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 /*
  56  * with EXT4_MB_HISTORY mballoc stores last N allocations in memory
  57  * and you can monitor it in /proc/fs/ext4/<dev>/mb_history
  58  */
  59 #define EXT4_MB_HISTORY
  60 #define EXT4_MB_HISTORY_ALLOC           1       /* allocation */
  61 #define EXT4_MB_HISTORY_PREALLOC        2       /* preallocated blocks used */
  62 #define EXT4_MB_HISTORY_DISCARD         4       /* preallocation discarded */
  63 #define EXT4_MB_HISTORY_FREE            8       /* free */
  64
  65 #define EXT4_MB_HISTORY_DEFAULT         (EXT4_MB_HISTORY_ALLOC | \
  66                                          EXT4_MB_HISTORY_PREALLOC)
  67
  68 /*
  69  * How long mballoc can look for a best extent (in found extents)
  70  */
  71 #define MB_DEFAULT_MAX_TO_SCAN          200
  72
  73 /*
  74  * How long mballoc must look for a best extent
  75  */
  76 #define MB_DEFAULT_MIN_TO_SCAN          10
  77
  78 /*
  79  * How many groups mballoc will scan looking for the best chunk
  80  */
  81 #define MB_DEFAULT_MAX_GROUPS_TO_SCAN   5
  82
  83 /*
  84  * with 'ext4_mb_stats' allocator will collect stats that will be
  85  * shown at umount. The collecting costs though!
  86  */
  87 #define MB_DEFAULT_STATS                1
  88
  89 /*
  90  * files smaller than MB_DEFAULT_STREAM_THRESHOLD are served
  91  * by the stream allocator, which purpose is to pack requests
  92  * as close each to other as possible to produce smooth I/O traffic
  93  * We use locality group prealloc space for stream request.
  94  * We can tune the same via /proc/fs/ext4/<parition>/stream_req
  95  */
  96 #define MB_DEFAULT_STREAM_THRESHOLD     16      /* 64K */
  97
  98 /*
  99  * for which requests use 2^N search using buddies
 100  */
 101 #define MB_DEFAULT_ORDER2_REQS          2
 102
 103 /*
 104  * default group prealloc size 512 blocks
 105  */
 106 #define MB_DEFAULT_GROUP_PREALLOC       512
 107
 108
 109 struct ext4_free_data {
 110         /* this links the free block information from group_info */
 111         struct rb_node node;
 112
 113         /* this links the free block information from ext4_sb_info */
 114         struct list_head list;
 115
 116         /* group which free block extent belongs */
 117         ext4_group_t group;
 118
 119         /* free block extent */
 120         ext4_grpblk_t start_blk;
 121         ext4_grpblk_t count;
 122
 123         /* transaction which freed this extent */
 124         tid_t   t_tid;
 125 };
 126
 127 struct ext4_prealloc_space {
 128         struct list_head        pa_inode_list;
 129         struct list_head        pa_group_list;
 130         union {
 131                 struct list_head pa_tmp_list;
 132                 struct rcu_head pa_rcu;
 133         } u;
 134         spinlock_t              pa_lock;
 135         atomic_t                pa_count;
 136         unsigned                pa_deleted;
 137         ext4_fsblk_t            pa_pstart;      /* phys. block */
 138         ext4_lblk_t             pa_lstart;      /* log. block */
 139         ext4_grpblk_t           pa_len;         /* len of preallocated chunk */
 140         ext4_grpblk_t           pa_free;        /* how many blocks are free */
 141         unsigned short          pa_type;        /* pa type. inode or group */
 142         spinlock_t              *pa_obj_lock;
 143         struct inode            *pa_inode;      /* hack, for history only */
 144 };
 145
 146 enum {
 147         MB_INODE_PA = 0,
 148         MB_GROUP_PA = 1
 149 };
 150
 151 struct ext4_free_extent {
 152         ext4_lblk_t fe_logical;
 153         ext4_grpblk_t fe_start;
 154         ext4_group_t fe_group;
 155         ext4_grpblk_t fe_len;
 156 };
 157
 158 /*
 159  * Locality group:
 160  *   we try to group all related changes together
 161  *   so that writeback can flush/allocate them together as well
 162  *   Size of lg_prealloc_list hash is determined by MB_DEFAULT_GROUP_PREALLOC
 163  *   (512). We store prealloc space into the hash based on the pa_free blocks
 164  *   order value.ie, fls(pa_free)-1;
 165  */
 166 #define PREALLOC_TB_SIZE 10
 167 struct ext4_locality_group {
 168         /* for allocator */
 169         /* to serialize allocates */
 170         struct mutex            lg_mutex;
 171         /* list of preallocations */
 172         struct list_head        lg_prealloc_list[PREALLOC_TB_SIZE];
 173         spinlock_t              lg_prealloc_lock;
 174 };
 175
 176 struct ext4_allocation_context {
 177         struct inode *ac_inode;
 178         struct super_block *ac_sb;
 179
 180         /* original request */
 181         struct ext4_free_extent ac_o_ex;
 182
 183         /* goal request (after normalization) */
 184         struct ext4_free_extent ac_g_ex;
 185
 186         /* the best found extent */
 187         struct ext4_free_extent ac_b_ex;
 188
 189         /* copy of the bext found extent taken before preallocation efforts */
 190         struct ext4_free_extent ac_f_ex;
 191
 192         /* number of iterations done. we have to track to limit searching */
 193         unsigned long ac_ex_scanned;
 194         __u16 ac_groups_scanned;
 195         __u16 ac_found;
 196         __u16 ac_tail;
 197         __u16 ac_buddy;
 198         __u16 ac_flags;         /* allocation hints */
 199         __u8 ac_status;
 200         __u8 ac_criteria;
 201         __u8 ac_repeats;
 202         __u8 ac_2order;         /* if request is to allocate 2^N blocks and
 203                                  * N > 0, the field stores N, otherwise 0 */
 204         __u8 ac_op;             /* operation, for history only */
 205         struct page *ac_bitmap_page;
 206         struct page *ac_buddy_page;
 207         /*
 208          * pointer to the held semaphore upon successful
 209          * block allocation
 210          */
 211         struct rw_semaphore *alloc_semp;
 212         struct ext4_prealloc_space *ac_pa;
 213         struct ext4_locality_group *ac_lg;
 214 };
 215
 216 #define AC_STATUS_CONTINUE      1
 217 #define AC_STATUS_FOUND         2
 218 #define AC_STATUS_BREAK         3
 219
 220 struct ext4_mb_history {
 221         struct ext4_free_extent orig;   /* orig allocation */
 222         struct ext4_free_extent goal;   /* goal allocation */
 223         struct ext4_free_extent result; /* result allocation */
 224         unsigned pid;
 225         unsigned ino;
 226         __u16 found;    /* how many extents have been found */
 227         __u16 groups;   /* how many groups have been scanned */
 228         __u16 tail;     /* what tail broke some buddy */
 229         __u16 buddy;    /* buddy the tail ^^^ broke */
 230         __u16 flags;
 231         __u8 cr:3;      /* which phase the result extent was found at */
 232         __u8 op:4;
 233         __u8 merged:1;
 234 };
 235
 236 struct ext4_buddy {
 237         struct page *bd_buddy_page;
 238         void *bd_buddy;
 239         struct page *bd_bitmap_page;
 240         void *bd_bitmap;
 241         struct ext4_group_info *bd_info;
 242         struct super_block *bd_sb;
 243         __u16 bd_blkbits;
 244         ext4_group_t bd_group;
 245         struct rw_semaphore *alloc_semp;
 246 };
 247 #define EXT4_MB_BITMAP(e4b)     ((e4b)->bd_bitmap)
 248 #define EXT4_MB_BUDDY(e4b)      ((e4b)->bd_buddy)
 249
 250 #ifndef EXT4_MB_HISTORY
 251 static inline void ext4_mb_store_history(struct ext4_allocation_context *ac)
 252 {
 253         return;
 254 }
 255 #endif
 256
 257 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
 258
 259 static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
 260                                         struct ext4_free_extent *fex)
 261 {
 262         ext4_fsblk_t block;
 263
 264         block = (ext4_fsblk_t) fex->fe_group * EXT4_BLOCKS_PER_GROUP(sb)
 265                         + fex->fe_start
 266                         + le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block);
 267         return block;
 268 }
 269 #endif