fs/ext4/ext4_extents.h

   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
  19 #ifndef _EXT4_EXTENTS
  20 #define _EXT4_EXTENTS
  21
  22 #include "ext4.h"
  23
  24 /*
  25  * With AGGRESSIVE_TEST defined, the capacity of index/leaf blocks
  26  * becomes very small, so index split, in-depth growing and
  27  * other hard changes happen much more often.
  28  * This is for debug purposes only.
  29  */
  30 #define AGGRESSIVE_TEST_
  31
  32 /*
  33  * With EXTENTS_STATS defined, the number of blocks and extents
  34  * are collected in the truncate path. They'll be shown at
  35  * umount time.
  36  */
  37 #define EXTENTS_STATS__
  38
  39 /*
  40  * If CHECK_BINSEARCH is defined, then the results of the binary search
  41  * will also be checked by linear search.
  42  */
  43 #define CHECK_BINSEARCH__
  44
  45 /*
  46  * Turn on EXT_DEBUG to get lots of info about extents operations.
  47  */
  48 #define EXT_DEBUG__
  49 #ifdef EXT_DEBUG
  50 #define ext_debug(fmt, ...)     printk(fmt, ##__VA_ARGS__)
  51 #else
  52 #define ext_debug(fmt, ...)     no_printk(fmt, ##__VA_ARGS__)
  53 #endif
  54
  55 /*
  56  * If EXT_STATS is defined then stats numbers are collected.
  57  * These number will be displayed at umount time.
  58  */
  59 #define EXT_STATS_
  60
  61
  62 /*
  63  * ext4_inode has i_block array (60 bytes total).
  64  * The first 12 bytes store ext4_extent_header;
  65  * the remainder stores an array of ext4_extent.
  66  * For non-inode extent blocks, ext4_extent_tail
  67  * follows the array.
  68  */
  69
  70 /*
  71  * This is the extent tail on-disk structure.
  72  * All other extent structures are 12 bytes long.  It turns out that
  73  * block_size % 12 >= 4 for at least all powers of 2 greater than 512, which
  74  * covers all valid ext4 block sizes.  Therefore, this tail structure can be
  75  * crammed into the end of the block without having to rebalance the tree.
  76  */
  77 struct ext4_extent_tail {
  78         __le32  et_checksum;    /* crc32c(uuid+inum+extent_block) */
  79 };
  80
  81 /*
  82  * This is the extent on-disk structure.
  83  * It's used at the bottom of the tree.
  84  */
  85 struct ext4_extent {
  86         __le32  ee_block;       /* first logical block extent covers */
  87         __le16  ee_len;         /* number of blocks covered by extent */
  88         __le16  ee_start_hi;    /* high 16 bits of physical block */
  89         __le32  ee_start_lo;    /* low 32 bits of physical block */
  90 };
  91
  92 /*
  93  * This is index on-disk structure.
  94  * It's used at all the levels except the bottom.
  95  */
  96 struct ext4_extent_idx {
  97         __le32  ei_block;       /* index covers logical blocks from 'block' */
  98         __le32  ei_leaf_lo;     /* pointer to the physical block of the next *
  99                                  * level. leaf or next index could be there */
 100         __le16  ei_leaf_hi;     /* high 16 bits of physical block */
 101         __u16   ei_unused;
 102 };
 103
 104 /*
 105  * Each block (leaves and indexes), even inode-stored has header.
 106  */
 107 struct ext4_extent_header {
 108         __le16  eh_magic;       /* probably will support different formats */
 109         __le16  eh_entries;     /* number of valid entries */
 110         __le16  eh_max;         /* capacity of store in entries */
 111         __le16  eh_depth;       /* has tree real underlying blocks? */
 112         __le32  eh_generation;  /* generation of the tree */
 113 };
 114
 115 #define EXT4_EXT_MAGIC          cpu_to_le16(0xf30a)
 116
 117 #define EXT4_EXTENT_TAIL_OFFSET(hdr) \
 118         (sizeof(struct ext4_extent_header) + \
 119          (sizeof(struct ext4_extent) * le16_to_cpu((hdr)->eh_max)))
 120
 121 static inline struct ext4_extent_tail *
 122 find_ext4_extent_tail(struct ext4_extent_header *eh)
 123 {
 124         return (struct ext4_extent_tail *)(((void *)eh) +
 125                                            EXT4_EXTENT_TAIL_OFFSET(eh));
 126 }
 127
 128 /*
 129  * Array of ext4_ext_path contains path to some extent.
 130  * Creation/lookup routines use it for traversal/splitting/etc.
 131  * Truncate uses it to simulate recursive walking.
 132  */
 133 struct ext4_ext_path {
 134         ext4_fsblk_t                    p_block;
 135         __u16                           p_depth;
 136         struct ext4_extent              *p_ext;
 137         struct ext4_extent_idx          *p_idx;
 138         struct ext4_extent_header       *p_hdr;
 139         struct buffer_head              *p_bh;
 140 };
 141
 142 /*
 143  * structure for external API
 144  */
 145
 146 /*
 147  * to be called by ext4_ext_walk_space()
 148  * negative retcode - error
 149  * positive retcode - signal for ext4_ext_walk_space(), see below
 150  * callback must return valid extent (passed or newly created)
 151  */
 152 typedef int (*ext_prepare_callback)(struct inode *, ext4_lblk_t,
 153                                         struct ext4_ext_cache *,
 154                                         struct ext4_extent *, void *);
 155
 156 #define EXT_CONTINUE   0
 157 #define EXT_BREAK      1
 158 #define EXT_REPEAT     2
 159
 160 /*
 161  * Maximum number of logical blocks in a file; ext4_extent's ee_block is
 162  * __le32.
 163  */
 164 #define EXT_MAX_BLOCKS  0xffffffff
 165
 166 /*
 167  * EXT_INIT_MAX_LEN is the maximum number of blocks we can have in an
 168  * initialized extent. This is 2^15 and not (2^16 - 1), since we use the
 169  * MSB of ee_len field in the extent datastructure to signify if this
 170  * particular extent is an initialized extent or an uninitialized (i.e.
 171  * preallocated).
 172  * EXT_UNINIT_MAX_LEN is the maximum number of blocks we can have in an
 173  * uninitialized extent.
 174  * If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an
 175  * uninitialized one. In other words, if MSB of ee_len is set, it is an
 176  * uninitialized extent with only one special scenario when ee_len = 0x8000.
 177  * In this case we can not have an uninitialized extent of zero length and
 178  * thus we make it as a special case of initialized extent with 0x8000 length.
 179  * This way we get better extent-to-group alignment for initialized extents.
 180  * Hence, the maximum number of blocks we can have in an *initialized*
 181  * extent is 2^15 (32768) and in an *uninitialized* extent is 2^15-1 (32767).
 182  */
 183 #define EXT_INIT_MAX_LEN        (1UL << 15)
 184 #define EXT_UNINIT_MAX_LEN      (EXT_INIT_MAX_LEN - 1)
 185
 186
 187 #define EXT_FIRST_EXTENT(__hdr__) \
 188         ((struct ext4_extent *) (((char *) (__hdr__)) +         \
 189                                  sizeof(struct ext4_extent_header)))
 190 #define EXT_FIRST_INDEX(__hdr__) \
 191         ((struct ext4_extent_idx *) (((char *) (__hdr__)) +     \
 192                                      sizeof(struct ext4_extent_header)))
 193 #define EXT_HAS_FREE_INDEX(__path__) \
 194         (le16_to_cpu((__path__)->p_hdr->eh_entries) \
 195                                      < le16_to_cpu((__path__)->p_hdr->eh_max))
 196 #define EXT_LAST_EXTENT(__hdr__) \
 197         (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
 198 #define EXT_LAST_INDEX(__hdr__) \
 199         (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
 200 #define EXT_MAX_EXTENT(__hdr__) \
 201         (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
 202 #define EXT_MAX_INDEX(__hdr__) \
 203         (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
 204
 205 static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode)
 206 {
 207         return (struct ext4_extent_header *) EXT4_I(inode)->i_data;
 208 }
 209
 210 static inline struct ext4_extent_header *ext_block_hdr(struct buffer_head *bh)
 211 {
 212         return (struct ext4_extent_header *) bh->b_data;
 213 }
 214
 215 static inline unsigned short ext_depth(struct inode *inode)
 216 {
 217         return le16_to_cpu(ext_inode_hdr(inode)->eh_depth);
 218 }
 219
 220 static inline void
 221 ext4_ext_invalidate_cache(struct inode *inode)
 222 {
 223         EXT4_I(inode)->i_cached_extent.ec_len = 0;
 224 }
 225
 226 static inline void ext4_ext_mark_uninitialized(struct ext4_extent *ext)
 227 {
 228         /* We can not have an uninitialized extent of zero length! */
 229         BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0);
 230         ext->ee_len |= cpu_to_le16(EXT_INIT_MAX_LEN);
 231 }
 232
 233 static inline int ext4_ext_is_uninitialized(struct ext4_extent *ext)
 234 {
 235         /* Extent with ee_len of 0x8000 is treated as an initialized extent */
 236         return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN);
 237 }
 238
 239 static inline int ext4_ext_get_actual_len(struct ext4_extent *ext)
 240 {
 241         return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ?
 242                 le16_to_cpu(ext->ee_len) :
 243                 (le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN));
 244 }
 245
 246 static inline void ext4_ext_mark_initialized(struct ext4_extent *ext)
 247 {
 248         ext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ext));
 249 }
 250
 251 /*
 252  * ext4_ext_pblock:
 253  * combine low and high parts of physical block number into ext4_fsblk_t
 254  */
 255 static inline ext4_fsblk_t ext4_ext_pblock(struct ext4_extent *ex)
 256 {
 257         ext4_fsblk_t block;
 258
 259         block = le32_to_cpu(ex->ee_start_lo);
 260         block |= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1;
 261         return block;
 262 }
 263
 264 /*
 265  * ext4_idx_pblock:
 266  * combine low and high parts of a leaf physical block number into ext4_fsblk_t
 267  */
 268 static inline ext4_fsblk_t ext4_idx_pblock(struct ext4_extent_idx *ix)
 269 {
 270         ext4_fsblk_t block;
 271
 272         block = le32_to_cpu(ix->ei_leaf_lo);
 273         block |= ((ext4_fsblk_t) le16_to_cpu(ix->ei_leaf_hi) << 31) << 1;
 274         return block;
 275 }
 276
 277 /*
 278  * ext4_ext_store_pblock:
 279  * stores a large physical block number into an extent struct,
 280  * breaking it into parts
 281  */
 282 static inline void ext4_ext_store_pblock(struct ext4_extent *ex,
 283                                          ext4_fsblk_t pb)
 284 {
 285         ex->ee_start_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
 286         ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
 287                                       0xffff);
 288 }
 289
 290 /*
 291  * ext4_idx_store_pblock:
 292  * stores a large physical block number into an index struct,
 293  * breaking it into parts
 294  */
 295 static inline void ext4_idx_store_pblock(struct ext4_extent_idx *ix,
 296                                          ext4_fsblk_t pb)
 297 {
 298         ix->ei_leaf_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
 299         ix->ei_leaf_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
 300                                      0xffff);
 301 }
 302
 303 extern int ext4_ext_calc_metadata_amount(struct inode *inode,
 304                                          ext4_lblk_t lblocks);
 305 extern int ext4_extent_tree_init(handle_t *, struct inode *);
 306 extern int ext4_ext_calc_credits_for_single_extent(struct inode *inode,
 307                                                    int num,
 308                                                    struct ext4_ext_path *path);
 309 extern int ext4_can_extents_be_merged(struct inode *inode,
 310                                       struct ext4_extent *ex1,
 311                                       struct ext4_extent *ex2);
 312 extern int ext4_ext_insert_extent(handle_t *, struct inode *, struct ext4_ext_path *, struct ext4_extent *, int);
 313 extern struct ext4_ext_path *ext4_ext_find_extent(struct inode *, ext4_lblk_t,
 314                                                         struct ext4_ext_path *);
 315 extern void ext4_ext_drop_refs(struct ext4_ext_path *);
 316 extern int ext4_ext_check_inode(struct inode *inode);
 317 extern int ext4_find_delalloc_cluster(struct inode *inode, ext4_lblk_t lblk,
 318                                       int search_hint_reverse);
 319 #endif /* _EXT4_EXTENTS */
 320