[Cluster-devel] [PATCH] GFS2: call gfs2_write_alloc_required for each chunk

[Steven Whitehouse <swhiteho@redhat.com>]

Hi,

Now in the -nmw tree. Thanks,

Steve.

On Thu, 2012-03-08 at 13:16 -0600, Benjamin Marzinski wrote:
> gfs2_fallocate was calling gfs2_write_alloc_required() once at the start of
> the function. This caused problems since gfs2_write_alloc_required used a
> long unsigned int for the len, but gfs2_fallocate could allocate a much
> larger amount.  This patch will move the call into the loop where the
> chunks are actually allocated and zeroed out. This will keep the allocation
> size under the limit, and also allow gfs2_fallocate to quickly skip over
> sections of the file that are already completely allocated.
> 
> fallcate_chunk was also not correctly setting the file size.  It was using the
> len veriable to find the last block written to, but by the time it was setting
> the size, the len variable had already been decremented to 0.
> 
> Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
> ---
>  fs/gfs2/file.c |   13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> Index: gfs2-3.0-nmw/fs/gfs2/file.c
> ===================================================================
> --- gfs2-3.0-nmw.orig/fs/gfs2/file.c
> +++ gfs2-3.0-nmw/fs/gfs2/file.c
> @@ -676,6 +676,7 @@ static int fallocate_chunk(struct inode 
>  	struct gfs2_inode *ip = GFS2_I(inode);
>  	struct buffer_head *dibh;
>  	int error;
> +	loff_t size = len;
>  	unsigned int nr_blks;
>  	sector_t lblock = offset >> inode->i_blkbits;
>  
> @@ -709,8 +710,8 @@ static int fallocate_chunk(struct inode 
>  			goto out;
>  		}
>  	}
> -	if (offset + len > inode->i_size && !(mode & FALLOC_FL_KEEP_SIZE))
> -		i_size_write(inode, offset + len);
> +	if (offset + size > inode->i_size && !(mode & FALLOC_FL_KEEP_SIZE))
> +		i_size_write(inode, offset + size);
>  
>  	mark_inode_dirty(inode);
>  
> @@ -779,12 +780,14 @@ static long gfs2_fallocate(struct file *
>  	if (unlikely(error))
>  		goto out_uninit;
>  
> -	if (!gfs2_write_alloc_required(ip, offset, len))
> -		goto out_unlock;
> -
>  	while (len > 0) {
>  		if (len < bytes)
>  			bytes = len;
> +		if (!gfs2_write_alloc_required(ip, offset, bytes)) {
> +			len -= bytes;
> +			offset += bytes;
> +			continue;
> +		}
>  		qa = gfs2_qadata_get(ip);
>  		if (!qa) {
>  			error = -ENOMEM;
>