rd: support XIP
Support direct_access XIP method with brd.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
index 8be67cd..b6d230b 100644
--- a/drivers/block/Kconfig
+++ b/drivers/block/Kconfig
@@ -357,6 +357,16 @@
The default value is 4096 kilobytes. Only change this if you know
what you are doing.
+config BLK_DEV_XIP
+ bool "Support XIP filesystems on RAM block device"
+ depends on BLK_DEV_RAM
+ default n
+ help
+ Support XIP filesystems (such as ext2 with XIP support on) on
+ top of block ram device. This will slightly enlarge the kernel, and
+ will prevent RAM block device backing store memory from being
+ allocated from highmem (only a problem for highmem systems).
+
config CDROM_PKTCDVD
tristate "Packet writing on CD/DVD media"
depends on !UML
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 50b659b..8536480 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -89,6 +89,7 @@
{
pgoff_t idx;
struct page *page;
+ gfp_t gfp_flags;
page = brd_lookup_page(brd, sector);
if (page)
@@ -97,7 +98,16 @@
/*
* Must use NOIO because we don't want to recurse back into the
* block or filesystem layers from page reclaim.
+ *
+ * Cannot support XIP and highmem, because our ->direct_access
+ * routine for XIP must return memory that is always addressable.
+ * If XIP was reworked to use pfns and kmap throughout, this
+ * restriction might be able to be lifted.
*/
+ gfp_flags = GFP_NOIO | __GFP_ZERO;
+#ifndef CONFIG_BLK_DEV_XIP
+ gfp_flags |= __GFP_HIGHMEM;
+#endif
page = alloc_page(GFP_NOIO | __GFP_HIGHMEM | __GFP_ZERO);
if (!page)
return NULL;
@@ -307,6 +317,28 @@
return 0;
}
+#ifdef CONFIG_BLK_DEV_XIP
+static int brd_direct_access (struct block_device *bdev, sector_t sector,
+ unsigned long *data)
+{
+ struct brd_device *brd = bdev->bd_disk->private_data;
+ struct page *page;
+
+ if (!brd)
+ return -ENODEV;
+ if (sector & (PAGE_SECTORS-1))
+ return -EINVAL;
+ if (sector + PAGE_SECTORS > get_capacity(bdev->bd_disk))
+ return -ERANGE;
+ page = brd_insert_page(brd, sector);
+ if (!page)
+ return -ENOMEM;
+ *data = (unsigned long)page_address(page);
+
+ return 0;
+}
+#endif
+
static int brd_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
@@ -342,8 +374,11 @@
}
static struct block_device_operations brd_fops = {
- .owner = THIS_MODULE,
- .ioctl = brd_ioctl,
+ .owner = THIS_MODULE,
+ .ioctl = brd_ioctl,
+#ifdef CONFIG_BLK_DEV_XIP
+ .direct_access = brd_direct_access,
+#endif
};
/*