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 #define MB_DEBUG__
  41 #ifdef MB_DEBUG
  42 #define mb_debug(fmt, a...)     printk(fmt, ##a)
  43 #else
  44 #define mb_debug(fmt, a...)
  45 #endif
  46
  47 /*
  48  * with EXT4_MB_HISTORY mballoc stores last N allocations in memory
  49  * and you can monitor it in /proc/fs/ext4/<dev>/mb_history
  50  */
  51 #define EXT4_MB_HISTORY
  52 #define EXT4_MB_HISTORY_ALLOC           1       /* allocation */
  53 #define EXT4_MB_HISTORY_PREALLOC        2       /* preallocated blocks used */
  54 #define EXT4_MB_HISTORY_DISCARD         4       /* preallocation discarded */
  55 #define EXT4_MB_HISTORY_FREE            8       /* free */
  56
  57 #define EXT4_MB_HISTORY_DEFAULT         (EXT4_MB_HISTORY_ALLOC | \
  58                                          EXT4_MB_HISTORY_PREALLOC)
  59
  60 /*
  61  * How long mballoc can look for a best extent (in found extents)
  62  */
  63 #define MB_DEFAULT_MAX_TO_SCAN          200
  64
  65 /*
  66  * How long mballoc must look for a best extent
  67  */
  68 #define MB_DEFAULT_MIN_TO_SCAN          10
  69
  70 /*
  71  * How many groups mballoc will scan looking for the best chunk
  72  */
  73 #define MB_DEFAULT_MAX_GROUPS_TO_SCAN   5
  74
  75 /*
  76  * with 'ext4_mb_stats' allocator will collect stats that will be
  77  * shown at umount. The collecting costs though!
  78  */
  79 #define MB_DEFAULT_STATS                1
  80
  81 /*
  82  * files smaller than MB_DEFAULT_STREAM_THRESHOLD are served
  83  * by the stream allocator, which purpose is to pack requests
  84  * as close each to other as possible to produce smooth I/O traffic
  85  * We use locality group prealloc space for stream request.
  86  * We can tune the same via /proc/fs/ext4/<parition>/stream_req
  87  */
  88 #define MB_DEFAULT_STREAM_THRESHOLD     16      /* 64K */
  89
  90 /*
  91  * for which requests use 2^N search using buddies
  92  */
  93 #define MB_DEFAULT_ORDER2_REQS          2
  94
  95 /*
  96  * default group prealloc size 512 blocks
  97  */
  98 #define MB_DEFAULT_GROUP_PREALLOC       512
  99
 100
 101 struct ext4_free_data {
 102         /* this links the free block information from group_info */
 103         struct rb_node node;
 104
 105         /* this links the free block information from ext4_sb_info */
 106         struct list_head list;
 107
 108         /* group which free block extent belongs */
 109         ext4_group_t group;
 110
 111         /* free block extent */
 112         ext4_grpblk_t start_blk;
 113         ext4_grpblk_t count;
 114
 115         /* transaction which freed this extent */
 116         tid_t   t_tid;
 117 };
 118
 119 struct ext4_prealloc_space {
 120         struct list_head        pa_inode_list;
 121         struct list_head        pa_group_list;
 122         union {
 123                 struct list_head pa_tmp_list;
 124                 struct rcu_head pa_rcu;
 125         } u;
 126         spinlock_t              pa_lock;
 127         atomic_t                pa_count;
 128         unsigned                pa_deleted;
 129         ext4_fsblk_t            pa_pstart;      /* phys. block */
 130         ext4_lblk_t             pa_lstart;      /* log. block */
 131         unsigned short          pa_len;         /* len of preallocated chunk */
 132         unsigned short          pa_free;        /* how many blocks are free */
 133         unsigned short          pa_type;        /* pa type. inode or group */
 134         spinlock_t              *pa_obj_lock;
 135         struct inode            *pa_inode;      /* hack, for history only */
 136 };
 137
 138 enum {
 139         MB_INODE_PA = 0,
 140         MB_GROUP_PA = 1
 141 };
 142
 143 struct ext4_free_extent {
 144         ext4_lblk_t fe_logical;
 145         ext4_grpblk_t fe_start;
 146         ext4_group_t fe_group;
 147         int fe_len;
 148 };
 149
 150 /*
 151  * Locality group:
 152  *   we try to group all related changes together
 153  *   so that writeback can flush/allocate them together as well
 154  *   Size of lg_prealloc_list hash is determined by MB_DEFAULT_GROUP_PREALLOC
 155  *   (512). We store prealloc space into the hash based on the pa_free blocks
 156  *   order value.ie, fls(pa_free)-1;
 157  */
 158 #define PREALLOC_TB_SIZE 10
 159 struct ext4_locality_group {
 160         /* for allocator */
 161         /* to serialize allocates */
 162         struct mutex            lg_mutex;
 163         /* list of preallocations */
 164         struct list_head        lg_prealloc_list[PREALLOC_TB_SIZE];
 165         spinlock_t              lg_prealloc_lock;
 166 };
 167
 168 struct ext4_allocation_context {
 169         struct inode *ac_inode;
 170         struct super_block *ac_sb;
 171
 172         /* original request */
 173         struct ext4_free_extent ac_o_ex;
 174
 175         /* goal request (after normalization) */
 176         struct ext4_free_extent ac_g_ex;
 177
 178         /* the best found extent */
 179         struct ext4_free_extent ac_b_ex;
 180
 181         /* copy of the bext found extent taken before preallocation efforts */
 182         struct ext4_free_extent ac_f_ex;
 183
 184         /* number of iterations done. we have to track to limit searching */
 185         unsigned long ac_ex_scanned;
 186         __u16 ac_groups_scanned;
 187         __u16 ac_found;
 188         __u16 ac_tail;
 189         __u16 ac_buddy;
 190         __u16 ac_flags;         /* allocation hints */
 191         __u8 ac_status;
 192         __u8 ac_criteria;
 193         __u8 ac_repeats;
 194         __u8 ac_2order;         /* if request is to allocate 2^N blocks and
 195                                  * N > 0, the field stores N, otherwise 0 */
 196         __u8 ac_op;             /* operation, for history only */
 197         struct page *ac_bitmap_page;
 198         struct page *ac_buddy_page;
 199         /*
 200          * pointer to the held semaphore upon successful
 201          * block allocation
 202          */
 203         struct rw_semaphore *alloc_semp;
 204         struct ext4_prealloc_space *ac_pa;
 205         struct ext4_locality_group *ac_lg;
 206 };
 207
 208 #define AC_STATUS_CONTINUE      1
 209 #define AC_STATUS_FOUND         2
 210 #define AC_STATUS_BREAK         3
 211
 212 struct ext4_mb_history {
 213         struct ext4_free_extent orig;   /* orig allocation */
 214         struct ext4_free_extent goal;   /* goal allocation */
 215         struct ext4_free_extent result; /* result allocation */
 216         unsigned pid;
 217         unsigned ino;
 218         __u16 found;    /* how many extents have been found */
 219         __u16 groups;   /* how many groups have been scanned */
 220         __u16 tail;     /* what tail broke some buddy */
 221         __u16 buddy;    /* buddy the tail ^^^ broke */
 222         __u16 flags;
 223         __u8 cr:3;      /* which phase the result extent was found at */
 224         __u8 op:4;
 225         __u8 merged:1;
 226 };
 227
 228 struct ext4_buddy {
 229         struct page *bd_buddy_page;
 230         void *bd_buddy;
 231         struct page *bd_bitmap_page;
 232         void *bd_bitmap;
 233         struct ext4_group_info *bd_info;
 234         struct super_block *bd_sb;
 235         __u16 bd_blkbits;
 236         ext4_group_t bd_group;
 237         struct rw_semaphore *alloc_semp;
 238 };
 239 #define EXT4_MB_BITMAP(e4b)     ((e4b)->bd_bitmap)
 240 #define EXT4_MB_BUDDY(e4b)      ((e4b)->bd_buddy)
 241
 242 #ifndef EXT4_MB_HISTORY
 243 static inline void ext4_mb_store_history(struct ext4_allocation_context *ac)
 244 {
 245         return;
 246 }
 247 #endif
 248
 249 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
 250
 251 static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
 252                                         struct ext4_free_extent *fex)
 253 {
 254         ext4_fsblk_t block;
 255
 256         block = (ext4_fsblk_t) fex->fe_group * EXT4_BLOCKS_PER_GROUP(sb)
 257                         + fex->fe_start
 258                         + le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block);
 259         return block;
 260 }
 261 #endif