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