original development tree for Linux kernel GTP module; now long in mainline.
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  1. /*
  2. * Copyright (c) 2003-2006, Cluster File Systems, Inc, info@clusterfs.com
  3. * Written by Alex Tomas <alex@clusterfs.com>
  4. *
  5. * This program is free software; you can redistribute it and/or modify
  6. * it under the terms of the GNU General Public License version 2 as
  7. * published by the Free Software Foundation.
  8. *
  9. * This program is distributed in the hope that it will be useful,
  10. * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11. * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  12. * GNU General Public License for more details.
  13. *
  14. * You should have received a copy of the GNU General Public Licens
  15. * along with this program; if not, write to the Free Software
  16. * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-
  17. */
  18. #ifndef _EXT4_EXTENTS
  19. #define _EXT4_EXTENTS
  20. #include "ext4.h"
  21. /*
  22. * With AGGRESSIVE_TEST defined, the capacity of index/leaf blocks
  23. * becomes very small, so index split, in-depth growing and
  24. * other hard changes happen much more often.
  25. * This is for debug purposes only.
  26. */
  27. #define AGGRESSIVE_TEST_
  28. /*
  29. * With EXTENTS_STATS defined, the number of blocks and extents
  30. * are collected in the truncate path. They'll be shown at
  31. * umount time.
  32. */
  33. #define EXTENTS_STATS__
  34. /*
  35. * If CHECK_BINSEARCH is defined, then the results of the binary search
  36. * will also be checked by linear search.
  37. */
  38. #define CHECK_BINSEARCH__
  39. /*
  40. * If EXT_STATS is defined then stats numbers are collected.
  41. * These number will be displayed at umount time.
  42. */
  43. #define EXT_STATS_
  44. /*
  45. * ext4_inode has i_block array (60 bytes total).
  46. * The first 12 bytes store ext4_extent_header;
  47. * the remainder stores an array of ext4_extent.
  48. * For non-inode extent blocks, ext4_extent_tail
  49. * follows the array.
  50. */
  51. /*
  52. * This is the extent tail on-disk structure.
  53. * All other extent structures are 12 bytes long. It turns out that
  54. * block_size % 12 >= 4 for at least all powers of 2 greater than 512, which
  55. * covers all valid ext4 block sizes. Therefore, this tail structure can be
  56. * crammed into the end of the block without having to rebalance the tree.
  57. */
  58. struct ext4_extent_tail {
  59. __le32 et_checksum; /* crc32c(uuid+inum+extent_block) */
  60. };
  61. /*
  62. * This is the extent on-disk structure.
  63. * It's used at the bottom of the tree.
  64. */
  65. struct ext4_extent {
  66. __le32 ee_block; /* first logical block extent covers */
  67. __le16 ee_len; /* number of blocks covered by extent */
  68. __le16 ee_start_hi; /* high 16 bits of physical block */
  69. __le32 ee_start_lo; /* low 32 bits of physical block */
  70. };
  71. /*
  72. * This is index on-disk structure.
  73. * It's used at all the levels except the bottom.
  74. */
  75. struct ext4_extent_idx {
  76. __le32 ei_block; /* index covers logical blocks from 'block' */
  77. __le32 ei_leaf_lo; /* pointer to the physical block of the next *
  78. * level. leaf or next index could be there */
  79. __le16 ei_leaf_hi; /* high 16 bits of physical block */
  80. __u16 ei_unused;
  81. };
  82. /*
  83. * Each block (leaves and indexes), even inode-stored has header.
  84. */
  85. struct ext4_extent_header {
  86. __le16 eh_magic; /* probably will support different formats */
  87. __le16 eh_entries; /* number of valid entries */
  88. __le16 eh_max; /* capacity of store in entries */
  89. __le16 eh_depth; /* has tree real underlying blocks? */
  90. __le32 eh_generation; /* generation of the tree */
  91. };
  92. #define EXT4_EXT_MAGIC cpu_to_le16(0xf30a)
  93. #define EXT4_EXTENT_TAIL_OFFSET(hdr) \
  94. (sizeof(struct ext4_extent_header) + \
  95. (sizeof(struct ext4_extent) * le16_to_cpu((hdr)->eh_max)))
  96. static inline struct ext4_extent_tail *
  97. find_ext4_extent_tail(struct ext4_extent_header *eh)
  98. {
  99. return (struct ext4_extent_tail *)(((void *)eh) +
  100. EXT4_EXTENT_TAIL_OFFSET(eh));
  101. }
  102. /*
  103. * Array of ext4_ext_path contains path to some extent.
  104. * Creation/lookup routines use it for traversal/splitting/etc.
  105. * Truncate uses it to simulate recursive walking.
  106. */
  107. struct ext4_ext_path {
  108. ext4_fsblk_t p_block;
  109. __u16 p_depth;
  110. struct ext4_extent *p_ext;
  111. struct ext4_extent_idx *p_idx;
  112. struct ext4_extent_header *p_hdr;
  113. struct buffer_head *p_bh;
  114. };
  115. /*
  116. * structure for external API
  117. */
  118. /*
  119. * EXT_INIT_MAX_LEN is the maximum number of blocks we can have in an
  120. * initialized extent. This is 2^15 and not (2^16 - 1), since we use the
  121. * MSB of ee_len field in the extent datastructure to signify if this
  122. * particular extent is an initialized extent or an uninitialized (i.e.
  123. * preallocated).
  124. * EXT_UNINIT_MAX_LEN is the maximum number of blocks we can have in an
  125. * uninitialized extent.
  126. * If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an
  127. * uninitialized one. In other words, if MSB of ee_len is set, it is an
  128. * uninitialized extent with only one special scenario when ee_len = 0x8000.
  129. * In this case we can not have an uninitialized extent of zero length and
  130. * thus we make it as a special case of initialized extent with 0x8000 length.
  131. * This way we get better extent-to-group alignment for initialized extents.
  132. * Hence, the maximum number of blocks we can have in an *initialized*
  133. * extent is 2^15 (32768) and in an *uninitialized* extent is 2^15-1 (32767).
  134. */
  135. #define EXT_INIT_MAX_LEN (1UL << 15)
  136. #define EXT_UNINIT_MAX_LEN (EXT_INIT_MAX_LEN - 1)
  137. #define EXT_FIRST_EXTENT(__hdr__) \
  138. ((struct ext4_extent *) (((char *) (__hdr__)) + \
  139. sizeof(struct ext4_extent_header)))
  140. #define EXT_FIRST_INDEX(__hdr__) \
  141. ((struct ext4_extent_idx *) (((char *) (__hdr__)) + \
  142. sizeof(struct ext4_extent_header)))
  143. #define EXT_HAS_FREE_INDEX(__path__) \
  144. (le16_to_cpu((__path__)->p_hdr->eh_entries) \
  145. < le16_to_cpu((__path__)->p_hdr->eh_max))
  146. #define EXT_LAST_EXTENT(__hdr__) \
  147. (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
  148. #define EXT_LAST_INDEX(__hdr__) \
  149. (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
  150. #define EXT_MAX_EXTENT(__hdr__) \
  151. (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
  152. #define EXT_MAX_INDEX(__hdr__) \
  153. (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
  154. static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode)
  155. {
  156. return (struct ext4_extent_header *) EXT4_I(inode)->i_data;
  157. }
  158. static inline struct ext4_extent_header *ext_block_hdr(struct buffer_head *bh)
  159. {
  160. return (struct ext4_extent_header *) bh->b_data;
  161. }
  162. static inline unsigned short ext_depth(struct inode *inode)
  163. {
  164. return le16_to_cpu(ext_inode_hdr(inode)->eh_depth);
  165. }
  166. static inline void ext4_ext_mark_uninitialized(struct ext4_extent *ext)
  167. {
  168. /* We can not have an uninitialized extent of zero length! */
  169. BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0);
  170. ext->ee_len |= cpu_to_le16(EXT_INIT_MAX_LEN);
  171. }
  172. static inline int ext4_ext_is_uninitialized(struct ext4_extent *ext)
  173. {
  174. /* Extent with ee_len of 0x8000 is treated as an initialized extent */
  175. return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN);
  176. }
  177. static inline int ext4_ext_get_actual_len(struct ext4_extent *ext)
  178. {
  179. return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ?
  180. le16_to_cpu(ext->ee_len) :
  181. (le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN));
  182. }
  183. static inline void ext4_ext_mark_initialized(struct ext4_extent *ext)
  184. {
  185. ext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ext));
  186. }
  187. /*
  188. * ext4_ext_pblock:
  189. * combine low and high parts of physical block number into ext4_fsblk_t
  190. */
  191. static inline ext4_fsblk_t ext4_ext_pblock(struct ext4_extent *ex)
  192. {
  193. ext4_fsblk_t block;
  194. block = le32_to_cpu(ex->ee_start_lo);
  195. block |= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1;
  196. return block;
  197. }
  198. /*
  199. * ext4_idx_pblock:
  200. * combine low and high parts of a leaf physical block number into ext4_fsblk_t
  201. */
  202. static inline ext4_fsblk_t ext4_idx_pblock(struct ext4_extent_idx *ix)
  203. {
  204. ext4_fsblk_t block;
  205. block = le32_to_cpu(ix->ei_leaf_lo);
  206. block |= ((ext4_fsblk_t) le16_to_cpu(ix->ei_leaf_hi) << 31) << 1;
  207. return block;
  208. }
  209. /*
  210. * ext4_ext_store_pblock:
  211. * stores a large physical block number into an extent struct,
  212. * breaking it into parts
  213. */
  214. static inline void ext4_ext_store_pblock(struct ext4_extent *ex,
  215. ext4_fsblk_t pb)
  216. {
  217. ex->ee_start_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
  218. ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
  219. 0xffff);
  220. }
  221. /*
  222. * ext4_idx_store_pblock:
  223. * stores a large physical block number into an index struct,
  224. * breaking it into parts
  225. */
  226. static inline void ext4_idx_store_pblock(struct ext4_extent_idx *ix,
  227. ext4_fsblk_t pb)
  228. {
  229. ix->ei_leaf_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
  230. ix->ei_leaf_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
  231. 0xffff);
  232. }
  233. #define ext4_ext_dirty(handle, inode, path) \
  234. __ext4_ext_dirty(__func__, __LINE__, (handle), (inode), (path))
  235. int __ext4_ext_dirty(const char *where, unsigned int line, handle_t *handle,
  236. struct inode *inode, struct ext4_ext_path *path);
  237. #endif /* _EXT4_EXTENTS */