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_linear;      /* consumed in one direction
 136                                                  * strictly, for grp prealloc */
 137         spinlock_t              *pa_obj_lock;
 138         struct inode            *pa_inode;      /* hack, for history only */
 139 };
 140
 141
 142 struct ext4_free_extent {
 143         ext4_lblk_t fe_logical;
 144         ext4_grpblk_t fe_start;
 145         ext4_group_t fe_group;
 146         int fe_len;
 147 };
 148
 149 /*
 150  * Locality group:
 151  *   we try to group all related changes together
 152  *   so that writeback can flush/allocate them together as well
 153  *   Size of lg_prealloc_list hash is determined by MB_DEFAULT_GROUP_PREALLOC
 154  *   (512). We store prealloc space into the hash based on the pa_free blocks
 155  *   order value.ie, fls(pa_free)-1;
 156  */
 157 #define PREALLOC_TB_SIZE 10
 158 struct ext4_locality_group {
 159         /* for allocator */
 160         /* to serialize allocates */
 161         struct mutex            lg_mutex;
 162         /* list of preallocations */
 163         struct list_head        lg_prealloc_list[PREALLOC_TB_SIZE];
 164         spinlock_t              lg_prealloc_lock;
 165 };
 166
 167 struct ext4_allocation_context {
 168         struct inode *ac_inode;
 169         struct super_block *ac_sb;
 170
 171         /* original request */
 172         struct ext4_free_extent ac_o_ex;
 173
 174         /* goal request (after normalization) */
 175         struct ext4_free_extent ac_g_ex;
 176
 177         /* the best found extent */
 178         struct ext4_free_extent ac_b_ex;
 179
 180         /* copy of the bext found extent taken before preallocation efforts */
 181         struct ext4_free_extent ac_f_ex;
 182
 183         /* number of iterations done. we have to track to limit searching */
 184         unsigned long ac_ex_scanned;
 185         __u16 ac_groups_scanned;
 186         __u16 ac_found;
 187         __u16 ac_tail;
 188         __u16 ac_buddy;
 189         __u16 ac_flags;         /* allocation hints */
 190         __u8 ac_status;
 191         __u8 ac_criteria;
 192         __u8 ac_repeats;
 193         __u8 ac_2order;         /* if request is to allocate 2^N blocks and
 194                                  * N > 0, the field stores N, otherwise 0 */
 195         __u8 ac_op;             /* operation, for history only */
 196         struct page *ac_bitmap_page;
 197         struct page *ac_buddy_page;
 198         /*
 199          * pointer to the held semaphore upon successful
 200          * block allocation
 201          */
 202         struct rw_semaphore *alloc_semp;
 203         struct ext4_prealloc_space *ac_pa;
 204         struct ext4_locality_group *ac_lg;
 205 };
 206
 207 #define AC_STATUS_CONTINUE      1
 208 #define AC_STATUS_FOUND         2
 209 #define AC_STATUS_BREAK         3
 210
 211 struct ext4_mb_history {
 212         struct ext4_free_extent orig;   /* orig allocation */
 213         struct ext4_free_extent goal;   /* goal allocation */
 214         struct ext4_free_extent result; /* result allocation */
 215         unsigned pid;
 216         unsigned ino;
 217         __u16 found;    /* how many extents have been found */
 218         __u16 groups;   /* how many groups have been scanned */
 219         __u16 tail;     /* what tail broke some buddy */
 220         __u16 buddy;    /* buddy the tail ^^^ broke */
 221         __u16 flags;
 222         __u8 cr:3;      /* which phase the result extent was found at */
 223         __u8 op:4;
 224         __u8 merged:1;
 225 };
 226
 227 struct ext4_buddy {
 228         struct page *bd_buddy_page;
 229         void *bd_buddy;
 230         struct page *bd_bitmap_page;
 231         void *bd_bitmap;
 232         struct ext4_group_info *bd_info;
 233         struct super_block *bd_sb;
 234         __u16 bd_blkbits;
 235         ext4_group_t bd_group;
 236         struct rw_semaphore *alloc_semp;
 237 };
 238 #define EXT4_MB_BITMAP(e4b)     ((e4b)->bd_bitmap)
 239 #define EXT4_MB_BUDDY(e4b)      ((e4b)->bd_buddy)
 240
 241 #ifndef EXT4_MB_HISTORY
 242 static inline void ext4_mb_store_history(struct ext4_allocation_context *ac)
 243 {
 244         return;
 245 }
 246 #endif
 247
 248 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
 249
 250 struct buffer_head *read_block_bitmap(struct super_block *, ext4_group_t);
 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