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  * with AGGRESSIVE_CHECK allocator runs consistency checks over
  27  * structures. these checks slow things down a lot
  28  */
  29 #define AGGRESSIVE_CHECK__
  30
  31 /*
  32  * with DOUBLE_CHECK defined mballoc creates persistent in-core
  33  * bitmaps, maintains and uses them to check for double allocations
  34  */
  35 #define DOUBLE_CHECK__
  36
  37 /*
  38  */
  39 #ifdef CONFIG_EXT4_DEBUG
  40 extern u8 mb_enable_debug;
  41
  42 #define mb_debug(n, fmt, a...)                                          \
  43         do {                                                            \
  44                 if ((n) <= mb_enable_debug) {                           \
  45                         printk(KERN_DEBUG "(%s, %d): %s: ",             \
  46                                __FILE__, __LINE__, __func__);           \
  47                         printk(fmt, ## a);                              \
  48                 }                                                       \
  49         } while (0)
  50 #else
  51 #define mb_debug(n, fmt, a...)
  52 #endif
  53
  54 #define EXT4_MB_HISTORY_ALLOC           1       /* allocation */
  55 #define EXT4_MB_HISTORY_PREALLOC        2       /* preallocated blocks used */
  56
  57 /*
  58  * How long mballoc can look for a best extent (in found extents)
  59  */
  60 #define MB_DEFAULT_MAX_TO_SCAN          200
  61
  62 /*
  63  * How long mballoc must look for a best extent
  64  */
  65 #define MB_DEFAULT_MIN_TO_SCAN          10
  66
  67 /*
  68  * How many groups mballoc will scan looking for the best chunk
  69  */
  70 #define MB_DEFAULT_MAX_GROUPS_TO_SCAN   5
  71
  72 /*
  73  * with 'ext4_mb_stats' allocator will collect stats that will be
  74  * shown at umount. The collecting costs though!
  75  */
  76 #define MB_DEFAULT_STATS                0
  77
  78 /*
  79  * files smaller than MB_DEFAULT_STREAM_THRESHOLD are served
  80  * by the stream allocator, which purpose is to pack requests
  81  * as close each to other as possible to produce smooth I/O traffic
  82  * We use locality group prealloc space for stream request.
  83  * We can tune the same via /proc/fs/ext4/<parition>/stream_req
  84  */
  85 #define MB_DEFAULT_STREAM_THRESHOLD     16      /* 64K */
  86
  87 /*
  88  * for which requests use 2^N search using buddies
  89  */
  90 #define MB_DEFAULT_ORDER2_REQS          2
  91
  92 /*
  93  * default group prealloc size 512 blocks
  94  */
  95 #define MB_DEFAULT_GROUP_PREALLOC       512
  96
  97
  98 struct ext4_free_data {
  99         /* this links the free block information from group_info */
 100         struct rb_node node;
 101
 102         /* this links the free block information from ext4_sb_info */
 103         struct list_head list;
 104
 105         /* group which free block extent belongs */
 106         ext4_group_t group;
 107
 108         /* free block extent */
 109         ext4_grpblk_t start_blk;
 110         ext4_grpblk_t count;
 111
 112         /* transaction which freed this extent */
 113         tid_t   t_tid;
 114 };
 115
 116 struct ext4_prealloc_space {
 117         struct list_head        pa_inode_list;
 118         struct list_head        pa_group_list;
 119         union {
 120                 struct list_head pa_tmp_list;
 121                 struct rcu_head pa_rcu;
 122         } u;
 123         spinlock_t              pa_lock;
 124         atomic_t                pa_count;
 125         unsigned                pa_deleted;
 126         ext4_fsblk_t            pa_pstart;      /* phys. block */
 127         ext4_lblk_t             pa_lstart;      /* log. block */
 128         ext4_grpblk_t           pa_len;         /* len of preallocated chunk */
 129         ext4_grpblk_t           pa_free;        /* how many blocks are free */
 130         unsigned short          pa_type;        /* pa type. inode or group */
 131         spinlock_t              *pa_obj_lock;
 132         struct inode            *pa_inode;      /* hack, for history only */
 133 };
 134
 135 enum {
 136         MB_INODE_PA = 0,
 137         MB_GROUP_PA = 1
 138 };
 139
 140 struct ext4_free_extent {
 141         ext4_lblk_t fe_logical;
 142         ext4_grpblk_t fe_start;
 143         ext4_group_t fe_group;
 144         ext4_grpblk_t fe_len;
 145 };
 146
 147 /*
 148  * Locality group:
 149  *   we try to group all related changes together
 150  *   so that writeback can flush/allocate them together as well
 151  *   Size of lg_prealloc_list hash is determined by MB_DEFAULT_GROUP_PREALLOC
 152  *   (512). We store prealloc space into the hash based on the pa_free blocks
 153  *   order value.ie, fls(pa_free)-1;
 154  */
 155 #define PREALLOC_TB_SIZE 10
 156 struct ext4_locality_group {
 157         /* for allocator */
 158         /* to serialize allocates */
 159         struct mutex            lg_mutex;
 160         /* list of preallocations */
 161         struct list_head        lg_prealloc_list[PREALLOC_TB_SIZE];
 162         spinlock_t              lg_prealloc_lock;
 163 };
 164
 165 struct ext4_allocation_context {
 166         struct inode *ac_inode;
 167         struct super_block *ac_sb;
 168
 169         /* original request */
 170         struct ext4_free_extent ac_o_ex;
 171
 172         /* goal request (normalized ac_o_ex) */
 173         struct ext4_free_extent ac_g_ex;
 174
 175         /* the best found extent */
 176         struct ext4_free_extent ac_b_ex;
 177
 178         /* copy of the bext found extent taken before preallocation efforts */
 179         struct ext4_free_extent ac_f_ex;
 180
 181         /* number of iterations done. we have to track to limit searching */
 182         unsigned long ac_ex_scanned;
 183         __u16 ac_groups_scanned;
 184         __u16 ac_found;
 185         __u16 ac_tail;
 186         __u16 ac_buddy;
 187         __u16 ac_flags;         /* allocation hints */
 188         __u8 ac_status;
 189         __u8 ac_criteria;
 190         __u8 ac_repeats;
 191         __u8 ac_2order;         /* if request is to allocate 2^N blocks and
 192                                  * N > 0, the field stores N, otherwise 0 */
 193         __u8 ac_op;             /* operation, for history only */
 194         struct page *ac_bitmap_page;
 195         struct page *ac_buddy_page;
 196         /*
 197          * pointer to the held semaphore upon successful
 198          * block allocation
 199          */
 200         struct rw_semaphore *alloc_semp;
 201         struct ext4_prealloc_space *ac_pa;
 202         struct ext4_locality_group *ac_lg;
 203 };
 204
 205 #define AC_STATUS_CONTINUE      1
 206 #define AC_STATUS_FOUND         2
 207 #define AC_STATUS_BREAK         3
 208
 209 struct ext4_buddy {
 210         struct page *bd_buddy_page;
 211         void *bd_buddy;
 212         struct page *bd_bitmap_page;
 213         void *bd_bitmap;
 214         struct ext4_group_info *bd_info;
 215         struct super_block *bd_sb;
 216         __u16 bd_blkbits;
 217         ext4_group_t bd_group;
 218         struct rw_semaphore *alloc_semp;
 219 };
 220 #define EXT4_MB_BITMAP(e4b)     ((e4b)->bd_bitmap)
 221 #define EXT4_MB_BUDDY(e4b)      ((e4b)->bd_buddy)
 222
 223 static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
 224                                         struct ext4_free_extent *fex)
 225 {
 226         return ext4_group_first_block_no(sb, fex->fe_group) + fex->fe_start;
 227 }
 228 #endif