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/version.h>
  21 #include <linux/blkdev.h>
  22 #include <linux/mutex.h>
  23 #include "ext4_jbd2.h"
  24 #include "ext4.h"
  25
  26 /*
  27  * with AGGRESSIVE_CHECK allocator runs consistency checks over
  28  * structures. these checks slow things down a lot
  29  */
  30 #define AGGRESSIVE_CHECK__
  31
  32 /*
  33  * with DOUBLE_CHECK defined mballoc creates persistent in-core
  34  * bitmaps, maintains and uses them to check for double allocations
  35  */
  36 #define DOUBLE_CHECK__
  37
  38 /*
  39  */
  40 #ifdef CONFIG_EXT4_DEBUG
  41 extern u8 mb_enable_debug;
  42
  43 #define mb_debug(n, fmt, a...)                                          \
  44         do {                                                            \
  45                 if ((n) <= mb_enable_debug) {                           \
  46                         printk(KERN_DEBUG "(%s, %d): %s: ",             \
  47                                __FILE__, __LINE__, __func__);           \
  48                         printk(fmt, ## a);                              \
  49                 }                                                       \
  50         } while (0)
  51 #else
  52 #define mb_debug(n, fmt, a...)
  53 #endif
  54
  55 #define EXT4_MB_HISTORY_ALLOC           1       /* allocation */
  56 #define EXT4_MB_HISTORY_PREALLOC        2       /* preallocated blocks used */
  57
  58 /*
  59  * How long mballoc can look for a best extent (in found extents)
  60  */
  61 #define MB_DEFAULT_MAX_TO_SCAN          200
  62
  63 /*
  64  * How long mballoc must look for a best extent
  65  */
  66 #define MB_DEFAULT_MIN_TO_SCAN          10
  67
  68 /*
  69  * How many groups mballoc will scan looking for the best chunk
  70  */
  71 #define MB_DEFAULT_MAX_GROUPS_TO_SCAN   5
  72
  73 /*
  74  * with 'ext4_mb_stats' allocator will collect stats that will be
  75  * shown at umount. The collecting costs though!
  76  */
  77 #define MB_DEFAULT_STATS                0
  78
  79 /*
  80  * files smaller than MB_DEFAULT_STREAM_THRESHOLD are served
  81  * by the stream allocator, which purpose is to pack requests
  82  * as close each to other as possible to produce smooth I/O traffic
  83  * We use locality group prealloc space for stream request.
  84  * We can tune the same via /proc/fs/ext4/<parition>/stream_req
  85  */
  86 #define MB_DEFAULT_STREAM_THRESHOLD     16      /* 64K */
  87
  88 /*
  89  * for which requests use 2^N search using buddies
  90  */
  91 #define MB_DEFAULT_ORDER2_REQS          2
  92
  93 /*
  94  * default group prealloc size 512 blocks
  95  */
  96 #define MB_DEFAULT_GROUP_PREALLOC       512
  97
  98
  99 struct ext4_free_data {
 100         /* this links the free block information from group_info */
 101         struct rb_node node;
 102
 103         /* this links the free block information from ext4_sb_info */
 104         struct list_head list;
 105
 106         /* group which free block extent belongs */
 107         ext4_group_t group;
 108
 109         /* free block extent */
 110         ext4_grpblk_t start_blk;
 111         ext4_grpblk_t count;
 112
 113         /* transaction which freed this extent */
 114         tid_t   t_tid;
 115 };
 116
 117 struct ext4_prealloc_space {
 118         struct list_head        pa_inode_list;
 119         struct list_head        pa_group_list;
 120         union {
 121                 struct list_head pa_tmp_list;
 122                 struct rcu_head pa_rcu;
 123         } u;
 124         spinlock_t              pa_lock;
 125         atomic_t                pa_count;
 126         unsigned                pa_deleted;
 127         ext4_fsblk_t            pa_pstart;      /* phys. block */
 128         ext4_lblk_t             pa_lstart;      /* log. block */
 129         ext4_grpblk_t           pa_len;         /* len of preallocated chunk */
 130         ext4_grpblk_t           pa_free;        /* how many blocks are free */
 131         unsigned short          pa_type;        /* pa type. inode or group */
 132         spinlock_t              *pa_obj_lock;
 133         struct inode            *pa_inode;      /* hack, for history only */
 134 };
 135
 136 enum {
 137         MB_INODE_PA = 0,
 138         MB_GROUP_PA = 1
 139 };
 140
 141 struct ext4_free_extent {
 142         ext4_lblk_t fe_logical;
 143         ext4_grpblk_t fe_start;
 144         ext4_group_t fe_group;
 145         ext4_grpblk_t fe_len;
 146 };
 147
 148 /*
 149  * Locality group:
 150  *   we try to group all related changes together
 151  *   so that writeback can flush/allocate them together as well
 152  *   Size of lg_prealloc_list hash is determined by MB_DEFAULT_GROUP_PREALLOC
 153  *   (512). We store prealloc space into the hash based on the pa_free blocks
 154  *   order value.ie, fls(pa_free)-1;
 155  */
 156 #define PREALLOC_TB_SIZE 10
 157 struct ext4_locality_group {
 158         /* for allocator */
 159         /* to serialize allocates */
 160         struct mutex            lg_mutex;
 161         /* list of preallocations */
 162         struct list_head        lg_prealloc_list[PREALLOC_TB_SIZE];
 163         spinlock_t              lg_prealloc_lock;
 164 };
 165
 166 struct ext4_allocation_context {
 167         struct inode *ac_inode;
 168         struct super_block *ac_sb;
 169
 170         /* original request */
 171         struct ext4_free_extent ac_o_ex;
 172
 173         /* goal request (after normalization) */
 174         struct ext4_free_extent ac_g_ex;
 175
 176         /* the best found extent */
 177         struct ext4_free_extent ac_b_ex;
 178
 179         /* copy of the bext found extent taken before preallocation efforts */
 180         struct ext4_free_extent ac_f_ex;
 181
 182         /* number of iterations done. we have to track to limit searching */
 183         unsigned long ac_ex_scanned;
 184         __u16 ac_groups_scanned;
 185         __u16 ac_found;
 186         __u16 ac_tail;
 187         __u16 ac_buddy;
 188         __u16 ac_flags;         /* allocation hints */
 189         __u8 ac_status;
 190         __u8 ac_criteria;
 191         __u8 ac_repeats;
 192         __u8 ac_2order;         /* if request is to allocate 2^N blocks and
 193                                  * N > 0, the field stores N, otherwise 0 */
 194         __u8 ac_op;             /* operation, for history only */
 195         struct page *ac_bitmap_page;
 196         struct page *ac_buddy_page;
 197         /*
 198          * pointer to the held semaphore upon successful
 199          * block allocation
 200          */
 201         struct rw_semaphore *alloc_semp;
 202         struct ext4_prealloc_space *ac_pa;
 203         struct ext4_locality_group *ac_lg;
 204 };
 205
 206 #define AC_STATUS_CONTINUE      1
 207 #define AC_STATUS_FOUND         2
 208 #define AC_STATUS_BREAK         3
 209
 210 struct ext4_buddy {
 211         struct page *bd_buddy_page;
 212         void *bd_buddy;
 213         struct page *bd_bitmap_page;
 214         void *bd_bitmap;
 215         struct ext4_group_info *bd_info;
 216         struct super_block *bd_sb;
 217         __u16 bd_blkbits;
 218         ext4_group_t bd_group;
 219         struct rw_semaphore *alloc_semp;
 220 };
 221 #define EXT4_MB_BITMAP(e4b)     ((e4b)->bd_bitmap)
 222 #define EXT4_MB_BUDDY(e4b)      ((e4b)->bd_buddy)
 223
 224 static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
 225                                         struct ext4_free_extent *fex)
 226 {
 227         ext4_fsblk_t block;
 228
 229         block = (ext4_fsblk_t) fex->fe_group * EXT4_BLOCKS_PER_GROUP(sb)
 230                         + fex->fe_start
 231                         + le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block);
 232         return block;
 233 }
 234 #endif