litmus-rt-budgetable-locks.git/.git - Unnamed repository; edit this file 'description' to name the repository.

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author	Richard Weinberger <richard@nod.at>	2015-02-27 16:55:20 -0500
committer	Richard Weinberger <richard@nod.at>	2015-03-26 18:27:47 -0400
commit	69886e676e89534953b12df77382504a7731f7bb (patch)
tree	2d2f096782861f19e28880a9d209269ac8aad371 /fs
parent	bc465aa9d045feb0e13b4a8f32cc33c1943f62d6 (diff)

hostfs: hostfs_file_open: Switch to data locking model

Instead of serializing hostfs_file_open() we can use a per inode mutex to protect ->mode. Signed-off-by: Richard Weinberger <richard@nod.at>

Diffstat (limited to 'fs')

-rw-r--r--

fs/hostfs/hostfs_kern.c

1 files changed, 7 insertions, 6 deletions

         int fd;
         fmode_t mode;
         struct inode vfs_inode;
+        struct mutex open_mutex;
 };
 static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode)
         hi->fd = -1;
         hi->mode = 0;
         inode_init_once(&hi->vfs_inode);
+        mutex_init(&hi->open_mutex);
         return &hi->vfs_inode;
 }
 static int hostfs_file_open(struct inode *ino, struct file *file)
 {
-        static DEFINE_MUTEX(open_mutex);
         char *name;
         fmode_t mode = 0;
         int err;
         if (fd < 0)
                 return fd;
-        mutex_lock(&open_mutex);
+        mutex_lock(&HOSTFS_I(ino)->open_mutex);
         /* somebody else had handled it first? */
         if ((mode & HOSTFS_I(ino)->mode) == mode) {
-                mutex_unlock(&open_mutex);
+                mutex_unlock(&HOSTFS_I(ino)->open_mutex);
                 return 0;
         }
         if ((mode | HOSTFS_I(ino)->mode) != mode) {
                 mode |= HOSTFS_I(ino)->mode;
-                mutex_unlock(&open_mutex);
+                mutex_unlock(&HOSTFS_I(ino)->open_mutex);
                 close_file(&fd);
                 goto retry;
         }
                 err = replace_file(fd, HOSTFS_I(ino)->fd);
                 close_file(&fd);
                 if (err < 0) {
-                        mutex_unlock(&open_mutex);
+                        mutex_unlock(&HOSTFS_I(ino)->open_mutex);
                         return err;
                 }
         }
         HOSTFS_I(ino)->mode = mode;
-        mutex_unlock(&open_mutex);
+        mutex_unlock(&HOSTFS_I(ino)->open_mutex);
         return 0;
 }

/* * 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/blktrace_api.h> #include <linux/hash.h> #include <linux/uaccess.h> #include <linux/pm_runtime.h> #include <trace/events/block.h> #include "blk.h" #include "blk-cgroup.h" static DEFINE_SPINLOCK(elv_list_lock); static LIST_HEAD(elv_list); /* * Merge hash stuff. */ #define rq_hash_key(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq)) /* * 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; struct elevator_queue *e = q->elevator; if (e->type->ops.elevator_allow_merge_fn) return e->type->ops.elevator_allow_merge_fn(q, rq, bio); return 1; } /* * can we safely merge with this request? */ bool elv_rq_merge_ok(struct request *rq, struct bio *bio) { if (!blk_rq_merge_ok(rq, bio)) return 0; if (!elv_iosched_allow_merge(rq, bio)) return 0; return 1; } EXPORT_SYMBOL(elv_rq_merge_ok); 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, bool try_loading) { struct elevator_type *e; spin_lock(&elv_list_lock); e = elevator_find(name); if (!e && try_loading) { spin_unlock(&elv_list_lock); request_module("%s-iosched", name); 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 char chosen_elevator[ELV_NAME_MAX]; static int __init elevator_setup(char *str) { /* * Be backwards-compatible with previous kernels, so users * won't get the wrong elevator. */ strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); return 1; } __setup("elevator=", elevator_setup); /* called during boot to load the elevator chosen by the elevator param */ void __init load_default_elevator_module(void) { struct elevator_type *e; if (!chosen_elevator[0]) return; spin_lock(&elv_list_lock); e = elevator_find(chosen_elevator); spin_unlock(&elv_list_lock); if (!e) request_module("%s-iosched", chosen_elevator); } static struct kobj_type elv_ktype; struct elevator_queue *elevator_alloc(struct request_queue *q, struct elevator_type *e) { struct elevator_queue *eq; eq = kzalloc_node(sizeof(*eq), GFP_KERNEL, q->node); if (unlikely(!eq)) goto err; eq->type = e; kobject_init(&eq->kobj, &elv_ktype); mutex_init(&eq->sysfs_lock); hash_init(eq->hash); return eq; err: kfree(eq); elevator_put(e); return NULL; } EXPORT_SYMBOL(elevator_alloc); static void elevator_release(struct kobject *kobj) { struct elevator_queue *e; e = container_of(kobj, struct elevator_queue, kobj); elevator_put(e->type); kfree(e); } int elevator_init(struct request_queue *q, char *name) { struct elevator_type *e = NULL; int err; /* * q->sysfs_lock must be held to provide mutual exclusion between * elevator_switch() and here. */ lockdep_assert_held(&q->sysfs_lock); if (unlikely(q->elevator)) return 0; INIT_LIST_HEAD(&q->queue_head); q->last_merge = NULL; q->end_sector = 0; q->boundary_rq = NULL; if (name) { e = elevator_get(name, true); if (!e) return -EINVAL; } /* * Use the default elevator specified by config boot param or * config option. Don't try to load modules as we could be running * off async and request_module() isn't allowed from async. */ if (!e && *chosen_elevator) { e = elevator_get(chosen_elevator, false); if (!e) printk(KERN_ERR "I/O scheduler %s not found\n", chosen_elevator); } if (!e) { e = elevator_get(CONFIG_DEFAULT_IOSCHED, false); if (!e) { printk(KERN_ERR "Default I/O scheduler not found. " \ "Using noop.\n"); e = elevator_get("noop", false); } } err = e->ops.elevator_init_fn(q, e); return 0; } EXPORT_SYMBOL(elevator_init); void elevator_exit(struct elevator_queue *e) { mutex_lock(&e->sysfs_lock); if (e->type->ops.elevator_exit_fn) e->type->ops.elevator_exit_fn(e); mutex_unlock(&e->sysfs_lock); kobject_put(&e->kobj); } EXPORT_SYMBOL(elevator_exit); static inline void __elv_rqhash_del(struct request *rq) { hash_del(&rq->hash); rq->cmd_flags &= ~REQ_HASHED; } 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) { struct elevator_queue *e = q->elevator; BUG_ON(ELV_ON_HASH(rq)); hash_add(e->hash, &rq->hash, rq_hash_key(rq)); rq->cmd_flags |= REQ_HASHED; } 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) { struct elevator_queue *e = q->elevator; struct hlist_node *next; struct request *rq; hash_for_each_possible_safe(e->hash, rq, next, hash, offset) { 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. */ void 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 (blk_rq_pos(rq) < blk_rq_pos(__rq)) p = &(*p)->rb_left; else if (blk_rq_pos(rq) >= blk_rq_pos(__rq)) p = &(*p)->rb_right; } rb_link_node(&rq->rb_node, parent, p); rb_insert_color(&rq->rb_node, root); } 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 < blk_rq_pos(rq)) n = n->rb_left; else if (sector > blk_rq_pos(rq)) 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_STARTED; list_for_each_prev(entry, &q->queue_head) { struct request *pos = list_entry_rq(entry); if ((rq->cmd_flags & REQ_DISCARD) != (pos->cmd_flags & REQ_DISCARD)) break; if (rq_data_dir(rq) != rq_data_dir(pos)) break; if (pos->cmd_flags & stop_flags) break; if (blk_rq_pos(rq) >= boundary) { if (blk_rq_pos(pos) < boundary) continue; } else { if (blk_rq_pos(pos) >= boundary) break; } if (blk_rq_pos(rq) >= blk_rq_pos(pos)) 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) { struct elevator_queue *e = q->elevator; struct request *__rq; int ret; /* * Levels of merges: * nomerges: No merges at all attempted * noxmerges: Only simple one-hit cache try * merges: All merge tries attempted */ if (blk_queue_nomerges(q)) return ELEVATOR_NO_MERGE; /* * First try one-hit cache. */ if (q->last_merge && elv_rq_merge_ok(q->last_merge, bio)) { ret = blk_try_merge(q->last_merge, bio); if (ret != ELEVATOR_NO_MERGE) { *req = q->last_merge; return ret; } } if (blk_queue_noxmerges(q)) return ELEVATOR_NO_MERGE; /* * See if our hash lookup can find a potential backmerge. */ __rq = elv_rqhash_find(q, bio->bi_iter.bi_sector); if (__rq && elv_rq_merge_ok(__rq, bio)) { *req = __rq; return ELEVATOR_BACK_MERGE; } if (e->type->ops.elevator_merge_fn) return e->type->ops.elevator_merge_fn(q, req, bio); return ELEVATOR_NO_MERGE; } /* * Attempt to do an insertion back merge. Only check for the case where * we can append 'rq' to an existing request, so we can throw 'rq' away * afterwards. * * Returns true if we merged, false otherwise */ static bool elv_attempt_insert_merge(struct request_queue *q, struct request *rq) { struct request *__rq; bool ret; if (blk_queue_nomerges(q)) return false; /* * First try one-hit cache. */ if (q->last_merge && blk_attempt_req_merge(q, q->last_merge, rq)) return true; if (blk_queue_noxmerges(q)) return false; ret = false; /* * See if our hash lookup can find a potential backmerge. */ while (1) { __rq = elv_rqhash_find(q, blk_rq_pos(rq)); if (!__rq || !blk_attempt_req_merge(q, __rq, rq)) break; /* The merged request could be merged with others, try again */ ret = true; rq = __rq; } return ret; } void elv_merged_request(struct request_queue *q, struct request *rq, int type) { struct elevator_queue *e = q->elevator; if (e->type->ops.elevator_merged_fn) e->type->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) { struct elevator_queue *e = q->elevator; const int next_sorted = next->cmd_flags & REQ_SORTED; if (next_sorted && e->type->ops.elevator_merge_req_fn) e->type->ops.elevator_merge_req_fn(q, rq, next); elv_rqhash_reposition(q, rq); if (next_sorted) { elv_rqhash_del(q, next); q->nr_sorted--; } q->last_merge = rq; } void elv_bio_merged(struct request_queue *q, struct request *rq, struct bio *bio) { struct elevator_queue *e = q->elevator; if (e->type->ops.elevator_bio_merged_fn) e->type->ops.elevator_bio_merged_fn(q, rq, bio); } #ifdef CONFIG_PM_RUNTIME static void blk_pm_requeue_request(struct request *rq) { if (rq->q->dev && !(rq->cmd_flags & REQ_PM)) rq->q->nr_pending--; } static void blk_pm_add_request(struct request_queue *q, struct request *rq) { if (q->dev && !(rq->cmd_flags & REQ_PM) && q->nr_pending++ == 0 && (q->rpm_status == RPM_SUSPENDED || q->rpm_status == RPM_SUSPENDING)) pm_request_resume(q->dev); } #else static inline void blk_pm_requeue_request(struct request *rq) {} static inline void blk_pm_add_request(struct request_queue *q, struct request *rq) { } #endif 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)) {


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