text: /*
   * GPL HEADER START
   *
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 only,
   * as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License version 2 for more details (a copy is included
   * in the LICENSE file that accompanied this code).
   *
   * You should have received a copy of the GNU General Public License
   * version 2 along with this program; If not, see
   * http://www.gnu.org/licenses/gpl-2.0.html
   *
   * GPL HEADER END
   */
  /*
   * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
   * Use is subject to license terms.
   *
   * Copyright (c) 2012, Intel Corporation.
   */
  /*
   * This file is part of Lustre, http://www.lustre.org/
   * Lustre is a trademark of Sun Microsystems, Inc.
   *
   * libcfs/libcfs/tracefile.c
   *
   * Author: Zach Brown <zab@clusterfs.com>
   * Author: Phil Schwan <phil@clusterfs.com>
   */
  
  #define DEBUG_SUBSYSTEM S_LNET
  #define LUSTRE_TRACEFILE_PRIVATE
  #define pr_fmt(fmt) "Lustre: " fmt
  #include "tracefile.h"
  
  #include "../../include/linux/libcfs/libcfs.h"
  
  /* XXX move things up to the top, comment */
  union cfs_trace_data_union (*cfs_trace_data[TCD_MAX_TYPES])[NR_CPUS] __cacheline_aligned;
  
  char cfs_tracefile[TRACEFILE_NAME_SIZE];
  long long cfs_tracefile_size = CFS_TRACEFILE_SIZE;
  static struct tracefiled_ctl trace_tctl;
  static DEFINE_MUTEX(cfs_trace_thread_mutex);
  static int thread_running;
  
  static atomic_t cfs_tage_allocated = ATOMIC_INIT(0);
  
  struct page_collection {
  	struct list_head	pc_pages;
  	/*
  	 * if this flag is set, collect_pages() will spill both
  	 * ->tcd_daemon_pages and ->tcd_pages to the ->pc_pages. Otherwise,
  	 * only ->tcd_pages are spilled.
  	 */
  	int			pc_want_daemon_pages;
  };
  
  struct tracefiled_ctl {
  	struct completion	tctl_start;
  	struct completion	tctl_stop;
  	wait_queue_head_t	tctl_waitq;
  	pid_t			tctl_pid;
  	atomic_t		tctl_shutdown;
  };
  
  /*
   * small data-structure for each page owned by tracefiled.
   */
  struct cfs_trace_page {
  	/*
  	 * page itself
  	 */
  	struct page		*page;
  	/*
  	 * linkage into one of the lists in trace_data_union or
  	 * page_collection
  	 */
  	struct list_head	linkage;
  	/*
  	 * number of bytes used within this page
  	 */
  	unsigned int		used;
  	/*
  	 * cpu that owns this page
  	 */
  	unsigned short		cpu;
  	/*
  	 * type(context) of this page
  	 */
  	unsigned short		type;
  };
  
  static void put_pages_on_tcd_daemon_list(struct page_collection *pc,
  					 struct cfs_trace_cpu_data *tcd);
  
  static inline struct cfs_trace_page *
  cfs_tage_from_list(struct list_head *list)
  {
  	return list_entry(list, struct cfs_trace_page, linkage);
  }
  
  static struct cfs_trace_page *cfs_tage_alloc(gfp_t gfp)
  {
  	struct page *page;
  	struct cfs_trace_page *tage;
  
  	/* My caller is trying to free memory */
  	if (!in_interrupt() && memory_pressure_get())
  		return NULL;
  
  	/*
  	 * Don't spam console with allocation failures: they will be reported
  	 * by upper layer anyway.
  	 */
  	gfp |= __GFP_NOWARN;
  	page = alloc_page(gfp);
  	if (!page)
  		return NULL;
  
  	tage = kmalloc(sizeof(*tage), gfp);
  	if (!tage) {
  		__free_page(page);
  		return NULL;
  	}
  
  	tage->page = page;
  	atomic_inc(&cfs_tage_allocated);
  	return tage;
  }
  
  static void cfs_tage_free(struct cfs_trace_page *tage)
  {
  	__free_page(tage->page);
  	kfree(tage);
  	atomic_dec(&cfs_tage_allocated);
  }
  
  static void cfs_tage_to_tail(struct cfs_trace_page *tage,
  			     struct list_head *queue)
  {
  	list_move_tail(&tage->linkage, queue);
  }
  
  int cfs_trace_refill_stock(struct cfs_trace_cpu_data *tcd, gfp_t gfp,
  			   struct list_head *stock)
  {
  	int i;
  
  	/*
  	 * XXX nikita: do NOT call portals_debug_msg() (CDEBUG/ENTRY/EXIT)
  	 * from here: this will lead to infinite recursion.
  	 */
  
  	for (i = 0; i + tcd->tcd_cur_stock_pages < TCD_STOCK_PAGES ; ++i) {
  		struct cfs_trace_page *tage;
  
  		tage = cfs_tage_alloc(gfp);
  		if (!tage)
  			break;
  		list_add_tail(&tage->linkage, stock);
  	}
  	return i;
  }
  
  /* return a page that has 'len' bytes left at the end */
  static struct cfs_trace_page *
  cfs_trace_get_tage_try(struct cfs_trace_cpu_data *tcd, unsigned long len)
  {
  	struct cfs_trace_page *tage;
  
  	if (tcd->tcd_cur_pages > 0) {
  		__LASSERT(!list_empty(&tcd->tcd_pages));
  		tage = cfs_tage_from_list(tcd->tcd_pages.prev);
  		if (tage->used + len <= PAGE_SIZE)
  			return tage;
  	}
  
  	if (tcd->tcd_cur_pages < tcd->tcd_max_pages) {
  		if (tcd->tcd_cur_stock_pages > 0) {
  			tage = cfs_tage_from_list(tcd->tcd_stock_pages.prev);
  			--tcd->tcd_cur_stock_pages;
  			list_del_init(&tage->linkage);
  		} else {
  			tage = cfs_tage_alloc(GFP_ATOMIC);
  			if (unlikely(!tage)) {
  				if (!memory_pressure_get() || in_interrupt())
  					pr_warn_ratelimited("cannot allocate a tage (%ld)\n",
  							    tcd->tcd_cur_pages);
  				return NULL;
  			}
  		}
  
  		tage->used = 0;
  		tage->cpu = smp_processor_id();
  		tage->type = tcd->tcd_type;
  		list_add_tail(&tage->linkage, &tcd->tcd_pages);
  		tcd->tcd_cur_pages++;
  
  		if (tcd->tcd_cur_pages > 8 && thread_running) {
  			struct tracefiled_ctl *tctl = &trace_tctl;
  			/*
  			 * wake up tracefiled to process some pages.
  			 */
  			wake_up(&tctl->tctl_waitq);
  		}
  		return tage;
  	}
  	return NULL;
  }
  
  static void cfs_tcd_shrink(struct cfs_trace_cpu_data *tcd)
  {
  	int pgcount = tcd->tcd_cur_pages / 10;
  	struct page_collection pc;
  	struct cfs_trace_page *tage;
  	struct cfs_trace_page *tmp;
  
  	/*
  	 * XXX nikita: do NOT call portals_debug_msg() (CDEBUG/ENTRY/EXIT)
  	 * from here: this will lead to infinite recursion.
  	 */
  
  	pr_warn_ratelimited("debug daemon buffer overflowed; discarding 10%% of pages (%d of %ld)\n",
  			    pgcount + 1, tcd->tcd_cur_pages);
  
  	INIT_LIST_HEAD(&pc.pc_pages);
  
  	list_for_each_entry_safe(tage, tmp, &tcd->tcd_pages, linkage) {
  		if (!pgcount--)
  			break;
  
  		list_move_tail(&tage->linkage, &pc.pc_pages);
  		tcd->tcd_cur_pages--;
  	}
  	put_pages_on_tcd_daemon_list(&pc, tcd);
  }
  
  /* return a page that has 'len' bytes left at the end */
  static struct cfs_trace_page *cfs_trace_get_tage(struct cfs_trace_cpu_data *tcd,
  						 unsigned long len)
  {
  	struct cfs_trace_page *tage;
  
  	/*
  	 * XXX nikita: do NOT call portals_debug_msg() (CDEBUG/ENTRY/EXIT)
  	 * from here: this will lead to infinite recursion.
  	 */
  
  	if (len > PAGE_SIZE) {
  		pr_err("cowardly refusing to write %lu bytes in a page\n", len);
  		return NULL;
  	}
  
  	tage = cfs_trace_get_tage_try(tcd, len);
  	if (tage)
  		return tage;
  	if (thread_running)
  		cfs_tcd_shrink(tcd);
  	if (tcd->tcd_cur_pages > 0) {
  		tage = cfs_tage_from_list(tcd->tcd_pages.next);
  		tage->used = 0;
  		cfs_tage_to_tail(tage, &tcd->tcd_pages);
  	}
  	return tage;
  }
  
  int libcfs_debug_msg(struct libcfs_debug_msg_data *msgdata,
  		     const char *format, ...)
  {
  	va_list args;
  	int rc;
  
  	va_start(args, format);
  	rc = libcfs_debug_vmsg2(msgdata, format, args, NULL);
  	va_end(args);
  
  	return rc;
  }
  EXPORT_SYMBOL(libcfs_debug_msg);
  
  int libcfs_debug_vmsg2(struct libcfs_debug_msg_data *msgdata,
  		       const char *format1, va_list args,
  		       const char *format2, ...)
  {
  	struct cfs_trace_cpu_data *tcd = NULL;
  	struct ptldebug_header header = { 0 };
  	struct cfs_trace_page *tage;
  	/* string_buf is used only if tcd != NULL, and is always set then */
  	char *string_buf = NULL;
  	char *debug_buf;
  	int known_size;
  	int needed = 85; /* average message length */
  	int max_nob;
  	va_list ap;
  	int depth;
  	int i;
  	int remain;
  	int mask = msgdata->msg_mask;
  	const char *file = kbasename(msgdata->msg_file);
  	struct cfs_debug_limit_state *cdls = msgdata->msg_cdls;
  
  	tcd = cfs_trace_get_tcd();
  
  	/* cfs_trace_get_tcd() grabs a lock, which disables preemption and
  	 * pins us to a particular CPU.  This avoids an smp_processor_id()
  	 * warning on Linux when debugging is enabled.
  	 */
  	cfs_set_ptldebug_header(&header, msgdata, CDEBUG_STACK());
  
  	if (!tcd)		/* arch may not log in IRQ context */
  		goto console;
  
  	if (!tcd->tcd_cur_pages)
  		header.ph_flags |= PH_FLAG_FIRST_RECORD;
  
  	if (tcd->tcd_shutting_down) {
  		cfs_trace_put_tcd(tcd);
  		tcd = NULL;
  		goto console;
  	}
  
  	depth = __current_nesting_level();
  	known_size = strlen(file) + 1 + depth;
  	if (msgdata->msg_fn)
  		known_size += strlen(msgdata->msg_fn) + 1;
  
  	if (libcfs_debug_binary)
  		known_size += sizeof(header);
  
  	/*
  	 * '2' used because vsnprintf return real size required for output
  	 * _without_ terminating NULL.
  	 * if needed is to small for this format.
  	 */
  	for (i = 0; i < 2; i++) {
  		tage = cfs_trace_get_tage(tcd, needed + known_size + 1);
  		if (!tage) {
  			if (needed + known_size > PAGE_SIZE)
  				mask |= D_ERROR;
  
  			cfs_trace_put_tcd(tcd);
  			tcd = NULL;
  			goto console;
  		}
  
  		string_buf = (char *)page_address(tage->page) +
  					tage->used + known_size;
  
  		max_nob = PAGE_SIZE - tage->used - known_size;
  		if (max_nob <= 0) {
  			pr_emerg("negative max_nob: %d\n", max_nob);
  			mask |= D_ERROR;
  			cfs_trace_put_tcd(tcd);
  			tcd = NULL;
  			goto console;
  		}
  
  		needed = 0;
  		if (format1) {
  			va_copy(ap, args);
  			needed = vsnprintf(string_buf, max_nob, format1, ap);
  			va_end(ap);
  		}
  
  		if (format2) {
  			remain = max_nob - needed;
  			if (remain < 0)
  				remain = 0;
  
  			va_start(ap, format2);
  			needed += vsnprintf(string_buf + needed, remain,
  					    format2, ap);
  			va_end(ap);
  		}
  
  		if (needed < max_nob) /* well. printing ok.. */
  			break;
  	}
  
  	if (*(string_buf + needed - 1) != '\n')
  		pr_info("format at %s:%d:%s doesn't end in newline\n", file,
  			msgdata->msg_line, msgdata->msg_fn);
  
  	header.ph_len = known_size + needed;
  	debug_buf = (char *)page_address(tage->page) + tage->used;
  
  	if (libcfs_debug_binary) {
  		memcpy(debug_buf, &header, sizeof(header));
  		tage->used += sizeof(header);
  		debug_buf += sizeof(header);
  	}
  
  	/* indent message according to the nesting level */
  	while (depth-- > 0) {
  		*(debug_buf++) = '.';
  		++tage->used;
  	}
  
  	strcpy(debug_buf, file);
  	tage->used += strlen(file) + 1;
  	debug_buf += strlen(file) + 1;
  
  	if (msgdata->msg_fn) {
  		strcpy(debug_buf, msgdata->msg_fn);
  		tage->used += strlen(msgdata->msg_fn) + 1;
  		debug_buf += strlen(msgdata->msg_fn) + 1;
  	}
  
  	__LASSERT(debug_buf == string_buf);
  
  	tage->used += needed;
  	__LASSERT(tage->used <= PAGE_SIZE);
  
  console:
  	if (!(mask & libcfs_printk)) {
  		/* no console output requested */
  		if (tcd)
  			cfs_trace_put_tcd(tcd);
  		return 1;
  	}
  
  	if (cdls) {
  		if (libcfs_console_ratelimit &&
  		    cdls->cdls_next &&		/* not first time ever */
  		    !cfs_time_after(cfs_time_current(), cdls->cdls_next)) {
  			/* skipping a console message */
  			cdls->cdls_count++;
  			if (tcd)
  				cfs_trace_put_tcd(tcd);
  			return 1;
  		}
  
  		if (cfs_time_after(cfs_time_current(),
  				   cdls->cdls_next + libcfs_console_max_delay +
  				   cfs_time_seconds(10))) {
  			/* last timeout was a long time ago */
  			cdls->cdls_delay /= libcfs_console_backoff * 4;
  		} else {
  			cdls->cdls_delay *= libcfs_console_backoff;
  		}
  
  		if (cdls->cdls_delay < libcfs_console_min_delay)
  			cdls->cdls_delay = libcfs_console_min_delay;
  		else if (cdls->cdls_delay > libcfs_console_max_delay)
  			cdls->cdls_delay = libcfs_console_max_delay;
  
  		/* ensure cdls_next is never zero after it's been seen */
  		cdls->cdls_next = (cfs_time_current() + cdls->cdls_delay) | 1;
  	}
  
  	if (tcd) {
  		cfs_print_to_console(&header, mask, string_buf, needed, file,
  				     msgdata->msg_fn);
  		cfs_trace_put_tcd(tcd);
  	} else {
  		string_buf = cfs_trace_get_console_buffer();
  
  		needed = 0;
  		if (format1) {
  			va_copy(ap, args);
  			needed = vsnprintf(string_buf,
  					   CFS_TRACE_CONSOLE_BUFFER_SIZE,
  					   format1, ap);
  			va_end(ap);
  		}
  		if (format2) {
  			remain = CFS_TRACE_CONSOLE_BUFFER_SIZE - needed;
  			if (remain > 0) {
  				va_start(ap, format2);
  				needed += vsnprintf(string_buf + needed, remain,
  						    format2, ap);
  				va_end(ap);
  			}
  		}
  		cfs_print_to_console(&header, mask,
  				     string_buf, needed, file, msgdata->msg_fn);
  
  		put_cpu();
  	}
  
  	if (cdls && cdls->cdls_count) {
  		string_buf = cfs_trace_get_console_buffer();
  
  		needed = snprintf(string_buf, CFS_TRACE_CONSOLE_BUFFER_SIZE,
  				  "Skipped %d previous similar message%s\n",
  				  cdls->cdls_count,
  				  (cdls->cdls_count > 1) ? "s" : "");
  
  		cfs_print_to_console(&header, mask,
  				     string_buf, needed, file, msgdata->msg_fn);
  
  		put_cpu();
  		cdls->cdls_count = 0;
  	}
  
  	return 0;
  }
  EXPORT_SYMBOL(libcfs_debug_vmsg2);
  
  void
  cfs_trace_assertion_failed(const char *str,
  			   struct libcfs_debug_msg_data *msgdata)
  {
  	struct ptldebug_header hdr;
  
  	libcfs_panic_in_progress = 1;
  	libcfs_catastrophe = 1;
  	mb();
  
  	cfs_set_ptldebug_header(&hdr, msgdata, CDEBUG_STACK());
  
  	cfs_print_to_console(&hdr, D_EMERG, str, strlen(str),
  			     msgdata->msg_file, msgdata->msg_fn);
  
  	panic("Lustre debug assertion failure\n");
  
  	/* not reached */
  }
  
  static void
  panic_collect_pages(struct page_collection *pc)
  {
  	/* Do the collect_pages job on a single CPU: assumes that all other
  	 * CPUs have been stopped during a panic.  If this isn't true for some
  	 * arch, this will have to be implemented separately in each arch.
  	 */
  	struct cfs_trace_cpu_data *tcd;
  	int i;
  	int j;
  
  	INIT_LIST_HEAD(&pc->pc_pages);
  
  	cfs_tcd_for_each(tcd, i, j) {
  		list_splice_init(&tcd->tcd_pages, &pc->pc_pages);
  		tcd->tcd_cur_pages = 0;
  
  		if (pc->pc_want_daemon_pages) {
  			list_splice_init(&tcd->tcd_daemon_pages, &pc->pc_pages);
  			tcd->tcd_cur_daemon_pages = 0;
  		}
  	}
  }
  
  static void collect_pages_on_all_cpus(struct page_collection *pc)
  {
  	struct cfs_trace_cpu_data *tcd;
  	int i, cpu;
  
  	for_each_possible_cpu(cpu) {
  		cfs_tcd_for_each_type_lock(tcd, i, cpu) {
  			list_splice_init(&tcd->tcd_pages, &pc->pc_pages);
  			tcd->tcd_cur_pages = 0;
  			if (pc->pc_want_daemon_pages) {
  				list_splice_init(&tcd->tcd_daemon_pages,
  						 &pc->pc_pages);
  				tcd->tcd_cur_daemon_pages = 0;
  			}
  		}
  	}
  }
  
  static void collect_pages(struct page_collection *pc)
  {
  	INIT_LIST_HEAD(&pc->pc_pages);
  
  	if (libcfs_panic_in_progress)
  		panic_collect_pages(pc);
  	else
  		collect_pages_on_all_cpus(pc);
  }
  
  static void put_pages_back_on_all_cpus(struct page_collection *pc)
  {
  	struct cfs_trace_cpu_data *tcd;
  	struct list_head *cur_head;
  	struct cfs_trace_page *tage;
  	struct cfs_trace_page *tmp;
  	int i, cpu;
  
  	for_each_possible_cpu(cpu) {
  		cfs_tcd_for_each_type_lock(tcd, i, cpu) {
  			cur_head = tcd->tcd_pages.next;
  
  			list_for_each_entry_safe(tage, tmp, &pc->pc_pages,
  						 linkage) {
  				__LASSERT_TAGE_INVARIANT(tage);
  
  				if (tage->cpu != cpu || tage->type != i)
  					continue;
  
  				cfs_tage_to_tail(tage, cur_head);
  				tcd->tcd_cur_pages++;
  			}
  		}
  	}
  }
  
  static void put_pages_back(struct page_collection *pc)
  {
  	if (!libcfs_panic_in_progress)
  		put_pages_back_on_all_cpus(pc);
  }
  
  /* Add pages to a per-cpu debug daemon ringbuffer.  This buffer makes sure that
   * we have a good amount of data at all times for dumping during an LBUG, even
   * if we have been steadily writing (and otherwise discarding) pages via the
   * debug daemon.
   */
  static void put_pages_on_tcd_daemon_list(struct page_collection *pc,
  					 struct cfs_trace_cpu_data *tcd)
  {
  	struct cfs_trace_page *tage;
  	struct cfs_trace_page *tmp;
  
  	list_for_each_entry_safe(tage, tmp, &pc->pc_pages, linkage) {
  		__LASSERT_TAGE_INVARIANT(tage);
  
  		if (tage->cpu != tcd->tcd_cpu || tage->type != tcd->tcd_type)
  			continue;
  
  		cfs_tage_to_tail(tage, &tcd->tcd_daemon_pages);
  		tcd->tcd_cur_daemon_pages++;
  
  		if (tcd->tcd_cur_daemon_pages > tcd->tcd_max_pages) {
  			struct cfs_trace_page *victim;
  
  			__LASSERT(!list_empty(&tcd->tcd_daemon_pages));
  			victim = cfs_tage_from_list(tcd->tcd_daemon_pages.next);
  
  			__LASSERT_TAGE_INVARIANT(victim);
  
  			list_del(&victim->linkage);
  			cfs_tage_free(victim);
  			tcd->tcd_cur_daemon_pages--;
  		}
  	}
  }
  
  static void put_pages_on_daemon_list(struct page_collection *pc)
  {
  	struct cfs_trace_cpu_data *tcd;
  	int i, cpu;
  
  	for_each_possible_cpu(cpu) {
  		cfs_tcd_for_each_type_lock(tcd, i, cpu)
  			put_pages_on_tcd_daemon_list(pc, tcd);
  	}
  }
  
  void cfs_trace_debug_print(void)
  {
  	struct page_collection pc;
  	struct cfs_trace_page *tage;
  	struct cfs_trace_page *tmp;
  
  	pc.pc_want_daemon_pages = 1;
  	collect_pages(&pc);
  	list_for_each_entry_safe(tage, tmp, &pc.pc_pages, linkage) {
  		char *p, *file, *fn;
  		struct page *page;
  
  		__LASSERT_TAGE_INVARIANT(tage);
  
  		page = tage->page;
  		p = page_address(page);
  		while (p < ((char *)page_address(page) + tage->used)) {
  			struct ptldebug_header *hdr;
  			int len;
  
  			hdr = (void *)p;
  			p += sizeof(*hdr);
  			file = p;
  			p += strlen(file) + 1;
  			fn = p;
  			p += strlen(fn) + 1;
  			len = hdr->ph_len - (int)(p - (char *)hdr);
  
  			cfs_print_to_console(hdr, D_EMERG, p, len, file, fn);
  
  			p += len;
  		}
  
  		list_del(&tage->linkage);
  		cfs_tage_free(tage);
  	}
  }
  
  int cfs_tracefile_dump_all_pages(char *filename)
  {
  	struct page_collection pc;
  	struct file *filp;
  	struct cfs_trace_page *tage;
  	struct cfs_trace_page *tmp;
  	char *buf;
  	mm_segment_t __oldfs;
  	int rc;
  
  	cfs_tracefile_write_lock();
  
  	filp = filp_open(filename, O_CREAT | O_EXCL | O_WRONLY | O_LARGEFILE,
  			 0600);
  	if (IS_ERR(filp)) {
  		rc = PTR_ERR(filp);
  		filp = NULL;
  		pr_err("LustreError: can't open %s for dump: rc %d\n",
  		       filename, rc);
  		goto out;
  	}
  
  	pc.pc_want_daemon_pages = 1;
  	collect_pages(&pc);
  	if (list_empty(&pc.pc_pages)) {
  		rc = 0;
  		goto close;
  	}
  	__oldfs = get_fs();
  	set_fs(get_ds());
  
  	/* ok, for now, just write the pages.  in the future we'll be building
  	 * iobufs with the pages and calling generic_direct_IO
  	 */
  	list_for_each_entry_safe(tage, tmp, &pc.pc_pages, linkage) {
  		__LASSERT_TAGE_INVARIANT(tage);
  
  		buf = kmap(tage->page);
  		rc = vfs_write(filp, (__force const char __user *)buf,
  			       tage->used, &filp->f_pos);
  		kunmap(tage->page);
  
  		if (rc != (int)tage->used) {
  			pr_warn("wanted to write %u but wrote %d\n", tage->used,
  				rc);
  			put_pages_back(&pc);
  			__LASSERT(list_empty(&pc.pc_pages));
  			break;
  		}
  		list_del(&tage->linkage);
  		cfs_tage_free(tage);
  	}
  	set_fs(__oldfs);
  	rc = vfs_fsync(filp, 1);
  	if (rc)
  		pr_err("sync returns %d\n", rc);
  close:
  	filp_close(filp, NULL);
  out:
  	cfs_tracefile_write_unlock();
  	return rc;
  }
  
  void cfs_trace_flush_pages(void)
  {
  	struct page_collection pc;
  	struct cfs_trace_page *tage;
  	struct cfs_trace_page *tmp;
  
  	pc.pc_want_daemon_pages = 1;
  	collect_pages(&pc);
  	list_for_each_entry_safe(tage, tmp, &pc.pc_pages, linkage) {
  		__LASSERT_TAGE_INVARIANT(tage);
  
  		list_del(&tage->linkage);
  		cfs_tage_free(tage);
  	}
  }
  
  int cfs_trace_copyin_string(char *knl_buffer, int knl_buffer_nob,
  			    const char __user *usr_buffer, int usr_buffer_nob)
  {
  	int nob;
  
  	if (usr_buffer_nob > knl_buffer_nob)
  		return -EOVERFLOW;
  
  	if (copy_from_user((void *)knl_buffer,
  			   usr_buffer, usr_buffer_nob))
  		return -EFAULT;
  
  	nob = strnlen(knl_buffer, usr_buffer_nob);
  	while (nob-- >= 0)		      /* strip trailing whitespace */
  		if (!isspace(knl_buffer[nob]))
  			break;
  
  	if (nob < 0)			    /* empty string */
  		return -EINVAL;
  
  	if (nob == knl_buffer_nob)	      /* no space to terminate */
  		return -EOVERFLOW;
  
  	knl_buffer[nob + 1] = 0;		/* terminate */
  	return 0;
  }
  EXPORT_SYMBOL(cfs_trace_copyin_string);
  
  int cfs_trace_copyout_string(char __user *usr_buffer, int usr_buffer_nob,
  			     const char *knl_buffer, char *append)
  {
  	/*
  	 * NB if 'append' != NULL, it's a single character to append to the
  	 * copied out string - usually "\n" or "" (i.e. a terminating zero byte)
  	 */
  	int nob = strlen(knl_buffer);
  
  	if (nob > usr_buffer_nob)
  		nob = usr_buffer_nob;
  
  	if (copy_to_user(usr_buffer, knl_buffer, nob))
  		return -EFAULT;
  
  	if (append && nob < usr_buffer_nob) {
  		if (copy_to_user(usr_buffer + nob, append, 1))
  			return -EFAULT;
  
  		nob++;
  	}
  
  	return nob;
  }
  EXPORT_SYMBOL(cfs_trace_copyout_string);
  
  int cfs_trace_allocate_string_buffer(char **str, int nob)
  {
  	if (nob > 2 * PAGE_SIZE)	    /* string must be "sensible" */
  		return -EINVAL;
  
  	*str = kmalloc(nob, GFP_KERNEL | __GFP_ZERO);
  	if (!*str)
  		return -ENOMEM;
  
  	return 0;
  }
  
  int cfs_trace_dump_debug_buffer_usrstr(void __user *usr_str, int usr_str_nob)
  {
  	char *str;
  	int rc;
  
  	rc = cfs_trace_allocate_string_buffer(&str, usr_str_nob + 1);
  	if (rc)
  		return rc;
  
  	rc = cfs_trace_copyin_string(str, usr_str_nob + 1,
  				     usr_str, usr_str_nob);
  	if (rc)
  		goto out;
  
  	if (str[0] != '/') {
  		rc = -EINVAL;
  		goto out;
  	}
  	rc = cfs_tracefile_dump_all_pages(str);
  out:
  	kfree(str);
  	return rc;
  }
  
  int cfs_trace_daemon_command(char *str)
  {
  	int rc = 0;
  
  	cfs_tracefile_write_lock();
  
  	if (!strcmp(str, "stop")) {
  		cfs_tracefile_write_unlock();
  		cfs_trace_stop_thread();
  		cfs_tracefile_write_lock();
  		memset(cfs_tracefile, 0, sizeof(cfs_tracefile));
  
  	} else if (!strncmp(str, "size=", 5)) {
  		unsigned long tmp;
  
  		rc = kstrtoul(str + 5, 10, &tmp);
  		if (!rc) {
  			if (tmp < 10 || tmp > 20480)
  				cfs_tracefile_size = CFS_TRACEFILE_SIZE;
  			else
  				cfs_tracefile_size = tmp << 20;
  		}
  	} else if (strlen(str) >= sizeof(cfs_tracefile)) {
  		rc = -ENAMETOOLONG;
  	} else if (str[0] != '/') {
  		rc = -EINVAL;
  	} else {
  		strcpy(cfs_tracefile, str);
  
  		pr_info("debug daemon will attempt to start writing to %s (%lukB max)\n",
  			cfs_tracefile,
  			(long)(cfs_tracefile_size >> 10));
  
  		cfs_trace_start_thread();
  	}
  
  	cfs_tracefile_write_unlock();
  	return rc;
  }
  
  int cfs_trace_daemon_command_usrstr(void __user *usr_str, int usr_str_nob)
  {
  	char *str;
  	int rc;
  
  	rc = cfs_trace_allocate_string_buffer(&str, usr_str_nob + 1);
  	if (rc)
  		return rc;
  
  	rc = cfs_trace_copyin_string(str, usr_str_nob + 1,
  				     usr_str, usr_str_nob);
  	if (!rc)
  		rc = cfs_trace_daemon_command(str);
  
  	kfree(str);
  	return rc;
  }
  
  int cfs_trace_set_debug_mb(int mb)
  {
  	int i;
  	int j;
  	int pages;
  	int limit = cfs_trace_max_debug_mb();
  	struct cfs_trace_cpu_data *tcd;
  
  	if (mb < num_possible_cpus()) {
  		pr_warn("%d MB is too small for debug buffer size, setting it to %d MB.\n",
  			mb, num_possible_cpus());
  		mb = num_possible_cpus();
  	}
  
  	if (mb > limit) {
  		pr_warn("%d MB is too large for debug buffer size, setting it to %d MB.\n",
  			mb, limit);
  		mb = limit;
  	}
  
  	mb /= num_possible_cpus();
  	pages = mb << (20 - PAGE_SHIFT);
  
  	cfs_tracefile_write_lock();
  
  	cfs_tcd_for_each(tcd, i, j)
  		tcd->tcd_max_pages = (pages * tcd->tcd_pages_factor) / 100;
  
  	cfs_tracefile_write_unlock();
  
  	return 0;
  }
  
  int cfs_trace_get_debug_mb(void)
  {
  	int i;
  	int j;
  	struct cfs_trace_cpu_data *tcd;
  	int total_pages = 0;
  
  	cfs_tracefile_read_lock();
  
  	cfs_tcd_for_each(tcd, i, j)
  		total_pages += tcd->tcd_max_pages;
  
  	cfs_tracefile_read_unlock();
  
  	return (total_pages >> (20 - PAGE_SHIFT)) + 1;
  }
  
  static int tracefiled(void *arg)
  {
  	struct page_collection pc;
  	struct tracefiled_ctl *tctl = arg;
  	struct cfs_trace_page *tage;
  	struct cfs_trace_page *tmp;
  	mm_segment_t __oldfs;
  	struct file *filp;
  	char *buf;
  	int last_loop = 0;
  	int rc;
  
  	/* we're started late enough that we pick up init's fs context */
  	/* this is so broken in uml?  what on earth is going on? */
  
  	complete(&tctl->tctl_start);
  
  	while (1) {
  		wait_queue_entry_t __wait;
  
  		pc.pc_want_daemon_pages = 0;
  		collect_pages(&pc);
  		if (list_empty(&pc.pc_pages))
  			goto end_loop;
  
  		filp = NULL;
  		cfs_tracefile_read_lock();
  		if (cfs_tracefile[0]) {
  			filp = filp_open(cfs_tracefile,
  					 O_CREAT | O_RDWR | O_LARGEFILE,
  					 0600);
  			if (IS_ERR(filp)) {
  				rc = PTR_ERR(filp);
  				filp = NULL;
  				pr_warn("couldn't open %s: %d\n", cfs_tracefile,
  					rc);
  			}
  		}
  		cfs_tracefile_read_unlock();
  		if (!filp) {
  			put_pages_on_daemon_list(&pc);
  			__LASSERT(list_empty(&pc.pc_pages));
  			goto end_loop;
  		}
  		__oldfs = get_fs();
  		set_fs(get_ds());
  
  		list_for_each_entry_safe(tage, tmp, &pc.pc_pages, linkage) {
  			static loff_t f_pos;
  
  			__LASSERT_TAGE_INVARIANT(tage);
  
  			if (f_pos >= (off_t)cfs_tracefile_size)
  				f_pos = 0;
  			else if (f_pos > i_size_read(file_inode(filp)))
  				f_pos = i_size_read(file_inode(filp));
  
  			buf = kmap(tage->page);
  			rc = vfs_write(filp, (__force const char __user *)buf,
  				       tage->used, &f_pos);
  			kunmap(tage->page);
  
  			if (rc != (int)tage->used) {
  				pr_warn("wanted to write %u but wrote %d\n",
  					tage->used, rc);
  				put_pages_back(&pc);
  				__LASSERT(list_empty(&pc.pc_pages));
  				break;
  			}
  		}
  		set_fs(__oldfs);
  
  		filp_close(filp, NULL);
  		put_pages_on_daemon_list(&pc);
  		if (!list_empty(&pc.pc_pages)) {
  			int i;
  
  			pr_alert("trace pages aren't empty\n");
  			pr_err("total cpus(%d): ", num_possible_cpus());
  			for (i = 0; i < num_possible_cpus(); i++)
  				if (cpu_online(i))
  					pr_cont("%d(on) ", i);
  				else
  					pr_cont("%d(off) ", i);
  			pr_cont("\n");
  
  			i = 0;
  			list_for_each_entry_safe(tage, tmp, &pc.pc_pages,
  						 linkage)
  				pr_err("page %d belongs to cpu %d\n",
  				       ++i, tage->cpu);
  			pr_err("There are %d pages unwritten\n", i);
  		}
  		__LASSERT(list_empty(&pc.pc_pages));
  end_loop:
  		if (atomic_read(&tctl->tctl_shutdown)) {
  			if (!last_loop) {
  				last_loop = 1;
  				continue;
  			} else {
  				break;
  			}
  		}
  		init_waitqueue_entry(&__wait, current);
  		add_wait_queue(&tctl->tctl_waitq, &__wait);
  		set_current_state(TASK_INTERRUPTIBLE);
  		schedule_timeout(cfs_time_seconds(1));
  		remove_wait_queue(&tctl->tctl_waitq, &__wait);
  	}
  	complete(&tctl->tctl_stop);
  	return 0;
  }
  
  int cfs_trace_start_thread(void)
  {
  	struct tracefiled_ctl *tctl = &trace_tctl;
  	struct task_struct *task;
  	int rc = 0;
  
  	mutex_lock(&cfs_trace_thread_mutex);
  	if (thread_running)
  		goto out;
  
  	init_completion(&tctl->tctl_start);
  	init_completion(&tctl->tctl_stop);
  	init_waitqueue_head(&tctl->tctl_waitq);
  	atomic_set(&tctl->tctl_shutdown, 0);
  
  	task = kthread_run(tracefiled, tctl, "ktracefiled");
  	if (IS_ERR(task)) {
  		rc = PTR_ERR(task);
  		goto out;
  	}
  
  	wait_for_completion(&tctl->tctl_start);
  	thread_running = 1;
  out:
  	mutex_unlock(&cfs_trace_thread_mutex);
  	return rc;
  }
  
  void cfs_trace_stop_thread(void)
  {
  	struct tracefiled_ctl *tctl = &trace_tctl;
  
  	mutex_lock(&cfs_trace_thread_mutex);
  	if (thread_running) {
  		pr_info("shutting down debug daemon thread...\n");
  		atomic_set(&tctl->tctl_shutdown, 1);
  		wait_for_completion(&tctl->tctl_stop);
  		thread_running = 0;
  	}
  	mutex_unlock(&cfs_trace_thread_mutex);
  }
  
  int cfs_tracefile_init(int max_pages)
  {
  	struct cfs_trace_cpu_data *tcd;
  	int i;
  	int j;
  	int rc;
  	int factor;
  
  	rc = cfs_tracefile_init_arch();
  	if (rc)
  		return rc;
  
  	cfs_tcd_for_each(tcd, i, j) {
  		/* tcd_pages_factor is initialized int tracefile_init_arch. */
  		factor = tcd->tcd_pages_factor;
  		INIT_LIST_HEAD(&tcd->tcd_pages);
  		INIT_LIST_HEAD(&tcd->tcd_stock_pages);
  		INIT_LIST_HEAD(&tcd->tcd_daemon_pages);
  		tcd->tcd_cur_pages = 0;
  		tcd->tcd_cur_stock_pages = 0;
  		tcd->tcd_cur_daemon_pages = 0;
  		tcd->tcd_max_pages = (max_pages * factor) / 100;
  		LASSERT(tcd->tcd_max_pages > 0);
  		tcd->tcd_shutting_down = 0;
  	}
  
  	return 0;
  }
  
  static void trace_cleanup_on_all_cpus(void)
  {
  	struct cfs_trace_cpu_data *tcd;
  	struct cfs_trace_page *tage;
  	struct cfs_trace_page *tmp;
  	int i, cpu;
  
  	for_each_possible_cpu(cpu) {
  		cfs_tcd_for_each_type_lock(tcd, i, cpu) {
  			tcd->tcd_shutting_down = 1;
  
  			list_for_each_entry_safe(tage, tmp, &tcd->tcd_pages,
  						 linkage) {
  				__LASSERT_TAGE_INVARIANT(tage);
  
  				list_del(&tage->linkage);
  				cfs_tage_free(tage);
  			}
  
  			tcd->tcd_cur_pages = 0;
  		}
  	}
  }
  
  static void cfs_trace_cleanup(void)
  {
  	struct page_collection pc;
  
  	INIT_LIST_HEAD(&pc.pc_pages);
  
  	trace_cleanup_on_all_cpus();
  
  	cfs_tracefile_fini_arch();
  }
  
  void cfs_tracefile_exit(void)
  {
  	cfs_trace_stop_thread();
  	cfs_trace_cleanup();
  }
  