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/marker.h>
  23 #include <linux/mutex.h>
  24 #include "ext4_jbd2.h"
  25 #include "ext4.h"
  26 #include "group.h"
  27
  28 /*
  29  * with AGGRESSIVE_CHECK allocator runs consistency checks over
  30  * structures. these checks slow things down a lot
  31  */
  32 #define AGGRESSIVE_CHECK__
  33
  34 /*
  35  * with DOUBLE_CHECK defined mballoc creates persistent in-core
  36  * bitmaps, maintains and uses them to check for double allocations
  37  */
  38 #define DOUBLE_CHECK__
  39
  40 /*
  41  */
  42 #define MB_DEBUG__
  43 #ifdef MB_DEBUG
  44 #define mb_debug(fmt, a...)     printk(fmt, ##a)
  45 #else
  46 #define mb_debug(fmt, a...)
  47 #endif
  48
  49 /*
  50  * with EXT4_MB_HISTORY mballoc stores last N allocations in memory
  51  * and you can monitor it in /proc/fs/ext4/<dev>/mb_history
  52  */
  53 #define EXT4_MB_HISTORY
  54 #define EXT4_MB_HISTORY_ALLOC           1       /* allocation */
  55 #define EXT4_MB_HISTORY_PREALLOC        2       /* preallocated blocks used */
  56 #define EXT4_MB_HISTORY_DISCARD         4       /* preallocation discarded */
  57 #define EXT4_MB_HISTORY_FREE            8       /* free */
  58
  59 #define EXT4_MB_HISTORY_DEFAULT         (EXT4_MB_HISTORY_ALLOC | \
  60                                          EXT4_MB_HISTORY_PREALLOC)
  61
  62 /*
  63  * How long mballoc can look for a best extent (in found extents)
  64  */
  65 #define MB_DEFAULT_MAX_TO_SCAN          200
  66
  67 /*
  68  * How long mballoc must look for a best extent
  69  */
  70 #define MB_DEFAULT_MIN_TO_SCAN          10
  71
  72 /*
  73  * How many groups mballoc will scan looking for the best chunk
  74  */
  75 #define MB_DEFAULT_MAX_GROUPS_TO_SCAN   5
  76
  77 /*
  78  * with 'ext4_mb_stats' allocator will collect stats that will be
  79  * shown at umount. The collecting costs though!
  80  */
  81 #define MB_DEFAULT_STATS                1
  82
  83 /*
  84  * files smaller than MB_DEFAULT_STREAM_THRESHOLD are served
  85  * by the stream allocator, which purpose is to pack requests
  86  * as close each to other as possible to produce smooth I/O traffic
  87  * We use locality group prealloc space for stream request.
  88  * We can tune the same via /proc/fs/ext4/<parition>/stream_req
  89  */
  90 #define MB_DEFAULT_STREAM_THRESHOLD     16      /* 64K */
  91
  92 /*
  93  * for which requests use 2^N search using buddies
  94  */
  95 #define MB_DEFAULT_ORDER2_REQS          2
  96
  97 /*
  98  * default group prealloc size 512 blocks
  99  */
 100 #define MB_DEFAULT_GROUP_PREALLOC       512
 101
 102
 103 struct ext4_free_data {
 104         /* this links the free block information from group_info */
 105         struct rb_node node;
 106
 107         /* this links the free block information from ext4_sb_info */
 108         struct list_head list;
 109
 110         /* group which free block extent belongs */
 111         ext4_group_t group;
 112
 113         /* free block extent */
 114         ext4_grpblk_t start_blk;
 115         ext4_grpblk_t count;
 116
 117         /* transaction which freed this extent */
 118         tid_t   t_tid;
 119 };
 120
 121 struct ext4_prealloc_space {
 122         struct list_head        pa_inode_list;
 123         struct list_head        pa_group_list;
 124         union {
 125                 struct list_head pa_tmp_list;
 126                 struct rcu_head pa_rcu;
 127         } u;
 128         spinlock_t              pa_lock;
 129         atomic_t                pa_count;
 130         unsigned                pa_deleted;
 131         ext4_fsblk_t            pa_pstart;      /* phys. block */
 132         ext4_lblk_t             pa_lstart;      /* log. block */
 133         unsigned short          pa_len;         /* len of preallocated chunk */
 134         unsigned short          pa_free;        /* how many blocks are free */
 135         unsigned short          pa_type;        /* pa type. inode or group */
 136         spinlock_t              *pa_obj_lock;
 137         struct inode            *pa_inode;      /* hack, for history only */
 138 };
 139
 140 enum {
 141         MB_INODE_PA = 0,
 142         MB_GROUP_PA = 1
 143 };
 144
 145 struct ext4_free_extent {
 146         ext4_lblk_t fe_logical;
 147         ext4_grpblk_t fe_start;
 148         ext4_group_t fe_group;
 149         int fe_len;
 150 };
 151
 152 /*
 153  * Locality group:
 154  *   we try to group all related changes together
 155  *   so that writeback can flush/allocate them together as well
 156  *   Size of lg_prealloc_list hash is determined by MB_DEFAULT_GROUP_PREALLOC
 157  *   (512). We store prealloc space into the hash based on the pa_free blocks
 158  *   order value.ie, fls(pa_free)-1;
 159  */
 160 #define PREALLOC_TB_SIZE 10
 161 struct ext4_locality_group {
 162         /* for allocator */
 163         /* to serialize allocates */
 164         struct mutex            lg_mutex;
 165         /* list of preallocations */
 166         struct list_head        lg_prealloc_list[PREALLOC_TB_SIZE];
 167         spinlock_t              lg_prealloc_lock;
 168 };
 169
 170 struct ext4_allocation_context {
 171         struct inode *ac_inode;
 172         struct super_block *ac_sb;
 173
 174         /* original request */
 175         struct ext4_free_extent ac_o_ex;
 176
 177         /* goal request (after normalization) */
 178         struct ext4_free_extent ac_g_ex;
 179
 180         /* the best found extent */
 181         struct ext4_free_extent ac_b_ex;
 182
 183         /* copy of the bext found extent taken before preallocation efforts */
 184         struct ext4_free_extent ac_f_ex;
 185
 186         /* number of iterations done. we have to track to limit searching */
 187         unsigned long ac_ex_scanned;
 188         __u16 ac_groups_scanned;
 189         __u16 ac_found;
 190         __u16 ac_tail;
 191         __u16 ac_buddy;
 192         __u16 ac_flags;         /* allocation hints */
 193         __u8 ac_status;
 194         __u8 ac_criteria;
 195         __u8 ac_repeats;
 196         __u8 ac_2order;         /* if request is to allocate 2^N blocks and
 197                                  * N > 0, the field stores N, otherwise 0 */
 198         __u8 ac_op;             /* operation, for history only */
 199         struct page *ac_bitmap_page;
 200         struct page *ac_buddy_page;
 201         /*
 202          * pointer to the held semaphore upon successful
 203          * block allocation
 204          */
 205         struct rw_semaphore *alloc_semp;
 206         struct ext4_prealloc_space *ac_pa;
 207         struct ext4_locality_group *ac_lg;
 208 };
 209
 210 #define AC_STATUS_CONTINUE      1
 211 #define AC_STATUS_FOUND         2
 212 #define AC_STATUS_BREAK         3
 213
 214 struct ext4_mb_history {
 215         struct ext4_free_extent orig;   /* orig allocation */
 216         struct ext4_free_extent goal;   /* goal allocation */
 217         struct ext4_free_extent result; /* result allocation */
 218         unsigned pid;
 219         unsigned ino;
 220         __u16 found;    /* how many extents have been found */
 221         __u16 groups;   /* how many groups have been scanned */
 222         __u16 tail;     /* what tail broke some buddy */
 223         __u16 buddy;    /* buddy the tail ^^^ broke */
 224         __u16 flags;
 225         __u8 cr:3;      /* which phase the result extent was found at */
 226         __u8 op:4;
 227         __u8 merged:1;
 228 };
 229
 230 struct ext4_buddy {
 231         struct page *bd_buddy_page;
 232         void *bd_buddy;
 233         struct page *bd_bitmap_page;
 234         void *bd_bitmap;
 235         struct ext4_group_info *bd_info;
 236         struct super_block *bd_sb;
 237         __u16 bd_blkbits;
 238         ext4_group_t bd_group;
 239         struct rw_semaphore *alloc_semp;
 240 };
 241 #define EXT4_MB_BITMAP(e4b)     ((e4b)->bd_bitmap)
 242 #define EXT4_MB_BUDDY(e4b)      ((e4b)->bd_buddy)
 243
 244 #ifndef EXT4_MB_HISTORY
 245 static inline void ext4_mb_store_history(struct ext4_allocation_context *ac)
 246 {
 247         return;
 248 }
 249 #endif
 250
 251 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
 252
 253 static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
 254                                         struct ext4_free_extent *fex)
 255 {
 256         ext4_fsblk_t block;
 257
 258         block = (ext4_fsblk_t) fex->fe_group * EXT4_BLOCKS_PER_GROUP(sb)
 259                         + fex->fe_start
 260                         + le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block);
 261         return block;
 262 }
 263 #endif