1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3  * Copyright (C) 2019 Arrikto, Inc. All Rights Reserved.
4  */
5 
6 #ifndef DM_CLONE_METADATA_H
7 #define DM_CLONE_METADATA_H
8 
9 #include "persistent-data/dm-block-manager.h"
10 #include "persistent-data/dm-space-map-metadata.h"
11 
12 #define DM_CLONE_METADATA_BLOCK_SIZE DM_SM_METADATA_BLOCK_SIZE
13 
14 /*
15  * The metadata device is currently limited in size.
16  */
17 #define DM_CLONE_METADATA_MAX_SECTORS DM_SM_METADATA_MAX_SECTORS
18 
19 /*
20  * A metadata device larger than 16GB triggers a warning.
21  */
22 #define DM_CLONE_METADATA_MAX_SECTORS_WARNING (16 * (1024 * 1024 * 1024 >> SECTOR_SHIFT))
23 
24 #define SPACE_MAP_ROOT_SIZE 128
25 
26 /* dm-clone metadata */
27 struct dm_clone_metadata;
28 
29 /*
30  * Set region status to hydrated.
31  *
32  * @cmd: The dm-clone metadata
33  * @region_nr: The region number
34  *
35  * This function doesn't block, so it's safe to call it from interrupt context.
36  */
37 int dm_clone_set_region_hydrated(struct dm_clone_metadata *cmd, unsigned long region_nr);
38 
39 /*
40  * Set status of all regions in the provided range to hydrated, if not already
41  * hydrated.
42  *
43  * @cmd: The dm-clone metadata
44  * @start: Starting region number
45  * @nr_regions: Number of regions in the range
46  *
47  * This function doesn't block, so it's safe to call it from interrupt context.
48  */
49 int dm_clone_cond_set_range(struct dm_clone_metadata *cmd, unsigned long start,
50 			    unsigned long nr_regions);
51 
52 /*
53  * Read existing or create fresh metadata.
54  *
55  * @bdev: The device storing the metadata
56  * @target_size: The target size
57  * @region_size: The region size
58  *
59  * @returns: The dm-clone metadata
60  *
61  * This function reads the superblock of @bdev and checks if it's all zeroes.
62  * If it is, it formats @bdev and creates fresh metadata. If it isn't, it
63  * validates the metadata stored in @bdev.
64  */
65 struct dm_clone_metadata *dm_clone_metadata_open(struct block_device *bdev,
66 						 sector_t target_size,
67 						 sector_t region_size);
68 
69 /*
70  * Free the resources related to metadata management.
71  */
72 void dm_clone_metadata_close(struct dm_clone_metadata *cmd);
73 
74 /*
75  * Commit dm-clone metadata to disk.
76  */
77 int dm_clone_metadata_commit(struct dm_clone_metadata *cmd);
78 
79 /*
80  * Reload the in core copy of the on-disk bitmap.
81  *
82  * This should be used after aborting a metadata transaction and setting the
83  * metadata to read-only, to invalidate the in-core cache and make it match the
84  * on-disk metadata.
85  *
86  * WARNING: It must not be called concurrently with either
87  * dm_clone_set_region_hydrated() or dm_clone_cond_set_range(), as it updates
88  * the region bitmap without taking the relevant spinlock. We don't take the
89  * spinlock because dm_clone_reload_in_core_bitset() does I/O, so it may block.
90  *
91  * But, it's safe to use it after calling dm_clone_metadata_set_read_only(),
92  * because the latter sets the metadata to read-only mode. Both
93  * dm_clone_set_region_hydrated() and dm_clone_cond_set_range() refuse to touch
94  * the region bitmap, after calling dm_clone_metadata_set_read_only().
95  */
96 int dm_clone_reload_in_core_bitset(struct dm_clone_metadata *cmd);
97 
98 /*
99  * Check whether dm-clone's metadata changed this transaction.
100  */
101 bool dm_clone_changed_this_transaction(struct dm_clone_metadata *cmd);
102 
103 /*
104  * Abort current metadata transaction and rollback metadata to the last
105  * committed transaction.
106  */
107 int dm_clone_metadata_abort(struct dm_clone_metadata *cmd);
108 
109 /*
110  * Switches metadata to a read only mode. Once read-only mode has been entered
111  * the following functions will return -EPERM:
112  *
113  *   dm_clone_metadata_commit()
114  *   dm_clone_set_region_hydrated()
115  *   dm_clone_cond_set_range()
116  *   dm_clone_metadata_abort()
117  */
118 void dm_clone_metadata_set_read_only(struct dm_clone_metadata *cmd);
119 void dm_clone_metadata_set_read_write(struct dm_clone_metadata *cmd);
120 
121 /*
122  * Returns true if the hydration of the destination device is finished.
123  */
124 bool dm_clone_is_hydration_done(struct dm_clone_metadata *cmd);
125 
126 /*
127  * Returns true if region @region_nr is hydrated.
128  */
129 bool dm_clone_is_region_hydrated(struct dm_clone_metadata *cmd, unsigned long region_nr);
130 
131 /*
132  * Returns true if all the regions in the range are hydrated.
133  */
134 bool dm_clone_is_range_hydrated(struct dm_clone_metadata *cmd,
135 				unsigned long start, unsigned long nr_regions);
136 
137 /*
138  * Returns the number of hydrated regions.
139  */
140 unsigned long dm_clone_nr_of_hydrated_regions(struct dm_clone_metadata *cmd);
141 
142 /*
143  * Returns the first unhydrated region with region_nr >= @start
144  */
145 unsigned long dm_clone_find_next_unhydrated_region(struct dm_clone_metadata *cmd,
146 						   unsigned long start);
147 
148 /*
149  * Get the number of free metadata blocks.
150  */
151 int dm_clone_get_free_metadata_block_count(struct dm_clone_metadata *cmd, dm_block_t *result);
152 
153 /*
154  * Get the total number of metadata blocks.
155  */
156 int dm_clone_get_metadata_dev_size(struct dm_clone_metadata *cmd, dm_block_t *result);
157 
158 #endif /* DM_CLONE_METADATA_H */
159