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  */
  27 #ifdef CONFIG_EXT4_DEBUG
  28 extern ushort ext4_mballoc_debug;
  29
  30 #define mb_debug(n, fmt, ...)                                           \
  31 do {                                                                    \
  32         if ((n) <= ext4_mballoc_debug) {                                \
  33                 printk(KERN_DEBUG "(%s, %d): %s: " fmt,                 \
  34                        __FILE__, __LINE__, __func__, ##__VA_ARGS__);    \
  35         }                                                               \
  36 } while (0)
  37 #else
  38 #define mb_debug(n, fmt, ...)   no_printk(fmt, ##__VA_ARGS__)
  39 #endif
  40
  41 #define EXT4_MB_HISTORY_ALLOC           1       /* allocation */
  42 #define EXT4_MB_HISTORY_PREALLOC        2       /* preallocated blocks used */
  43
  44 /*
  45  * How long mballoc can look for a best extent (in found extents)
  46  */
  47 #define MB_DEFAULT_MAX_TO_SCAN          200
  48
  49 /*
  50  * How long mballoc must look for a best extent
  51  */
  52 #define MB_DEFAULT_MIN_TO_SCAN          10
  53
  54 /*
  55  * with 'ext4_mb_stats' allocator will collect stats that will be
  56  * shown at umount. The collecting costs though!
  57  */
  58 #define MB_DEFAULT_STATS                0
  59
  60 /*
  61  * files smaller than MB_DEFAULT_STREAM_THRESHOLD are served
  62  * by the stream allocator, which purpose is to pack requests
  63  * as close each to other as possible to produce smooth I/O traffic
  64  * We use locality group prealloc space for stream request.
  65  * We can tune the same via /proc/fs/ext4/<parition>/stream_req
  66  */
  67 #define MB_DEFAULT_STREAM_THRESHOLD     16      /* 64K */
  68
  69 /*
  70  * for which requests use 2^N search using buddies
  71  */
  72 #define MB_DEFAULT_ORDER2_REQS          2
  73
  74 /*
  75  * default group prealloc size 512 blocks
  76  */
  77 #define MB_DEFAULT_GROUP_PREALLOC       512
  78
  79
  80 struct ext4_free_data {
  81         /* MUST be the first member */
  82         struct ext4_journal_cb_entry    efd_jce;
  83
  84         /* ext4_free_data private data starts from here */
  85
  86         /* this links the free block information from group_info */
  87         struct rb_node                  efd_node;
  88
  89         /* group which free block extent belongs */
  90         ext4_group_t                    efd_group;
  91
  92         /* free block extent */
  93         ext4_grpblk_t                   efd_start_cluster;
  94         ext4_grpblk_t                   efd_count;
  95
  96         /* transaction which freed this extent */
  97         tid_t                           efd_tid;
  98 };
  99
 100 struct ext4_prealloc_space {
 101         struct list_head        pa_inode_list;
 102         struct list_head        pa_group_list;
 103         union {
 104                 struct list_head pa_tmp_list;
 105                 struct rcu_head pa_rcu;
 106         } u;
 107         spinlock_t              pa_lock;
 108         atomic_t                pa_count;
 109         unsigned                pa_deleted;
 110         ext4_fsblk_t            pa_pstart;      /* phys. block */
 111         ext4_lblk_t             pa_lstart;      /* log. block */
 112         ext4_grpblk_t           pa_len;         /* len of preallocated chunk */
 113         ext4_grpblk_t           pa_free;        /* how many blocks are free */
 114         unsigned short          pa_type;        /* pa type. inode or group */
 115         spinlock_t              *pa_obj_lock;
 116         struct inode            *pa_inode;      /* hack, for history only */
 117 };
 118
 119 enum {
 120         MB_INODE_PA = 0,
 121         MB_GROUP_PA = 1
 122 };
 123
 124 struct ext4_free_extent {
 125         ext4_lblk_t fe_logical;
 126         ext4_grpblk_t fe_start; /* In cluster units */
 127         ext4_group_t fe_group;
 128         ext4_grpblk_t fe_len;   /* In cluster units */
 129 };
 130
 131 /*
 132  * Locality group:
 133  *   we try to group all related changes together
 134  *   so that writeback can flush/allocate them together as well
 135  *   Size of lg_prealloc_list hash is determined by MB_DEFAULT_GROUP_PREALLOC
 136  *   (512). We store prealloc space into the hash based on the pa_free blocks
 137  *   order value.ie, fls(pa_free)-1;
 138  */
 139 #define PREALLOC_TB_SIZE 10
 140 struct ext4_locality_group {
 141         /* for allocator */
 142         /* to serialize allocates */
 143         struct mutex            lg_mutex;
 144         /* list of preallocations */
 145         struct list_head        lg_prealloc_list[PREALLOC_TB_SIZE];
 146         spinlock_t              lg_prealloc_lock;
 147 };
 148
 149 struct ext4_allocation_context {
 150         struct inode *ac_inode;
 151         struct super_block *ac_sb;
 152
 153         /* original request */
 154         struct ext4_free_extent ac_o_ex;
 155
 156         /* goal request (normalized ac_o_ex) */
 157         struct ext4_free_extent ac_g_ex;
 158
 159         /* the best found extent */
 160         struct ext4_free_extent ac_b_ex;
 161
 162         /* copy of the best found extent taken before preallocation efforts */
 163         struct ext4_free_extent ac_f_ex;
 164
 165         __u16 ac_groups_scanned;
 166         __u16 ac_found;
 167         __u16 ac_tail;
 168         __u16 ac_buddy;
 169         __u16 ac_flags;         /* allocation hints */
 170         __u8 ac_status;
 171         __u8 ac_criteria;
 172         __u8 ac_2order;         /* if request is to allocate 2^N blocks and
 173                                  * N > 0, the field stores N, otherwise 0 */
 174         __u8 ac_op;             /* operation, for history only */
 175         struct page *ac_bitmap_page;
 176         struct page *ac_buddy_page;
 177         struct ext4_prealloc_space *ac_pa;
 178         struct ext4_locality_group *ac_lg;
 179 };
 180
 181 #define AC_STATUS_CONTINUE      1
 182 #define AC_STATUS_FOUND         2
 183 #define AC_STATUS_BREAK         3
 184
 185 struct ext4_buddy {
 186         struct page *bd_buddy_page;
 187         void *bd_buddy;
 188         struct page *bd_bitmap_page;
 189         void *bd_bitmap;
 190         struct ext4_group_info *bd_info;
 191         struct super_block *bd_sb;
 192         __u16 bd_blkbits;
 193         ext4_group_t bd_group;
 194 };
 195
 196 static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
 197                                         struct ext4_free_extent *fex)
 198 {
 199         return ext4_group_first_block_no(sb, fex->fe_group) +
 200                 (fex->fe_start << EXT4_SB(sb)->s_cluster_bits);
 201 }
 202 #endif