LXR linux/fs/ext4/mballoc.h

   1/*
   2 *  fs/ext4/mballoc.h
   3 *
   4 *  Written by: Alex Tomas <alex@clusterfs.com>
   5 *
   6 */
   7#ifndef _EXT4_MBALLOC_H
   8#define _EXT4_MBALLOC_H
   9
  10#include <linux/time.h>
  11#include <linux/fs.h>
  12#include <linux/namei.h>
  13#include <linux/quotaops.h>
  14#include <linux/buffer_head.h>
  15#include <linux/module.h>
  16#include <linux/swap.h>
  17#include <linux/proc_fs.h>
  18#include <linux/pagemap.h>
  19#include <linux/seq_file.h>
  20#include <linux/blkdev.h>
  21#include <linux/mutex.h>
  22#include "ext4_jbd2.h"
  23#include "ext4.h"
  24
  25/*
  26 */
  27#ifdef CONFIG_EXT4_DEBUG
  28extern ushort ext4_mballoc_debug;
  29
  30#define mb_debug(n, fmt, a...)                                          \
  31        do {                                                            \
  32                if ((n) <= ext4_mballoc_debug) {                        \
  33                        printk(KERN_DEBUG "(%s, %d): %s: ",             \
  34                               __FILE__, __LINE__, __func__);           \
  35                        printk(fmt, ## a);                              \
  36                }                                                       \
  37        } while (0)
  38#else
  39#define mb_debug(n, fmt, a...)          no_printk(fmt, ## a)
  40#endif
  41
  42#define EXT4_MB_HISTORY_ALLOC           1       /* allocation */
  43#define EXT4_MB_HISTORY_PREALLOC        2       /* preallocated blocks used */
  44
  45/*
  46 * How long mballoc can look for a best extent (in found extents)
  47 */
  48#define MB_DEFAULT_MAX_TO_SCAN          200
  49
  50/*
  51 * How long mballoc must look for a best extent
  52 */
  53#define MB_DEFAULT_MIN_TO_SCAN          10
  54
  55/*
  56 * with 'ext4_mb_stats' allocator will collect stats that will be
  57 * shown at umount. The collecting costs though!
  58 */
  59#define MB_DEFAULT_STATS                0
  60
  61/*
  62 * files smaller than MB_DEFAULT_STREAM_THRESHOLD are served
  63 * by the stream allocator, which purpose is to pack requests
  64 * as close each to other as possible to produce smooth I/O traffic
  65 * We use locality group prealloc space for stream request.
  66 * We can tune the same via /proc/fs/ext4/<parition>/stream_req
  67 */
  68#define MB_DEFAULT_STREAM_THRESHOLD     16      /* 64K */
  69
  70/*
  71 * for which requests use 2^N search using buddies
  72 */
  73#define MB_DEFAULT_ORDER2_REQS          2
  74
  75/*
  76 * default group prealloc size 512 blocks
  77 */
  78#define MB_DEFAULT_GROUP_PREALLOC       512
  79
  80
  81struct ext4_free_data {
  82        /* MUST be the first member */
  83        struct ext4_journal_cb_entry    efd_jce;
  84
  85        /* ext4_free_data private data starts from here */
  86
  87        /* this links the free block information from group_info */
  88        struct rb_node                  efd_node;
  89
  90        /* group which free block extent belongs */
  91        ext4_group_t                    efd_group;
  92
  93        /* free block extent */
  94        ext4_grpblk_t                   efd_start_cluster;
  95        ext4_grpblk_t                   efd_count;
  96
  97        /* transaction which freed this extent */
  98        tid_t                           efd_tid;
  99};
 100
 101struct ext4_prealloc_space {
 102        struct list_head        pa_inode_list;
 103        struct list_head        pa_group_list;
 104        union {
 105                struct list_head pa_tmp_list;
 106                struct rcu_head pa_rcu;
 107        } u;
 108        spinlock_t              pa_lock;
 109        atomic_t                pa_count;
 110        unsigned                pa_deleted;
 111        ext4_fsblk_t            pa_pstart;      /* phys. block */
 112        ext4_lblk_t             pa_lstart;      /* log. block */
 113        ext4_grpblk_t           pa_len;         /* len of preallocated chunk */
 114        ext4_grpblk_t           pa_free;        /* how many blocks are free */
 115        unsigned short          pa_type;        /* pa type. inode or group */
 116        spinlock_t              *pa_obj_lock;
 117        struct inode            *pa_inode;      /* hack, for history only */
 118};
 119
 120enum {
 121        MB_INODE_PA = 0,
 122        MB_GROUP_PA = 1
 123};
 124
 125struct ext4_free_extent {
 126        ext4_lblk_t fe_logical;
 127        ext4_grpblk_t fe_start; /* In cluster units */
 128        ext4_group_t fe_group;
 129        ext4_grpblk_t fe_len;   /* In cluster units */
 130};
 131
 132/*
 133 * Locality group:
 134 *   we try to group all related changes together
 135 *   so that writeback can flush/allocate them together as well
 136 *   Size of lg_prealloc_list hash is determined by MB_DEFAULT_GROUP_PREALLOC
 137 *   (512). We store prealloc space into the hash based on the pa_free blocks
 138 *   order value.ie, fls(pa_free)-1;
 139 */
 140#define PREALLOC_TB_SIZE 10
 141struct ext4_locality_group {
 142        /* for allocator */
 143        /* to serialize allocates */
 144        struct mutex            lg_mutex;
 145        /* list of preallocations */
 146        struct list_head        lg_prealloc_list[PREALLOC_TB_SIZE];
 147        spinlock_t              lg_prealloc_lock;
 148};
 149
 150struct ext4_allocation_context {
 151        struct inode *ac_inode;
 152        struct super_block *ac_sb;
 153
 154        /* original request */
 155        struct ext4_free_extent ac_o_ex;
 156
 157        /* goal request (normalized ac_o_ex) */
 158        struct ext4_free_extent ac_g_ex;
 159
 160        /* the best found extent */
 161        struct ext4_free_extent ac_b_ex;
 162
 163        /* copy of the best found extent taken before preallocation efforts */
 164        struct ext4_free_extent ac_f_ex;
 165
 166        __u16 ac_groups_scanned;
 167        __u16 ac_found;
 168        __u16 ac_tail;
 169        __u16 ac_buddy;
 170        __u16 ac_flags;         /* allocation hints */
 171        __u8 ac_status;
 172        __u8 ac_criteria;
 173        __u8 ac_2order;         /* if request is to allocate 2^N blocks and
 174                                 * N > 0, the field stores N, otherwise 0 */
 175        __u8 ac_op;             /* operation, for history only */
 176        struct page *ac_bitmap_page;
 177        struct page *ac_buddy_page;
 178        struct ext4_prealloc_space *ac_pa;
 179        struct ext4_locality_group *ac_lg;
 180};
 181
 182#define AC_STATUS_CONTINUE      1
 183#define AC_STATUS_FOUND         2
 184#define AC_STATUS_BREAK         3
 185
 186struct ext4_buddy {
 187        struct page *bd_buddy_page;
 188        void *bd_buddy;
 189        struct page *bd_bitmap_page;
 190        void *bd_bitmap;
 191        struct ext4_group_info *bd_info;
 192        struct super_block *bd_sb;
 193        __u16 bd_blkbits;
 194        ext4_group_t bd_group;
 195};
 196
 197static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
 198                                        struct ext4_free_extent *fex)
 199{
 200        return ext4_group_first_block_no(sb, fex->fe_group) +
 201                (fex->fe_start << EXT4_SB(sb)->s_cluster_bits);
 202}
 203#endif
 204