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 "ext4_jbd2.h"
  22 #include "ext4.h"
  23 #include "group.h"
  24
  25 /*
  26  * with AGGRESSIVE_CHECK allocator runs consistency checks over
  27  * structures. these checks slow things down a lot
  28  */
  29 #define AGGRESSIVE_CHECK__
  30
  31 /*
  32  * with DOUBLE_CHECK defined mballoc creates persistent in-core
  33  * bitmaps, maintains and uses them to check for double allocations
  34  */
  35 #define DOUBLE_CHECK__
  36
  37 /*
  38  */
  39 #define MB_DEBUG__
  40 #ifdef MB_DEBUG
  41 #define mb_debug(fmt, a...)     printk(fmt, ##a)
  42 #else
  43 #define mb_debug(fmt, a...)
  44 #endif
  45
  46 /*
  47  * with EXT4_MB_HISTORY mballoc stores last N allocations in memory
  48  * and you can monitor it in /proc/fs/ext4/<dev>/mb_history
  49  */
  50 #define EXT4_MB_HISTORY
  51 #define EXT4_MB_HISTORY_ALLOC           1       /* allocation */
  52 #define EXT4_MB_HISTORY_PREALLOC        2       /* preallocated blocks used */
  53 #define EXT4_MB_HISTORY_DISCARD         4       /* preallocation discarded */
  54 #define EXT4_MB_HISTORY_FREE            8       /* free */
  55
  56 #define EXT4_MB_HISTORY_DEFAULT         (EXT4_MB_HISTORY_ALLOC | \
  57                                          EXT4_MB_HISTORY_PREALLOC)
  58
  59 /*
  60  * How long mballoc can look for a best extent (in found extents)
  61  */
  62 #define MB_DEFAULT_MAX_TO_SCAN          200
  63
  64 /*
  65  * How long mballoc must look for a best extent
  66  */
  67 #define MB_DEFAULT_MIN_TO_SCAN          10
  68
  69 /*
  70  * How many groups mballoc will scan looking for the best chunk
  71  */
  72 #define MB_DEFAULT_MAX_GROUPS_TO_SCAN   5
  73
  74 /*
  75  * with 'ext4_mb_stats' allocator will collect stats that will be
  76  * shown at umount. The collecting costs though!
  77  */
  78 #define MB_DEFAULT_STATS                1
  79
  80 /*
  81  * files smaller than MB_DEFAULT_STREAM_THRESHOLD are served
  82  * by the stream allocator, which purpose is to pack requests
  83  * as close each to other as possible to produce smooth I/O traffic
  84  * We use locality group prealloc space for stream request.
  85  * We can tune the same via /proc/fs/ext4/<parition>/stream_req
  86  */
  87 #define MB_DEFAULT_STREAM_THRESHOLD     16      /* 64K */
  88
  89 /*
  90  * for which requests use 2^N search using buddies
  91  */
  92 #define MB_DEFAULT_ORDER2_REQS          2
  93
  94 /*
  95  * default group prealloc size 512 blocks
  96  */
  97 #define MB_DEFAULT_GROUP_PREALLOC       512
  98
  99 static struct kmem_cache *ext4_pspace_cachep;
 100 static struct kmem_cache *ext4_ac_cachep;
 101 static struct kmem_cache *ext4_free_ext_cachep;
 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         unsigned short  bb_counters[];
 132 };
 133
 134 #define EXT4_GROUP_INFO_NEED_INIT_BIT   0
 135 #define EXT4_GROUP_INFO_LOCKED_BIT      1
 136
 137 #define EXT4_MB_GRP_NEED_INIT(grp)      \
 138         (test_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &((grp)->bb_state)))
 139
 140
 141 struct ext4_prealloc_space {
 142         struct list_head        pa_inode_list;
 143         struct list_head        pa_group_list;
 144         union {
 145                 struct list_head pa_tmp_list;
 146                 struct rcu_head pa_rcu;
 147         } u;
 148         spinlock_t              pa_lock;
 149         atomic_t                pa_count;
 150         unsigned                pa_deleted;
 151         ext4_fsblk_t            pa_pstart;      /* phys. block */
 152         ext4_lblk_t             pa_lstart;      /* log. block */
 153         unsigned short          pa_len;         /* len of preallocated chunk */
 154         unsigned short          pa_free;        /* how many blocks are free */
 155         unsigned short          pa_linear;      /* consumed in one direction
 156                                                  * strictly, for grp prealloc */
 157         spinlock_t              *pa_obj_lock;
 158         struct inode            *pa_inode;      /* hack, for history only */
 159 };
 160
 161
 162 struct ext4_free_extent {
 163         ext4_lblk_t fe_logical;
 164         ext4_grpblk_t fe_start;
 165         ext4_group_t fe_group;
 166         int fe_len;
 167 };
 168
 169 /*
 170  * Locality group:
 171  *   we try to group all related changes together
 172  *   so that writeback can flush/allocate them together as well
 173  *   Size of lg_prealloc_list hash is determined by MB_DEFAULT_GROUP_PREALLOC
 174  *   (512). We store prealloc space into the hash based on the pa_free blocks
 175  *   order value.ie, fls(pa_free)-1;
 176  */
 177 #define PREALLOC_TB_SIZE 10
 178 struct ext4_locality_group {
 179         /* for allocator */
 180         /* to serialize allocates */
 181         struct mutex            lg_mutex;
 182         /* list of preallocations */
 183         struct list_head        lg_prealloc_list[PREALLOC_TB_SIZE];
 184         spinlock_t              lg_prealloc_lock;
 185 };
 186
 187 struct ext4_allocation_context {
 188         struct inode *ac_inode;
 189         struct super_block *ac_sb;
 190
 191         /* original request */
 192         struct ext4_free_extent ac_o_ex;
 193
 194         /* goal request (after normalization) */
 195         struct ext4_free_extent ac_g_ex;
 196
 197         /* the best found extent */
 198         struct ext4_free_extent ac_b_ex;
 199
 200         /* copy of the bext found extent taken before preallocation efforts */
 201         struct ext4_free_extent ac_f_ex;
 202
 203         /* number of iterations done. we have to track to limit searching */
 204         unsigned long ac_ex_scanned;
 205         __u16 ac_groups_scanned;
 206         __u16 ac_found;
 207         __u16 ac_tail;
 208         __u16 ac_buddy;
 209         __u16 ac_flags;         /* allocation hints */
 210         __u8 ac_status;
 211         __u8 ac_criteria;
 212         __u8 ac_repeats;
 213         __u8 ac_2order;         /* if request is to allocate 2^N blocks and
 214                                  * N > 0, the field stores N, otherwise 0 */
 215         __u8 ac_op;             /* operation, for history only */
 216         struct page *ac_bitmap_page;
 217         struct page *ac_buddy_page;
 218         struct ext4_prealloc_space *ac_pa;
 219         struct ext4_locality_group *ac_lg;
 220 };
 221
 222 #define AC_STATUS_CONTINUE      1
 223 #define AC_STATUS_FOUND         2
 224 #define AC_STATUS_BREAK         3
 225
 226 struct ext4_mb_history {
 227         struct ext4_free_extent orig;   /* orig allocation */
 228         struct ext4_free_extent goal;   /* goal allocation */
 229         struct ext4_free_extent result; /* result allocation */
 230         unsigned pid;
 231         unsigned ino;
 232         __u16 found;    /* how many extents have been found */
 233         __u16 groups;   /* how many groups have been scanned */
 234         __u16 tail;     /* what tail broke some buddy */
 235         __u16 buddy;    /* buddy the tail ^^^ broke */
 236         __u16 flags;
 237         __u8 cr:3;      /* which phase the result extent was found at */
 238         __u8 op:4;
 239         __u8 merged:1;
 240 };
 241
 242 struct ext4_buddy {
 243         struct page *bd_buddy_page;
 244         void *bd_buddy;
 245         struct page *bd_bitmap_page;
 246         void *bd_bitmap;
 247         struct ext4_group_info *bd_info;
 248         struct super_block *bd_sb;
 249         __u16 bd_blkbits;
 250         ext4_group_t bd_group;
 251 };
 252 #define EXT4_MB_BITMAP(e4b)     ((e4b)->bd_bitmap)
 253 #define EXT4_MB_BUDDY(e4b)      ((e4b)->bd_buddy)
 254
 255 #ifndef EXT4_MB_HISTORY
 256 static inline void ext4_mb_store_history(struct ext4_allocation_context *ac)
 257 {
 258         return;
 259 }
 260 #else
 261 static void ext4_mb_store_history(struct ext4_allocation_context *ac);
 262 #endif
 263
 264 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
 265
 266 struct buffer_head *read_block_bitmap(struct super_block *, ext4_group_t);
 267
 268 static void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
 269                                         ext4_group_t group);
 270 static void ext4_mb_poll_new_transaction(struct super_block *, handle_t *);
 271 static void ext4_mb_free_committed_blocks(struct super_block *);
 272 static void ext4_mb_return_to_preallocation(struct inode *inode,
 273                                         struct ext4_buddy *e4b, sector_t block,
 274                                         int count);
 275 static void ext4_mb_put_pa(struct ext4_allocation_context *,
 276                         struct super_block *, struct ext4_prealloc_space *pa);
 277 static int ext4_mb_init_per_dev_proc(struct super_block *sb);
 278 static int ext4_mb_destroy_per_dev_proc(struct super_block *sb);
 279
 280
 281 static inline void ext4_lock_group(struct super_block *sb, ext4_group_t group)
 282 {
 283         struct ext4_group_info *grinfo = ext4_get_group_info(sb, group);
 284
 285         bit_spin_lock(EXT4_GROUP_INFO_LOCKED_BIT, &(grinfo->bb_state));
 286 }
 287
 288 static inline void ext4_unlock_group(struct super_block *sb,
 289                                         ext4_group_t group)
 290 {
 291         struct ext4_group_info *grinfo = ext4_get_group_info(sb, group);
 292
 293         bit_spin_unlock(EXT4_GROUP_INFO_LOCKED_BIT, &(grinfo->bb_state));
 294 }
 295
 296 static inline int ext4_is_group_locked(struct super_block *sb,
 297                                         ext4_group_t group)
 298 {
 299         struct ext4_group_info *grinfo = ext4_get_group_info(sb, group);
 300
 301         return bit_spin_is_locked(EXT4_GROUP_INFO_LOCKED_BIT,
 302                                                 &(grinfo->bb_state));
 303 }
 304
 305 static ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
 306                                         struct ext4_free_extent *fex)
 307 {
 308         ext4_fsblk_t block;
 309
 310         block = (ext4_fsblk_t) fex->fe_group * EXT4_BLOCKS_PER_GROUP(sb)
 311                         + fex->fe_start
 312                         + le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block);
 313         return block;
 314 }
 315 #endif