[Cluster-devel] [PATCH v2] GFS2: directly write blocks past i_size

[Steven Whitehouse]

Hi,

That looks much better, thanks for fixing that. I've pushed it into the
-fixes tree,

Steve.

On Thu, 2011-03-17 at 21:54 -0500, Benjamin Marzinski wrote:
> GFS2 was relying on the writepage code to write out the zeroed data for
> fallocate.  However, with FALLOC_FL_KEEP_SIZE set, this may be past i_size.
> If it is, it will be ignored.  To work around this, gfs2 now calls
> write_dirty_buffer directly on the buffer_heads when FALLOC_FL_KEEP_SIZE
> is set, and it's writing past i_size.
> 
> This version is just a cleanup of my last version
> 
> Signed-off-by: Benjamin Marzinski <bmarzins at redhat.com>
> ---
>  fs/gfs2/file.c |   58 +++++++++++++++++++++++++++++++++++++++++++++++----------
>  1 file changed, 48 insertions(+), 10 deletions(-)
> 
> Index: gfs2-2.6-nmw/fs/gfs2/file.c
> ===================================================================
> --- gfs2-2.6-nmw.orig/fs/gfs2/file.c
> +++ gfs2-2.6-nmw/fs/gfs2/file.c
> @@ -617,18 +617,51 @@ static ssize_t gfs2_file_aio_write(struc
>  	return generic_file_aio_write(iocb, iov, nr_segs, pos);
>  }
>  
> -static void empty_write_end(struct page *page, unsigned from,
> -			   unsigned to)
> +static int empty_write_end(struct page *page, unsigned from,
> +			   unsigned to, int mode)
>  {
> -	struct gfs2_inode *ip = GFS2_I(page->mapping->host);
> +	struct inode *inode = page->mapping->host;
> +	struct gfs2_inode *ip = GFS2_I(inode);
> +	struct buffer_head *bh;
> +	unsigned offset, blksize = 1 << inode->i_blkbits;
> +	pgoff_t end_index = i_size_read(inode) >> PAGE_CACHE_SHIFT;
>  
>  	zero_user(page, from, to-from);
>  	mark_page_accessed(page);
>  
> -	if (!gfs2_is_writeback(ip))
> -		gfs2_page_add_databufs(ip, page, from, to);
> +	if (page->index < end_index || !(mode & FALLOC_FL_KEEP_SIZE)) {
> +		if (!gfs2_is_writeback(ip))
> +			gfs2_page_add_databufs(ip, page, from, to);
> +
> +		block_commit_write(page, from, to);
> +		return 0;
> +	}
> +
> +	offset = 0;
> +	bh = page_buffers(page);
> +	while (offset < to) {
> +		if (offset >= from) {
> +			set_buffer_uptodate(bh);
> +			mark_buffer_dirty(bh);
> +			clear_buffer_new(bh);
> +			write_dirty_buffer(bh, WRITE);
> +		}
> +		offset += blksize;
> +		bh = bh->b_this_page;
> +	}
>  
> -	block_commit_write(page, from, to);
> +	offset = 0;
> +	bh = page_buffers(page);
> +	while (offset < to) {
> +		if (offset >= from) {
> +			wait_on_buffer(bh);
> +			if (!buffer_uptodate(bh))
> +				return -EIO;
> +		}
> +		offset += blksize;
> +		bh = bh->b_this_page;
> +	}
> +	return 0;
>  }
>  
>  static int needs_empty_write(sector_t block, struct inode *inode)
> @@ -643,7 +676,8 @@ static int needs_empty_write(sector_t bl
>  	return !buffer_mapped(&bh_map);
>  }
>  
> -static int write_empty_blocks(struct page *page, unsigned from, unsigned to)
> +static int write_empty_blocks(struct page *page, unsigned from, unsigned to,
> +			      int mode)
>  {
>  	struct inode *inode = page->mapping->host;
>  	unsigned start, end, next, blksize;
> @@ -668,7 +702,9 @@ static int write_empty_blocks(struct pag
>  							  gfs2_block_map);
>  				if (unlikely(ret))
>  					return ret;
> -				empty_write_end(page, start, end);
> +				ret = empty_write_end(page, start, end, mode);
> +				if (unlikely(ret))
> +					return ret;
>  				end = 0;
>  			}
>  			start = next;
> @@ -682,7 +718,9 @@ static int write_empty_blocks(struct pag
>  		ret = __block_write_begin(page, start, end - start, gfs2_block_map);
>  		if (unlikely(ret))
>  			return ret;
> -		empty_write_end(page, start, end);
> +		ret = empty_write_end(page, start, end, mode);
> +		if (unlikely(ret))
> +			return ret;
>  	}
>  
>  	return 0;
> @@ -731,7 +769,7 @@ static int fallocate_chunk(struct inode 
>  
>  		if (curr == end)
>  			to = end_offset;
> -		error = write_empty_blocks(page, from, to);
> +		error = write_empty_blocks(page, from, to, mode);
>  		if (!error && offset + to > inode->i_size &&
>  		    !(mode & FALLOC_FL_KEEP_SIZE)) {
>  			i_size_write(inode, offset + to);
>