LXR linux/include/linux/ext4_fs

   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 _LINUX_EXT4_EXTENTS
  20#define _LINUX_EXT4_EXTENTS
  21
  22#include <linux/ext4_fs.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 * If EXT_DEBUG is defined you can use the 'extdebug' mount option
  47 * to get lots of info about what's going on.
  48 */
  49#define EXT_DEBUG__
  50#ifdef EXT_DEBUG
  51#define ext_debug(a...)         printk(a)
  52#else
  53#define ext_debug(a...)
  54#endif
  55
  56/*
  57 * If EXT_STATS is defined then stats numbers are collected.
  58 * These number will be displayed at umount time.
  59 */
  60#define EXT_STATS_
  61
  62
  63/*
  64 * ext4_inode has i_block array (60 bytes total).
  65 * The first 12 bytes store ext4_extent_header;
  66 * the remainder stores an array of ext4_extent.
  67 */
  68
  69/*
  70 * This is the extent on-disk structure.
  71 * It's used at the bottom of the tree.
  72 */
  73struct ext4_extent {
  74        __le32  ee_block;       /* first logical block extent covers */
  75        __le16  ee_len;         /* number of blocks covered by extent */
  76        __le16  ee_start_hi;    /* high 16 bits of physical block */
  77        __le32  ee_start_lo;    /* low 32 bits of physical block */
  78};
  79
  80/*
  81 * This is index on-disk structure.
  82 * It's used at all the levels except the bottom.
  83 */
  84struct ext4_extent_idx {
  85        __le32  ei_block;       /* index covers logical blocks from 'block' */
  86        __le32  ei_leaf_lo;     /* pointer to the physical block of the next *
  87                                 * level. leaf or next index could be there */
  88        __le16  ei_leaf_hi;     /* high 16 bits of physical block */
  89        __u16   ei_unused;
  90};
  91
  92/*
  93 * Each block (leaves and indexes), even inode-stored has header.
  94 */
  95struct ext4_extent_header {
  96        __le16  eh_magic;       /* probably will support different formats */
  97        __le16  eh_entries;     /* number of valid entries */
  98        __le16  eh_max;         /* capacity of store in entries */
  99        __le16  eh_depth;       /* has tree real underlying blocks? */
 100        __le32  eh_generation;  /* generation of the tree */
 101};
 102
 103#define EXT4_EXT_MAGIC          cpu_to_le16(0xf30a)
 104
 105/*
 106 * Array of ext4_ext_path contains path to some extent.
 107 * Creation/lookup routines use it for traversal/splitting/etc.
 108 * Truncate uses it to simulate recursive walking.
 109 */
 110struct ext4_ext_path {
 111        ext4_fsblk_t                    p_block;
 112        __u16                           p_depth;
 113        struct ext4_extent              *p_ext;
 114        struct ext4_extent_idx          *p_idx;
 115        struct ext4_extent_header       *p_hdr;
 116        struct buffer_head              *p_bh;
 117};
 118
 119/*
 120 * structure for external API
 121 */
 122
 123#define EXT4_EXT_CACHE_NO       0
 124#define EXT4_EXT_CACHE_GAP      1
 125#define EXT4_EXT_CACHE_EXTENT   2
 126
 127
 128#define EXT_MAX_BLOCK   0xffffffff
 129
 130/*
 131 * EXT_INIT_MAX_LEN is the maximum number of blocks we can have in an
 132 * initialized extent. This is 2^15 and not (2^16 - 1), since we use the
 133 * MSB of ee_len field in the extent datastructure to signify if this
 134 * particular extent is an initialized extent or an uninitialized (i.e.
 135 * preallocated).
 136 * EXT_UNINIT_MAX_LEN is the maximum number of blocks we can have in an
 137 * uninitialized extent.
 138 * If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an
 139 * uninitialized one. In other words, if MSB of ee_len is set, it is an
 140 * uninitialized extent with only one special scenario when ee_len = 0x8000.
 141 * In this case we can not have an uninitialized extent of zero length and
 142 * thus we make it as a special case of initialized extent with 0x8000 length.
 143 * This way we get better extent-to-group alignment for initialized extents.
 144 * Hence, the maximum number of blocks we can have in an *initialized*
 145 * extent is 2^15 (32768) and in an *uninitialized* extent is 2^15-1 (32767).
 146 */
 147#define EXT_INIT_MAX_LEN        (1UL << 15)
 148#define EXT_UNINIT_MAX_LEN      (EXT_INIT_MAX_LEN - 1)
 149
 150
 151#define EXT_FIRST_EXTENT(__hdr__) \
 152        ((struct ext4_extent *) (((char *) (__hdr__)) +         \
 153                                 sizeof(struct ext4_extent_header)))
 154#define EXT_FIRST_INDEX(__hdr__) \
 155        ((struct ext4_extent_idx *) (((char *) (__hdr__)) +     \
 156                                     sizeof(struct ext4_extent_header)))
 157#define EXT_HAS_FREE_INDEX(__path__) \
 158        (le16_to_cpu((__path__)->p_hdr->eh_entries) \
 159                                     < le16_to_cpu((__path__)->p_hdr->eh_max))
 160#define EXT_LAST_EXTENT(__hdr__) \
 161        (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
 162#define EXT_LAST_INDEX(__hdr__) \
 163        (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
 164#define EXT_MAX_EXTENT(__hdr__) \
 165        (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
 166#define EXT_MAX_INDEX(__hdr__) \
 167        (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
 168
 169static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode)
 170{
 171        return (struct ext4_extent_header *) EXT4_I(inode)->i_data;
 172}
 173
 174static inline struct ext4_extent_header *ext_block_hdr(struct buffer_head *bh)
 175{
 176        return (struct ext4_extent_header *) bh->b_data;
 177}
 178
 179static inline unsigned short ext_depth(struct inode *inode)
 180{
 181        return le16_to_cpu(ext_inode_hdr(inode)->eh_depth);
 182}
 183
 184static inline void ext4_ext_tree_changed(struct inode *inode)
 185{
 186        EXT4_I(inode)->i_ext_generation++;
 187}
 188
 189static inline void
 190ext4_ext_invalidate_cache(struct inode *inode)
 191{
 192        EXT4_I(inode)->i_cached_extent.ec_type = EXT4_EXT_CACHE_NO;
 193}
 194
 195static inline void ext4_ext_mark_uninitialized(struct ext4_extent *ext)
 196{
 197        /* We can not have an uninitialized extent of zero length! */
 198        BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0);
 199        ext->ee_len |= cpu_to_le16(EXT_INIT_MAX_LEN);
 200}
 201
 202static inline int ext4_ext_is_uninitialized(struct ext4_extent *ext)
 203{
 204        /* Extent with ee_len of 0x8000 is treated as an initialized extent */
 205        return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN);
 206}
 207
 208static inline int ext4_ext_get_actual_len(struct ext4_extent *ext)
 209{
 210        return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ?
 211                le16_to_cpu(ext->ee_len) :
 212                (le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN));
 213}
 214
 215extern ext4_fsblk_t idx_pblock(struct ext4_extent_idx *);
 216extern void ext4_ext_store_pblock(struct ext4_extent *, ext4_fsblk_t);
 217extern int ext4_extent_tree_init(handle_t *, struct inode *);
 218extern int ext4_ext_calc_credits_for_insert(struct inode *, struct ext4_ext_path *);
 219extern int ext4_ext_try_to_merge(struct inode *inode,
 220                                 struct ext4_ext_path *path,
 221                                 struct ext4_extent *);
 222extern unsigned int ext4_ext_check_overlap(struct inode *, struct ext4_extent *, struct ext4_ext_path *);
 223extern int ext4_ext_insert_extent(handle_t *, struct inode *, struct ext4_ext_path *, struct ext4_extent *);
 224extern struct ext4_ext_path *ext4_ext_find_extent(struct inode *, ext4_lblk_t,
 225                                                        struct ext4_ext_path *);
 226extern int ext4_ext_search_left(struct inode *, struct ext4_ext_path *,
 227                                                ext4_lblk_t *, ext4_fsblk_t *);
 228extern int ext4_ext_search_right(struct inode *, struct ext4_ext_path *,
 229                                                ext4_lblk_t *, ext4_fsblk_t *);
 230extern void ext4_ext_drop_refs(struct ext4_ext_path *);
 231#endif /* _LINUX_EXT4_EXTENTS */
 232
 233