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 "ext4_jbd2.h"
  24 #include "ext4.h"
  25 #include "group.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 static struct kmem_cache *ext4_pspace_cachep;
 102 static struct kmem_cache *ext4_ac_cachep;
 103 static struct kmem_cache *ext4_free_ext_cachep;
 104
 105 struct ext4_free_data {
 106         /* this links the free block information from group_info */
 107         struct rb_node node;
 108
 109         /* this links the free block information from ext4_sb_info */
 110         struct list_head list;
 111
 112         /* group which free block extent belongs */
 113         ext4_group_t group;
 114
 115         /* free block extent */
 116         ext4_grpblk_t start_blk;
 117         ext4_grpblk_t count;
 118
 119         /* transaction which freed this extent */
 120         tid_t   t_tid;
 121 };
 122
 123 struct ext4_group_info {
 124         unsigned long   bb_state;
 125         struct rb_root  bb_free_root;
 126         unsigned short  bb_first_free;
 127         unsigned short  bb_free;
 128         unsigned short  bb_fragments;
 129         struct          list_head bb_prealloc_list;
 130 #ifdef DOUBLE_CHECK
 131         void            *bb_bitmap;
 132 #endif
 133         unsigned short  bb_counters[];
 134 };
 135
 136 #define EXT4_GROUP_INFO_NEED_INIT_BIT   0
 137 #define EXT4_GROUP_INFO_LOCKED_BIT      1
 138
 139 #define EXT4_MB_GRP_NEED_INIT(grp)      \
 140         (test_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &((grp)->bb_state)))
 141
 142
 143 struct ext4_prealloc_space {
 144         struct list_head        pa_inode_list;
 145         struct list_head        pa_group_list;
 146         union {
 147                 struct list_head pa_tmp_list;
 148                 struct rcu_head pa_rcu;
 149         } u;
 150         spinlock_t              pa_lock;
 151         atomic_t                pa_count;
 152         unsigned                pa_deleted;
 153         ext4_fsblk_t            pa_pstart;      /* phys. block */
 154         ext4_lblk_t             pa_lstart;      /* log. block */
 155         unsigned short          pa_len;         /* len of preallocated chunk */
 156         unsigned short          pa_free;        /* how many blocks are free */
 157         unsigned short          pa_linear;      /* consumed in one direction
 158                                                  * strictly, for grp prealloc */
 159         spinlock_t              *pa_obj_lock;
 160         struct inode            *pa_inode;      /* hack, for history only */
 161 };
 162
 163
 164 struct ext4_free_extent {
 165         ext4_lblk_t fe_logical;
 166         ext4_grpblk_t fe_start;
 167         ext4_group_t fe_group;
 168         int fe_len;
 169 };
 170
 171 /*
 172  * Locality group:
 173  *   we try to group all related changes together
 174  *   so that writeback can flush/allocate them together as well
 175  *   Size of lg_prealloc_list hash is determined by MB_DEFAULT_GROUP_PREALLOC
 176  *   (512). We store prealloc space into the hash based on the pa_free blocks
 177  *   order value.ie, fls(pa_free)-1;
 178  */
 179 #define PREALLOC_TB_SIZE 10
 180 struct ext4_locality_group {
 181         /* for allocator */
 182         /* to serialize allocates */
 183         struct mutex            lg_mutex;
 184         /* list of preallocations */
 185         struct list_head        lg_prealloc_list[PREALLOC_TB_SIZE];
 186         spinlock_t              lg_prealloc_lock;
 187 };
 188
 189 struct ext4_allocation_context {
 190         struct inode *ac_inode;
 191         struct super_block *ac_sb;
 192
 193         /* original request */
 194         struct ext4_free_extent ac_o_ex;
 195
 196         /* goal request (after normalization) */
 197         struct ext4_free_extent ac_g_ex;
 198
 199         /* the best found extent */
 200         struct ext4_free_extent ac_b_ex;
 201
 202         /* copy of the bext found extent taken before preallocation efforts */
 203         struct ext4_free_extent ac_f_ex;
 204
 205         /* number of iterations done. we have to track to limit searching */
 206         unsigned long ac_ex_scanned;
 207         __u16 ac_groups_scanned;
 208         __u16 ac_found;
 209         __u16 ac_tail;
 210         __u16 ac_buddy;
 211         __u16 ac_flags;         /* allocation hints */
 212         __u8 ac_status;
 213         __u8 ac_criteria;
 214         __u8 ac_repeats;
 215         __u8 ac_2order;         /* if request is to allocate 2^N blocks and
 216                                  * N > 0, the field stores N, otherwise 0 */
 217         __u8 ac_op;             /* operation, for history only */
 218         struct page *ac_bitmap_page;
 219         struct page *ac_buddy_page;
 220         struct ext4_prealloc_space *ac_pa;
 221         struct ext4_locality_group *ac_lg;
 222 };
 223
 224 #define AC_STATUS_CONTINUE      1
 225 #define AC_STATUS_FOUND         2
 226 #define AC_STATUS_BREAK         3
 227
 228 struct ext4_mb_history {
 229         struct ext4_free_extent orig;   /* orig allocation */
 230         struct ext4_free_extent goal;   /* goal allocation */
 231         struct ext4_free_extent result; /* result allocation */
 232         unsigned pid;
 233         unsigned ino;
 234         __u16 found;    /* how many extents have been found */
 235         __u16 groups;   /* how many groups have been scanned */
 236         __u16 tail;     /* what tail broke some buddy */
 237         __u16 buddy;    /* buddy the tail ^^^ broke */
 238         __u16 flags;
 239         __u8 cr:3;      /* which phase the result extent was found at */
 240         __u8 op:4;
 241         __u8 merged:1;
 242 };
 243
 244 struct ext4_buddy {
 245         struct page *bd_buddy_page;
 246         void *bd_buddy;
 247         struct page *bd_bitmap_page;
 248         void *bd_bitmap;
 249         struct ext4_group_info *bd_info;
 250         struct super_block *bd_sb;
 251         __u16 bd_blkbits;
 252         ext4_group_t bd_group;
 253 };
 254 #define EXT4_MB_BITMAP(e4b)     ((e4b)->bd_bitmap)
 255 #define EXT4_MB_BUDDY(e4b)      ((e4b)->bd_buddy)
 256
 257 #ifndef EXT4_MB_HISTORY
 258 static inline void ext4_mb_store_history(struct ext4_allocation_context *ac)
 259 {
 260         return;
 261 }
 262 #else
 263 static void ext4_mb_store_history(struct ext4_allocation_context *ac);
 264 #endif
 265
 266 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
 267
 268 struct buffer_head *read_block_bitmap(struct super_block *, ext4_group_t);
 269
 270 static void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
 271                                         ext4_group_t group);
 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 static void release_blocks_on_commit(journal_t *journal, transaction_t *txn);
 280
 281
 282 static inline void ext4_lock_group(struct super_block *sb, ext4_group_t group)
 283 {
 284         struct ext4_group_info *grinfo = ext4_get_group_info(sb, group);
 285
 286         bit_spin_lock(EXT4_GROUP_INFO_LOCKED_BIT, &(grinfo->bb_state));
 287 }
 288
 289 static inline void ext4_unlock_group(struct super_block *sb,
 290                                         ext4_group_t group)
 291 {
 292         struct ext4_group_info *grinfo = ext4_get_group_info(sb, group);
 293
 294         bit_spin_unlock(EXT4_GROUP_INFO_LOCKED_BIT, &(grinfo->bb_state));
 295 }
 296
 297 static inline int ext4_is_group_locked(struct super_block *sb,
 298                                         ext4_group_t group)
 299 {
 300         struct ext4_group_info *grinfo = ext4_get_group_info(sb, group);
 301
 302         return bit_spin_is_locked(EXT4_GROUP_INFO_LOCKED_BIT,
 303                                                 &(grinfo->bb_state));
 304 }
 305
 306 static ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
 307                                         struct ext4_free_extent *fex)
 308 {
 309         ext4_fsblk_t block;
 310
 311         block = (ext4_fsblk_t) fex->fe_group * EXT4_BLOCKS_PER_GROUP(sb)
 312                         + fex->fe_start
 313                         + le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block);
 314         return block;
 315 }
 316 #endif