Commit 75acb9cd authored by Nick Piggin's avatar Nick Piggin Committed by Linus Torvalds

rd: support XIP

Support direct_access XIP method with brd.
Signed-off-by: default avatarNick Piggin <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 9db5579b
......@@ -357,6 +357,16 @@ config BLK_DEV_RAM_SIZE
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
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).
tristate "Packet writing on CD/DVD media"
depends on !UML
......@@ -89,6 +89,7 @@ static struct page *brd_insert_page(struct brd_device *brd, sector_t sector)
pgoff_t idx;
struct page *page;
gfp_t gfp_flags;
page = brd_lookup_page(brd, sector);
if (page)
......@@ -97,7 +98,16 @@ static struct page *brd_insert_page(struct brd_device *brd, sector_t sector)
* 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;
gfp_flags |= __GFP_HIGHMEM;
page = alloc_page(GFP_NOIO | __GFP_HIGHMEM | __GFP_ZERO);
if (!page)
return NULL;
......@@ -307,6 +317,28 @@ out:
return 0;
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;
static int brd_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
......@@ -342,8 +374,11 @@ static int brd_ioctl(struct inode *inode, struct file *file,
static struct block_device_operations brd_fops = {
.owner = THIS_MODULE,
.ioctl = brd_ioctl,
.owner = THIS_MODULE,
.ioctl = brd_ioctl,
.direct_access = brd_direct_access,
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