aboutsummaryrefslogtreecommitdiffstats
path: root/MAINTAINERS
Commit message (Expand)AuthorAge
* USB: MAINTAINERS entry for amd5536udcThomas Dahlmann2007-07-19
* Merge branch 'release' of git://lm-sensors.org/kernel/mhoffman/hwmon-2.6Linus Torvalds2007-07-19
|\
| * hwmon/dme1737: Add documentationJuerg Haefliger2007-07-19
| * hwmon: New maintainerMark M. Hoffman2007-07-19
* | drivers/edac: add to maintainers new infoDouglas Thompson2007-07-19
* | drivers/edac: update MAINTAINERS files for EDACDouglas Thompson2007-07-19
* | add POSIX clocks and timers maintainerIngo Molnar2007-07-19
* | Suspend MAINTAINERS updatePavel Machek2007-07-19
* | Blackfin ethernet driver: on chip ethernet MAC controller driverBryan Wu2007-07-18
* | [x86 setup] MAINTAINERS: document x86 setup code git treeH. Peter Anvin2007-07-18
* | Merge branch 'upstream' of git://git.infradead.org/~dedekind/ubi-2.6Linus Torvalds2007-07-18
|\ \
| * | UBI: fix MAINTAINERSArtem Bityutskiy2007-07-18
* | | zs: move to the serial subsystemMaciej W. Rozycki2007-07-18
|/ /
* | bsg: mark FUJITA Tomonori as bsg maintainerJens Axboe2007-07-17
* | Merge branch 'for-linus' of git://git.kernel.dk/data/git/linux-2.6-blockLinus Torvalds2007-07-16
|\ \
| * | remove the documentation for the legacy CDROM driversAdrian Bunk2007-07-16
* | | more scheduled OSS driver removalAdrian Bunk2007-07-16
* | | m32r: A MAINTAINERS entry for the M32R architectureHirokazu Takata2007-07-16
* | | Add entries to MAINTAINERS for I/OAT and DMAENGINENelson, Shannon2007-07-16
|/ /
* | Merge git://git.infradead.org/battery-2.6Linus Torvalds2007-07-15
|\ \
| * | MAINTAINERS: Add maintainers for power supply subsystem and driversAnton Vorontsov2007-07-15
* | | [NET]: Add macvlan driverPatrick McHardy2007-07-14
|/ /
* | Merge master.kernel.org:/pub/scm/linux/kernel/git/gregkh/usb-2.6Linus Torvalds2007-07-12
|\ \
| * | USB: Pete's taking over usblpPete Zaitcev2007-07-12
* | | Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rol...Linus Torvalds2007-07-12
|\ \ \ | |/ / |/| |
| * | IB: Update MAINTAINERS with Hal's new email addressRoland Dreier2007-07-12
| * | IB: Update mailing list addressRoland Dreier2007-07-09
| * | IB/ipath: Update MAINTAINERS entryArthur Jones2007-07-09
* | | Merge master.kernel.org:/pub/scm/linux/kernel/git/davej/agpgartLinus Torvalds2007-07-12
|\ \ \
| * | | [AGPGART] Hand off AGP maintainence.Dave Jones2007-07-09
* | | | Merge master.kernel.org:/pub/scm/linux/kernel/git/gregkh/pci-2.6Linus Torvalds2007-07-12
|\ \ \ \
| * | | | PCI: remove cpqphp driver maintainerGreg Kroah-Hartman2007-07-11
* | | | | Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/ne...Linus Torvalds2007-07-12
|\ \ \ \ \
| * | | | | [L2TP]: Add PPPoL2TP maintainerJames Chapman2007-07-11
| |/ / / /
* / / / / x86 setup: MAINTAINERS: formally take responsibility for the i386 boot codeH. Peter Anvin2007-07-12
|/ / / /
* | | | Merge branch 'upstream-linus' of master.kernel.org:/pub/scm/linux/kernel/git/...Linus Torvalds2007-07-10
|\ \ \ \
| * | | | ps3: gigabit ethernet driver for PS3, take3Masakazu Mokuno2007-07-10
| | |/ / | |/| |
* / | | Input: update MAINTAINERS to explicitly mention touchscreensRobert P. J. Day2007-07-10
|/ / /
* | / [PATCH] Add rtl8187 wireless driverMichael Wu2007-07-08
| |/ |/|
* | MAINTAINERS new kernel janitors mlmaximilian attems2007-07-06
* | Update MAINTAINERS for USB network devicesPeter Korsgaard2007-07-02
|/
* [XFS] Update the MAINTAINERS file entry for XFS - change git repo name.Tim Shimmin2007-06-19
* Merge branch 'for-linus' of git://oss.sgi.com:8090/xfs/xfs-2.6 into for-linusTim Shimmin2007-06-19
|\
| * [XFS] Update the MAINTAINERS file entry for XFS.Timothy Shimmin2007-06-11
* | Blackfin RTC drivers: update MAINTAINERS informationMike Frysinger2007-06-11
* | Blackfin arch: fixup Blackfin MAINTIANERS team member listBryan Wu2007-06-11
|/
* MAINTAINERS: correctionsAlan Cox2007-06-08
* reiserfs: mailing list has movedJeff Mahoney2007-06-08
* NET: add MAINTAINERS entry for ucc_geth driverLi Yang2007-06-03
* Update tulip maintainer email addressValerie Henson2007-06-03
generated by cgit v1.2.2 (git 2.25.0) at 2025-09-14 05:13:04 -0400
id='n852' href='#n852'>852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 
/*
 *  Block device elevator/IO-scheduler.
 *
 *  Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
 *
 * 30042000 Jens Axboe <axboe@kernel.dk> :
 *
 * Split the elevator a bit so that it is possible to choose a different
 * one or even write a new "plug in". There are three pieces:
 * - elevator_fn, inserts a new request in the queue list
 * - elevator_merge_fn, decides whether a new buffer can be merged with
 *   an existing request
 * - elevator_dequeue_fn, called when a request is taken off the active list
 *
 * 20082000 Dave Jones <davej@suse.de> :
 * Removed tests for max-bomb-segments, which was breaking elvtune
 *  when run without -bN
 *
 * Jens:
 * - Rework again to work with bio instead of buffer_heads
 * - loose bi_dev comparisons, partition handling is right now
 * - completely modularize elevator setup and teardown
 *
 */
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/blkdev.h>
#include <linux/elevator.h>
#include <linux/bio.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/compiler.h>
#include <linux/delay.h>
#include <linux/blktrace_api.h>
#include <linux/hash.h>

#include <asm/uaccess.h>

static DEFINE_SPINLOCK(elv_list_lock);
static LIST_HEAD(elv_list);

/*
 * Merge hash stuff.
 */
static const int elv_hash_shift = 6;
#define ELV_HASH_BLOCK(sec)	((sec) >> 3)
#define ELV_HASH_FN(sec)	\
		(hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift))
#define ELV_HASH_ENTRIES	(1 << elv_hash_shift)
#define rq_hash_key(rq)		((rq)->sector + (rq)->nr_sectors)
#define ELV_ON_HASH(rq)		(!hlist_unhashed(&(rq)->hash))

/*
 * Query io scheduler to see if the current process issuing bio may be
 * merged with rq.
 */
static int elv_iosched_allow_merge(struct request *rq, struct bio *bio)
{
	struct request_queue *q = rq->q;
	elevator_t *e = q->elevator;

	if (e->ops->elevator_allow_merge_fn)
		return e->ops->elevator_allow_merge_fn(q, rq, bio);

	return 1;
}

/*
 * can we safely merge with this request?
 */
int elv_rq_merge_ok(struct request *rq, struct bio *bio)
{
	if (!rq_mergeable(rq))
		return 0;

	/*
	 * different data direction or already started, don't merge
	 */
	if (bio_data_dir(bio) != rq_data_dir(rq))
		return 0;

	/*
	 * must be same device and not a special request
	 */
	if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special)
		return 0;

	/*
	 * only merge integrity protected bio into ditto rq
	 */
	if (bio_integrity(bio) != blk_integrity_rq(rq))
		return 0;

	if (!elv_iosched_allow_merge(rq, bio))
		return 0;

	return 1;
}
EXPORT_SYMBOL(elv_rq_merge_ok);

static inline int elv_try_merge(struct request *__rq, struct bio *bio)
{
	int ret = ELEVATOR_NO_MERGE;

	/*
	 * we can merge and sequence is ok, check if it's possible
	 */
	if (elv_rq_merge_ok(__rq, bio)) {
		if (__rq->sector + __rq->nr_sectors == bio->bi_sector)
			ret = ELEVATOR_BACK_MERGE;
		else if (__rq->sector - bio_sectors(bio) == bio->bi_sector)
			ret = ELEVATOR_FRONT_MERGE;
	}

	return ret;
}

static struct elevator_type *elevator_find(const char *name)
{
	struct elevator_type *e;

	list_for_each_entry(e, &elv_list, list) {
		if (!strcmp(e->elevator_name, name))
			return e;
	}

	return NULL;
}

static void elevator_put(struct elevator_type *e)
{
	module_put(e->elevator_owner);
}

static struct elevator_type *elevator_get(const char *name)
{
	struct elevator_type *e;

	spin_lock(&elv_list_lock);

	e = elevator_find(name);
	if (!e) {
		char elv[ELV_NAME_MAX + strlen("-iosched")];

		spin_unlock(&elv_list_lock);

		if (!strcmp(name, "anticipatory"))
			sprintf(elv, "as-iosched");
		else
			sprintf(elv, "%s-iosched", name);

		request_module("%s", elv);
		spin_lock(&elv_list_lock);
		e = elevator_find(name);
	}

	if (e && !try_module_get(e->elevator_owner))
		e = NULL;

	spin_unlock(&elv_list_lock);

	return e;
}

static void *elevator_init_queue(struct request_queue *q,
				 struct elevator_queue *eq)
{
	return eq->ops->elevator_init_fn(q);
}

static void elevator_attach(struct request_queue *q, struct elevator_queue *eq,
			   void *data)
{
	q->elevator = eq;
	eq->elevator_data = data;
}

static char chosen_elevator[16];

static int __init elevator_setup(char *str)
{
	/*
	 * Be backwards-compatible with previous kernels, so users
	 * won't get the wrong elevator.
	 */
	if (!strcmp(str, "as"))
		strcpy(chosen_elevator, "anticipatory");
	else
		strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1);
	return 1;
}

__setup("elevator=", elevator_setup);

static struct kobj_type elv_ktype;

static elevator_t *elevator_alloc(struct request_queue *q,
				  struct elevator_type *e)
{
	elevator_t *eq;
	int i;

	eq = kmalloc_node(sizeof(elevator_t), GFP_KERNEL | __GFP_ZERO, q->node);
	if (unlikely(!eq))
		goto err;

	eq->ops = &e->ops;
	eq->elevator_type = e;
	kobject_init(&eq->kobj, &elv_ktype);
	mutex_init(&eq->sysfs_lock);

	eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES,
					GFP_KERNEL, q->node);
	if (!eq->hash)
		goto err;

	for (i = 0; i < ELV_HASH_ENTRIES; i++)
		INIT_HLIST_HEAD(&eq->hash[i]);

	return eq;
err:
	kfree(eq);
	elevator_put(e);
	return NULL;
}

static void elevator_release(struct kobject *kobj)
{
	elevator_t *e = container_of(kobj, elevator_t, kobj);

	elevator_put(e->elevator_type);
	kfree(e->hash);
	kfree(e);
}

int elevator_init(struct request_queue *q, char *name)
{
	struct elevator_type *e = NULL;
	struct elevator_queue *eq;
	int ret = 0;
	void *data;

	INIT_LIST_HEAD(&q->queue_head);
	q->last_merge = NULL;
	q->end_sector = 0;
	q->boundary_rq = NULL;

	if (name) {
		e = elevator_get(name);
		if (!e)
			return -EINVAL;
	}

	if (!e && *chosen_elevator) {
		e = elevator_get(chosen_elevator);
		if (!e)
			printk(KERN_ERR "I/O scheduler %s not found\n",
							chosen_elevator);
	}

	if (!e) {
		e = elevator_get(CONFIG_DEFAULT_IOSCHED);
		if (!e) {
			printk(KERN_ERR
				"Default I/O scheduler not found. " \
				"Using noop.\n");
			e = elevator_get("noop");
		}
	}

	eq = elevator_alloc(q, e);
	if (!eq)
		return -ENOMEM;

	data = elevator_init_queue(q, eq);
	if (!data) {
		kobject_put(&eq->kobj);
		return -ENOMEM;
	}

	elevator_attach(q, eq, data);
	return ret;
}
EXPORT_SYMBOL(elevator_init);

void elevator_exit(elevator_t *e)
{
	mutex_lock(&e->sysfs_lock);
	if (e->ops->elevator_exit_fn)
		e->ops->elevator_exit_fn(e);
	e->ops = NULL;
	mutex_unlock(&e->sysfs_lock);

	kobject_put(&e->kobj);
}
EXPORT_SYMBOL(elevator_exit);

static void elv_activate_rq(struct request_queue *q, struct request *rq)
{
	elevator_t *e = q->elevator;

	if (e->ops->elevator_activate_req_fn)
		e->ops->elevator_activate_req_fn(q, rq);
}

static void elv_deactivate_rq(struct request_queue *q, struct request *rq)
{
	elevator_t *e = q->elevator;

	if (e->ops->elevator_deactivate_req_fn)
		e->ops->elevator_deactivate_req_fn(q, rq);
}

static inline void __elv_rqhash_del(struct request *rq)
{
	hlist_del_init(&rq->hash);
}

static void elv_rqhash_del(struct request_queue *q, struct request *rq)
{
	if (ELV_ON_HASH(rq))
		__elv_rqhash_del(rq);
}

static void elv_rqhash_add(struct request_queue *q, struct request *rq)
{
	elevator_t *e = q->elevator;

	BUG_ON(ELV_ON_HASH(rq));
	hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]);
}

static void elv_rqhash_reposition(struct request_queue *q, struct request *rq)
{
	__elv_rqhash_del(rq);
	elv_rqhash_add(q, rq);
}

static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset)
{
	elevator_t *e = q->elevator;
	struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)];
	struct hlist_node *entry, *next;
	struct request *rq;

	hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) {
		BUG_ON(!ELV_ON_HASH(rq));

		if (unlikely(!rq_mergeable(rq))) {
			__elv_rqhash_del(rq);
			continue;
		}

		if (rq_hash_key(rq) == offset)
			return rq;
	}

	return NULL;
}

/*
 * RB-tree support functions for inserting/lookup/removal of requests
 * in a sorted RB tree.
 */
struct request *elv_rb_add(struct rb_root *root, struct request *rq)
{
	struct rb_node **p = &root->rb_node;
	struct rb_node *parent = NULL;
	struct request *__rq;

	while (*p) {
		parent = *p;
		__rq = rb_entry(parent, struct request, rb_node);

		if (rq->sector < __rq->sector)
			p = &(*p)->rb_left;
		else if (rq->sector > __rq->sector)
			p = &(*p)->rb_right;
		else
			return __rq;
	}

	rb_link_node(&rq->rb_node, parent, p);
	rb_insert_color(&rq->rb_node, root);
	return NULL;
}
EXPORT_SYMBOL(elv_rb_add);

void elv_rb_del(struct rb_root *root, struct request *rq)
{
	BUG_ON(RB_EMPTY_NODE(&rq->rb_node));
	rb_erase(&rq->rb_node, root);
	RB_CLEAR_NODE(&rq->rb_node);
}
EXPORT_SYMBOL(elv_rb_del);

struct request *elv_rb_find(struct rb_root *root, sector_t sector)
{
	struct rb_node *n = root->rb_node;
	struct request *rq;

	while (n) {
		rq = rb_entry(n, struct request, rb_node);

		if (sector < rq->sector)
			n = n->rb_left;
		else if (sector > rq->sector)
			n = n->rb_right;
		else
			return rq;
	}

	return NULL;
}
EXPORT_SYMBOL(elv_rb_find);

/*
 * Insert rq into dispatch queue of q.  Queue lock must be held on
 * entry.  rq is sort instead into the dispatch queue. To be used by
 * specific elevators.
 */
void elv_dispatch_sort(struct request_queue *q, struct request *rq)
{
	sector_t boundary;
	struct list_head *entry;
	int stop_flags;

	if (q->last_merge == rq)
		q->last_merge = NULL;

	elv_rqhash_del(q, rq);

	q->nr_sorted--;

	boundary = q->end_sector;
	stop_flags = REQ_SOFTBARRIER | REQ_HARDBARRIER | REQ_STARTED;
	list_for_each_prev(entry, &q->queue_head) {
		struct request *pos = list_entry_rq(entry);

		if (rq_data_dir(rq) != rq_data_dir(pos))
			break;
		if (pos->cmd_flags & stop_flags)
			break;
		if (rq->sector >= boundary) {
			if (pos->sector < boundary)
				continue;
		} else {
			if (pos->sector >= boundary)
				break;
		}
		if (rq->sector >= pos->sector)
			break;
	}

	list_add(&rq->queuelist, entry);
}
EXPORT_SYMBOL(elv_dispatch_sort);

/*
 * Insert rq into dispatch queue of q.  Queue lock must be held on
 * entry.  rq is added to the back of the dispatch queue. To be used by
 * specific elevators.
 */
void elv_dispatch_add_tail(struct request_queue *q, struct request *rq)
{
	if (q->last_merge == rq)
		q->last_merge = NULL;

	elv_rqhash_del(q, rq);

	q->nr_sorted--;

	q->end_sector = rq_end_sector(rq);
	q->boundary_rq = rq;
	list_add_tail(&rq->queuelist, &q->queue_head);
}
EXPORT_SYMBOL(elv_dispatch_add_tail);

int elv_merge(struct request_queue *q, struct request **req, struct bio *bio)
{
	elevator_t *e = q->elevator;
	struct request *__rq;
	int ret;

	/*
	 * First try one-hit cache.
	 */
	if (q->last_merge) {
		ret = elv_try_merge(q->last_merge, bio);
		if (ret != ELEVATOR_NO_MERGE) {
			*req = q->last_merge;
			return ret;
		}
	}

	if (blk_queue_nomerges(q))
		return ELEVATOR_NO_MERGE;

	/*
	 * See if our hash lookup can find a potential backmerge.
	 */
	__rq = elv_rqhash_find(q, bio->bi_sector);
	if (__rq && elv_rq_merge_ok(__rq, bio)) {
		*req = __rq;
		return ELEVATOR_BACK_MERGE;
	}

	if (e->ops->elevator_merge_fn)
		return e->ops->elevator_merge_fn(q, req, bio);

	return ELEVATOR_NO_MERGE;
}

void elv_merged_request(struct request_queue *q, struct request *rq, int type)
{
	elevator_t *e = q->elevator;

	if (e->ops->elevator_merged_fn)
		e->ops->elevator_merged_fn(q, rq, type);

	if (type == ELEVATOR_BACK_MERGE)
		elv_rqhash_reposition(q, rq);

	q->last_merge = rq;
}

void elv_merge_requests(struct request_queue *q, struct request *rq,
			     struct request *next)
{
	elevator_t *e = q->elevator;

	if (e->ops->elevator_merge_req_fn)
		e->ops->elevator_merge_req_fn(q, rq, next);

	elv_rqhash_reposition(q, rq);
	elv_rqhash_del(q, next);

	q->nr_sorted--;
	q->last_merge = rq;
}

void elv_requeue_request(struct request_queue *q, struct request *rq)
{
	/*
	 * it already went through dequeue, we need to decrement the
	 * in_flight count again
	 */
	if (blk_account_rq(rq)) {
		q->in_flight--;
		if (blk_sorted_rq(rq))
			elv_deactivate_rq(q, rq);
	}

	rq->cmd_flags &= ~REQ_STARTED;

	elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE);
}

static void elv_drain_elevator(struct request_queue *q)
{
	static int printed;
	while (q->elevator->ops->elevator_dispatch_fn(q, 1))
		;
	if (q->nr_sorted == 0)
		return;
	if (printed++ < 10) {
		printk(KERN_ERR "%s: forced dispatching is broken "
		       "(nr_sorted=%u), please report this\n",
		       q->elevator->elevator_type->elevator_name, q->nr_sorted);
	}
}

void elv_insert(struct request_queue *q, struct request *rq, int where)
{
	struct list_head *pos;
	unsigned ordseq;
	int unplug_it = 1;

	blk_add_trace_rq(q, rq, BLK_TA_INSERT);

	rq->q = q;

	switch (where) {
	case ELEVATOR_INSERT_FRONT:
		rq->cmd_flags |= REQ_SOFTBARRIER;

		list_add(&rq->queuelist, &q->queue_head);
		break;

	case ELEVATOR_INSERT_BACK:
		rq->cmd_flags |= REQ_SOFTBARRIER;
		elv_drain_elevator(q);
		list_add_tail(&rq->queuelist, &q->queue_head);
		/*
		 * We kick the queue here for the following reasons.
		 * - The elevator might have returned NULL previously
		 *   to delay requests and returned them now.  As the
		 *   queue wasn't empty before this request, ll_rw_blk
		 *   won't run the queue on return, resulting in hang.
		 * - Usually, back inserted requests won't be merged
		 *   with anything.  There's no point in delaying queue
		 *   processing.
		 */
		blk_remove_plug(q);
		q->request_fn(q);
		break;

	case ELEVATOR_INSERT_SORT:
		BUG_ON(!blk_fs_request(rq));
		rq->cmd_flags |= REQ_SORTED;
		q->nr_sorted++;
		if (rq_mergeable(rq)) {
			elv_rqhash_add(q, rq);
			if (!q->last_merge)
				q->last_merge = rq;
		}

		/*
		 * Some ioscheds (cfq) run q->request_fn directly, so
		 * rq cannot be accessed after calling
		 * elevator_add_req_fn.
		 */
		q->elevator->ops->elevator_add_req_fn(q, rq);
		break;

	case ELEVATOR_INSERT_REQUEUE:
		/*
		 * If ordered flush isn't in progress, we do front
		 * insertion; otherwise, requests should be requeued
		 * in ordseq order.
		 */
		rq->cmd_flags |= REQ_SOFTBARRIER;

		/*
		 * Most requeues happen because of a busy condition,
		 * don't force unplug of the queue for that case.
		 */
		unplug_it = 0;

		if (q->ordseq == 0) {
			list_add(&rq->queuelist, &q->queue_head);
			break;
		}

		ordseq = blk_ordered_req_seq(rq);

		list_for_each(pos, &q->queue_head) {
			struct request *pos_rq = list_entry_rq(pos);
			if (ordseq <= blk_ordered_req_seq(pos_rq))
				break;
		}

		list_add_tail(&rq->queuelist, pos);
		break;

	default:
		printk(KERN_ERR "%s: bad insertion point %d\n",
		       __func__, where);
		BUG();
	}

	if (unplug_it && blk_queue_plugged(q)) {
		int nrq = q->rq.count[READ] + q->rq.count[WRITE]
			- q->in_flight;

		if (nrq >= q->unplug_thresh)
			__generic_unplug_device(q);
	}
}

void __elv_add_request(struct request_queue *q, struct request *rq, int where,
		       int plug)
{
	if (q->ordcolor)
		rq->cmd_flags |= REQ_ORDERED_COLOR;

	if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) {
		/*
		 * toggle ordered color
		 */
		if (blk_barrier_rq(rq))
			q->ordcolor ^= 1;

		/*
		 * barriers implicitly indicate back insertion
		 */
		if (where == ELEVATOR_INSERT_SORT)
			where = ELEVATOR_INSERT_BACK;

		/*
		 * this request is scheduling boundary, update
		 * end_sector
		 */
		if (blk_fs_request(rq)) {
			q->end_sector = rq_end_sector(rq);
			q->boundary_rq = rq;
		}
	} else if (!(rq->cmd_flags & REQ_ELVPRIV) &&
		    where == ELEVATOR_INSERT_SORT)
		where = ELEVATOR_INSERT_BACK;

	if (plug)
		blk_plug_device(q);

	elv_insert(q, rq, where);
}
EXPORT_SYMBOL(__elv_add_request);

void elv_add_request(struct request_queue *q, struct request *rq, int where,
		     int plug)
{
	unsigned long flags;

	spin_lock_irqsave(q->queue_lock, flags);
	__elv_add_request(q, rq, where, plug);
	spin_unlock_irqrestore(q->queue_lock, flags);
}
EXPORT_SYMBOL(elv_add_request);

static inline struct request *__elv_next_request(struct request_queue *q)
{
	struct request *rq;

	while (1) {
		while (!list_empty(&q->queue_head)) {
			rq = list_entry_rq(q->queue_head.next);
			if (blk_do_ordered(q, &rq))
				return rq;
		}

		if (!q->elevator->ops->elevator_dispatch_fn(q, 0))
			return NULL;
	}
}

struct request *elv_next_request(struct request_queue *q)
{
	struct request *rq;
	int ret;

	while ((rq = __elv_next_request(q)) != NULL) {
		/*
		 * Kill the empty barrier place holder, the driver must
		 * not ever see it.
		 */
		if (blk_empty_barrier(rq)) {
			end_queued_request(rq, 1);
			continue;
		}
		if (!(rq->cmd_flags & REQ_STARTED)) {
			/*
			 * This is the first time the device driver
			 * sees this request (possibly after
			 * requeueing).  Notify IO scheduler.
			 */
			if (blk_sorted_rq(rq))
				elv_activate_rq(q, rq);

			/*
			 * just mark as started even if we don't start
			 * it, a request that has been delayed should
			 * not be passed by new incoming requests
			 */
			rq->cmd_flags |= REQ_STARTED;
			blk_add_trace_rq(q, rq, BLK_TA_ISSUE);
		}

		if (!q->boundary_rq || q->boundary_rq == rq) {
			q->end_sector = rq_end_sector(rq);
			q->boundary_rq = NULL;
		}

		if (rq->cmd_flags & REQ_DONTPREP)
			break;

		if (q->dma_drain_size && rq->data_len) {
			/*
			 * make sure space for the drain appears we
			 * know we can do this because max_hw_segments
			 * has been adjusted to be one fewer than the
			 * device can handle
			 */
			rq->nr_phys_segments++;
			rq->nr_hw_segments++;
		}

		if (!q->prep_rq_fn)
			break;

		ret = q->prep_rq_fn(q, rq);
		if (ret == BLKPREP_OK) {
			break;
		} else if (ret == BLKPREP_DEFER) {
			/*
			 * the request may have been (partially) prepped.
			 * we need to keep this request in the front to
			 * avoid resource deadlock.  REQ_STARTED will
			 * prevent other fs requests from passing this one.
			 */
			if (q->dma_drain_size && rq->data_len &&
			    !(rq->cmd_flags & REQ_DONTPREP)) {
				/*
				 * remove the space for the drain we added
				 * so that we don't add it again
				 */
				--rq->nr_phys_segments;
				--rq->nr_hw_segments;
			}

			rq = NULL;
			break;
		} else if (ret == BLKPREP_KILL) {
			rq->cmd_flags |= REQ_QUIET;
			end_queued_request(rq, 0);
		} else {
			printk(KERN_ERR "%s: bad return=%d\n", __func__, ret);
			break;
		}
	}

	return rq;
}
EXPORT_SYMBOL(elv_next_request);

void elv_dequeue_request(struct request_queue *q, struct request *rq)
{
	BUG_ON(list_empty(&rq->queuelist));
	BUG_ON(ELV_ON_HASH(rq));

	list_del_init(&rq->queuelist);

	/*
	 * the time frame between a request being removed from the lists
	 * and to it is freed is accounted as io that is in progress at
	 * the driver side.
	 */
	if (blk_account_rq(rq))
		q->in_flight++;
}
EXPORT_SYMBOL(elv_dequeue_request);

int elv_queue_empty(struct request_queue *q)
{
	elevator_t *e = q->elevator;

	if (!list_empty(&q->queue_head))
		return 0;

	if (e->ops->elevator_queue_empty_fn)
		return e->ops->elevator_queue_empty_fn(q);

	return 1;
}
EXPORT_SYMBOL(elv_queue_empty);

struct request *elv_latter_request(struct request_queue *q, struct request *rq)
{
	elevator_t *e = q->elevator;

	if (e->ops->elevator_latter_req_fn)
		return e->ops->elevator_latter_req_fn(q, rq);
	return NULL;
}

struct request *elv_former_request(struct request_queue *q, struct request *rq)
{
	elevator_t *e = q->elevator;

	if (e->ops->elevator_former_req_fn)
		return e->ops->elevator_former_req_fn(q, rq);
	return NULL;
}

int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
{
	elevator_t *e = q->elevator;

	if (e->ops->elevator_set_req_fn)
		return e->ops->elevator_set_req_fn(q, rq, gfp_mask);

	rq->elevator_private = NULL;
	return 0;
}

void elv_put_request(struct request_queue *q, struct request *rq)
{
	elevator_t *e = q->elevator;

	if (e->ops->elevator_put_req_fn)
		e->ops->elevator_put_req_fn(rq);
}

int elv_may_queue(struct request_queue *q, int rw)
{
	elevator_t *e = q->elevator;

	if (e->ops->elevator_may_queue_fn)
		return e->ops->elevator_may_queue_fn(q, rw);

	return ELV_MQUEUE_MAY;
}

void elv_completed_request(struct request_queue *q, struct request *rq)
{
	elevator_t *e = q->elevator;

	/*
	 * request is released from the driver, io must be done
	 */
	if (blk_account_rq(rq)) {
		q->in_flight--;
		if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn)
			e->ops->elevator_completed_req_fn(q, rq);
	}

	/*
	 * Check if the queue is waiting for fs requests to be
	 * drained for flush sequence.
	 */
	if (unlikely(q->ordseq)) {
		struct request *first_rq = list_entry_rq(q->queue_head.next);
		if (q->in_flight == 0 &&
		    blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN &&
		    blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) {
			blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0);
			q->request_fn(q);
		}
	}
}

#define to_elv(atr) container_of((atr), struct elv_fs_entry, attr)

static ssize_t
elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
{
	elevator_t *e = container_of(kobj, elevator_t, kobj);
	struct elv_fs_entry *entry = to_elv(attr);
	ssize_t error;

	if (!entry->show)
		return -EIO;

	mutex_lock(&e->sysfs_lock);
	error = e->ops ? entry->show(e, page) : -ENOENT;
	mutex_unlock(&e->sysfs_lock);
	return error;
}

static ssize_t
elv_attr_store(struct kobject *kobj, struct attribute *attr,
	       const char *page, size_t length)
{
	elevator_t *e = container_of(kobj, elevator_t, kobj);
	struct elv_fs_entry *entry = to_elv(attr);
	ssize_t error;

	if (!entry->store)
		return -EIO;

	mutex_lock(&e->sysfs_lock);
	error = e->ops ? entry->store(e, page, length) : -ENOENT;
	mutex_unlock(&e->sysfs_lock);
	return error;
}

static struct sysfs_ops elv_sysfs_ops = {
	.show	= elv_attr_show,
	.store	= elv_attr_store,
};

static struct kobj_type elv_ktype = {
	.sysfs_ops	= &elv_sysfs_ops,
	.release	= elevator_release,
};

int elv_register_queue(struct request_queue *q)
{
	elevator_t *e = q->elevator;
	int error;

	error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched");
	if (!error) {
		struct elv_fs_entry *attr = e->elevator_type->elevator_attrs;
		if (attr) {
			while (attr->attr.name) {
				if (sysfs_create_file(&e->kobj, &attr->attr))
					break;
				attr++;
			}
		}
		kobject_uevent(&e->kobj, KOBJ_ADD);
	}
	return error;
}

static void __elv_unregister_queue(elevator_t *e)
{
	kobject_uevent(&e->kobj, KOBJ_REMOVE);
	kobject_del(&e->kobj);
}

void elv_unregister_queue(struct request_queue *q)
{
	if (q)
		__elv_unregister_queue(q->elevator);
}

void elv_register(struct elevator_type *e)
{
	char *def = "";

	spin_lock(&elv_list_lock);
	BUG_ON(elevator_find(e->elevator_name));
	list_add_tail(&e->list, &elv_list);
	spin_unlock(&elv_list_lock);

	if (!strcmp(e->elevator_name, chosen_elevator) ||
			(!*chosen_elevator &&
			 !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED)))
				def = " (default)";

	printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name,
								def);
}
EXPORT_SYMBOL_GPL(elv_register);

void elv_unregister(struct elevator_type *e)
{
	struct task_struct *g, *p;

	/*
	 * Iterate every thread in the process to remove the io contexts.
	 */
	if (e->ops.trim) {
		read_lock(&tasklist_lock);
		do_each_thread(g, p) {
			task_lock(p);
			if (p->io_context)
				e->ops.trim(p->io_context);
			task_unlock(p);
		} while_each_thread(g, p);
		read_unlock(&tasklist_lock);
	}

	spin_lock(&elv_list_lock);
	list_del_init(&e->list);
	spin_unlock(&elv_list_lock);
}
EXPORT_SYMBOL_GPL(elv_unregister);

/*
 * switch to new_e io scheduler. be careful not to introduce deadlocks -
 * we don't free the old io scheduler, before we have allocated what we
 * need for the new one. this way we have a chance of going back to the old
 * one, if the new one fails init for some reason.
 */
static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
{
	elevator_t *old_elevator, *e;
	void *data;

	/*
	 * Allocate new elevator
	 */
	e = elevator_alloc(q, new_e);
	if (!e)
		return 0;

	data = elevator_init_queue(q, e);
	if (!data) {
		kobject_put(&e->kobj);
		return 0;
	}

	/*
	 * Turn on BYPASS and drain all requests w/ elevator private data
	 */
	spin_lock_irq(q->queue_lock);

	queue_flag_set(QUEUE_FLAG_ELVSWITCH, q);

	elv_drain_elevator(q);

	while (q->rq.elvpriv) {
		blk_remove_plug(q);
		q->request_fn(q);
		spin_unlock_irq(q->queue_lock);
		msleep(10);
		spin_lock_irq(q->queue_lock);
		elv_drain_elevator(q);
	}

	/*
	 * Remember old elevator.
	 */
	old_elevator = q->elevator;

	/*
	 * attach and start new elevator
	 */
	elevator_attach(q, e, data);

	spin_unlock_irq(q->queue_lock);

	__elv_unregister_queue(old_elevator);

	if (elv_register_queue(q))
		goto fail_register;

	/*
	 * finally exit old elevator and turn off BYPASS.
	 */
	elevator_exit(old_elevator);
	spin_lock_irq(q->queue_lock);
	queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q);
	spin_unlock_irq(q->queue_lock);

	blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name);

	return 1;

fail_register:
	/*
	 * switch failed, exit the new io scheduler and reattach the old
	 * one again (along with re-adding the sysfs dir)
	 */
	elevator_exit(e);
	q->elevator = old_elevator;
	elv_register_queue(q);

	spin_lock_irq(q->queue_lock);
	queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q);
	spin_unlock_irq(q->queue_lock);

	return 0;
}

ssize_t elv_iosched_store(struct request_queue *q, const char *name,
			  size_t count)
{
	char elevator_name[ELV_NAME_MAX];
	size_t len;
	struct elevator_type *e;

	elevator_name[sizeof(elevator_name) - 1] = '\0';
	strncpy(elevator_name, name, sizeof(elevator_name) - 1);
	len = strlen(elevator_name);

	if (len && elevator_name[len - 1] == '\n')
		elevator_name[len - 1] = '\0';

	e = elevator_get(elevator_name);
	if (!e) {
		printk(KERN_ERR "elevator: type %s not found\n", elevator_name);
		return -EINVAL;
	}

	if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) {
		elevator_put(e);
		return count;
	}

	if (!elevator_switch(q, e))
		printk(KERN_ERR "elevator: switch to %s failed\n",
							elevator_name);
	return count;
}

ssize_t elv_iosched_show(struct request_queue *q, char *name)
{
	elevator_t *e = q->elevator;
	struct elevator_type *elv = e->elevator_type;
	struct elevator_type *__e;
	int len = 0;

	spin_lock(&elv_list_lock);
	list_for_each_entry(__e, &elv_list, list) {
		if (!strcmp(elv->elevator_name, __e->elevator_name))
			len += sprintf(name+len, "[%s] ", elv->elevator_name);
		else
			len += sprintf(name+len, "%s ", __e->elevator_name);
	}
	spin_unlock(&elv_list_lock);

	len += sprintf(len+name, "\n");
	return len;
}

struct request *elv_rb_former_request(struct request_queue *q,
				      struct request *rq)
{
	struct rb_node *rbprev = rb_prev(&rq->rb_node);

	if (rbprev)
		return rb_entry_rq(rbprev);

	return NULL;
}
EXPORT_SYMBOL(elv_rb_former_request);

struct request *elv_rb_latter_request(struct request_queue *q,
				      struct request *rq)
{
	struct rb_node *rbnext = rb_next(&rq->rb_node);

	if (rbnext)
		return rb_entry_rq(rbnext);

	return NULL;
}
EXPORT_SYMBOL(elv_rb_latter_request);
generated by cgit v1.2.2 (git 2.25.0) at 2025-09-14 05:13:02 -0400