1 |
62 |
marcus.erl |
#ifndef _RAID5_H
|
2 |
|
|
#define _RAID5_H
|
3 |
|
|
|
4 |
|
|
#include <linux/raid/md.h>
|
5 |
|
|
#include <linux/raid/xor.h>
|
6 |
|
|
|
7 |
|
|
/*
|
8 |
|
|
*
|
9 |
|
|
* Each stripe contains one buffer per disc. Each buffer can be in
|
10 |
|
|
* one of a number of states stored in "flags". Changes between
|
11 |
|
|
* these states happen *almost* exclusively under a per-stripe
|
12 |
|
|
* spinlock. Some very specific changes can happen in bi_end_io, and
|
13 |
|
|
* these are not protected by the spin lock.
|
14 |
|
|
*
|
15 |
|
|
* The flag bits that are used to represent these states are:
|
16 |
|
|
* R5_UPTODATE and R5_LOCKED
|
17 |
|
|
*
|
18 |
|
|
* State Empty == !UPTODATE, !LOCK
|
19 |
|
|
* We have no data, and there is no active request
|
20 |
|
|
* State Want == !UPTODATE, LOCK
|
21 |
|
|
* A read request is being submitted for this block
|
22 |
|
|
* State Dirty == UPTODATE, LOCK
|
23 |
|
|
* Some new data is in this buffer, and it is being written out
|
24 |
|
|
* State Clean == UPTODATE, !LOCK
|
25 |
|
|
* We have valid data which is the same as on disc
|
26 |
|
|
*
|
27 |
|
|
* The possible state transitions are:
|
28 |
|
|
*
|
29 |
|
|
* Empty -> Want - on read or write to get old data for parity calc
|
30 |
|
|
* Empty -> Dirty - on compute_parity to satisfy write/sync request.(RECONSTRUCT_WRITE)
|
31 |
|
|
* Empty -> Clean - on compute_block when computing a block for failed drive
|
32 |
|
|
* Want -> Empty - on failed read
|
33 |
|
|
* Want -> Clean - on successful completion of read request
|
34 |
|
|
* Dirty -> Clean - on successful completion of write request
|
35 |
|
|
* Dirty -> Clean - on failed write
|
36 |
|
|
* Clean -> Dirty - on compute_parity to satisfy write/sync (RECONSTRUCT or RMW)
|
37 |
|
|
*
|
38 |
|
|
* The Want->Empty, Want->Clean, Dirty->Clean, transitions
|
39 |
|
|
* all happen in b_end_io at interrupt time.
|
40 |
|
|
* Each sets the Uptodate bit before releasing the Lock bit.
|
41 |
|
|
* This leaves one multi-stage transition:
|
42 |
|
|
* Want->Dirty->Clean
|
43 |
|
|
* This is safe because thinking that a Clean buffer is actually dirty
|
44 |
|
|
* will at worst delay some action, and the stripe will be scheduled
|
45 |
|
|
* for attention after the transition is complete.
|
46 |
|
|
*
|
47 |
|
|
* There is one possibility that is not covered by these states. That
|
48 |
|
|
* is if one drive has failed and there is a spare being rebuilt. We
|
49 |
|
|
* can't distinguish between a clean block that has been generated
|
50 |
|
|
* from parity calculations, and a clean block that has been
|
51 |
|
|
* successfully written to the spare ( or to parity when resyncing).
|
52 |
|
|
* To distingush these states we have a stripe bit STRIPE_INSYNC that
|
53 |
|
|
* is set whenever a write is scheduled to the spare, or to the parity
|
54 |
|
|
* disc if there is no spare. A sync request clears this bit, and
|
55 |
|
|
* when we find it set with no buffers locked, we know the sync is
|
56 |
|
|
* complete.
|
57 |
|
|
*
|
58 |
|
|
* Buffers for the md device that arrive via make_request are attached
|
59 |
|
|
* to the appropriate stripe in one of two lists linked on b_reqnext.
|
60 |
|
|
* One list (bh_read) for read requests, one (bh_write) for write.
|
61 |
|
|
* There should never be more than one buffer on the two lists
|
62 |
|
|
* together, but we are not guaranteed of that so we allow for more.
|
63 |
|
|
*
|
64 |
|
|
* If a buffer is on the read list when the associated cache buffer is
|
65 |
|
|
* Uptodate, the data is copied into the read buffer and it's b_end_io
|
66 |
|
|
* routine is called. This may happen in the end_request routine only
|
67 |
|
|
* if the buffer has just successfully been read. end_request should
|
68 |
|
|
* remove the buffers from the list and then set the Uptodate bit on
|
69 |
|
|
* the buffer. Other threads may do this only if they first check
|
70 |
|
|
* that the Uptodate bit is set. Once they have checked that they may
|
71 |
|
|
* take buffers off the read queue.
|
72 |
|
|
*
|
73 |
|
|
* When a buffer on the write list is committed for write it is copied
|
74 |
|
|
* into the cache buffer, which is then marked dirty, and moved onto a
|
75 |
|
|
* third list, the written list (bh_written). Once both the parity
|
76 |
|
|
* block and the cached buffer are successfully written, any buffer on
|
77 |
|
|
* a written list can be returned with b_end_io.
|
78 |
|
|
*
|
79 |
|
|
* The write list and read list both act as fifos. The read list is
|
80 |
|
|
* protected by the device_lock. The write and written lists are
|
81 |
|
|
* protected by the stripe lock. The device_lock, which can be
|
82 |
|
|
* claimed while the stipe lock is held, is only for list
|
83 |
|
|
* manipulations and will only be held for a very short time. It can
|
84 |
|
|
* be claimed from interrupts.
|
85 |
|
|
*
|
86 |
|
|
*
|
87 |
|
|
* Stripes in the stripe cache can be on one of two lists (or on
|
88 |
|
|
* neither). The "inactive_list" contains stripes which are not
|
89 |
|
|
* currently being used for any request. They can freely be reused
|
90 |
|
|
* for another stripe. The "handle_list" contains stripes that need
|
91 |
|
|
* to be handled in some way. Both of these are fifo queues. Each
|
92 |
|
|
* stripe is also (potentially) linked to a hash bucket in the hash
|
93 |
|
|
* table so that it can be found by sector number. Stripes that are
|
94 |
|
|
* not hashed must be on the inactive_list, and will normally be at
|
95 |
|
|
* the front. All stripes start life this way.
|
96 |
|
|
*
|
97 |
|
|
* The inactive_list, handle_list and hash bucket lists are all protected by the
|
98 |
|
|
* device_lock.
|
99 |
|
|
* - stripes on the inactive_list never have their stripe_lock held.
|
100 |
|
|
* - stripes have a reference counter. If count==0, they are on a list.
|
101 |
|
|
* - If a stripe might need handling, STRIPE_HANDLE is set.
|
102 |
|
|
* - When refcount reaches zero, then if STRIPE_HANDLE it is put on
|
103 |
|
|
* handle_list else inactive_list
|
104 |
|
|
*
|
105 |
|
|
* This, combined with the fact that STRIPE_HANDLE is only ever
|
106 |
|
|
* cleared while a stripe has a non-zero count means that if the
|
107 |
|
|
* refcount is 0 and STRIPE_HANDLE is set, then it is on the
|
108 |
|
|
* handle_list and if recount is 0 and STRIPE_HANDLE is not set, then
|
109 |
|
|
* the stripe is on inactive_list.
|
110 |
|
|
*
|
111 |
|
|
* The possible transitions are:
|
112 |
|
|
* activate an unhashed/inactive stripe (get_active_stripe())
|
113 |
|
|
* lockdev check-hash unlink-stripe cnt++ clean-stripe hash-stripe unlockdev
|
114 |
|
|
* activate a hashed, possibly active stripe (get_active_stripe())
|
115 |
|
|
* lockdev check-hash if(!cnt++)unlink-stripe unlockdev
|
116 |
|
|
* attach a request to an active stripe (add_stripe_bh())
|
117 |
|
|
* lockdev attach-buffer unlockdev
|
118 |
|
|
* handle a stripe (handle_stripe())
|
119 |
|
|
* lockstripe clrSTRIPE_HANDLE ...
|
120 |
|
|
* (lockdev check-buffers unlockdev) ..
|
121 |
|
|
* change-state ..
|
122 |
|
|
* record io/ops needed unlockstripe schedule io/ops
|
123 |
|
|
* release an active stripe (release_stripe())
|
124 |
|
|
* lockdev if (!--cnt) { if STRIPE_HANDLE, add to handle_list else add to inactive-list } unlockdev
|
125 |
|
|
*
|
126 |
|
|
* The refcount counts each thread that have activated the stripe,
|
127 |
|
|
* plus raid5d if it is handling it, plus one for each active request
|
128 |
|
|
* on a cached buffer, and plus one if the stripe is undergoing stripe
|
129 |
|
|
* operations.
|
130 |
|
|
*
|
131 |
|
|
* Stripe operations are performed outside the stripe lock,
|
132 |
|
|
* the stripe operations are:
|
133 |
|
|
* -copying data between the stripe cache and user application buffers
|
134 |
|
|
* -computing blocks to save a disk access, or to recover a missing block
|
135 |
|
|
* -updating the parity on a write operation (reconstruct write and
|
136 |
|
|
* read-modify-write)
|
137 |
|
|
* -checking parity correctness
|
138 |
|
|
* -running i/o to disk
|
139 |
|
|
* These operations are carried out by raid5_run_ops which uses the async_tx
|
140 |
|
|
* api to (optionally) offload operations to dedicated hardware engines.
|
141 |
|
|
* When requesting an operation handle_stripe sets the pending bit for the
|
142 |
|
|
* operation and increments the count. raid5_run_ops is then run whenever
|
143 |
|
|
* the count is non-zero.
|
144 |
|
|
* There are some critical dependencies between the operations that prevent some
|
145 |
|
|
* from being requested while another is in flight.
|
146 |
|
|
* 1/ Parity check operations destroy the in cache version of the parity block,
|
147 |
|
|
* so we prevent parity dependent operations like writes and compute_blocks
|
148 |
|
|
* from starting while a check is in progress. Some dma engines can perform
|
149 |
|
|
* the check without damaging the parity block, in these cases the parity
|
150 |
|
|
* block is re-marked up to date (assuming the check was successful) and is
|
151 |
|
|
* not re-read from disk.
|
152 |
|
|
* 2/ When a write operation is requested we immediately lock the affected
|
153 |
|
|
* blocks, and mark them as not up to date. This causes new read requests
|
154 |
|
|
* to be held off, as well as parity checks and compute block operations.
|
155 |
|
|
* 3/ Once a compute block operation has been requested handle_stripe treats
|
156 |
|
|
* that block as if it is up to date. raid5_run_ops guaruntees that any
|
157 |
|
|
* operation that is dependent on the compute block result is initiated after
|
158 |
|
|
* the compute block completes.
|
159 |
|
|
*/
|
160 |
|
|
|
161 |
|
|
struct stripe_head {
|
162 |
|
|
struct hlist_node hash;
|
163 |
|
|
struct list_head lru; /* inactive_list or handle_list */
|
164 |
|
|
struct raid5_private_data *raid_conf;
|
165 |
|
|
sector_t sector; /* sector of this row */
|
166 |
|
|
int pd_idx; /* parity disk index */
|
167 |
|
|
unsigned long state; /* state flags */
|
168 |
|
|
atomic_t count; /* nr of active thread/requests */
|
169 |
|
|
spinlock_t lock;
|
170 |
|
|
int bm_seq; /* sequence number for bitmap flushes */
|
171 |
|
|
int disks; /* disks in stripe */
|
172 |
|
|
/* stripe_operations
|
173 |
|
|
* @pending - pending ops flags (set for request->issue->complete)
|
174 |
|
|
* @ack - submitted ops flags (set for issue->complete)
|
175 |
|
|
* @complete - completed ops flags (set for complete)
|
176 |
|
|
* @target - STRIPE_OP_COMPUTE_BLK target
|
177 |
|
|
* @count - raid5_runs_ops is set to run when this is non-zero
|
178 |
|
|
*/
|
179 |
|
|
struct stripe_operations {
|
180 |
|
|
unsigned long pending;
|
181 |
|
|
unsigned long ack;
|
182 |
|
|
unsigned long complete;
|
183 |
|
|
int target;
|
184 |
|
|
int count;
|
185 |
|
|
u32 zero_sum_result;
|
186 |
|
|
} ops;
|
187 |
|
|
struct r5dev {
|
188 |
|
|
struct bio req;
|
189 |
|
|
struct bio_vec vec;
|
190 |
|
|
struct page *page;
|
191 |
|
|
struct bio *toread, *read, *towrite, *written;
|
192 |
|
|
sector_t sector; /* sector of this page */
|
193 |
|
|
unsigned long flags;
|
194 |
|
|
} dev[1]; /* allocated with extra space depending of RAID geometry */
|
195 |
|
|
};
|
196 |
|
|
|
197 |
|
|
/* stripe_head_state - collects and tracks the dynamic state of a stripe_head
|
198 |
|
|
* for handle_stripe. It is only valid under spin_lock(sh->lock);
|
199 |
|
|
*/
|
200 |
|
|
struct stripe_head_state {
|
201 |
|
|
int syncing, expanding, expanded;
|
202 |
|
|
int locked, uptodate, to_read, to_write, failed, written;
|
203 |
|
|
int to_fill, compute, req_compute, non_overwrite;
|
204 |
|
|
int failed_num;
|
205 |
|
|
};
|
206 |
|
|
|
207 |
|
|
/* r6_state - extra state data only relevant to r6 */
|
208 |
|
|
struct r6_state {
|
209 |
|
|
int p_failed, q_failed, qd_idx, failed_num[2];
|
210 |
|
|
};
|
211 |
|
|
|
212 |
|
|
/* Flags */
|
213 |
|
|
#define R5_UPTODATE 0 /* page contains current data */
|
214 |
|
|
#define R5_LOCKED 1 /* IO has been submitted on "req" */
|
215 |
|
|
#define R5_OVERWRITE 2 /* towrite covers whole page */
|
216 |
|
|
/* and some that are internal to handle_stripe */
|
217 |
|
|
#define R5_Insync 3 /* rdev && rdev->in_sync at start */
|
218 |
|
|
#define R5_Wantread 4 /* want to schedule a read */
|
219 |
|
|
#define R5_Wantwrite 5
|
220 |
|
|
#define R5_Overlap 7 /* There is a pending overlapping request on this block */
|
221 |
|
|
#define R5_ReadError 8 /* seen a read error here recently */
|
222 |
|
|
#define R5_ReWrite 9 /* have tried to over-write the readerror */
|
223 |
|
|
|
224 |
|
|
#define R5_Expanded 10 /* This block now has post-expand data */
|
225 |
|
|
#define R5_Wantcompute 11 /* compute_block in progress treat as
|
226 |
|
|
* uptodate
|
227 |
|
|
*/
|
228 |
|
|
#define R5_Wantfill 12 /* dev->toread contains a bio that needs
|
229 |
|
|
* filling
|
230 |
|
|
*/
|
231 |
|
|
#define R5_Wantprexor 13 /* distinguish blocks ready for rmw from
|
232 |
|
|
* other "towrites"
|
233 |
|
|
*/
|
234 |
|
|
/*
|
235 |
|
|
* Write method
|
236 |
|
|
*/
|
237 |
|
|
#define RECONSTRUCT_WRITE 1
|
238 |
|
|
#define READ_MODIFY_WRITE 2
|
239 |
|
|
/* not a write method, but a compute_parity mode */
|
240 |
|
|
#define CHECK_PARITY 3
|
241 |
|
|
|
242 |
|
|
/*
|
243 |
|
|
* Stripe state
|
244 |
|
|
*/
|
245 |
|
|
#define STRIPE_HANDLE 2
|
246 |
|
|
#define STRIPE_SYNCING 3
|
247 |
|
|
#define STRIPE_INSYNC 4
|
248 |
|
|
#define STRIPE_PREREAD_ACTIVE 5
|
249 |
|
|
#define STRIPE_DELAYED 6
|
250 |
|
|
#define STRIPE_DEGRADED 7
|
251 |
|
|
#define STRIPE_BIT_DELAY 8
|
252 |
|
|
#define STRIPE_EXPANDING 9
|
253 |
|
|
#define STRIPE_EXPAND_SOURCE 10
|
254 |
|
|
#define STRIPE_EXPAND_READY 11
|
255 |
|
|
/*
|
256 |
|
|
* Operations flags (in issue order)
|
257 |
|
|
*/
|
258 |
|
|
#define STRIPE_OP_BIOFILL 0
|
259 |
|
|
#define STRIPE_OP_COMPUTE_BLK 1
|
260 |
|
|
#define STRIPE_OP_PREXOR 2
|
261 |
|
|
#define STRIPE_OP_BIODRAIN 3
|
262 |
|
|
#define STRIPE_OP_POSTXOR 4
|
263 |
|
|
#define STRIPE_OP_CHECK 5
|
264 |
|
|
#define STRIPE_OP_IO 6
|
265 |
|
|
|
266 |
|
|
/* modifiers to the base operations
|
267 |
|
|
* STRIPE_OP_MOD_REPAIR_PD - compute the parity block and write it back
|
268 |
|
|
* STRIPE_OP_MOD_DMA_CHECK - parity is not corrupted by the check
|
269 |
|
|
*/
|
270 |
|
|
#define STRIPE_OP_MOD_REPAIR_PD 7
|
271 |
|
|
#define STRIPE_OP_MOD_DMA_CHECK 8
|
272 |
|
|
|
273 |
|
|
/*
|
274 |
|
|
* Plugging:
|
275 |
|
|
*
|
276 |
|
|
* To improve write throughput, we need to delay the handling of some
|
277 |
|
|
* stripes until there has been a chance that several write requests
|
278 |
|
|
* for the one stripe have all been collected.
|
279 |
|
|
* In particular, any write request that would require pre-reading
|
280 |
|
|
* is put on a "delayed" queue until there are no stripes currently
|
281 |
|
|
* in a pre-read phase. Further, if the "delayed" queue is empty when
|
282 |
|
|
* a stripe is put on it then we "plug" the queue and do not process it
|
283 |
|
|
* until an unplug call is made. (the unplug_io_fn() is called).
|
284 |
|
|
*
|
285 |
|
|
* When preread is initiated on a stripe, we set PREREAD_ACTIVE and add
|
286 |
|
|
* it to the count of prereading stripes.
|
287 |
|
|
* When write is initiated, or the stripe refcnt == 0 (just in case) we
|
288 |
|
|
* clear the PREREAD_ACTIVE flag and decrement the count
|
289 |
|
|
* Whenever the 'handle' queue is empty and the device is not plugged, we
|
290 |
|
|
* move any strips from delayed to handle and clear the DELAYED flag and set
|
291 |
|
|
* PREREAD_ACTIVE.
|
292 |
|
|
* In stripe_handle, if we find pre-reading is necessary, we do it if
|
293 |
|
|
* PREREAD_ACTIVE is set, else we set DELAYED which will send it to the delayed queue.
|
294 |
|
|
* HANDLE gets cleared if stripe_handle leave nothing locked.
|
295 |
|
|
*/
|
296 |
|
|
|
297 |
|
|
|
298 |
|
|
struct disk_info {
|
299 |
|
|
mdk_rdev_t *rdev;
|
300 |
|
|
};
|
301 |
|
|
|
302 |
|
|
struct raid5_private_data {
|
303 |
|
|
struct hlist_head *stripe_hashtbl;
|
304 |
|
|
mddev_t *mddev;
|
305 |
|
|
struct disk_info *spare;
|
306 |
|
|
int chunk_size, level, algorithm;
|
307 |
|
|
int max_degraded;
|
308 |
|
|
int raid_disks;
|
309 |
|
|
int max_nr_stripes;
|
310 |
|
|
|
311 |
|
|
/* used during an expand */
|
312 |
|
|
sector_t expand_progress; /* MaxSector when no expand happening */
|
313 |
|
|
sector_t expand_lo; /* from here up to expand_progress it out-of-bounds
|
314 |
|
|
* as we haven't flushed the metadata yet
|
315 |
|
|
*/
|
316 |
|
|
int previous_raid_disks;
|
317 |
|
|
|
318 |
|
|
struct list_head handle_list; /* stripes needing handling */
|
319 |
|
|
struct list_head delayed_list; /* stripes that have plugged requests */
|
320 |
|
|
struct list_head bitmap_list; /* stripes delaying awaiting bitmap update */
|
321 |
|
|
struct bio *retry_read_aligned; /* currently retrying aligned bios */
|
322 |
|
|
struct bio *retry_read_aligned_list; /* aligned bios retry list */
|
323 |
|
|
atomic_t preread_active_stripes; /* stripes with scheduled io */
|
324 |
|
|
atomic_t active_aligned_reads;
|
325 |
|
|
|
326 |
|
|
atomic_t reshape_stripes; /* stripes with pending writes for reshape */
|
327 |
|
|
/* unfortunately we need two cache names as we temporarily have
|
328 |
|
|
* two caches.
|
329 |
|
|
*/
|
330 |
|
|
int active_name;
|
331 |
|
|
char cache_name[2][20];
|
332 |
|
|
struct kmem_cache *slab_cache; /* for allocating stripes */
|
333 |
|
|
|
334 |
|
|
int seq_flush, seq_write;
|
335 |
|
|
int quiesce;
|
336 |
|
|
|
337 |
|
|
int fullsync; /* set to 1 if a full sync is needed,
|
338 |
|
|
* (fresh device added).
|
339 |
|
|
* Cleared when a sync completes.
|
340 |
|
|
*/
|
341 |
|
|
|
342 |
|
|
struct page *spare_page; /* Used when checking P/Q in raid6 */
|
343 |
|
|
|
344 |
|
|
/*
|
345 |
|
|
* Free stripes pool
|
346 |
|
|
*/
|
347 |
|
|
atomic_t active_stripes;
|
348 |
|
|
struct list_head inactive_list;
|
349 |
|
|
wait_queue_head_t wait_for_stripe;
|
350 |
|
|
wait_queue_head_t wait_for_overlap;
|
351 |
|
|
int inactive_blocked; /* release of inactive stripes blocked,
|
352 |
|
|
* waiting for 25% to be free
|
353 |
|
|
*/
|
354 |
|
|
int pool_size; /* number of disks in stripeheads in pool */
|
355 |
|
|
spinlock_t device_lock;
|
356 |
|
|
struct disk_info *disks;
|
357 |
|
|
};
|
358 |
|
|
|
359 |
|
|
typedef struct raid5_private_data raid5_conf_t;
|
360 |
|
|
|
361 |
|
|
#define mddev_to_conf(mddev) ((raid5_conf_t *) mddev->private)
|
362 |
|
|
|
363 |
|
|
/*
|
364 |
|
|
* Our supported algorithms
|
365 |
|
|
*/
|
366 |
|
|
#define ALGORITHM_LEFT_ASYMMETRIC 0
|
367 |
|
|
#define ALGORITHM_RIGHT_ASYMMETRIC 1
|
368 |
|
|
#define ALGORITHM_LEFT_SYMMETRIC 2
|
369 |
|
|
#define ALGORITHM_RIGHT_SYMMETRIC 3
|
370 |
|
|
|
371 |
|
|
#endif
|