1/*
  2 * Copyright (c) 2010 Red Hat, Inc. All Rights Reserved.
  3 *
  4 * This program is free software; you can redistribute it and/or
  5 * modify it under the terms of the GNU General Public License as
  6 * published by the Free Software Foundation.
  7 *
  8 * This program is distributed in the hope that it would be useful,
  9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 11 * GNU General Public License for more details.
 12 *
 13 * You should have received a copy of the GNU General Public License
 14 * along with this program; if not, write the Free Software Foundation,
 15 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 16 */
 17
 18#include "xfs.h"
 19#include "xfs_fs.h"
 20#include "xfs_types.h"
 21#include "xfs_bit.h"
 22#include "xfs_log.h"
 23#include "xfs_inum.h"
 
 
 24#include "xfs_trans.h"
 25#include "xfs_trans_priv.h"
 
 26#include "xfs_log_priv.h"
 27#include "xfs_sb.h"
 28#include "xfs_ag.h"
 29#include "xfs_mount.h"
 30#include "xfs_error.h"
 31#include "xfs_alloc.h"
 32#include "xfs_discard.h"
 33
 34/*
 35 * Perform initial CIL structure initialisation. If the CIL is not
 36 * enabled in this filesystem, ensure the log->l_cilp is null so
 37 * we can check this conditional to determine if we are doing delayed
 38 * logging or not.
 39 */
 40int
 41xlog_cil_init(
 42	struct log	*log)
 43{
 44	struct xfs_cil	*cil;
 45	struct xfs_cil_ctx *ctx;
 46
 47	log->l_cilp = NULL;
 48	if (!(log->l_mp->m_flags & XFS_MOUNT_DELAYLOG))
 49		return 0;
 50
 51	cil = kmem_zalloc(sizeof(*cil), KM_SLEEP|KM_MAYFAIL);
 52	if (!cil)
 53		return ENOMEM;
 54
 55	ctx = kmem_zalloc(sizeof(*ctx), KM_SLEEP|KM_MAYFAIL);
 56	if (!ctx) {
 57		kmem_free(cil);
 58		return ENOMEM;
 59	}
 60
 61	INIT_LIST_HEAD(&cil->xc_cil);
 62	INIT_LIST_HEAD(&cil->xc_committing);
 63	spin_lock_init(&cil->xc_cil_lock);
 64	init_rwsem(&cil->xc_ctx_lock);
 65	init_waitqueue_head(&cil->xc_commit_wait);
 66
 67	INIT_LIST_HEAD(&ctx->committing);
 68	INIT_LIST_HEAD(&ctx->busy_extents);
 69	ctx->sequence = 1;
 70	ctx->cil = cil;
 71	cil->xc_ctx = ctx;
 72	cil->xc_current_sequence = ctx->sequence;
 73
 74	cil->xc_log = log;
 75	log->l_cilp = cil;
 76	return 0;
 77}
 78
 79void
 80xlog_cil_destroy(
 81	struct log	*log)
 82{
 83	if (!log->l_cilp)
 84		return;
 85
 86	if (log->l_cilp->xc_ctx) {
 87		if (log->l_cilp->xc_ctx->ticket)
 88			xfs_log_ticket_put(log->l_cilp->xc_ctx->ticket);
 89		kmem_free(log->l_cilp->xc_ctx);
 90	}
 91
 92	ASSERT(list_empty(&log->l_cilp->xc_cil));
 93	kmem_free(log->l_cilp);
 94}
 95
 96/*
 97 * Allocate a new ticket. Failing to get a new ticket makes it really hard to
 98 * recover, so we don't allow failure here. Also, we allocate in a context that
 99 * we don't want to be issuing transactions from, so we need to tell the
100 * allocation code this as well.
101 *
102 * We don't reserve any space for the ticket - we are going to steal whatever
103 * space we require from transactions as they commit. To ensure we reserve all
104 * the space required, we need to set the current reservation of the ticket to
105 * zero so that we know to steal the initial transaction overhead from the
106 * first transaction commit.
107 */
108static struct xlog_ticket *
109xlog_cil_ticket_alloc(
110	struct log	*log)
111{
112	struct xlog_ticket *tic;
113
114	tic = xlog_ticket_alloc(log, 0, 1, XFS_TRANSACTION, 0,
115				KM_SLEEP|KM_NOFS);
116	tic->t_trans_type = XFS_TRANS_CHECKPOINT;
117
118	/*
119	 * set the current reservation to zero so we know to steal the basic
120	 * transaction overhead reservation from the first transaction commit.
121	 */
122	tic->t_curr_res = 0;
 
123	return tic;
124}
125
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
126/*
127 * After the first stage of log recovery is done, we know where the head and
128 * tail of the log are. We need this log initialisation done before we can
129 * initialise the first CIL checkpoint context.
130 *
131 * Here we allocate a log ticket to track space usage during a CIL push.  This
132 * ticket is passed to xlog_write() directly so that we don't slowly leak log
133 * space by failing to account for space used by log headers and additional
134 * region headers for split regions.
135 */
136void
137xlog_cil_init_post_recovery(
138	struct log	*log)
139{
140	if (!log->l_cilp)
141		return;
142
143	log->l_cilp->xc_ctx->ticket = xlog_cil_ticket_alloc(log);
144	log->l_cilp->xc_ctx->sequence = 1;
145	log->l_cilp->xc_ctx->commit_lsn = xlog_assign_lsn(log->l_curr_cycle,
146								log->l_curr_block);
 
 
 
 
 
 
 
 
147}
148
149/*
150 * Format log item into a flat buffers
151 *
152 * For delayed logging, we need to hold a formatted buffer containing all the
153 * changes on the log item. This enables us to relog the item in memory and
154 * write it out asynchronously without needing to relock the object that was
155 * modified at the time it gets written into the iclog.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
156 *
157 * This function builds a vector for the changes in each log item in the
158 * transaction. It then works out the length of the buffer needed for each log
159 * item, allocates them and formats the vector for the item into the buffer.
160 * The buffer is then attached to the log item are then inserted into the
161 * Committed Item List for tracking until the next checkpoint is written out.
162 *
163 * We don't set up region headers during this process; we simply copy the
164 * regions into the flat buffer. We can do this because we still have to do a
165 * formatting step to write the regions into the iclog buffer.  Writing the
166 * ophdrs during the iclog write means that we can support splitting large
167 * regions across iclog boundares without needing a change in the format of the
168 * item/region encapsulation.
169 *
170 * Hence what we need to do now is change the rewrite the vector array to point
171 * to the copied region inside the buffer we just allocated. This allows us to
172 * format the regions into the iclog as though they are being formatted
173 * directly out of the objects themselves.
174 */
175static void
176xlog_cil_format_items(
177	struct log		*log,
178	struct xfs_log_vec	*log_vector)
179{
180	struct xfs_log_vec *lv;
181
182	ASSERT(log_vector);
183	for (lv = log_vector; lv; lv = lv->lv_next) {
184		void	*ptr;
185		int	index;
186		int	len = 0;
187
188		/* build the vector array and calculate it's length */
189		IOP_FORMAT(lv->lv_item, lv->lv_iovecp);
190		for (index = 0; index < lv->lv_niovecs; index++)
191			len += lv->lv_iovecp[index].i_len;
192
193		lv->lv_buf_len = len;
194		lv->lv_buf = kmem_alloc(lv->lv_buf_len, KM_SLEEP|KM_NOFS);
195		ptr = lv->lv_buf;
196
197		for (index = 0; index < lv->lv_niovecs; index++) {
198			struct xfs_log_iovec *vec = &lv->lv_iovecp[index];
199
200			memcpy(ptr, vec->i_addr, vec->i_len);
201			vec->i_addr = ptr;
202			ptr += vec->i_len;
 
 
203		}
204		ASSERT(ptr == lv->lv_buf + lv->lv_buf_len);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
205	}
 
206}
207
208/*
209 * Prepare the log item for insertion into the CIL. Calculate the difference in
210 * log space and vectors it will consume, and if it is a new item pin it as
211 * well.
212 */
213STATIC void
214xfs_cil_prepare_item(
215	struct log		*log,
216	struct xfs_log_vec	*lv,
217	int			*len,
218	int			*diff_iovecs)
219{
220	struct xfs_log_vec	*old = lv->lv_item->li_lv;
 
 
221
222	if (old) {
223		/* existing lv on log item, space used is a delta */
224		ASSERT(!list_empty(&lv->lv_item->li_cil));
225		ASSERT(old->lv_buf && old->lv_buf_len && old->lv_niovecs);
226
227		*len += lv->lv_buf_len - old->lv_buf_len;
228		*diff_iovecs += lv->lv_niovecs - old->lv_niovecs;
229		kmem_free(old->lv_buf);
230		kmem_free(old);
231	} else {
232		/* new lv, must pin the log item */
233		ASSERT(!lv->lv_item->li_lv);
234		ASSERT(list_empty(&lv->lv_item->li_cil));
235
236		*len += lv->lv_buf_len;
237		*diff_iovecs += lv->lv_niovecs;
238		IOP_PIN(lv->lv_item);
239
 
 
240	}
241
242	/* attach new log vector to log item */
243	lv->lv_item->li_lv = lv;
244
245	/*
246	 * If this is the first time the item is being committed to the
247	 * CIL, store the sequence number on the log item so we can
248	 * tell in future commits whether this is the first checkpoint
249	 * the item is being committed into.
250	 */
251	if (!lv->lv_item->li_seq)
252		lv->lv_item->li_seq = log->l_cilp->xc_ctx->sequence;
253}
254
255/*
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
256 * Insert the log items into the CIL and calculate the difference in space
257 * consumed by the item. Add the space to the checkpoint ticket and calculate
258 * if the change requires additional log metadata. If it does, take that space
259 * as well. Remove the amount of space we addded to the checkpoint ticket from
260 * the current transaction ticket so that the accounting works out correctly.
261 */
262static void
263xlog_cil_insert_items(
264	struct log		*log,
265	struct xfs_log_vec	*log_vector,
266	struct xlog_ticket	*ticket)
267{
268	struct xfs_cil		*cil = log->l_cilp;
269	struct xfs_cil_ctx	*ctx = cil->xc_ctx;
270	struct xfs_log_vec	*lv;
271	int			len = 0;
272	int			diff_iovecs = 0;
273	int			iclog_space;
 
 
 
274
275	ASSERT(log_vector);
276
277	/*
278	 * Do all the accounting aggregation and switching of log vectors
279	 * around in a separate loop to the insertion of items into the CIL.
280	 * Then we can do a separate loop to update the CIL within a single
281	 * lock/unlock pair. This reduces the number of round trips on the CIL
282	 * lock from O(nr_logvectors) to O(1) and greatly reduces the overall
283	 * hold time for the transaction commit.
284	 *
285	 * If this is the first time the item is being placed into the CIL in
286	 * this context, pin it so it can't be written to disk until the CIL is
287	 * flushed to the iclog and the iclog written to disk.
288	 *
289	 * We can do this safely because the context can't checkpoint until we
290	 * are done so it doesn't matter exactly how we update the CIL.
291	 */
292	for (lv = log_vector; lv; lv = lv->lv_next)
293		xfs_cil_prepare_item(log, lv, &len, &diff_iovecs);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
294
295	/* account for space used by new iovec headers  */
296	len += diff_iovecs * sizeof(xlog_op_header_t);
 
 
 
 
 
 
 
 
 
297
298	spin_lock(&cil->xc_cil_lock);
 
 
 
 
 
 
 
 
 
 
 
299
300	/* move the items to the tail of the CIL */
301	for (lv = log_vector; lv; lv = lv->lv_next)
302		list_move_tail(&lv->lv_item->li_cil, &cil->xc_cil);
 
 
 
 
 
 
 
 
303
304	ctx->nvecs += diff_iovecs;
 
 
 
 
 
305
306	/*
307	 * Now transfer enough transaction reservation to the context ticket
308	 * for the checkpoint. The context ticket is special - the unit
309	 * reservation has to grow as well as the current reservation as we
310	 * steal from tickets so we can correctly determine the space used
311	 * during the transaction commit.
312	 */
313	if (ctx->ticket->t_curr_res == 0) {
314		/* first commit in checkpoint, steal the header reservation */
315		ASSERT(ticket->t_curr_res >= ctx->ticket->t_unit_res + len);
316		ctx->ticket->t_curr_res = ctx->ticket->t_unit_res;
317		ticket->t_curr_res -= ctx->ticket->t_unit_res;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
318	}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
319
320	/* do we need space for more log record headers? */
321	iclog_space = log->l_iclog_size - log->l_iclog_hsize;
322	if (len > 0 && (ctx->space_used / iclog_space !=
323				(ctx->space_used + len) / iclog_space)) {
324		int hdrs;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
325
326		hdrs = (len + iclog_space - 1) / iclog_space;
327		/* need to take into account split region headers, too */
328		hdrs *= log->l_iclog_hsize + sizeof(struct xlog_op_header);
329		ctx->ticket->t_unit_res += hdrs;
330		ctx->ticket->t_curr_res += hdrs;
331		ticket->t_curr_res -= hdrs;
332		ASSERT(ticket->t_curr_res >= len);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
333	}
334	ticket->t_curr_res -= len;
335	ctx->space_used += len;
336
337	spin_unlock(&cil->xc_cil_lock);
 
 
 
 
 
 
 
338}
339
340static void
341xlog_cil_free_logvec(
342	struct xfs_log_vec	*log_vector)
343{
344	struct xfs_log_vec	*lv;
345
346	for (lv = log_vector; lv; ) {
347		struct xfs_log_vec *next = lv->lv_next;
348		kmem_free(lv->lv_buf);
349		kmem_free(lv);
350		lv = next;
351	}
352}
353
354/*
355 * Mark all items committed and clear busy extents. We free the log vector
356 * chains in a separate pass so that we unpin the log items as quickly as
357 * possible.
358 */
359static void
360xlog_cil_committed(
361	void	*args,
362	int	abort)
363{
364	struct xfs_cil_ctx	*ctx = args;
365	struct xfs_mount	*mp = ctx->cil->xc_log->l_mp;
 
366
367	xfs_trans_committed_bulk(ctx->cil->xc_log->l_ailp, ctx->lv_chain,
368					ctx->start_lsn, abort);
 
 
 
 
 
 
 
 
 
 
 
369
370	xfs_alloc_busy_sort(&ctx->busy_extents);
371	xfs_alloc_busy_clear(mp, &ctx->busy_extents,
372			     (mp->m_flags & XFS_MOUNT_DISCARD) && !abort);
373
374	spin_lock(&ctx->cil->xc_cil_lock);
375	list_del(&ctx->committing);
376	spin_unlock(&ctx->cil->xc_cil_lock);
377
378	xlog_cil_free_logvec(ctx->lv_chain);
 
 
379
380	if (!list_empty(&ctx->busy_extents)) {
381		ASSERT(mp->m_flags & XFS_MOUNT_DISCARD);
382
 
 
383		xfs_discard_extents(mp, &ctx->busy_extents);
384		xfs_alloc_busy_clear(mp, &ctx->busy_extents, false);
385	}
386
387	kmem_free(ctx);
388}
389
390/*
391 * Push the Committed Item List to the log. If @push_seq flag is zero, then it
392 * is a background flush and so we can chose to ignore it. Otherwise, if the
393 * current sequence is the same as @push_seq we need to do a flush. If
394 * @push_seq is less than the current sequence, then it has already been
395 * flushed and we don't need to do anything - the caller will wait for it to
396 * complete if necessary.
397 *
398 * @push_seq is a value rather than a flag because that allows us to do an
399 * unlocked check of the sequence number for a match. Hence we can allows log
400 * forces to run racily and not issue pushes for the same sequence twice. If we
401 * get a race between multiple pushes for the same sequence they will block on
402 * the first one and then abort, hence avoiding needless pushes.
403 */
404STATIC int
405xlog_cil_push(
406	struct log		*log,
407	xfs_lsn_t		push_seq)
408{
409	struct xfs_cil		*cil = log->l_cilp;
410	struct xfs_log_vec	*lv;
411	struct xfs_cil_ctx	*ctx;
412	struct xfs_cil_ctx	*new_ctx;
413	struct xlog_in_core	*commit_iclog;
414	struct xlog_ticket	*tic;
415	int			num_lv;
416	int			num_iovecs;
417	int			len;
418	int			error = 0;
419	struct xfs_trans_header thdr;
420	struct xfs_log_iovec	lhdr;
421	struct xfs_log_vec	lvhdr = { NULL };
422	xfs_lsn_t		commit_lsn;
423
424	if (!cil)
425		return 0;
 
 
 
 
426
427	ASSERT(!push_seq || push_seq <= cil->xc_ctx->sequence);
 
 
 
 
 
 
 
 
 
 
 
 
428
429	new_ctx = kmem_zalloc(sizeof(*new_ctx), KM_SLEEP|KM_NOFS);
430	new_ctx->ticket = xlog_cil_ticket_alloc(log);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
431
432	/*
433	 * Lock out transaction commit, but don't block for background pushes
434	 * unless we are well over the CIL space limit. See the definition of
435	 * XLOG_CIL_HARD_SPACE_LIMIT() for the full explanation of the logic
436	 * used here.
437	 */
438	if (!down_write_trylock(&cil->xc_ctx_lock)) {
439		if (!push_seq &&
440		    cil->xc_ctx->space_used < XLOG_CIL_HARD_SPACE_LIMIT(log))
441			goto out_free_ticket;
442		down_write(&cil->xc_ctx_lock);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
443	}
444	ctx = cil->xc_ctx;
 
 
445
446	/* check if we've anything to push */
447	if (list_empty(&cil->xc_cil))
448		goto out_skip;
 
 
 
 
 
 
 
 
 
 
449
450	/* check for spurious background flush */
451	if (!push_seq && cil->xc_ctx->space_used < XLOG_CIL_SPACE_LIMIT(log))
452		goto out_skip;
 
 
453
454	/* check for a previously pushed seqeunce */
455	if (push_seq && push_seq < cil->xc_ctx->sequence)
456		goto out_skip;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
457
458	/*
459	 * pull all the log vectors off the items in the CIL, and
460	 * remove the items from the CIL. We don't need the CIL lock
461	 * here because it's only needed on the transaction commit
462	 * side which is currently locked out by the flush lock.
463	 */
464	lv = NULL;
465	num_lv = 0;
466	num_iovecs = 0;
467	len = 0;
468	while (!list_empty(&cil->xc_cil)) {
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
469		struct xfs_log_item	*item;
470		int			i;
471
472		item = list_first_entry(&cil->xc_cil,
473					struct xfs_log_item, li_cil);
474		list_del_init(&item->li_cil);
475		if (!ctx->lv_chain)
476			ctx->lv_chain = item->li_lv;
477		else
478			lv->lv_next = item->li_lv;
 
 
479		lv = item->li_lv;
 
 
 
 
 
 
 
 
 
 
480		item->li_lv = NULL;
 
 
481
482		num_lv++;
483		num_iovecs += lv->lv_niovecs;
484		for (i = 0; i < lv->lv_niovecs; i++)
485			len += lv->lv_iovecp[i].i_len;
 
 
 
 
 
 
486	}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
487
488	/*
489	 * initialise the new context and attach it to the CIL. Then attach
490	 * the current context to the CIL committing lsit so it can be found
491	 * during log forces to extract the commit lsn of the sequence that
492	 * needs to be forced.
 
 
493	 */
494	INIT_LIST_HEAD(&new_ctx->committing);
495	INIT_LIST_HEAD(&new_ctx->busy_extents);
496	new_ctx->sequence = ctx->sequence + 1;
497	new_ctx->cil = cil;
498	cil->xc_ctx = new_ctx;
499
500	/*
501	 * mirror the new sequence into the cil structure so that we can do
502	 * unlocked checks against the current sequence in log forces without
503	 * risking deferencing a freed context pointer.
504	 */
505	cil->xc_current_sequence = new_ctx->sequence;
 
 
 
 
 
 
 
 
 
 
 
506
507	/*
508	 * The switch is now done, so we can drop the context lock and move out
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
509	 * of a shared context. We can't just go straight to the commit record,
510	 * though - we need to synchronise with previous and future commits so
511	 * that the commit records are correctly ordered in the log to ensure
512	 * that we process items during log IO completion in the correct order.
513	 *
514	 * For example, if we get an EFI in one checkpoint and the EFD in the
515	 * next (e.g. due to log forces), we do not want the checkpoint with
516	 * the EFD to be committed before the checkpoint with the EFI.  Hence
517	 * we must strictly order the commit records of the checkpoints so
518	 * that: a) the checkpoint callbacks are attached to the iclogs in the
519	 * correct order; and b) the checkpoints are replayed in correct order
520	 * in log recovery.
521	 *
522	 * Hence we need to add this context to the committing context list so
523	 * that higher sequences will wait for us to write out a commit record
524	 * before they do.
 
 
 
 
 
 
525	 */
526	spin_lock(&cil->xc_cil_lock);
527	list_add(&ctx->committing, &cil->xc_committing);
528	spin_unlock(&cil->xc_cil_lock);
529	up_write(&cil->xc_ctx_lock);
530
531	/*
 
 
 
 
 
 
 
532	 * Build a checkpoint transaction header and write it to the log to
533	 * begin the transaction. We need to account for the space used by the
534	 * transaction header here as it is not accounted for in xlog_write().
535	 *
536	 * The LSN we need to pass to the log items on transaction commit is
537	 * the LSN reported by the first log vector write. If we use the commit
538	 * record lsn then we can move the tail beyond the grant write head.
539	 */
540	tic = ctx->ticket;
541	thdr.th_magic = XFS_TRANS_HEADER_MAGIC;
542	thdr.th_type = XFS_TRANS_CHECKPOINT;
543	thdr.th_tid = tic->t_tid;
544	thdr.th_num_items = num_iovecs;
545	lhdr.i_addr = &thdr;
546	lhdr.i_len = sizeof(xfs_trans_header_t);
547	lhdr.i_type = XLOG_REG_TYPE_TRANSHDR;
548	tic->t_curr_res -= lhdr.i_len + sizeof(xlog_op_header_t);
549
550	lvhdr.lv_niovecs = 1;
551	lvhdr.lv_iovecp = &lhdr;
552	lvhdr.lv_next = ctx->lv_chain;
553
554	error = xlog_write(log, &lvhdr, tic, &ctx->start_lsn, NULL, 0);
555	if (error)
556		goto out_abort_free_ticket;
557
558	/*
559	 * now that we've written the checkpoint into the log, strictly
560	 * order the commit records so replay will get them in the right order.
 
 
 
561	 */
562restart:
563	spin_lock(&cil->xc_cil_lock);
564	list_for_each_entry(new_ctx, &cil->xc_committing, committing) {
565		/*
566		 * Higher sequences will wait for this one so skip them.
567		 * Don't wait for own own sequence, either.
568		 */
569		if (new_ctx->sequence >= ctx->sequence)
570			continue;
571		if (!new_ctx->commit_lsn) {
 
 
 
 
 
 
 
 
 
 
572			/*
573			 * It is still being pushed! Wait for the push to
574			 * complete, then start again from the beginning.
 
575			 */
576			xlog_wait(&cil->xc_commit_wait, &cil->xc_cil_lock);
577			goto restart;
578		}
579	}
580	spin_unlock(&cil->xc_cil_lock);
581
582	/* xfs_log_done always frees the ticket on error. */
583	commit_lsn = xfs_log_done(log->l_mp, tic, &commit_iclog, 0);
584	if (commit_lsn == -1)
585		goto out_abort;
586
587	/* attach all the transactions w/ busy extents to iclog */
588	ctx->log_cb.cb_func = xlog_cil_committed;
589	ctx->log_cb.cb_arg = ctx;
590	error = xfs_log_notify(log->l_mp, commit_iclog, &ctx->log_cb);
591	if (error)
592		goto out_abort;
593
594	/*
595	 * now the checkpoint commit is complete and we've attached the
596	 * callbacks to the iclog we can assign the commit LSN to the context
597	 * and wake up anyone who is waiting for the commit to complete.
 
 
 
 
 
598	 */
599	spin_lock(&cil->xc_cil_lock);
600	ctx->commit_lsn = commit_lsn;
601	wake_up_all(&cil->xc_commit_wait);
602	spin_unlock(&cil->xc_cil_lock);
603
604	/* release the hounds! */
605	return xfs_log_release_iclog(log->l_mp, commit_iclog);
 
 
 
 
 
 
 
606
607out_skip:
608	up_write(&cil->xc_ctx_lock);
609out_free_ticket:
610	xfs_log_ticket_put(new_ctx->ticket);
611	kmem_free(new_ctx);
612	return 0;
 
613
614out_abort_free_ticket:
615	xfs_log_ticket_put(tic);
616out_abort:
617	xlog_cil_committed(ctx, XFS_LI_ABORTED);
618	return XFS_ERROR(EIO);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
619}
620
621/*
622 * Commit a transaction with the given vector to the Committed Item List.
623 *
624 * To do this, we need to format the item, pin it in memory if required and
625 * account for the space used by the transaction. Once we have done that we
626 * need to release the unused reservation for the transaction, attach the
627 * transaction to the checkpoint context so we carry the busy extents through
628 * to checkpoint completion, and then unlock all the items in the transaction.
629 *
630 * For more specific information about the order of operations in
631 * xfs_log_commit_cil() please refer to the comments in
632 * xfs_trans_commit_iclog().
633 *
634 * Called with the context lock already held in read mode to lock out
635 * background commit, returns without it held once background commits are
636 * allowed again.
637 */
638void
639xfs_log_commit_cil(
640	struct xfs_mount	*mp,
641	struct xfs_trans	*tp,
642	struct xfs_log_vec	*log_vector,
643	xfs_lsn_t		*commit_lsn,
644	int			flags)
645{
646	struct log		*log = mp->m_log;
647	int			log_flags = 0;
648	int			push = 0;
649
650	if (flags & XFS_TRANS_RELEASE_LOG_RES)
651		log_flags = XFS_LOG_REL_PERM_RESERV;
652
653	/*
654	 * do all the hard work of formatting items (including memory
655	 * allocation) outside the CIL context lock. This prevents stalling CIL
656	 * pushes when we are low on memory and a transaction commit spends a
657	 * lot of time in memory reclaim.
658	 */
659	xlog_cil_format_items(log, log_vector);
660
661	/* lock out background commit */
662	down_read(&log->l_cilp->xc_ctx_lock);
663	if (commit_lsn)
664		*commit_lsn = log->l_cilp->xc_ctx->sequence;
665
666	xlog_cil_insert_items(log, log_vector, tp->t_ticket);
667
668	/* check we didn't blow the reservation */
669	if (tp->t_ticket->t_curr_res < 0)
670		xlog_print_tic_res(log->l_mp, tp->t_ticket);
671
672	/* attach the transaction to the CIL if it has any busy extents */
673	if (!list_empty(&tp->t_busy)) {
674		spin_lock(&log->l_cilp->xc_cil_lock);
675		list_splice_init(&tp->t_busy,
676					&log->l_cilp->xc_ctx->busy_extents);
677		spin_unlock(&log->l_cilp->xc_cil_lock);
678	}
679
680	tp->t_commit_lsn = *commit_lsn;
681	xfs_log_done(mp, tp->t_ticket, NULL, log_flags);
 
 
 
 
 
682	xfs_trans_unreserve_and_mod_sb(tp);
683
684	/*
685	 * Once all the items of the transaction have been copied to the CIL,
686	 * the items can be unlocked and freed.
687	 *
688	 * This needs to be done before we drop the CIL context lock because we
689	 * have to update state in the log items and unlock them before they go
690	 * to disk. If we don't, then the CIL checkpoint can race with us and
691	 * we can run checkpoint completion before we've updated and unlocked
692	 * the log items. This affects (at least) processing of stale buffers,
693	 * inodes and EFIs.
694	 */
695	xfs_trans_free_items(tp, *commit_lsn, 0);
 
 
 
 
 
 
 
696
697	/* check for background commit before unlock */
698	if (log->l_cilp->xc_ctx->space_used > XLOG_CIL_SPACE_LIMIT(log))
699		push = 1;
700
701	up_read(&log->l_cilp->xc_ctx_lock);
 
 
 
 
 
 
 
 
 
 
 
 
702
703	/*
704	 * We need to push CIL every so often so we don't cache more than we
705	 * can fit in the log. The limit really is that a checkpoint can't be
706	 * more than half the log (the current checkpoint is not allowed to
707	 * overwrite the previous checkpoint), but commit latency and memory
708	 * usage limit this to a smaller size in most cases.
709	 */
710	if (push)
711		xlog_cil_push(log, 0);
712}
713
714/*
715 * Conditionally push the CIL based on the sequence passed in.
716 *
717 * We only need to push if we haven't already pushed the sequence
718 * number given. Hence the only time we will trigger a push here is
719 * if the push sequence is the same as the current context.
720 *
721 * We return the current commit lsn to allow the callers to determine if a
722 * iclog flush is necessary following this call.
723 *
724 * XXX: Initially, just push the CIL unconditionally and return whatever
725 * commit lsn is there. It'll be empty, so this is broken for now.
726 */
727xfs_lsn_t
728xlog_cil_force_lsn(
729	struct log	*log,
730	xfs_lsn_t	sequence)
731{
732	struct xfs_cil		*cil = log->l_cilp;
733	struct xfs_cil_ctx	*ctx;
734	xfs_lsn_t		commit_lsn = NULLCOMMITLSN;
735
736	ASSERT(sequence <= cil->xc_current_sequence);
737
 
 
 
 
738	/*
739	 * check to see if we need to force out the current context.
740	 * xlog_cil_push() handles racing pushes for the same sequence,
741	 * so no need to deal with it here.
742	 */
743	if (sequence == cil->xc_current_sequence)
744		xlog_cil_push(log, sequence);
745
746	/*
747	 * See if we can find a previous sequence still committing.
748	 * We need to wait for all previous sequence commits to complete
749	 * before allowing the force of push_seq to go ahead. Hence block
750	 * on commits for those as well.
751	 */
752restart:
753	spin_lock(&cil->xc_cil_lock);
754	list_for_each_entry(ctx, &cil->xc_committing, committing) {
 
 
 
 
 
 
 
755		if (ctx->sequence > sequence)
756			continue;
757		if (!ctx->commit_lsn) {
758			/*
759			 * It is still being pushed! Wait for the push to
760			 * complete, then start again from the beginning.
761			 */
762			xlog_wait(&cil->xc_commit_wait, &cil->xc_cil_lock);
 
763			goto restart;
764		}
765		if (ctx->sequence != sequence)
766			continue;
767		/* found it! */
768		commit_lsn = ctx->commit_lsn;
769	}
770	spin_unlock(&cil->xc_cil_lock);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
771	return commit_lsn;
 
 
 
 
 
 
 
 
 
 
 
772}
773
774/*
775 * Check if the current log item was first committed in this sequence.
776 * We can't rely on just the log item being in the CIL, we have to check
777 * the recorded commit sequence number.
778 *
779 * Note: for this to be used in a non-racy manner, it has to be called with
780 * CIL flushing locked out. As a result, it should only be used during the
781 * transaction commit process when deciding what to format into the item.
782 */
783bool
784xfs_log_item_in_current_chkpt(
785	struct xfs_log_item *lip)
786{
787	struct xfs_cil_ctx *ctx;
788
789	if (!(lip->li_mountp->m_flags & XFS_MOUNT_DELAYLOG))
790		return false;
791	if (list_empty(&lip->li_cil))
792		return false;
793
794	ctx = lip->li_mountp->m_log->l_cilp->xc_ctx;
795
 
 
 
796	/*
797	 * li_seq is written on the first commit of a log item to record the
798	 * first checkpoint it is written to. Hence if it is different to the
799	 * current sequence, we're in a new checkpoint.
800	 */
801	if (XFS_LSN_CMP(lip->li_seq, ctx->sequence) != 0)
802		return false;
803	return true;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
804}