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/blkdev.h>
  21 #include <linux/mutex.h>
  22 #include "ext4_jbd2.h"
  23 #include "ext4.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 #ifdef CONFIG_EXT4_DEBUG
  40 extern u8 mb_enable_debug;
  41
  42 #define mb_debug(n, fmt, a...)                                          \
  43         do {                                                            \
  44                 if ((n) <= mb_enable_debug) {                           \
  45                         printk(KERN_DEBUG "(%s, %d): %s: ",             \
  46                                __FILE__, __LINE__, __func__);           \
  47                         printk(fmt, ## a);                              \
  48                 }                                                       \
  49         } while (0)
  50 #else
  51 #define mb_debug(n, fmt, a...)
  52 #endif
  53
  54 #define EXT4_MB_HISTORY_ALLOC           1       /* allocation */
  55 #define EXT4_MB_HISTORY_PREALLOC        2       /* preallocated blocks used */
  56
  57 /*
  58  * How long mballoc can look for a best extent (in found extents)
  59  */
  60 #define MB_DEFAULT_MAX_TO_SCAN          200
  61
  62 /*
  63  * How long mballoc must look for a best extent
  64  */
  65 #define MB_DEFAULT_MIN_TO_SCAN          10
  66
  67 /*
  68  * How many groups mballoc will scan looking for the best chunk
  69  */
  70 #define MB_DEFAULT_MAX_GROUPS_TO_SCAN   5
  71
  72 /*
  73  * with 'ext4_mb_stats' allocator will collect stats that will be
  74  * shown at umount. The collecting costs though!
  75  */
  76 #define MB_DEFAULT_STATS                0
  77
  78 /*
  79  * files smaller than MB_DEFAULT_STREAM_THRESHOLD are served
  80  * by the stream allocator, which purpose is to pack requests
  81  * as close each to other as possible to produce smooth I/O traffic
  82  * We use locality group prealloc space for stream request.
  83  * We can tune the same via /proc/fs/ext4/<parition>/stream_req
  84  */
  85 #define MB_DEFAULT_STREAM_THRESHOLD     16      /* 64K */
  86
  87 /*
  88  * for which requests use 2^N search using buddies
  89  */
  90 #define MB_DEFAULT_ORDER2_REQS          2
  91
  92 /*
  93  * default group prealloc size 512 blocks
  94  */
  95 #define MB_DEFAULT_GROUP_PREALLOC       512
  96
  97
  98 struct ext4_free_data {
  99         /* MUST be the first member */
 100         struct ext4_journal_cb_entry    efd_jce;
 101
 102         /* ext4_free_data private data starts from here */
 103
 104         /* this links the free block information from group_info */
 105         struct rb_node                  efd_node;
 106
 107         /* group which free block extent belongs */
 108         ext4_group_t                    efd_group;
 109
 110         /* free block extent */
 111         ext4_grpblk_t                   efd_start_cluster;
 112         ext4_grpblk_t                   efd_count;
 113
 114         /* transaction which freed this extent */
 115         tid_t                           efd_tid;
 116 };
 117
 118 struct ext4_prealloc_space {
 119         struct list_head        pa_inode_list;
 120         struct list_head        pa_group_list;
 121         union {
 122                 struct list_head pa_tmp_list;
 123                 struct rcu_head pa_rcu;
 124         } u;
 125         spinlock_t              pa_lock;
 126         atomic_t                pa_count;
 127         unsigned                pa_deleted;
 128         ext4_fsblk_t            pa_pstart;      /* phys. block */
 129         ext4_lblk_t             pa_lstart;      /* log. block */
 130         ext4_grpblk_t           pa_len;         /* len of preallocated chunk */
 131         ext4_grpblk_t           pa_free;        /* how many blocks are free */
 132         unsigned short          pa_type;        /* pa type. inode or group */
 133         spinlock_t              *pa_obj_lock;
 134         struct inode            *pa_inode;      /* hack, for history only */
 135 };
 136
 137 enum {
 138         MB_INODE_PA = 0,
 139         MB_GROUP_PA = 1
 140 };
 141
 142 struct ext4_free_extent {
 143         ext4_lblk_t fe_logical;
 144         ext4_grpblk_t fe_start; /* In cluster units */
 145         ext4_group_t fe_group;
 146         ext4_grpblk_t fe_len;   /* In cluster units */
 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 (normalized ac_o_ex) */
 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 best 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_2order;         /* if request is to allocate 2^N blocks and
 193                                  * N > 0, the field stores N, otherwise 0 */
 194         __u8 ac_op;             /* operation, for history only */
 195         struct page *ac_bitmap_page;
 196         struct page *ac_buddy_page;
 197         struct ext4_prealloc_space *ac_pa;
 198         struct ext4_locality_group *ac_lg;
 199 };
 200
 201 #define AC_STATUS_CONTINUE      1
 202 #define AC_STATUS_FOUND         2
 203 #define AC_STATUS_BREAK         3
 204
 205 struct ext4_buddy {
 206         struct page *bd_buddy_page;
 207         void *bd_buddy;
 208         struct page *bd_bitmap_page;
 209         void *bd_bitmap;
 210         struct ext4_group_info *bd_info;
 211         struct super_block *bd_sb;
 212         __u16 bd_blkbits;
 213         ext4_group_t bd_group;
 214 };
 215
 216 static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
 217                                         struct ext4_free_extent *fex)
 218 {
 219         return ext4_group_first_block_no(sb, fex->fe_group) +
 220                 (fex->fe_start << EXT4_SB(sb)->s_cluster_bits);
 221 }
 222 #endif