From 054730446315d2a9a41f4232ebf1d5034244d054 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Fri, 16 Aug 2013 10:54:19 -0400 Subject: [PATCH] dm cache: add data block size limits to code and Documentation Place upper bound on the cache's data block size (1GB). Inform users that the data block size can't be any arbitrary number, i.e. its value must be between 32KB and 1GB. Also, it should be a multiple of 32KB. Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon Acked-by: Joe Thornber --- Documentation/device-mapper/cache.txt | 3 ++- drivers/md/dm-cache-target.c | 17 ++++++++++------- 2 files changed, 12 insertions(+), 8 deletions(-) diff --git a/Documentation/device-mapper/cache.txt b/Documentation/device-mapper/cache.txt index af99c45..33d45ee 100644 --- a/Documentation/device-mapper/cache.txt +++ b/Documentation/device-mapper/cache.txt @@ -58,7 +58,8 @@ Fixed block size The origin is divided up into blocks of a fixed size. This block size is configurable when you first create the cache. Typically we've been -using block sizes of 256k - 1024k. +using block sizes of 256KB - 1024KB. The block size must be between 64 +(32KB) and 2097152 (1GB) and a multiple of 64 (32KB). Having a fixed block size simplifies the target a lot. But it is something of a compromise. For instance, a small part of a block may be diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c index 0df3ec0..31985ea 100644 --- a/drivers/md/dm-cache-target.c +++ b/drivers/md/dm-cache-target.c @@ -67,9 +67,11 @@ static void free_bitset(unsigned long *bits) #define MIGRATION_COUNT_WINDOW 10 /* - * The block size of the device holding cache data must be >= 32KB + * The block size of the device holding cache data must be + * between 32KB and 1GB. */ #define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (32 * 1024 >> SECTOR_SHIFT) +#define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT) /* * FIXME: the cache is read/write for the time being. @@ -1687,24 +1689,25 @@ static int parse_origin_dev(struct cache_args *ca, struct dm_arg_set *as, static int parse_block_size(struct cache_args *ca, struct dm_arg_set *as, char **error) { - unsigned long tmp; + unsigned long block_size; if (!at_least_one_arg(as, error)) return -EINVAL; - if (kstrtoul(dm_shift_arg(as), 10, &tmp) || !tmp || - tmp < DATA_DEV_BLOCK_SIZE_MIN_SECTORS || - tmp & (DATA_DEV_BLOCK_SIZE_MIN_SECTORS - 1)) { + if (kstrtoul(dm_shift_arg(as), 10, &block_size) || !block_size || + block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS || + block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS || + block_size & (DATA_DEV_BLOCK_SIZE_MIN_SECTORS - 1)) { *error = "Invalid data block size"; return -EINVAL; } - if (tmp > ca->cache_sectors) { + if (block_size > ca->cache_sectors) { *error = "Data block size is larger than the cache device"; return -EINVAL; } - ca->block_size = tmp; + ca->block_size = block_size; return 0; } -- 2.7.4