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_group_info {
 122         unsigned long   bb_state;
 123         struct rb_root  bb_free_root;
 124         unsigned short  bb_first_free;
 125         unsigned short  bb_free;
 126         unsigned short  bb_fragments;
 127         struct          list_head bb_prealloc_list;
 128 #ifdef DOUBLE_CHECK
 129         void            *bb_bitmap;
 130 #endif
 131         struct rw_semaphore alloc_sem;
 132         unsigned short  bb_counters[];
 133 };
 134
 135 #define EXT4_GROUP_INFO_NEED_INIT_BIT   0
 136 #define EXT4_GROUP_INFO_LOCKED_BIT      1
 137
 138 #define EXT4_MB_GRP_NEED_INIT(grp)      \
 139         (test_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &((grp)->bb_state)))
 140
 141
 142 struct ext4_prealloc_space {
 143         struct list_head        pa_inode_list;
 144         struct list_head        pa_group_list;
 145         union {
 146                 struct list_head pa_tmp_list;
 147                 struct rcu_head pa_rcu;
 148         } u;
 149         spinlock_t              pa_lock;
 150         atomic_t                pa_count;
 151         unsigned                pa_deleted;
 152         ext4_fsblk_t            pa_pstart;      /* phys. block */
 153         ext4_lblk_t             pa_lstart;      /* log. block */
 154         unsigned short          pa_len;         /* len of preallocated chunk */
 155         unsigned short          pa_free;        /* how many blocks are free */
 156         unsigned short          pa_linear;      /* consumed in one direction
 157                                                  * strictly, for grp prealloc */
 158         spinlock_t              *pa_obj_lock;
 159         struct inode            *pa_inode;      /* hack, for history only */
 160 };
 161
 162
 163 struct ext4_free_extent {
 164         ext4_lblk_t fe_logical;
 165         ext4_grpblk_t fe_start;
 166         ext4_group_t fe_group;
 167         int fe_len;
 168 };
 169
 170 /*
 171  * Locality group:
 172  *   we try to group all related changes together
 173  *   so that writeback can flush/allocate them together as well
 174  *   Size of lg_prealloc_list hash is determined by MB_DEFAULT_GROUP_PREALLOC
 175  *   (512). We store prealloc space into the hash based on the pa_free blocks
 176  *   order value.ie, fls(pa_free)-1;
 177  */
 178 #define PREALLOC_TB_SIZE 10
 179 struct ext4_locality_group {
 180         /* for allocator */
 181         /* to serialize allocates */
 182         struct mutex            lg_mutex;
 183         /* list of preallocations */
 184         struct list_head        lg_prealloc_list[PREALLOC_TB_SIZE];
 185         spinlock_t              lg_prealloc_lock;
 186 };
 187
 188 struct ext4_allocation_context {
 189         struct inode *ac_inode;
 190         struct super_block *ac_sb;
 191
 192         /* original request */
 193         struct ext4_free_extent ac_o_ex;
 194
 195         /* goal request (after normalization) */
 196         struct ext4_free_extent ac_g_ex;
 197
 198         /* the best found extent */
 199         struct ext4_free_extent ac_b_ex;
 200
 201         /* copy of the bext found extent taken before preallocation efforts */
 202         struct ext4_free_extent ac_f_ex;
 203
 204         /* number of iterations done. we have to track to limit searching */
 205         unsigned long ac_ex_scanned;
 206         __u16 ac_groups_scanned;
 207         __u16 ac_found;
 208         __u16 ac_tail;
 209         __u16 ac_buddy;
 210         __u16 ac_flags;         /* allocation hints */
 211         __u8 ac_status;
 212         __u8 ac_criteria;
 213         __u8 ac_repeats;
 214         __u8 ac_2order;         /* if request is to allocate 2^N blocks and
 215                                  * N > 0, the field stores N, otherwise 0 */
 216         __u8 ac_op;             /* operation, for history only */
 217         struct page *ac_bitmap_page;
 218         struct page *ac_buddy_page;
 219         /*
 220          * pointer to the held semaphore upon successful
 221          * block allocation
 222          */
 223         struct rw_semaphore *alloc_semp;
 224         struct ext4_prealloc_space *ac_pa;
 225         struct ext4_locality_group *ac_lg;
 226 };
 227
 228 #define AC_STATUS_CONTINUE      1
 229 #define AC_STATUS_FOUND         2
 230 #define AC_STATUS_BREAK         3
 231
 232 struct ext4_mb_history {
 233         struct ext4_free_extent orig;   /* orig allocation */
 234         struct ext4_free_extent goal;   /* goal allocation */
 235         struct ext4_free_extent result; /* result allocation */
 236         unsigned pid;
 237         unsigned ino;
 238         __u16 found;    /* how many extents have been found */
 239         __u16 groups;   /* how many groups have been scanned */
 240         __u16 tail;     /* what tail broke some buddy */
 241         __u16 buddy;    /* buddy the tail ^^^ broke */
 242         __u16 flags;
 243         __u8 cr:3;      /* which phase the result extent was found at */
 244         __u8 op:4;
 245         __u8 merged:1;
 246 };
 247
 248 struct ext4_buddy {
 249         struct page *bd_buddy_page;
 250         void *bd_buddy;
 251         struct page *bd_bitmap_page;
 252         void *bd_bitmap;
 253         struct ext4_group_info *bd_info;
 254         struct super_block *bd_sb;
 255         __u16 bd_blkbits;
 256         ext4_group_t bd_group;
 257         struct rw_semaphore *alloc_semp;
 258 };
 259 #define EXT4_MB_BITMAP(e4b)     ((e4b)->bd_bitmap)
 260 #define EXT4_MB_BUDDY(e4b)      ((e4b)->bd_buddy)
 261
 262 #ifndef EXT4_MB_HISTORY
 263 static inline void ext4_mb_store_history(struct ext4_allocation_context *ac)
 264 {
 265         return;
 266 }
 267 #endif
 268
 269 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
 270
 271 struct buffer_head *read_block_bitmap(struct super_block *, ext4_group_t);
 272
 273
 274 static inline void ext4_lock_group(struct super_block *sb, ext4_group_t group)
 275 {
 276         struct ext4_group_info *grinfo = ext4_get_group_info(sb, group);
 277
 278         bit_spin_lock(EXT4_GROUP_INFO_LOCKED_BIT, &(grinfo->bb_state));
 279 }
 280
 281 static inline void ext4_unlock_group(struct super_block *sb,
 282                                         ext4_group_t group)
 283 {
 284         struct ext4_group_info *grinfo = ext4_get_group_info(sb, group);
 285
 286         bit_spin_unlock(EXT4_GROUP_INFO_LOCKED_BIT, &(grinfo->bb_state));
 287 }
 288
 289 static inline int ext4_is_group_locked(struct super_block *sb,
 290                                         ext4_group_t group)
 291 {
 292         struct ext4_group_info *grinfo = ext4_get_group_info(sb, group);
 293
 294         return bit_spin_is_locked(EXT4_GROUP_INFO_LOCKED_BIT,
 295                                                 &(grinfo->bb_state));
 296 }
 297
 298 static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
 299                                         struct ext4_free_extent *fex)
 300 {
 301         ext4_fsblk_t block;
 302
 303         block = (ext4_fsblk_t) fex->fe_group * EXT4_BLOCKS_PER_GROUP(sb)
 304                         + fex->fe_start
 305                         + le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block);
 306         return block;
 307 }
 308 #endif