03.857969384 -0700
> +++ linux-2.6.12-rc4.xip/mm/filemap.h	2005-05-25 03:08:09.388885784 -0700
> @@ -15,6 +15,12 @@
>  #include <linux/config.h>
>  #include <asm/uaccess.h>
>  
> +typedef int (file_read_t)(struct file * filp, loff_t *ppos,
> +		read_descriptor_t * desc, read_actor_t actor):
> +typedef int (file_write_t)(struct kiocb *iocb, const struct iovec *iov,
> +		unsigned long nr_segs, loff_t pos, loff_t *ppos,
> +		size_t count, ssize_t written);
> +
>  extern size_t
>  __filemap_copy_from_user_iovec(char *vaddr, 
>  			       const struct iovec *iov,
> diff -X dontdiff -Narup linux-2.6.12-rc4/mm/filemap_xip.c linux-2.6.12-rc4.xip/mm/filemap_xip.c
> --- linux-2.6.12-rc4/mm/filemap_xip.c	2005-05-25 03:05:55.369259864 -0700
> +++ linux-2.6.12-rc4.xip/mm/filemap_xip.c	2005-05-25 02:58:27.200391888 -0700
> @@ -114,62 +114,6 @@ out:
>  		file_accessed(filp);
>  }
>  
> -/*
> - * This is the "read()" routine for all filesystems
> - * that uses the get_xip_page address space operation.
> - */
> -static ssize_t
> -__xip_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
> -		unsigned long nr_segs, loff_t *ppos)
> -{
> -	struct file *filp = iocb->ki_filp;
> -	ssize_t retval;
> -	unsigned long seg;
> -	size_t count;
> -
> -	count = 0;
> -	for (seg = 0; seg < nr_segs; seg++) {
> -		const struct iovec *iv = &iov[seg];
> -
> -		/*
> -		 * If any segment has a negative length, or the cumulative
> -		 * length ever wraps negative then return -EINVAL.
> -		 */
> -		count += iv->iov_len;
> -		if (unlikely((ssize_t)(count|iv->iov_len) < 0))
> -			return -EINVAL;
> -		if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
> -			continue;
> -		if (seg == 0)
> -			return -EFAULT;
> -		nr_segs = seg;
> -		count -= iv->iov_len;	/* This segment is no good */
> -		break;
> -	}
> -
> -	retval = 0;
> -	if (count) {
> -		for (seg = 0; seg < nr_segs; seg++) {
> -			read_descriptor_t desc;
> -
> -			desc.written = 0;
> -			desc.arg.buf = iov[seg].iov_base;
> -			desc.count = iov[seg].iov_len;
> -			if (desc.count == 0)
> -				continue;
> -			desc.error = 0;
> -			do_xip_mapping_read(filp->f_mapping, &filp->f_ra, filp,
> -					    ppos, &desc, file_read_actor);
> -			retval += desc.written;
> -			if (!retval) {
> -				retval = desc.error;
> -				break;
> -			}
> -		}
> -	}
> -	return retval;
> -}
> -
>  ssize_t
>  xip_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count,
>  		  loff_t pos)
> @@ -177,7 +121,8 @@ xip_file_aio_read(struct kiocb *iocb, ch
>  	struct iovec local_iov = { .iov_base = buf, .iov_len = count };
>  
>  	BUG_ON(iocb->ki_pos != pos);
> -	return __xip_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos);
> +	return __generic_file_aio_read_internal(iocb, &local_iov, 1, 
> +			&iocb->ki_pos, do_xip_mapping_read);
>  }
>  EXPORT_SYMBOL_GPL(xip_file_aio_read);
>  
> @@ -188,7 +133,8 @@ xip_file_readv(struct file *filp, const 
>  	struct kiocb kiocb;
>  
>  	init_sync_kiocb(&kiocb, filp);
> -	return __xip_file_aio_read(&kiocb, iov, nr_segs, ppos);
> +	return __generic_file_aio_read_internal(&kiocb, iov, nr_segs, 
> +			ppos, do_xip_mapping_read);
>  }
>  EXPORT_SYMBOL_GPL(xip_file_readv);
>  
> @@ -423,74 +369,14 @@ do_xip_file_write(struct kiocb *iocb, co
>  }
>  
>  static ssize_t
> -xip_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
> -				unsigned long nr_segs, loff_t *ppos)
> -{
> -	struct file *file = iocb->ki_filp;
> -	struct address_space * mapping = file->f_mapping;
> -	size_t ocount;		/* original count */
> -	size_t count;		/* after file limit checks */
> -	struct inode 	*inode = mapping->host;
> -	unsigned long	seg;
> -	loff_t		pos;
> -	ssize_t		written;
> -	ssize_t		err;
> -
> -	ocount = 0;
> -	for (seg = 0; seg < nr_segs; seg++) {
> -		const struct iovec *iv = &iov[seg];
> -
> -		/*
> -		 * If any segment has a negative length, or the cumulative
> -		 * length ever wraps negative then return -EINVAL.
> -		 */
> -		ocount += iv->iov_len;
> -		if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
> -			return -EINVAL;
> -		if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
> -			continue;
> -		if (seg == 0)
> -			return -EFAULT;
> -		nr_segs = seg;
> -		ocount -= iv->iov_len;	/* This segment is no good */
> -		break;
> -	}
> -
> -	count = ocount;
> -	pos = *ppos;
> -
> -	vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
> -
> -	written = 0;
> -
> -	err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
> -	if (err)
> -		goto out;
> -
> -	if (count == 0)
> -		goto out;
> -
> -	err = remove_suid(file->f_dentry);
> -	if (err)
> -		goto out;
> -
> -	inode_update_time(inode, 1);
> -
> -	/* use execute in place to copy directly to disk */
> -	written = do_xip_file_write (iocb, iov,
> -				  nr_segs, pos, ppos, count);
> - out:
> -	return written ? written : err;
> -}
> -
> -static ssize_t
>  __xip_file_write_nolock(struct file *file, const struct iovec *iov,
>  			unsigned long nr_segs, loff_t *ppos)
>  {
>  	struct kiocb kiocb;
>  
>  	init_sync_kiocb(&kiocb, file);
> -	return xip_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
> +	return __generic_file_aio_write_nolock_internal(&kiocb, iov, 
> +			nr_segs, ppos, do_xip_file_write);
>  }
>  
>  ssize_t
> @@ -507,7 +393,8 @@ xip_file_aio_write(struct kiocb *iocb, c
>  	BUG_ON(iocb->ki_pos != pos);
>  
>  	down(&inode->i_sem);
> -	ret = xip_file_aio_write_nolock(iocb, &local_iov, 1, &iocb->ki_pos);
> +	ret = __generic_file_aio_write_nolock_internal(iocb, &local_iov, 
> +			1, &iocb->ki_pos, do_xip_file_write);
>  	up(&inode->i_sem);
>  	return ret;
>  }


-- 
Suparna Bhattacharya (suparna@in.ibm.com)
Linux Technology Center
IBM Software Lab, India