Commit dd22f551 authored by Matthew Wilcox's avatar Matthew Wilcox Committed by Jens Axboe

block: Change direct_access calling convention

In order to support accesses to larger chunks of memory, pass in a
'size' parameter (counted in bytes), and return the amount available at
that address.

Add a new helper function, bdev_direct_access(), to handle common
functionality including partition handling, checking the length requested
is positive, checking for the sector being page-aligned, and checking
the length of the request does not pass the end of the partition.
Signed-off-by: default avatarMatthew Wilcox <[email protected]>
Reviewed-by: default avatarJan Kara <[email protected]>
Reviewed-by: default avatarBoaz Harrosh <[email protected]>
Signed-off-by: default avatarJens Axboe <[email protected]>
parent c761d96b
......@@ -28,12 +28,15 @@ Implementation
Execute-in-place is implemented in three steps: block device operation,
address space operation, and file operations.
A block device operation named direct_access is used to retrieve a
reference (pointer) to a block on-disk. The reference is supposed to be
cpu-addressable, physical address and remain valid until the release operation
is performed. A struct block_device reference is used to address the device,
and a sector_t argument is used to identify the individual block. As an
alternative, memory technology devices can be used for this.
A block device operation named direct_access is used to translate the
block device sector number to a page frame number (pfn) that identifies
the physical page for the memory. It also returns a kernel virtual
address that can be used to access the memory.
The direct_access method takes a 'size' parameter that indicates the
number of bytes being requested. The function should return the number
of bytes that can be contiguously accessed at that offset. It may also
return a negative errno if an error occurs.
The block device operation is optional, these block devices support it as of
today:
......
......@@ -139,26 +139,17 @@ axon_ram_make_request(struct request_queue *queue, struct bio *bio)
* axon_ram_direct_access - direct_access() method for block device
* @device, @sector, @data: see block_device_operations method
*/
static int
static long
axon_ram_direct_access(struct block_device *device, sector_t sector,
void **kaddr, unsigned long *pfn)
void **kaddr, unsigned long *pfn, long size)
{
struct axon_ram_bank *bank = device->bd_disk->private_data;
loff_t offset;
offset = sector;
if (device->bd_part != NULL)
offset += device->bd_part->start_sect;
offset <<= AXON_RAM_SECTOR_SHIFT;
if (offset >= bank->size) {
dev_err(&bank->device->dev, "Access outside of address space\n");
return -ERANGE;
}
loff_t offset = (loff_t)sector << AXON_RAM_SECTOR_SHIFT;
*kaddr = (void *)(bank->ph_addr + offset);
*pfn = virt_to_phys(kaddr) >> PAGE_SHIFT;
return 0;
return bank->size - offset;
}
static const struct block_device_operations axon_ram_devops = {
......
......@@ -370,25 +370,25 @@ static int brd_rw_page(struct block_device *bdev, sector_t sector,
}
#ifdef CONFIG_BLK_DEV_XIP
static int brd_direct_access(struct block_device *bdev, sector_t sector,
void **kaddr, unsigned long *pfn)
static long brd_direct_access(struct block_device *bdev, sector_t sector,
void **kaddr, unsigned long *pfn, long size)
{
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 -ENOSPC;
*kaddr = page_address(page);
*pfn = page_to_pfn(page);
return 0;
/*
* TODO: If size > PAGE_SIZE, we could look to see if the next page in
* the file happens to be mapped to the next page of physical RAM.
*/
return PAGE_SIZE;
}
#endif
......
......@@ -28,8 +28,8 @@
static int dcssblk_open(struct block_device *bdev, fmode_t mode);
static void dcssblk_release(struct gendisk *disk, fmode_t mode);
static void dcssblk_make_request(struct request_queue *q, struct bio *bio);
static int dcssblk_direct_access(struct block_device *bdev, sector_t secnum,
void **kaddr, unsigned long *pfn);
static long dcssblk_direct_access(struct block_device *bdev, sector_t secnum,
void **kaddr, unsigned long *pfn, long size);
static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
......@@ -866,25 +866,22 @@ dcssblk_make_request(struct request_queue *q, struct bio *bio)
bio_io_error(bio);
}
static int
static long
dcssblk_direct_access (struct block_device *bdev, sector_t secnum,
void **kaddr, unsigned long *pfn)
void **kaddr, unsigned long *pfn, long size)
{
struct dcssblk_dev_info *dev_info;
unsigned long pgoff;
unsigned long offset, dev_sz;
dev_info = bdev->bd_disk->private_data;
if (!dev_info)
return -ENODEV;
if (secnum % (PAGE_SIZE/512))
return -EINVAL;
pgoff = secnum / (PAGE_SIZE / 512);
if ((pgoff+1)*PAGE_SIZE-1 > dev_info->end - dev_info->start)
return -ERANGE;
*kaddr = (void *) (dev_info->start+pgoff*PAGE_SIZE);
dev_sz = dev_info->end - dev_info->start;
offset = secnum * 512;
*kaddr = (void *) (dev_info->start + offset);
*pfn = virt_to_phys(*kaddr) >> PAGE_SHIFT;
return 0;
return dev_sz - offset;
}
static void
......
......@@ -429,6 +429,46 @@ int bdev_write_page(struct block_device *bdev, sector_t sector,
}
EXPORT_SYMBOL_GPL(bdev_write_page);
/**
* bdev_direct_access() - Get the address for directly-accessibly memory
* @bdev: The device containing the memory
* @sector: The offset within the device
* @addr: Where to put the address of the memory
* @pfn: The Page Frame Number for the memory
* @size: The number of bytes requested
*
* If a block device is made up of directly addressable memory, this function
* will tell the caller the PFN and the address of the memory. The address
* may be directly dereferenced within the kernel without the need to call
* ioremap(), kmap() or similar. The PFN is suitable for inserting into
* page tables.
*
* Return: negative errno if an error occurs, otherwise the number of bytes
* accessible at this address.
*/
long bdev_direct_access(struct block_device *bdev, sector_t sector,
void **addr, unsigned long *pfn, long size)
{
long avail;
const struct block_device_operations *ops = bdev->bd_disk->fops;
if (size < 0)
return size;
if (!ops->direct_access)
return -EOPNOTSUPP;
if ((sector + DIV_ROUND_UP(size, 512)) >
part_nr_sects_read(bdev->bd_part))
return -ERANGE;
sector += get_start_sect(bdev);
if (sector % (PAGE_SIZE / 512))
return -EINVAL;
avail = ops->direct_access(bdev, sector, addr, pfn, size);
if (!avail)
return -ERANGE;
return min(avail, size);
}
EXPORT_SYMBOL_GPL(bdev_direct_access);
/*
* pseudo-fs
*/
......
......@@ -13,18 +13,12 @@
#include "ext2.h"
#include "xip.h"
static inline int
__inode_direct_access(struct inode *inode, sector_t block,
void **kaddr, unsigned long *pfn)
static inline long __inode_direct_access(struct inode *inode, sector_t block,
void **kaddr, unsigned long *pfn, long size)
{
struct block_device *bdev = inode->i_sb->s_bdev;
const struct block_device_operations *ops = bdev->bd_disk->fops;
sector_t sector;
sector = block * (PAGE_SIZE / 512); /* ext2 block to bdev sector */
BUG_ON(!ops->direct_access);
return ops->direct_access(bdev, sector, kaddr, pfn);
sector_t sector = block * (PAGE_SIZE / 512);
return bdev_direct_access(bdev, sector, kaddr, pfn, size);
}
static inline int
......@@ -53,12 +47,13 @@ ext2_clear_xip_target(struct inode *inode, sector_t block)
{
void *kaddr;
unsigned long pfn;
int rc;
long size;
rc = __inode_direct_access(inode, block, &kaddr, &pfn);
if (!rc)
clear_page(kaddr);
return rc;
size = __inode_direct_access(inode, block, &kaddr, &pfn, PAGE_SIZE);
if (size < 0)
return size;
clear_page(kaddr);
return 0;
}
void ext2_xip_verify_sb(struct super_block *sb)
......@@ -77,7 +72,7 @@ void ext2_xip_verify_sb(struct super_block *sb)
int ext2_get_xip_mem(struct address_space *mapping, pgoff_t pgoff, int create,
void **kmem, unsigned long *pfn)
{
int rc;
long rc;
sector_t block;
/* first, retrieve the sector number */
......@@ -86,6 +81,6 @@ int ext2_get_xip_mem(struct address_space *mapping, pgoff_t pgoff, int create,
return rc;
/* retrieve address of the target data */
rc = __inode_direct_access(mapping->host, block, kmem, pfn);
return rc;
rc = __inode_direct_access(mapping->host, block, kmem, pfn, PAGE_SIZE);
return (rc < 0) ? rc : 0;
}
......@@ -1601,8 +1601,8 @@ struct block_device_operations {
int (*rw_page)(struct block_device *, sector_t, struct page *, int rw);
int (*ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
int (*compat_ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
int (*direct_access) (struct block_device *, sector_t,
void **, unsigned long *);
long (*direct_access)(struct block_device *, sector_t,
void **, unsigned long *pfn, long size);
unsigned int (*check_events) (struct gendisk *disk,
unsigned int clearing);
/* ->media_changed() is DEPRECATED, use ->check_events() instead */
......@@ -1620,6 +1620,8 @@ extern int __blkdev_driver_ioctl(struct block_device *, fmode_t, unsigned int,
extern int bdev_read_page(struct block_device *, sector_t, struct page *);
extern int bdev_write_page(struct block_device *, sector_t, struct page *,
struct writeback_control *);
extern long bdev_direct_access(struct block_device *, sector_t, void **addr,
unsigned long *pfn, long size);
#else /* CONFIG_BLOCK */
struct block_device;
......
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