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