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
40extern 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
98struct ext4_free_data {
99	/* this links the free block information from group_info */
100	struct rb_node node;
101
102	/* this links the free block information from ext4_sb_info */
103	struct list_head list;
104
105	/* group which free block extent belongs */
106	ext4_group_t group;
107
108	/* free block extent */
109	ext4_grpblk_t start_blk;
110	ext4_grpblk_t count;
111
112	/* transaction which freed this extent */
113	tid_t	t_tid;
114};
115
116struct ext4_prealloc_space {
117	struct list_head	pa_inode_list;
118	struct list_head	pa_group_list;
119	union {
120		struct list_head pa_tmp_list;
121		struct rcu_head	pa_rcu;
122	} u;
123	spinlock_t		pa_lock;
124	atomic_t		pa_count;
125	unsigned		pa_deleted;
126	ext4_fsblk_t		pa_pstart;	/* phys. block */
127	ext4_lblk_t		pa_lstart;	/* log. block */
128	ext4_grpblk_t		pa_len;		/* len of preallocated chunk */
129	ext4_grpblk_t		pa_free;	/* how many blocks are free */
130	unsigned short		pa_type;	/* pa type. inode or group */
131	spinlock_t		*pa_obj_lock;
132	struct inode		*pa_inode;	/* hack, for history only */
133};
134
135enum {
136	MB_INODE_PA = 0,
137	MB_GROUP_PA = 1
138};
139
140struct ext4_free_extent {
141	ext4_lblk_t fe_logical;
142	ext4_grpblk_t fe_start;
143	ext4_group_t fe_group;
144	ext4_grpblk_t fe_len;
145};
146
147/*
148 * Locality group:
149 *   we try to group all related changes together
150 *   so that writeback can flush/allocate them together as well
151 *   Size of lg_prealloc_list hash is determined by MB_DEFAULT_GROUP_PREALLOC
152 *   (512). We store prealloc space into the hash based on the pa_free blocks
153 *   order value.ie, fls(pa_free)-1;
154 */
155#define PREALLOC_TB_SIZE 10
156struct ext4_locality_group {
157	/* for allocator */
158	/* to serialize allocates */
159	struct mutex		lg_mutex;
160	/* list of preallocations */
161	struct list_head	lg_prealloc_list[PREALLOC_TB_SIZE];
162	spinlock_t		lg_prealloc_lock;
163};
164
165struct ext4_allocation_context {
166	struct inode *ac_inode;
167	struct super_block *ac_sb;
168
169	/* original request */
170	struct ext4_free_extent ac_o_ex;
171
172	/* goal request (after normalization) */
173	struct ext4_free_extent ac_g_ex;
174
175	/* the best found extent */
176	struct ext4_free_extent ac_b_ex;
177
178	/* copy of the bext found extent taken before preallocation efforts */
179	struct ext4_free_extent ac_f_ex;
180
181	/* number of iterations done. we have to track to limit searching */
182	unsigned long ac_ex_scanned;
183	__u16 ac_groups_scanned;
184	__u16 ac_found;
185	__u16 ac_tail;
186	__u16 ac_buddy;
187	__u16 ac_flags;		/* allocation hints */
188	__u8 ac_status;
189	__u8 ac_criteria;
190	__u8 ac_repeats;
191	__u8 ac_2order;		/* if request is to allocate 2^N blocks and
192				 * N > 0, the field stores N, otherwise 0 */
193	__u8 ac_op;		/* operation, for history only */
194	struct page *ac_bitmap_page;
195	struct page *ac_buddy_page;
196	/*
197	 * pointer to the held semaphore upon successful
198	 * block allocation
199	 */
200	struct rw_semaphore *alloc_semp;
201	struct ext4_prealloc_space *ac_pa;
202	struct ext4_locality_group *ac_lg;
203};
204
205#define AC_STATUS_CONTINUE	1
206#define AC_STATUS_FOUND		2
207#define AC_STATUS_BREAK		3
208
209struct ext4_buddy {
210	struct page *bd_buddy_page;
211	void *bd_buddy;
212	struct page *bd_bitmap_page;
213	void *bd_bitmap;
214	struct ext4_group_info *bd_info;
215	struct super_block *bd_sb;
216	__u16 bd_blkbits;
217	ext4_group_t bd_group;
218	struct rw_semaphore *alloc_semp;
219};
220#define EXT4_MB_BITMAP(e4b)	((e4b)->bd_bitmap)
221#define EXT4_MB_BUDDY(e4b)	((e4b)->bd_buddy)
222
223static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
224					struct ext4_free_extent *fex)
225{
226	return ext4_group_first_block_no(sb, fex->fe_group) + fex->fe_start;
227}
228#endif
229