| 1 | /* |
| 2 | * linux/fs/ext2/xip.c |
| 3 | * |
| 4 | * Copyright (C) 2005 IBM Corporation |
| 5 | * Author: Carsten Otte (cotte@de.ibm.com) |
| 6 | */ |
| 7 | |
| 8 | #include <linux/mm.h> |
| 9 | #include <linux/fs.h> |
| 10 | #include <linux/genhd.h> |
| 11 | #include <linux/buffer_head.h> |
| 12 | #include <linux/blkdev.h> |
| 13 | #include "ext2.h" |
| 14 | #include "xip.h" |
| 15 | |
| 16 | static inline int |
| 17 | __inode_direct_access(struct inode *inode, sector_t block, |
| 18 | void **kaddr, unsigned long *pfn) |
| 19 | { |
| 20 | struct block_device *bdev = inode->i_sb->s_bdev; |
| 21 | const struct block_device_operations *ops = bdev->bd_disk->fops; |
| 22 | sector_t sector; |
| 23 | |
| 24 | sector = block * (PAGE_SIZE / 512); /* ext2 block to bdev sector */ |
| 25 | |
| 26 | BUG_ON(!ops->direct_access); |
| 27 | return ops->direct_access(bdev, sector, kaddr, pfn); |
| 28 | } |
| 29 | |
| 30 | static inline int |
| 31 | __ext2_get_block(struct inode *inode, pgoff_t pgoff, int create, |
| 32 | sector_t *result) |
| 33 | { |
| 34 | struct buffer_head tmp; |
| 35 | int rc; |
| 36 | |
| 37 | memset(&tmp, 0, sizeof(struct buffer_head)); |
| 38 | tmp.b_size = 1 << inode->i_blkbits; |
| 39 | rc = ext2_get_block(inode, pgoff, &tmp, create); |
| 40 | *result = tmp.b_blocknr; |
| 41 | |
| 42 | /* did we get a sparse block (hole in the file)? */ |
| 43 | if (!tmp.b_blocknr && !rc) { |
| 44 | BUG_ON(create); |
| 45 | rc = -ENODATA; |
| 46 | } |
| 47 | |
| 48 | return rc; |
| 49 | } |
| 50 | |
| 51 | int |
| 52 | ext2_clear_xip_target(struct inode *inode, sector_t block) |
| 53 | { |
| 54 | void *kaddr; |
| 55 | unsigned long pfn; |
| 56 | int rc; |
| 57 | |
| 58 | rc = __inode_direct_access(inode, block, &kaddr, &pfn); |
| 59 | if (!rc) |
| 60 | clear_page(kaddr); |
| 61 | return rc; |
| 62 | } |
| 63 | |
| 64 | void ext2_xip_verify_sb(struct super_block *sb) |
| 65 | { |
| 66 | struct ext2_sb_info *sbi = EXT2_SB(sb); |
| 67 | |
| 68 | if ((sbi->s_mount_opt & EXT2_MOUNT_XIP) && |
| 69 | !sb->s_bdev->bd_disk->fops->direct_access) { |
| 70 | sbi->s_mount_opt &= (~EXT2_MOUNT_XIP); |
| 71 | ext2_msg(sb, KERN_WARNING, |
| 72 | "warning: ignoring xip option - " |
| 73 | "not supported by bdev"); |
| 74 | } |
| 75 | } |
| 76 | |
| 77 | int ext2_get_xip_mem(struct address_space *mapping, pgoff_t pgoff, int create, |
| 78 | void **kmem, unsigned long *pfn) |
| 79 | { |
| 80 | int rc; |
| 81 | sector_t block; |
| 82 | |
| 83 | /* first, retrieve the sector number */ |
| 84 | rc = __ext2_get_block(mapping->host, pgoff, create, &block); |
| 85 | if (rc) |
| 86 | return rc; |
| 87 | |
| 88 | /* retrieve address of the target data */ |
| 89 | rc = __inode_direct_access(mapping->host, block, kmem, pfn); |
| 90 | return rc; |
| 91 | } |