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 ushort ext4_mballoc_debug;
41
42#define mb_debug(n, fmt, a...)	                                        \
43	do {								\
44		if ((n) <= ext4_mballoc_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...)		no_printk(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
93struct 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
113struct 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
132enum {
133	MB_INODE_PA = 0,
134	MB_GROUP_PA = 1
135};
136
137struct 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
153struct 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
162struct 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	__u16 ac_groups_scanned;
179	__u16 ac_found;
180	__u16 ac_tail;
181	__u16 ac_buddy;
182	__u16 ac_flags;		/* allocation hints */
183	__u8 ac_status;
184	__u8 ac_criteria;
185	__u8 ac_2order;		/* if request is to allocate 2^N blocks and
186				 * N > 0, the field stores N, otherwise 0 */
187	__u8 ac_op;		/* operation, for history only */
188	struct page *ac_bitmap_page;
189	struct page *ac_buddy_page;
190	struct ext4_prealloc_space *ac_pa;
191	struct ext4_locality_group *ac_lg;
192};
193
194#define AC_STATUS_CONTINUE	1
195#define AC_STATUS_FOUND		2
196#define AC_STATUS_BREAK		3
197
198struct ext4_buddy {
199	struct page *bd_buddy_page;
200	void *bd_buddy;
201	struct page *bd_bitmap_page;
202	void *bd_bitmap;
203	struct ext4_group_info *bd_info;
204	struct super_block *bd_sb;
205	__u16 bd_blkbits;
206	ext4_group_t bd_group;
207};
208
209static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
210					struct ext4_free_extent *fex)
211{
212	return ext4_group_first_block_no(sb, fex->fe_group) +
213		(fex->fe_start << EXT4_SB(sb)->s_cluster_bits);
214}
215#endif
216