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  * with 'ext4_mb_stats' allocator will collect stats that will be
  69  * shown at umount. The collecting costs though!
  70  */
  71 #define MB_DEFAULT_STATS                0
  72
  73 /*
  74  * files smaller than MB_DEFAULT_STREAM_THRESHOLD are served
  75  * by the stream allocator, which purpose is to pack requests
  76  * as close each to other as possible to produce smooth I/O traffic
  77  * We use locality group prealloc space for stream request.
  78  * We can tune the same via /proc/fs/ext4/<parition>/stream_req
  79  */
  80 #define MB_DEFAULT_STREAM_THRESHOLD     16      /* 64K */
  81
  82 /*
  83  * for which requests use 2^N search using buddies
  84  */
  85 #define MB_DEFAULT_ORDER2_REQS          2
  86
  87 /*
  88  * default group prealloc size 512 blocks
  89  */
  90 #define MB_DEFAULT_GROUP_PREALLOC       512
  91
  92
  93 struct ext4_free_data {
  94         /* MUST be the first member */
  95         struct ext4_journal_cb_entry    efd_jce;
  96
  97         /* ext4_free_data private data starts from here */
  98
  99         /* this links the free block information from group_info */
 100         struct rb_node                  efd_node;
 101
 102         /* group which free block extent belongs */
 103         ext4_group_t                    efd_group;
 104
 105         /* free block extent */
 106         ext4_grpblk_t                   efd_start_cluster;
 107         ext4_grpblk_t                   efd_count;
 108
 109         /* transaction which freed this extent */
 110         tid_t                           efd_tid;
 111 };
 112
 113 struct ext4_prealloc_space {
 114         struct list_head        pa_inode_list;
 115         struct list_head        pa_group_list;
 116         union {
 117                 struct list_head pa_tmp_list;
 118                 struct rcu_head pa_rcu;
 119         } u;
 120         spinlock_t              pa_lock;
 121         atomic_t                pa_count;
 122         unsigned                pa_deleted;
 123         ext4_fsblk_t            pa_pstart;      /* phys. block */
 124         ext4_lblk_t             pa_lstart;      /* log. block */
 125         ext4_grpblk_t           pa_len;         /* len of preallocated chunk */
 126         ext4_grpblk_t           pa_free;        /* how many blocks are free */
 127         unsigned short          pa_type;        /* pa type. inode or group */
 128         spinlock_t              *pa_obj_lock;
 129         struct inode            *pa_inode;      /* hack, for history only */
 130 };
 131
 132 enum {
 133         MB_INODE_PA = 0,
 134         MB_GROUP_PA = 1
 135 };
 136
 137 struct ext4_free_extent {
 138         ext4_lblk_t fe_logical;
 139         ext4_grpblk_t fe_start; /* In cluster units */
 140         ext4_group_t fe_group;
 141         ext4_grpblk_t fe_len;   /* In cluster units */
 142 };
 143
 144 /*
 145  * Locality group:
 146  *   we try to group all related changes together
 147  *   so that writeback can flush/allocate them together as well
 148  *   Size of lg_prealloc_list hash is determined by MB_DEFAULT_GROUP_PREALLOC
 149  *   (512). We store prealloc space into the hash based on the pa_free blocks
 150  *   order value.ie, fls(pa_free)-1;
 151  */
 152 #define PREALLOC_TB_SIZE 10
 153 struct ext4_locality_group {
 154         /* for allocator */
 155         /* to serialize allocates */
 156         struct mutex            lg_mutex;
 157         /* list of preallocations */
 158         struct list_head        lg_prealloc_list[PREALLOC_TB_SIZE];
 159         spinlock_t              lg_prealloc_lock;
 160 };
 161
 162 struct ext4_allocation_context {
 163         struct inode *ac_inode;
 164         struct super_block *ac_sb;
 165
 166         /* original request */
 167         struct ext4_free_extent ac_o_ex;
 168
 169         /* goal request (normalized ac_o_ex) */
 170         struct ext4_free_extent ac_g_ex;
 171
 172         /* the best found extent */
 173         struct ext4_free_extent ac_b_ex;
 174
 175         /* copy of the best found extent taken before preallocation efforts */
 176         struct ext4_free_extent ac_f_ex;
 177
 178         /* number of iterations done. we have to track to limit searching */
 179         unsigned long ac_ex_scanned;
 180         __u16 ac_groups_scanned;
 181         __u16 ac_found;
 182         __u16 ac_tail;
 183         __u16 ac_buddy;
 184         __u16 ac_flags;         /* allocation hints */
 185         __u8 ac_status;
 186         __u8 ac_criteria;
 187         __u8 ac_2order;         /* if request is to allocate 2^N blocks and
 188                                  * N > 0, the field stores N, otherwise 0 */
 189         __u8 ac_op;             /* operation, for history only */
 190         struct page *ac_bitmap_page;
 191         struct page *ac_buddy_page;
 192         struct ext4_prealloc_space *ac_pa;
 193         struct ext4_locality_group *ac_lg;
 194 };
 195
 196 #define AC_STATUS_CONTINUE      1
 197 #define AC_STATUS_FOUND         2
 198 #define AC_STATUS_BREAK         3
 199
 200 struct ext4_buddy {
 201         struct page *bd_buddy_page;
 202         void *bd_buddy;
 203         struct page *bd_bitmap_page;
 204         void *bd_bitmap;
 205         struct ext4_group_info *bd_info;
 206         struct super_block *bd_sb;
 207         __u16 bd_blkbits;
 208         ext4_group_t bd_group;
 209 };
 210
 211 static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
 212                                         struct ext4_free_extent *fex)
 213 {
 214         return ext4_group_first_block_no(sb, fex->fe_group) +
 215                 (fex->fe_start << EXT4_SB(sb)->s_cluster_bits);
 216 }
 217 #endif