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-rw-r--r--Documentation/device-mapper/cache.txt3
-rw-r--r--drivers/md/dm-cache-target.c17
2 files changed, 12 insertions, 8 deletions
diff --git a/Documentation/device-mapper/cache.txt b/Documentation/device-mapper/cache.txt
index af99c458c841..33d45ee0b737 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 0df3ec085ebb..31985ea81408 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;
}
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