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 <linux/mutex.h>
24 #include "ext4_jbd2.h"
25 #include "ext4.h"
26 #include "group.h"
27
28 /*
29 * with AGGRESSIVE_CHECK allocator runs consistency checks over
30 * structures. these checks slow things down a lot
31 */
32 #define AGGRESSIVE_CHECK__
33
34 /*
35 * with DOUBLE_CHECK defined mballoc creates persistent in-core
36 * bitmaps, maintains and uses them to check for double allocations
37 */
38 #define DOUBLE_CHECK__
39
40 /*
41 */
42 #define MB_DEBUG__
43 #ifdef MB_DEBUG
44 #define mb_debug(fmt, a...) printk(fmt, ##a)
45 #else
46 #define mb_debug(fmt, a...)
47 #endif
48
49 /*
50 * with EXT4_MB_HISTORY mballoc stores last N allocations in memory
51 * and you can monitor it in /proc/fs/ext4/<dev>/mb_history
52 */
53 #define EXT4_MB_HISTORY
54 #define EXT4_MB_HISTORY_ALLOC 1 /* allocation */
55 #define EXT4_MB_HISTORY_PREALLOC 2 /* preallocated blocks used */
56 #define EXT4_MB_HISTORY_DISCARD 4 /* preallocation discarded */
57 #define EXT4_MB_HISTORY_FREE 8 /* free */
58
59 #define EXT4_MB_HISTORY_DEFAULT (EXT4_MB_HISTORY_ALLOC | \
60 EXT4_MB_HISTORY_PREALLOC)
61
62 /*
63 * How long mballoc can look for a best extent (in found extents)
64 */
65 #define MB_DEFAULT_MAX_TO_SCAN 200
66
67 /*
68 * How long mballoc must look for a best extent
69 */
70 #define MB_DEFAULT_MIN_TO_SCAN 10
71
72 /*
73 * How many groups mballoc will scan looking for the best chunk
74 */
75 #define MB_DEFAULT_MAX_GROUPS_TO_SCAN 5
76
77 /*
78 * with 'ext4_mb_stats' allocator will collect stats that will be
79 * shown at umount. The collecting costs though!
80 */
81 #define MB_DEFAULT_STATS 1
82
83 /*
84 * files smaller than MB_DEFAULT_STREAM_THRESHOLD are served
85 * by the stream allocator, which purpose is to pack requests
86 * as close each to other as possible to produce smooth I/O traffic
87 * We use locality group prealloc space for stream request.
88 * We can tune the same via /proc/fs/ext4/<parition>/stream_req
89 */
90 #define MB_DEFAULT_STREAM_THRESHOLD 16 /* 64K */
91
92 /*
93 * for which requests use 2^N search using buddies
94 */
95 #define MB_DEFAULT_ORDER2_REQS 2
96
97 /*
98 * default group prealloc size 512 blocks
99 */
100 #define MB_DEFAULT_GROUP_PREALLOC 512
101
102
103 struct ext4_free_data {
104 /* this links the free block information from group_info */
105 struct rb_node node;
106
107 /* this links the free block information from ext4_sb_info */
108 struct list_head list;
109
110 /* group which free block extent belongs */
111 ext4_group_t group;
112
113 /* free block extent */
114 ext4_grpblk_t start_blk;
115 ext4_grpblk_t count;
116
117 /* transaction which freed this extent */
118 tid_t t_tid;
119 };
120
121 struct ext4_prealloc_space {
122 struct list_head pa_inode_list;
123 struct list_head pa_group_list;
124 union {
125 struct list_head pa_tmp_list;
126 struct rcu_head pa_rcu;
127 } u;
128 spinlock_t pa_lock;
129 atomic_t pa_count;
130 unsigned pa_deleted;
131 ext4_fsblk_t pa_pstart; /* phys. block */
132 ext4_lblk_t pa_lstart; /* log. block */
133 unsigned short pa_len; /* len of preallocated chunk */
134 unsigned short pa_free; /* how many blocks are free */
135 unsigned short pa_linear; /* consumed in one direction
136 * strictly, for grp prealloc */
137 spinlock_t *pa_obj_lock;
138 struct inode *pa_inode; /* hack, for history only */
139 };
140
141
142 struct ext4_free_extent {
143 ext4_lblk_t fe_logical;
144 ext4_grpblk_t fe_start;
145 ext4_group_t fe_group;
146 int fe_len;
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 (after normalization) */
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 bext 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_repeats;
193 __u8 ac_2order; /* if request is to allocate 2^N blocks and
194 * N > 0, the field stores N, otherwise 0 */
195 __u8 ac_op; /* operation, for history only */
196 struct page *ac_bitmap_page;
197 struct page *ac_buddy_page;
198 /*
199 * pointer to the held semaphore upon successful
200 * block allocation
201 */
202 struct rw_semaphore *alloc_semp;
203 struct ext4_prealloc_space *ac_pa;
204 struct ext4_locality_group *ac_lg;
205 };
206
207 #define AC_STATUS_CONTINUE 1
208 #define AC_STATUS_FOUND 2
209 #define AC_STATUS_BREAK 3
210
211 struct ext4_mb_history {
212 struct ext4_free_extent orig; /* orig allocation */
213 struct ext4_free_extent goal; /* goal allocation */
214 struct ext4_free_extent result; /* result allocation */
215 unsigned pid;
216 unsigned ino;
217 __u16 found; /* how many extents have been found */
218 __u16 groups; /* how many groups have been scanned */
219 __u16 tail; /* what tail broke some buddy */
220 __u16 buddy; /* buddy the tail ^^^ broke */
221 __u16 flags;
222 __u8 cr:3; /* which phase the result extent was found at */
223 __u8 op:4;
224 __u8 merged:1;
225 };
226
227 struct ext4_buddy {
228 struct page *bd_buddy_page;
229 void *bd_buddy;
230 struct page *bd_bitmap_page;
231 void *bd_bitmap;
232 struct ext4_group_info *bd_info;
233 struct super_block *bd_sb;
234 __u16 bd_blkbits;
235 ext4_group_t bd_group;
236 struct rw_semaphore *alloc_semp;
237 };
238 #define EXT4_MB_BITMAP(e4b) ((e4b)->bd_bitmap)
239 #define EXT4_MB_BUDDY(e4b) ((e4b)->bd_buddy)
240
241 #ifndef EXT4_MB_HISTORY
ext4_mb_store_history(struct ext4_allocation_context * ac)242 static inline void ext4_mb_store_history(struct ext4_allocation_context *ac)
243 {
244 return;
245 }
246 #endif
247
248 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
249
250 struct buffer_head *read_block_bitmap(struct super_block *, ext4_group_t);
ext4_grp_offs_to_block(struct super_block * sb,struct ext4_free_extent * fex)251 static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
252 struct ext4_free_extent *fex)
253 {
254 ext4_fsblk_t block;
255
256 block = (ext4_fsblk_t) fex->fe_group * EXT4_BLOCKS_PER_GROUP(sb)
257 + fex->fe_start
258 + le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block);
259 return block;
260 }
261 #endif
262