diff options
| -rw-r--r-- | Documentation/filesystems/xip.txt | 15 | ||||
| -rw-r--r-- | arch/powerpc/sysdev/axonram.c | 17 | ||||
| -rw-r--r-- | drivers/block/brd.c | 14 | ||||
| -rw-r--r-- | drivers/s390/block/dcssblk.c | 21 | ||||
| -rw-r--r-- | fs/block_dev.c | 40 | ||||
| -rw-r--r-- | fs/ext2/xip.c | 31 | ||||
| -rw-r--r-- | include/linux/blkdev.h | 6 |
7 files changed, 86 insertions, 58 deletions
diff --git a/Documentation/filesystems/xip.txt b/Documentation/filesystems/xip.txt index 0466ee569278..b77472949ede 100644 --- a/Documentation/filesystems/xip.txt +++ b/Documentation/filesystems/xip.txt @@ -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: diff --git a/arch/powerpc/sysdev/axonram.c b/arch/powerpc/sysdev/axonram.c index f532c92bf99d..20f8afe855d1 100644 --- a/arch/powerpc/sysdev/axonram.c +++ b/arch/powerpc/sysdev/axonram.c @@ -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 = { diff --git a/drivers/block/brd.c b/drivers/block/brd.c index 3598110d2cef..89e90ec52f28 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -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 diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c index b550c8c8d010..31d6884f3351 100644 --- a/drivers/s390/block/dcssblk.c +++ b/drivers/s390/block/dcssblk.c @@ -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 @@ fail: 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 diff --git a/fs/block_dev.c b/fs/block_dev.c index b48c41bf0f86..f314c2c0567d 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -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 */ diff --git a/fs/ext2/xip.c b/fs/ext2/xip.c index e98171a11cfe..bbc5fec6ff7f 100644 --- a/fs/ext2/xip.c +++ b/fs/ext2/xip.c @@ -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; } diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 92f4b4b288dd..e9086be6d9a0 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -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; |