Add a module option 'rd_blksize' to allow the user to change
the sector size of the RAM disks.
Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
---
drivers/block/brd.c | 50 +++++++++++++++++++++++++++++++--------------
1 file changed, 35 insertions(+), 15 deletions(-)
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 90e1b6c4fbc8..0c5f3dbbb77c 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -30,7 +30,7 @@
/*
* Each block ramdisk device has a xarray of folios that stores the folios
* containing the block device's contents. A brd folio's ->index is its offset
- * in PAGE_SIZE units. This is similar to, but in no way connected with,
+ * in brd_sector_size units. This is similar to, but in no way connected with,
* the kernel's pagecache or buffer cache (which sit above our block device).
*/
struct brd_device {
@@ -43,9 +43,11 @@ struct brd_device {
*/
struct xarray brd_folios;
u64 brd_nr_folios;
+ unsigned int brd_sector_shift;
+ unsigned int brd_sector_size;
};
-#define BRD_SECTOR_SHIFT(b) (PAGE_SHIFT - SECTOR_SHIFT)
+#define BRD_SECTOR_SHIFT(b) ((b)->brd_sector_shift - SECTOR_SHIFT)
static pgoff_t brd_sector_index(struct brd_device *brd, sector_t sector)
{
@@ -85,7 +87,7 @@ static int brd_insert_folio(struct brd_device *brd, sector_t sector, gfp_t gfp)
{
pgoff_t idx;
struct folio *folio, *cur;
- unsigned int rd_sector_order = get_order(PAGE_SIZE);
+ unsigned int rd_sector_order = get_order(brd->brd_sector_size);
int ret = 0;
folio = brd_lookup_folio(brd, sector);
@@ -140,7 +142,7 @@ static void brd_free_folios(struct brd_device *brd)
static int copy_to_brd_setup(struct brd_device *brd, sector_t sector, size_t n,
gfp_t gfp)
{
- unsigned int rd_sector_size = PAGE_SIZE;
+ unsigned int rd_sector_size = brd->brd_sector_size;
unsigned int offset = brd_sector_offset(brd, sector);
size_t copy;
int ret;
@@ -163,7 +165,7 @@ static void copy_to_brd(struct brd_device *brd, const void *src,
sector_t sector, size_t n)
{
struct folio *folio;
- unsigned int rd_sector_size = PAGE_SIZE;
+ unsigned int rd_sector_size = brd->brd_sector_size;
unsigned int offset = brd_sector_offset(brd, sector);
size_t copy;
@@ -181,7 +183,7 @@ static void copy_from_brd(void *dst, struct brd_device *brd,
sector_t sector, size_t n)
{
struct folio *folio;
- unsigned int rd_sector_size = PAGE_SIZE;
+ unsigned int rd_sector_size = brd->brd_sector_size;
unsigned int offset = brd_sector_offset(brd, sector);
size_t copy;
@@ -279,6 +281,10 @@ static int max_part = 1;
module_param(max_part, int, 0444);
MODULE_PARM_DESC(max_part, "Num Minors to reserve between devices");
+static unsigned int rd_blksize = PAGE_SIZE;
+module_param(rd_blksize, uint, 0444);
+MODULE_PARM_DESC(rd_blksize, "Blocksize of each RAM disk in bytes.");
+
MODULE_LICENSE("GPL");
MODULE_ALIAS_BLOCKDEV_MAJOR(RAMDISK_MAJOR);
MODULE_ALIAS("rd");
@@ -305,6 +311,7 @@ static int brd_alloc(int i)
struct brd_device *brd;
struct gendisk *disk;
char buf[DISK_NAME_LEN];
+ unsigned int rd_max_sectors;
int err = -ENOMEM;
list_for_each_entry(brd, &brd_devices, brd_list)
@@ -315,6 +322,25 @@ static int brd_alloc(int i)
return -ENOMEM;
brd->brd_number = i;
list_add_tail(&brd->brd_list, &brd_devices);
+ if (!is_power_of_2(rd_blksize)) {
+ pr_err("rd_blksize %d is not supported\n", rd_blksize);
+ err = -EINVAL;
+ goto out_free_dev;
+ }
+ if (rd_blksize < SECTOR_SIZE) {
+ pr_err("rd_blksize must be at least 512 bytes\n");
+ err = -EINVAL;
+ goto out_free_dev;
+ }
+ /* We can't allocate more than MAX_ORDER pages */
+ rd_max_sectors = (1ULL << MAX_ORDER) << PAGE_SECTORS_SHIFT;
+ if ((rd_blksize >> SECTOR_SHIFT) > rd_max_sectors) {
+ pr_err("rd_blocksize too large\n");
+ err = -EINVAL;
+ goto out_free_dev;
+ }
+ brd->brd_sector_shift = ilog2(rd_blksize);
+ brd->brd_sector_size = rd_blksize;
xa_init(&brd->brd_folios);
@@ -334,15 +360,9 @@ static int brd_alloc(int i)
disk->private_data = brd;
strscpy(disk->disk_name, buf, DISK_NAME_LEN);
set_capacity(disk, rd_size * 2);
-
- /*
- * This is so fdisk will align partitions on 4k, because of
- * direct_access API needing 4k alignment, returning a PFN
- * (This is only a problem on very small devices <= 4M,
- * otherwise fdisk will align on 1M. Regardless this call
- * is harmless)
- */
- blk_queue_physical_block_size(disk->queue, PAGE_SIZE);
+
+ blk_queue_physical_block_size(disk->queue, rd_blksize);
+ blk_queue_max_hw_sectors(disk->queue, rd_max_sectors);
/* Tell the block layer that this is not a rotational device */
blk_queue_flag_set(QUEUE_FLAG_NONROT, disk->queue);
--
2.35.3
