xip.c 2.0 KB

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  1. /*
  2. * linux/fs/ext2/xip.c
  3. *
  4. * Copyright (C) 2005 IBM Corporation
  5. * Author: Carsten Otte (cotte@de.ibm.com)
  6. */
  7. #include <linux/mm.h>
  8. #include <linux/fs.h>
  9. #include <linux/genhd.h>
  10. #include <linux/buffer_head.h>
  11. #include <linux/ext2_fs_sb.h>
  12. #include <linux/ext2_fs.h>
  13. #include "ext2.h"
  14. #include "xip.h"
  15. static inline int
  16. __inode_direct_access(struct inode *inode, sector_t sector,
  17. unsigned long *data)
  18. {
  19. BUG_ON(!inode->i_sb->s_bdev->bd_disk->fops->direct_access);
  20. return inode->i_sb->s_bdev->bd_disk->fops
  21. ->direct_access(inode->i_sb->s_bdev,sector,data);
  22. }
  23. static inline int
  24. __ext2_get_sector(struct inode *inode, sector_t offset, int create,
  25. sector_t *result)
  26. {
  27. struct buffer_head tmp;
  28. int rc;
  29. memset(&tmp, 0, sizeof(struct buffer_head));
  30. rc = ext2_get_block(inode, offset/ (PAGE_SIZE/512), &tmp,
  31. create);
  32. *result = tmp.b_blocknr;
  33. /* did we get a sparse block (hole in the file)? */
  34. if (!tmp.b_blocknr && !rc) {
  35. BUG_ON(create);
  36. rc = -ENODATA;
  37. }
  38. return rc;
  39. }
  40. int
  41. ext2_clear_xip_target(struct inode *inode, int block)
  42. {
  43. sector_t sector = block * (PAGE_SIZE/512);
  44. unsigned long data;
  45. int rc;
  46. rc = __inode_direct_access(inode, sector, &data);
  47. if (!rc)
  48. clear_page((void*)data);
  49. return rc;
  50. }
  51. void ext2_xip_verify_sb(struct super_block *sb)
  52. {
  53. struct ext2_sb_info *sbi = EXT2_SB(sb);
  54. if ((sbi->s_mount_opt & EXT2_MOUNT_XIP) &&
  55. !sb->s_bdev->bd_disk->fops->direct_access) {
  56. sbi->s_mount_opt &= (~EXT2_MOUNT_XIP);
  57. ext2_warning(sb, __FUNCTION__,
  58. "ignoring xip option - not supported by bdev");
  59. }
  60. }
  61. struct page *
  62. ext2_get_xip_page(struct address_space *mapping, sector_t offset,
  63. int create)
  64. {
  65. int rc;
  66. unsigned long data;
  67. sector_t sector;
  68. /* first, retrieve the sector number */
  69. rc = __ext2_get_sector(mapping->host, offset, create, &sector);
  70. if (rc)
  71. goto error;
  72. /* retrieve address of the target data */
  73. rc = __inode_direct_access
  74. (mapping->host, sector * (PAGE_SIZE/512), &data);
  75. if (!rc)
  76. return virt_to_page(data);
  77. error:
  78. return ERR_PTR(rc);
  79. }