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1#
2# Block device driver configuration
3#
4
5menuconfig MD
6 bool "Multiple devices driver support (RAID and LVM)"
7 depends on BLOCK
8 help
9 Support multiple physical spindles through a single logical device.
10 Required for RAID and logical volume management.
11
12if MD
13
14config BLK_DEV_MD
15 tristate "RAID support"
16 ---help---
17 This driver lets you combine several hard disk partitions into one
18 logical block device. This can be used to simply append one
19 partition to another one or to combine several redundant hard disks
20 into a RAID1/4/5 device so as to provide protection against hard
21 disk failures. This is called "Software RAID" since the combining of
22 the partitions is done by the kernel. "Hardware RAID" means that the
23 combining is done by a dedicated controller; if you have such a
24 controller, you do not need to say Y here.
25
26 More information about Software RAID on Linux is contained in the
27 Software RAID mini-HOWTO, available from
28 <http://www.tldp.org/docs.html#howto>. There you will also learn
29 where to get the supporting user space utilities raidtools.
30
31 If unsure, say N.
32
33config MD_AUTODETECT
34 bool "Autodetect RAID arrays during kernel boot"
35 depends on BLK_DEV_MD=y
36 default y
37 ---help---
38 If you say Y here, then the kernel will try to autodetect raid
39 arrays as part of its boot process.
40
41 If you don't use raid and say Y, this autodetection can cause
42 a several-second delay in the boot time due to various
43 synchronisation steps that are part of this step.
44
45 If unsure, say Y.
46
47config MD_LINEAR
48 tristate "Linear (append) mode"
49 depends on BLK_DEV_MD
50 ---help---
51 If you say Y here, then your multiple devices driver will be able to
52 use the so-called linear mode, i.e. it will combine the hard disk
53 partitions by simply appending one to the other.
54
55 To compile this as a module, choose M here: the module
56 will be called linear.
57
58 If unsure, say Y.
59
60config MD_RAID0
61 tristate "RAID-0 (striping) mode"
62 depends on BLK_DEV_MD
63 ---help---
64 If you say Y here, then your multiple devices driver will be able to
65 use the so-called raid0 mode, i.e. it will combine the hard disk
66 partitions into one logical device in such a fashion as to fill them
67 up evenly, one chunk here and one chunk there. This will increase
68 the throughput rate if the partitions reside on distinct disks.
69
70 Information about Software RAID on Linux is contained in the
71 Software-RAID mini-HOWTO, available from
72 <http://www.tldp.org/docs.html#howto>. There you will also
73 learn where to get the supporting user space utilities raidtools.
74
75 To compile this as a module, choose M here: the module
76 will be called raid0.
77
78 If unsure, say Y.
79
80config MD_RAID1
81 tristate "RAID-1 (mirroring) mode"
82 depends on BLK_DEV_MD
83 ---help---
84 A RAID-1 set consists of several disk drives which are exact copies
85 of each other. In the event of a mirror failure, the RAID driver
86 will continue to use the operational mirrors in the set, providing
87 an error free MD (multiple device) to the higher levels of the
88 kernel. In a set with N drives, the available space is the capacity
89 of a single drive, and the set protects against a failure of (N - 1)
90 drives.
91
92 Information about Software RAID on Linux is contained in the
93 Software-RAID mini-HOWTO, available from
94 <http://www.tldp.org/docs.html#howto>. There you will also
95 learn where to get the supporting user space utilities raidtools.
96
97 If you want to use such a RAID-1 set, say Y. To compile this code
98 as a module, choose M here: the module will be called raid1.
99
100 If unsure, say Y.
101
102config MD_RAID10
103 tristate "RAID-10 (mirrored striping) mode"
104 depends on BLK_DEV_MD
105 ---help---
106 RAID-10 provides a combination of striping (RAID-0) and
107 mirroring (RAID-1) with easier configuration and more flexible
108 layout.
109 Unlike RAID-0, but like RAID-1, RAID-10 requires all devices to
110 be the same size (or at least, only as much as the smallest device
111 will be used).
112 RAID-10 provides a variety of layouts that provide different levels
113 of redundancy and performance.
114
115 RAID-10 requires mdadm-1.7.0 or later, available at:
116
117 ftp://ftp.kernel.org/pub/linux/utils/raid/mdadm/
118
119 If unsure, say Y.
120
121config MD_RAID456
122 tristate "RAID-4/RAID-5/RAID-6 mode"
123 depends on BLK_DEV_MD
124 select RAID6_PQ
125 select ASYNC_MEMCPY
126 select ASYNC_XOR
127 select ASYNC_PQ
128 select ASYNC_RAID6_RECOV
129 ---help---
130 A RAID-5 set of N drives with a capacity of C MB per drive provides
131 the capacity of C * (N - 1) MB, and protects against a failure
132 of a single drive. For a given sector (row) number, (N - 1) drives
133 contain data sectors, and one drive contains the parity protection.
134 For a RAID-4 set, the parity blocks are present on a single drive,
135 while a RAID-5 set distributes the parity across the drives in one
136 of the available parity distribution methods.
137
138 A RAID-6 set of N drives with a capacity of C MB per drive
139 provides the capacity of C * (N - 2) MB, and protects
140 against a failure of any two drives. For a given sector
141 (row) number, (N - 2) drives contain data sectors, and two
142 drives contains two independent redundancy syndromes. Like
143 RAID-5, RAID-6 distributes the syndromes across the drives
144 in one of the available parity distribution methods.
145
146 Information about Software RAID on Linux is contained in the
147 Software-RAID mini-HOWTO, available from
148 <http://www.tldp.org/docs.html#howto>. There you will also
149 learn where to get the supporting user space utilities raidtools.
150
151 If you want to use such a RAID-4/RAID-5/RAID-6 set, say Y. To
152 compile this code as a module, choose M here: the module
153 will be called raid456.
154
155 If unsure, say Y.
156
157config MULTICORE_RAID456
158 bool "RAID-4/RAID-5/RAID-6 Multicore processing (EXPERIMENTAL)"
159 depends on MD_RAID456
160 depends on SMP
161 depends on EXPERIMENTAL
162 ---help---
163 Enable the raid456 module to dispatch per-stripe raid operations to a
164 thread pool.
165
166 If unsure, say N.
167
168config MD_MULTIPATH
169 tristate "Multipath I/O support"
170 depends on BLK_DEV_MD
171 help
172 MD_MULTIPATH provides a simple multi-path personality for use
173 the MD framework. It is not under active development. New
174 projects should consider using DM_MULTIPATH which has more
175 features and more testing.
176
177 If unsure, say N.
178
179config MD_FAULTY
180 tristate "Faulty test module for MD"
181 depends on BLK_DEV_MD
182 help
183 The "faulty" module allows for a block device that occasionally returns
184 read or write errors. It is useful for testing.
185
186 In unsure, say N.
187
188config BLK_DEV_DM
189 tristate "Device mapper support"
190 ---help---
191 Device-mapper is a low level volume manager. It works by allowing
192 people to specify mappings for ranges of logical sectors. Various
193 mapping types are available, in addition people may write their own
194 modules containing custom mappings if they wish.
195
196 Higher level volume managers such as LVM2 use this driver.
197
198 To compile this as a module, choose M here: the module will be
199 called dm-mod.
200
201 If unsure, say N.
202
203config DM_DEBUG
204 boolean "Device mapper debugging support"
205 depends on BLK_DEV_DM
206 ---help---
207 Enable this for messages that may help debug device-mapper problems.
208
209 If unsure, say N.
210
211config DM_BUFIO
212 tristate
213 depends on BLK_DEV_DM && EXPERIMENTAL
214 ---help---
215 This interface allows you to do buffered I/O on a device and acts
216 as a cache, holding recently-read blocks in memory and performing
217 delayed writes.
218
219source "drivers/md/persistent-data/Kconfig"
220
221config DM_CRYPT
222 tristate "Crypt target support"
223 depends on BLK_DEV_DM
224 select CRYPTO
225 select CRYPTO_CBC
226 ---help---
227 This device-mapper target allows you to create a device that
228 transparently encrypts the data on it. You'll need to activate
229 the ciphers you're going to use in the cryptoapi configuration.
230
231 Information on how to use dm-crypt can be found on
232
233 <http://www.saout.de/misc/dm-crypt/>
234
235 To compile this code as a module, choose M here: the module will
236 be called dm-crypt.
237
238 If unsure, say N.
239
240config DM_SNAPSHOT
241 tristate "Snapshot target"
242 depends on BLK_DEV_DM
243 ---help---
244 Allow volume managers to take writable snapshots of a device.
245
246config DM_THIN_PROVISIONING
247 tristate "Thin provisioning target (EXPERIMENTAL)"
248 depends on BLK_DEV_DM && EXPERIMENTAL
249 select DM_PERSISTENT_DATA
250 ---help---
251 Provides thin provisioning and snapshots that share a data store.
252
253config DM_DEBUG_BLOCK_STACK_TRACING
254 boolean "Keep stack trace of thin provisioning block lock holders"
255 depends on STACKTRACE_SUPPORT && DM_THIN_PROVISIONING
256 select STACKTRACE
257 ---help---
258 Enable this for messages that may help debug problems with the
259 block manager locking used by thin provisioning.
260
261 If unsure, say N.
262
263config DM_DEBUG_SPACE_MAPS
264 boolean "Extra validation for thin provisioning space maps"
265 depends on DM_THIN_PROVISIONING
266 ---help---
267 Enable this for messages that may help debug problems with the
268 space maps used by thin provisioning.
269
270 If unsure, say N.
271
272config DM_MIRROR
273 tristate "Mirror target"
274 depends on BLK_DEV_DM
275 ---help---
276 Allow volume managers to mirror logical volumes, also
277 needed for live data migration tools such as 'pvmove'.
278
279config DM_RAID
280 tristate "RAID 1/4/5/6 target"
281 depends on BLK_DEV_DM
282 select MD_RAID1
283 select MD_RAID456
284 select BLK_DEV_MD
285 ---help---
286 A dm target that supports RAID1, RAID4, RAID5 and RAID6 mappings
287
288 A RAID-5 set of N drives with a capacity of C MB per drive provides
289 the capacity of C * (N - 1) MB, and protects against a failure
290 of a single drive. For a given sector (row) number, (N - 1) drives
291 contain data sectors, and one drive contains the parity protection.
292 For a RAID-4 set, the parity blocks are present on a single drive,
293 while a RAID-5 set distributes the parity across the drives in one
294 of the available parity distribution methods.
295
296 A RAID-6 set of N drives with a capacity of C MB per drive
297 provides the capacity of C * (N - 2) MB, and protects
298 against a failure of any two drives. For a given sector
299 (row) number, (N - 2) drives contain data sectors, and two
300 drives contains two independent redundancy syndromes. Like
301 RAID-5, RAID-6 distributes the syndromes across the drives
302 in one of the available parity distribution methods.
303
304config DM_LOG_USERSPACE
305 tristate "Mirror userspace logging (EXPERIMENTAL)"
306 depends on DM_MIRROR && EXPERIMENTAL && NET
307 select CONNECTOR
308 ---help---
309 The userspace logging module provides a mechanism for
310 relaying the dm-dirty-log API to userspace. Log designs
311 which are more suited to userspace implementation (e.g.
312 shared storage logs) or experimental logs can be implemented
313 by leveraging this framework.
314
315config DM_ZERO
316 tristate "Zero target"
317 depends on BLK_DEV_DM
318 ---help---
319 A target that discards writes, and returns all zeroes for
320 reads. Useful in some recovery situations.
321
322config DM_MULTIPATH
323 tristate "Multipath target"
324 depends on BLK_DEV_DM
325 # nasty syntax but means make DM_MULTIPATH independent
326 # of SCSI_DH if the latter isn't defined but if
327 # it is, DM_MULTIPATH must depend on it. We get a build
328 # error if SCSI_DH=m and DM_MULTIPATH=y
329 depends on SCSI_DH || !SCSI_DH
330 ---help---
331 Allow volume managers to support multipath hardware.
332
333config DM_MULTIPATH_QL
334 tristate "I/O Path Selector based on the number of in-flight I/Os"
335 depends on DM_MULTIPATH
336 ---help---
337 This path selector is a dynamic load balancer which selects
338 the path with the least number of in-flight I/Os.
339
340 If unsure, say N.
341
342config DM_MULTIPATH_ST
343 tristate "I/O Path Selector based on the service time"
344 depends on DM_MULTIPATH
345 ---help---
346 This path selector is a dynamic load balancer which selects
347 the path expected to complete the incoming I/O in the shortest
348 time.
349
350 If unsure, say N.
351
352config DM_DELAY
353 tristate "I/O delaying target (EXPERIMENTAL)"
354 depends on BLK_DEV_DM && EXPERIMENTAL
355 ---help---
356 A target that delays reads and/or writes and can send
357 them to different devices. Useful for testing.
358
359 If unsure, say N.
360
361config DM_UEVENT
362 bool "DM uevents"
363 depends on BLK_DEV_DM
364 ---help---
365 Generate udev events for DM events.
366
367config DM_FLAKEY
368 tristate "Flakey target (EXPERIMENTAL)"
369 depends on BLK_DEV_DM && EXPERIMENTAL
370 ---help---
371 A target that intermittently fails I/O for debugging purposes.
372
373config DM_VERITY
374 tristate "Verity target support (EXPERIMENTAL)"
375 depends on BLK_DEV_DM && EXPERIMENTAL
376 select CRYPTO
377 select CRYPTO_HASH
378 select DM_BUFIO
379 ---help---
380 This device-mapper target creates a read-only device that
381 transparently validates the data on one underlying device against
382 a pre-generated tree of cryptographic checksums stored on a second
383 device.
384
385 You'll need to activate the digests you're going to use in the
386 cryptoapi configuration.
387
388 To compile this code as a module, choose M here: the module will
389 be called dm-verity.
390
391 If unsure, say N.
392
393endif # MD
1# SPDX-License-Identifier: GPL-2.0-only
2#
3# Block device driver configuration
4#
5
6menuconfig MD
7 bool "Multiple devices driver support (RAID and LVM)"
8 depends on BLOCK
9 select SRCU
10 help
11 Support multiple physical spindles through a single logical device.
12 Required for RAID and logical volume management.
13
14if MD
15
16config BLK_DEV_MD
17 tristate "RAID support"
18 ---help---
19 This driver lets you combine several hard disk partitions into one
20 logical block device. This can be used to simply append one
21 partition to another one or to combine several redundant hard disks
22 into a RAID1/4/5 device so as to provide protection against hard
23 disk failures. This is called "Software RAID" since the combining of
24 the partitions is done by the kernel. "Hardware RAID" means that the
25 combining is done by a dedicated controller; if you have such a
26 controller, you do not need to say Y here.
27
28 More information about Software RAID on Linux is contained in the
29 Software RAID mini-HOWTO, available from
30 <http://www.tldp.org/docs.html#howto>. There you will also learn
31 where to get the supporting user space utilities raidtools.
32
33 If unsure, say N.
34
35config MD_AUTODETECT
36 bool "Autodetect RAID arrays during kernel boot"
37 depends on BLK_DEV_MD=y
38 default y
39 ---help---
40 If you say Y here, then the kernel will try to autodetect raid
41 arrays as part of its boot process.
42
43 If you don't use raid and say Y, this autodetection can cause
44 a several-second delay in the boot time due to various
45 synchronisation steps that are part of this step.
46
47 If unsure, say Y.
48
49config MD_LINEAR
50 tristate "Linear (append) mode"
51 depends on BLK_DEV_MD
52 ---help---
53 If you say Y here, then your multiple devices driver will be able to
54 use the so-called linear mode, i.e. it will combine the hard disk
55 partitions by simply appending one to the other.
56
57 To compile this as a module, choose M here: the module
58 will be called linear.
59
60 If unsure, say Y.
61
62config MD_RAID0
63 tristate "RAID-0 (striping) mode"
64 depends on BLK_DEV_MD
65 ---help---
66 If you say Y here, then your multiple devices driver will be able to
67 use the so-called raid0 mode, i.e. it will combine the hard disk
68 partitions into one logical device in such a fashion as to fill them
69 up evenly, one chunk here and one chunk there. This will increase
70 the throughput rate if the partitions reside on distinct disks.
71
72 Information about Software RAID on Linux is contained in the
73 Software-RAID mini-HOWTO, available from
74 <http://www.tldp.org/docs.html#howto>. There you will also
75 learn where to get the supporting user space utilities raidtools.
76
77 To compile this as a module, choose M here: the module
78 will be called raid0.
79
80 If unsure, say Y.
81
82config MD_RAID1
83 tristate "RAID-1 (mirroring) mode"
84 depends on BLK_DEV_MD
85 ---help---
86 A RAID-1 set consists of several disk drives which are exact copies
87 of each other. In the event of a mirror failure, the RAID driver
88 will continue to use the operational mirrors in the set, providing
89 an error free MD (multiple device) to the higher levels of the
90 kernel. In a set with N drives, the available space is the capacity
91 of a single drive, and the set protects against a failure of (N - 1)
92 drives.
93
94 Information about Software RAID on Linux is contained in the
95 Software-RAID mini-HOWTO, available from
96 <http://www.tldp.org/docs.html#howto>. There you will also
97 learn where to get the supporting user space utilities raidtools.
98
99 If you want to use such a RAID-1 set, say Y. To compile this code
100 as a module, choose M here: the module will be called raid1.
101
102 If unsure, say Y.
103
104config MD_RAID10
105 tristate "RAID-10 (mirrored striping) mode"
106 depends on BLK_DEV_MD
107 ---help---
108 RAID-10 provides a combination of striping (RAID-0) and
109 mirroring (RAID-1) with easier configuration and more flexible
110 layout.
111 Unlike RAID-0, but like RAID-1, RAID-10 requires all devices to
112 be the same size (or at least, only as much as the smallest device
113 will be used).
114 RAID-10 provides a variety of layouts that provide different levels
115 of redundancy and performance.
116
117 RAID-10 requires mdadm-1.7.0 or later, available at:
118
119 https://www.kernel.org/pub/linux/utils/raid/mdadm/
120
121 If unsure, say Y.
122
123config MD_RAID456
124 tristate "RAID-4/RAID-5/RAID-6 mode"
125 depends on BLK_DEV_MD
126 select RAID6_PQ
127 select LIBCRC32C
128 select ASYNC_MEMCPY
129 select ASYNC_XOR
130 select ASYNC_PQ
131 select ASYNC_RAID6_RECOV
132 ---help---
133 A RAID-5 set of N drives with a capacity of C MB per drive provides
134 the capacity of C * (N - 1) MB, and protects against a failure
135 of a single drive. For a given sector (row) number, (N - 1) drives
136 contain data sectors, and one drive contains the parity protection.
137 For a RAID-4 set, the parity blocks are present on a single drive,
138 while a RAID-5 set distributes the parity across the drives in one
139 of the available parity distribution methods.
140
141 A RAID-6 set of N drives with a capacity of C MB per drive
142 provides the capacity of C * (N - 2) MB, and protects
143 against a failure of any two drives. For a given sector
144 (row) number, (N - 2) drives contain data sectors, and two
145 drives contains two independent redundancy syndromes. Like
146 RAID-5, RAID-6 distributes the syndromes across the drives
147 in one of the available parity distribution methods.
148
149 Information about Software RAID on Linux is contained in the
150 Software-RAID mini-HOWTO, available from
151 <http://www.tldp.org/docs.html#howto>. There you will also
152 learn where to get the supporting user space utilities raidtools.
153
154 If you want to use such a RAID-4/RAID-5/RAID-6 set, say Y. To
155 compile this code as a module, choose M here: the module
156 will be called raid456.
157
158 If unsure, say Y.
159
160config MD_MULTIPATH
161 tristate "Multipath I/O support"
162 depends on BLK_DEV_MD
163 help
164 MD_MULTIPATH provides a simple multi-path personality for use
165 the MD framework. It is not under active development. New
166 projects should consider using DM_MULTIPATH which has more
167 features and more testing.
168
169 If unsure, say N.
170
171config MD_FAULTY
172 tristate "Faulty test module for MD"
173 depends on BLK_DEV_MD
174 help
175 The "faulty" module allows for a block device that occasionally returns
176 read or write errors. It is useful for testing.
177
178 In unsure, say N.
179
180
181config MD_CLUSTER
182 tristate "Cluster Support for MD"
183 depends on BLK_DEV_MD
184 depends on DLM
185 default n
186 ---help---
187 Clustering support for MD devices. This enables locking and
188 synchronization across multiple systems on the cluster, so all
189 nodes in the cluster can access the MD devices simultaneously.
190
191 This brings the redundancy (and uptime) of RAID levels across the
192 nodes of the cluster. Currently, it can work with raid1 and raid10
193 (limited support).
194
195 If unsure, say N.
196
197source "drivers/md/bcache/Kconfig"
198
199config BLK_DEV_DM_BUILTIN
200 bool
201
202config BLK_DEV_DM
203 tristate "Device mapper support"
204 select BLK_DEV_DM_BUILTIN
205 depends on DAX || DAX=n
206 ---help---
207 Device-mapper is a low level volume manager. It works by allowing
208 people to specify mappings for ranges of logical sectors. Various
209 mapping types are available, in addition people may write their own
210 modules containing custom mappings if they wish.
211
212 Higher level volume managers such as LVM2 use this driver.
213
214 To compile this as a module, choose M here: the module will be
215 called dm-mod.
216
217 If unsure, say N.
218
219config DM_DEBUG
220 bool "Device mapper debugging support"
221 depends on BLK_DEV_DM
222 ---help---
223 Enable this for messages that may help debug device-mapper problems.
224
225 If unsure, say N.
226
227config DM_BUFIO
228 tristate
229 depends on BLK_DEV_DM
230 ---help---
231 This interface allows you to do buffered I/O on a device and acts
232 as a cache, holding recently-read blocks in memory and performing
233 delayed writes.
234
235config DM_DEBUG_BLOCK_MANAGER_LOCKING
236 bool "Block manager locking"
237 depends on DM_BUFIO
238 ---help---
239 Block manager locking can catch various metadata corruption issues.
240
241 If unsure, say N.
242
243config DM_DEBUG_BLOCK_STACK_TRACING
244 bool "Keep stack trace of persistent data block lock holders"
245 depends on STACKTRACE_SUPPORT && DM_DEBUG_BLOCK_MANAGER_LOCKING
246 select STACKTRACE
247 ---help---
248 Enable this for messages that may help debug problems with the
249 block manager locking used by thin provisioning and caching.
250
251 If unsure, say N.
252
253config DM_BIO_PRISON
254 tristate
255 depends on BLK_DEV_DM
256 ---help---
257 Some bio locking schemes used by other device-mapper targets
258 including thin provisioning.
259
260source "drivers/md/persistent-data/Kconfig"
261
262config DM_UNSTRIPED
263 tristate "Unstriped target"
264 depends on BLK_DEV_DM
265 ---help---
266 Unstripes I/O so it is issued solely on a single drive in a HW
267 RAID0 or dm-striped target.
268
269config DM_CRYPT
270 tristate "Crypt target support"
271 depends on BLK_DEV_DM
272 select CRYPTO
273 select CRYPTO_CBC
274 select CRYPTO_ESSIV
275 ---help---
276 This device-mapper target allows you to create a device that
277 transparently encrypts the data on it. You'll need to activate
278 the ciphers you're going to use in the cryptoapi configuration.
279
280 For further information on dm-crypt and userspace tools see:
281 <https://gitlab.com/cryptsetup/cryptsetup/wikis/DMCrypt>
282
283 To compile this code as a module, choose M here: the module will
284 be called dm-crypt.
285
286 If unsure, say N.
287
288config DM_SNAPSHOT
289 tristate "Snapshot target"
290 depends on BLK_DEV_DM
291 select DM_BUFIO
292 ---help---
293 Allow volume managers to take writable snapshots of a device.
294
295config DM_THIN_PROVISIONING
296 tristate "Thin provisioning target"
297 depends on BLK_DEV_DM
298 select DM_PERSISTENT_DATA
299 select DM_BIO_PRISON
300 ---help---
301 Provides thin provisioning and snapshots that share a data store.
302
303config DM_CACHE
304 tristate "Cache target (EXPERIMENTAL)"
305 depends on BLK_DEV_DM
306 default n
307 select DM_PERSISTENT_DATA
308 select DM_BIO_PRISON
309 ---help---
310 dm-cache attempts to improve performance of a block device by
311 moving frequently used data to a smaller, higher performance
312 device. Different 'policy' plugins can be used to change the
313 algorithms used to select which blocks are promoted, demoted,
314 cleaned etc. It supports writeback and writethrough modes.
315
316config DM_CACHE_SMQ
317 tristate "Stochastic MQ Cache Policy (EXPERIMENTAL)"
318 depends on DM_CACHE
319 default y
320 ---help---
321 A cache policy that uses a multiqueue ordered by recent hits
322 to select which blocks should be promoted and demoted.
323 This is meant to be a general purpose policy. It prioritises
324 reads over writes. This SMQ policy (vs MQ) offers the promise
325 of less memory utilization, improved performance and increased
326 adaptability in the face of changing workloads.
327
328config DM_WRITECACHE
329 tristate "Writecache target"
330 depends on BLK_DEV_DM
331 ---help---
332 The writecache target caches writes on persistent memory or SSD.
333 It is intended for databases or other programs that need extremely
334 low commit latency.
335
336 The writecache target doesn't cache reads because reads are supposed
337 to be cached in standard RAM.
338
339config DM_ERA
340 tristate "Era target (EXPERIMENTAL)"
341 depends on BLK_DEV_DM
342 default n
343 select DM_PERSISTENT_DATA
344 select DM_BIO_PRISON
345 ---help---
346 dm-era tracks which parts of a block device are written to
347 over time. Useful for maintaining cache coherency when using
348 vendor snapshots.
349
350config DM_CLONE
351 tristate "Clone target (EXPERIMENTAL)"
352 depends on BLK_DEV_DM
353 default n
354 select DM_PERSISTENT_DATA
355 ---help---
356 dm-clone produces a one-to-one copy of an existing, read-only source
357 device into a writable destination device. The cloned device is
358 visible/mountable immediately and the copy of the source device to the
359 destination device happens in the background, in parallel with user
360 I/O.
361
362 If unsure, say N.
363
364config DM_MIRROR
365 tristate "Mirror target"
366 depends on BLK_DEV_DM
367 ---help---
368 Allow volume managers to mirror logical volumes, also
369 needed for live data migration tools such as 'pvmove'.
370
371config DM_LOG_USERSPACE
372 tristate "Mirror userspace logging"
373 depends on DM_MIRROR && NET
374 select CONNECTOR
375 ---help---
376 The userspace logging module provides a mechanism for
377 relaying the dm-dirty-log API to userspace. Log designs
378 which are more suited to userspace implementation (e.g.
379 shared storage logs) or experimental logs can be implemented
380 by leveraging this framework.
381
382config DM_RAID
383 tristate "RAID 1/4/5/6/10 target"
384 depends on BLK_DEV_DM
385 select MD_RAID0
386 select MD_RAID1
387 select MD_RAID10
388 select MD_RAID456
389 select BLK_DEV_MD
390 ---help---
391 A dm target that supports RAID1, RAID10, RAID4, RAID5 and RAID6 mappings
392
393 A RAID-5 set of N drives with a capacity of C MB per drive provides
394 the capacity of C * (N - 1) MB, and protects against a failure
395 of a single drive. For a given sector (row) number, (N - 1) drives
396 contain data sectors, and one drive contains the parity protection.
397 For a RAID-4 set, the parity blocks are present on a single drive,
398 while a RAID-5 set distributes the parity across the drives in one
399 of the available parity distribution methods.
400
401 A RAID-6 set of N drives with a capacity of C MB per drive
402 provides the capacity of C * (N - 2) MB, and protects
403 against a failure of any two drives. For a given sector
404 (row) number, (N - 2) drives contain data sectors, and two
405 drives contains two independent redundancy syndromes. Like
406 RAID-5, RAID-6 distributes the syndromes across the drives
407 in one of the available parity distribution methods.
408
409config DM_ZERO
410 tristate "Zero target"
411 depends on BLK_DEV_DM
412 ---help---
413 A target that discards writes, and returns all zeroes for
414 reads. Useful in some recovery situations.
415
416config DM_MULTIPATH
417 tristate "Multipath target"
418 depends on BLK_DEV_DM
419 # nasty syntax but means make DM_MULTIPATH independent
420 # of SCSI_DH if the latter isn't defined but if
421 # it is, DM_MULTIPATH must depend on it. We get a build
422 # error if SCSI_DH=m and DM_MULTIPATH=y
423 depends on !SCSI_DH || SCSI
424 ---help---
425 Allow volume managers to support multipath hardware.
426
427config DM_MULTIPATH_QL
428 tristate "I/O Path Selector based on the number of in-flight I/Os"
429 depends on DM_MULTIPATH
430 ---help---
431 This path selector is a dynamic load balancer which selects
432 the path with the least number of in-flight I/Os.
433
434 If unsure, say N.
435
436config DM_MULTIPATH_ST
437 tristate "I/O Path Selector based on the service time"
438 depends on DM_MULTIPATH
439 ---help---
440 This path selector is a dynamic load balancer which selects
441 the path expected to complete the incoming I/O in the shortest
442 time.
443
444 If unsure, say N.
445
446config DM_DELAY
447 tristate "I/O delaying target"
448 depends on BLK_DEV_DM
449 ---help---
450 A target that delays reads and/or writes and can send
451 them to different devices. Useful for testing.
452
453 If unsure, say N.
454
455config DM_DUST
456 tristate "Bad sector simulation target"
457 depends on BLK_DEV_DM
458 ---help---
459 A target that simulates bad sector behavior.
460 Useful for testing.
461
462 If unsure, say N.
463
464config DM_INIT
465 bool "DM \"dm-mod.create=\" parameter support"
466 depends on BLK_DEV_DM=y
467 ---help---
468 Enable "dm-mod.create=" parameter to create mapped devices at init time.
469 This option is useful to allow mounting rootfs without requiring an
470 initramfs.
471 See Documentation/admin-guide/device-mapper/dm-init.rst for dm-mod.create="..."
472 format.
473
474 If unsure, say N.
475
476config DM_UEVENT
477 bool "DM uevents"
478 depends on BLK_DEV_DM
479 ---help---
480 Generate udev events for DM events.
481
482config DM_FLAKEY
483 tristate "Flakey target"
484 depends on BLK_DEV_DM
485 ---help---
486 A target that intermittently fails I/O for debugging purposes.
487
488config DM_VERITY
489 tristate "Verity target support"
490 depends on BLK_DEV_DM
491 select CRYPTO
492 select CRYPTO_HASH
493 select DM_BUFIO
494 ---help---
495 This device-mapper target creates a read-only device that
496 transparently validates the data on one underlying device against
497 a pre-generated tree of cryptographic checksums stored on a second
498 device.
499
500 You'll need to activate the digests you're going to use in the
501 cryptoapi configuration.
502
503 To compile this code as a module, choose M here: the module will
504 be called dm-verity.
505
506 If unsure, say N.
507
508config DM_VERITY_VERIFY_ROOTHASH_SIG
509 def_bool n
510 bool "Verity data device root hash signature verification support"
511 depends on DM_VERITY
512 select SYSTEM_DATA_VERIFICATION
513 help
514 Add ability for dm-verity device to be validated if the
515 pre-generated tree of cryptographic checksums passed has a pkcs#7
516 signature file that can validate the roothash of the tree.
517
518 If unsure, say N.
519
520config DM_VERITY_FEC
521 bool "Verity forward error correction support"
522 depends on DM_VERITY
523 select REED_SOLOMON
524 select REED_SOLOMON_DEC8
525 ---help---
526 Add forward error correction support to dm-verity. This option
527 makes it possible to use pre-generated error correction data to
528 recover from corrupted blocks.
529
530 If unsure, say N.
531
532config DM_SWITCH
533 tristate "Switch target support (EXPERIMENTAL)"
534 depends on BLK_DEV_DM
535 ---help---
536 This device-mapper target creates a device that supports an arbitrary
537 mapping of fixed-size regions of I/O across a fixed set of paths.
538 The path used for any specific region can be switched dynamically
539 by sending the target a message.
540
541 To compile this code as a module, choose M here: the module will
542 be called dm-switch.
543
544 If unsure, say N.
545
546config DM_LOG_WRITES
547 tristate "Log writes target support"
548 depends on BLK_DEV_DM
549 ---help---
550 This device-mapper target takes two devices, one device to use
551 normally, one to log all write operations done to the first device.
552 This is for use by file system developers wishing to verify that
553 their fs is writing a consistent file system at all times by allowing
554 them to replay the log in a variety of ways and to check the
555 contents.
556
557 To compile this code as a module, choose M here: the module will
558 be called dm-log-writes.
559
560 If unsure, say N.
561
562config DM_INTEGRITY
563 tristate "Integrity target support"
564 depends on BLK_DEV_DM
565 select BLK_DEV_INTEGRITY
566 select DM_BUFIO
567 select CRYPTO
568 select ASYNC_XOR
569 ---help---
570 This device-mapper target emulates a block device that has
571 additional per-sector tags that can be used for storing
572 integrity information.
573
574 This integrity target is used with the dm-crypt target to
575 provide authenticated disk encryption or it can be used
576 standalone.
577
578 To compile this code as a module, choose M here: the module will
579 be called dm-integrity.
580
581config DM_ZONED
582 tristate "Drive-managed zoned block device target support"
583 depends on BLK_DEV_DM
584 depends on BLK_DEV_ZONED
585 ---help---
586 This device-mapper target takes a host-managed or host-aware zoned
587 block device and exposes most of its capacity as a regular block
588 device (drive-managed zoned block device) without any write
589 constraints. This is mainly intended for use with file systems that
590 do not natively support zoned block devices but still want to
591 benefit from the increased capacity offered by SMR disks. Other uses
592 by applications using raw block devices (for example object stores)
593 are also possible.
594
595 To compile this code as a module, choose M here: the module will
596 be called dm-zoned.
597
598 If unsure, say N.
599
600endif # MD