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
40 extern 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 
98 struct ext4_free_data {
99 	/* MUST be the first member */
100 	struct ext4_journal_cb_entry	efd_jce;
101 
102 	/* ext4_free_data private data starts from here */
103 
104 	/* this links the free block information from group_info */
105 	struct rb_node			efd_node;
106 
107 	/* group which free block extent belongs */
108 	ext4_group_t			efd_group;
109 
110 	/* free block extent */
111 	ext4_grpblk_t			efd_start_cluster;
112 	ext4_grpblk_t			efd_count;
113 
114 	/* transaction which freed this extent */
115 	tid_t				efd_tid;
116 };
117 
118 struct ext4_prealloc_space {
119 	struct list_head	pa_inode_list;
120 	struct list_head	pa_group_list;
121 	union {
122 		struct list_head pa_tmp_list;
123 		struct rcu_head	pa_rcu;
124 	} u;
125 	spinlock_t		pa_lock;
126 	atomic_t		pa_count;
127 	unsigned		pa_deleted;
128 	ext4_fsblk_t		pa_pstart;	/* phys. block */
129 	ext4_lblk_t		pa_lstart;	/* log. block */
130 	ext4_grpblk_t		pa_len;		/* len of preallocated chunk */
131 	ext4_grpblk_t		pa_free;	/* how many blocks are free */
132 	unsigned short		pa_type;	/* pa type. inode or group */
133 	spinlock_t		*pa_obj_lock;
134 	struct inode		*pa_inode;	/* hack, for history only */
135 };
136 
137 enum {
138 	MB_INODE_PA = 0,
139 	MB_GROUP_PA = 1
140 };
141 
142 struct ext4_free_extent {
143 	ext4_lblk_t fe_logical;
144 	ext4_grpblk_t fe_start;	/* In cluster units */
145 	ext4_group_t fe_group;
146 	ext4_grpblk_t fe_len;	/* In cluster units */
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 (normalized ac_o_ex) */
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 best 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_2order;		/* if request is to allocate 2^N blocks and
193 				 * N > 0, the field stores N, otherwise 0 */
194 	__u8 ac_op;		/* operation, for history only */
195 	struct page *ac_bitmap_page;
196 	struct page *ac_buddy_page;
197 	struct ext4_prealloc_space *ac_pa;
198 	struct ext4_locality_group *ac_lg;
199 };
200 
201 #define AC_STATUS_CONTINUE	1
202 #define AC_STATUS_FOUND		2
203 #define AC_STATUS_BREAK		3
204 
205 struct ext4_buddy {
206 	struct page *bd_buddy_page;
207 	void *bd_buddy;
208 	struct page *bd_bitmap_page;
209 	void *bd_bitmap;
210 	struct ext4_group_info *bd_info;
211 	struct super_block *bd_sb;
212 	__u16 bd_blkbits;
213 	ext4_group_t bd_group;
214 };
215 
ext4_grp_offs_to_block(struct super_block * sb,struct ext4_free_extent * fex)216 static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
217 					struct ext4_free_extent *fex)
218 {
219 	return ext4_group_first_block_no(sb, fex->fe_group) +
220 		(fex->fe_start << EXT4_SB(sb)->s_cluster_bits);
221 }
222 #endif
223