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rd: support XIP

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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>
This commit is contained in:
Nick Piggin 2008-02-08 04:19:50 -08:00 committed by Linus Torvalds
parent 9db5579be4
commit 75acb9cd2e
2 changed files with 47 additions and 2 deletions
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10
drivers/block/Kconfig
View file

@ -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
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

39
drivers/block/brd.c
View file

@ -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;
#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 @@ out:
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 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,
#ifdef CONFIG_BLK_DEV_XIP
.direct_access = brd_direct_access,
#endif
};
/*