1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  fs/ext4/mballoc.h
4  *
5  *  Written by: Alex Tomas <alex@clusterfs.com>
6  *
7  */
8 #ifndef _EXT4_MBALLOC_H
9 #define _EXT4_MBALLOC_H
10 
11 #include <linux/time.h>
12 #include <linux/fs.h>
13 #include <linux/namei.h>
14 #include <linux/quotaops.h>
15 #include <linux/buffer_head.h>
16 #include <linux/module.h>
17 #include <linux/swap.h>
18 #include <linux/proc_fs.h>
19 #include <linux/pagemap.h>
20 #include <linux/seq_file.h>
21 #include <linux/blkdev.h>
22 #include <linux/mutex.h>
23 #include "ext4_jbd2.h"
24 #include "ext4.h"
25 
26 /*
27  */
28 #ifdef CONFIG_EXT4_DEBUG
29 extern ushort ext4_mballoc_debug;
30 
31 #define mb_debug(n, fmt, ...)	                                        \
32 do {									\
33 	if ((n) <= ext4_mballoc_debug) {				\
34 		printk(KERN_DEBUG "(%s, %d): %s: " fmt,			\
35 		       __FILE__, __LINE__, __func__, ##__VA_ARGS__);	\
36 	}								\
37 } while (0)
38 #else
39 #define mb_debug(n, fmt, ...)	no_printk(fmt, ##__VA_ARGS__)
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 	/* this links the free block information from sb_info */
83 	struct list_head		efd_list;
84 
85 	/* this links the free block information from group_info */
86 	struct rb_node			efd_node;
87 
88 	/* group which free block extent belongs */
89 	ext4_group_t			efd_group;
90 
91 	/* free block extent */
92 	ext4_grpblk_t			efd_start_cluster;
93 	ext4_grpblk_t			efd_count;
94 
95 	/* transaction which freed this extent */
96 	tid_t				efd_tid;
97 };
98 
99 struct ext4_prealloc_space {
100 	struct list_head	pa_inode_list;
101 	struct list_head	pa_group_list;
102 	union {
103 		struct list_head pa_tmp_list;
104 		struct rcu_head	pa_rcu;
105 	} u;
106 	spinlock_t		pa_lock;
107 	atomic_t		pa_count;
108 	unsigned		pa_deleted;
109 	ext4_fsblk_t		pa_pstart;	/* phys. block */
110 	ext4_lblk_t		pa_lstart;	/* log. block */
111 	ext4_grpblk_t		pa_len;		/* len of preallocated chunk */
112 	ext4_grpblk_t		pa_free;	/* how many blocks are free */
113 	unsigned short		pa_type;	/* pa type. inode or group */
114 	spinlock_t		*pa_obj_lock;
115 	struct inode		*pa_inode;	/* hack, for history only */
116 };
117 
118 enum {
119 	MB_INODE_PA = 0,
120 	MB_GROUP_PA = 1
121 };
122 
123 struct ext4_free_extent {
124 	ext4_lblk_t fe_logical;
125 	ext4_grpblk_t fe_start;	/* In cluster units */
126 	ext4_group_t fe_group;
127 	ext4_grpblk_t fe_len;	/* In cluster units */
128 };
129 
130 /*
131  * Locality group:
132  *   we try to group all related changes together
133  *   so that writeback can flush/allocate them together as well
134  *   Size of lg_prealloc_list hash is determined by MB_DEFAULT_GROUP_PREALLOC
135  *   (512). We store prealloc space into the hash based on the pa_free blocks
136  *   order value.ie, fls(pa_free)-1;
137  */
138 #define PREALLOC_TB_SIZE 10
139 struct ext4_locality_group {
140 	/* for allocator */
141 	/* to serialize allocates */
142 	struct mutex		lg_mutex;
143 	/* list of preallocations */
144 	struct list_head	lg_prealloc_list[PREALLOC_TB_SIZE];
145 	spinlock_t		lg_prealloc_lock;
146 };
147 
148 struct ext4_allocation_context {
149 	struct inode *ac_inode;
150 	struct super_block *ac_sb;
151 
152 	/* original request */
153 	struct ext4_free_extent ac_o_ex;
154 
155 	/* goal request (normalized ac_o_ex) */
156 	struct ext4_free_extent ac_g_ex;
157 
158 	/* the best found extent */
159 	struct ext4_free_extent ac_b_ex;
160 
161 	/* copy of the best found extent taken before preallocation efforts */
162 	struct ext4_free_extent ac_f_ex;
163 
164 	__u16 ac_groups_scanned;
165 	__u16 ac_found;
166 	__u16 ac_tail;
167 	__u16 ac_buddy;
168 	__u16 ac_flags;		/* allocation hints */
169 	__u8 ac_status;
170 	__u8 ac_criteria;
171 	__u8 ac_2order;		/* if request is to allocate 2^N blocks and
172 				 * N > 0, the field stores N, otherwise 0 */
173 	__u8 ac_op;		/* operation, for history only */
174 	struct page *ac_bitmap_page;
175 	struct page *ac_buddy_page;
176 	struct ext4_prealloc_space *ac_pa;
177 	struct ext4_locality_group *ac_lg;
178 };
179 
180 #define AC_STATUS_CONTINUE	1
181 #define AC_STATUS_FOUND		2
182 #define AC_STATUS_BREAK		3
183 
184 struct ext4_buddy {
185 	struct page *bd_buddy_page;
186 	void *bd_buddy;
187 	struct page *bd_bitmap_page;
188 	void *bd_bitmap;
189 	struct ext4_group_info *bd_info;
190 	struct super_block *bd_sb;
191 	__u16 bd_blkbits;
192 	ext4_group_t bd_group;
193 };
194 
ext4_grp_offs_to_block(struct super_block * sb,struct ext4_free_extent * fex)195 static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
196 					struct ext4_free_extent *fex)
197 {
198 	return ext4_group_first_block_no(sb, fex->fe_group) +
199 		(fex->fe_start << EXT4_SB(sb)->s_cluster_bits);
200 }
201 
202 typedef int (*ext4_mballoc_query_range_fn)(
203 	struct super_block		*sb,
204 	ext4_group_t			agno,
205 	ext4_grpblk_t			start,
206 	ext4_grpblk_t			len,
207 	void				*priv);
208 
209 int
210 ext4_mballoc_query_range(
211 	struct super_block		*sb,
212 	ext4_group_t			agno,
213 	ext4_grpblk_t			start,
214 	ext4_grpblk_t			end,
215 	ext4_mballoc_query_range_fn	formatter,
216 	void				*priv);
217 
218 #endif
219