Re: [PATCH] btrfs: use kmalloc for lzo de/compress buffer

[David Sterba]

On Fri, Feb 15, 2013 at 10:08:21PM +0900, Kyungsik Lee wrote:
> The size of de/compress buffer and LZO1X_MEM_COMPRESS is small enough.

Unfortunatelly it is not.

include/linux/lzo.h:

#define LZO1X_MEM_COMPRESS      (16384 * sizeof(unsigned char *))

128k with 8 byte pointers

> @@ -54,9 +53,10 @@ static struct list_head *lzo_alloc_workspace(void)
>  	if (!workspace)
>  		return ERR_PTR(-ENOMEM);
>  
> -	workspace->mem = vmalloc(LZO1X_MEM_COMPRESS);

vmalloc needed

> -	workspace->buf = vmalloc(PAGE_CACHE_SIZE);

kmalloc is ok here

> -	workspace->cbuf = vmalloc(lzo1x_worst_compress(PAGE_CACHE_SIZE));

#define lzo1x_worst_compress(x) ((x) + ((x) / 16) + 64 + 3)

4096+4096/16+64+3 = 4419

vmalloc needed as well

david
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