diff options
Diffstat (limited to 'fs/gfs2/glock.c')
| -rw-r--r-- | fs/gfs2/glock.c | 2210 |
1 files changed, 2210 insertions, 0 deletions
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c new file mode 100644 index 000000000..14d11ccda --- /dev/null +++ b/fs/gfs2/glock.c @@ -0,0 +1,2210 @@ +/* + * Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved. + * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved. + * + * This copyrighted material is made available to anyone wishing to use, + * modify, copy, or redistribute it subject to the terms and conditions + * of the GNU General Public License version 2. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/sched.h> +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <linux/buffer_head.h> +#include <linux/delay.h> +#include <linux/sort.h> +#include <linux/hash.h> +#include <linux/jhash.h> +#include <linux/kallsyms.h> +#include <linux/gfs2_ondisk.h> +#include <linux/list.h> +#include <linux/wait.h> +#include <linux/module.h> +#include <linux/uaccess.h> +#include <linux/seq_file.h> +#include <linux/debugfs.h> +#include <linux/kthread.h> +#include <linux/freezer.h> +#include <linux/workqueue.h> +#include <linux/jiffies.h> +#include <linux/rcupdate.h> +#include <linux/rculist_bl.h> +#include <linux/bit_spinlock.h> +#include <linux/percpu.h> +#include <linux/list_sort.h> +#include <linux/lockref.h> +#include <linux/rhashtable.h> + +#include "gfs2.h" +#include "incore.h" +#include "glock.h" +#include "glops.h" +#include "inode.h" +#include "lops.h" +#include "meta_io.h" +#include "quota.h" +#include "super.h" +#include "util.h" +#include "bmap.h" +#define CREATE_TRACE_POINTS +#include "trace_gfs2.h" + +struct gfs2_glock_iter { + struct gfs2_sbd *sdp; /* incore superblock */ + struct rhashtable_iter hti; /* rhashtable iterator */ + struct gfs2_glock *gl; /* current glock struct */ + loff_t last_pos; /* last position */ +}; + +typedef void (*glock_examiner) (struct gfs2_glock * gl); + +static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target); + +static struct dentry *gfs2_root; +static struct workqueue_struct *glock_workqueue; +struct workqueue_struct *gfs2_delete_workqueue; +static LIST_HEAD(lru_list); +static atomic_t lru_count = ATOMIC_INIT(0); +static DEFINE_SPINLOCK(lru_lock); + +#define GFS2_GL_HASH_SHIFT 15 +#define GFS2_GL_HASH_SIZE BIT(GFS2_GL_HASH_SHIFT) + +static const struct rhashtable_params ht_parms = { + .nelem_hint = GFS2_GL_HASH_SIZE * 3 / 4, + .key_len = offsetofend(struct lm_lockname, ln_type), + .key_offset = offsetof(struct gfs2_glock, gl_name), + .head_offset = offsetof(struct gfs2_glock, gl_node), +}; + +static struct rhashtable gl_hash_table; + +#define GLOCK_WAIT_TABLE_BITS 12 +#define GLOCK_WAIT_TABLE_SIZE (1 << GLOCK_WAIT_TABLE_BITS) +static wait_queue_head_t glock_wait_table[GLOCK_WAIT_TABLE_SIZE] __cacheline_aligned; + +struct wait_glock_queue { + struct lm_lockname *name; + wait_queue_entry_t wait; +}; + +static int glock_wake_function(wait_queue_entry_t *wait, unsigned int mode, + int sync, void *key) +{ + struct wait_glock_queue *wait_glock = + container_of(wait, struct wait_glock_queue, wait); + struct lm_lockname *wait_name = wait_glock->name; + struct lm_lockname *wake_name = key; + + if (wake_name->ln_sbd != wait_name->ln_sbd || + wake_name->ln_number != wait_name->ln_number || + wake_name->ln_type != wait_name->ln_type) + return 0; + return autoremove_wake_function(wait, mode, sync, key); +} + +static wait_queue_head_t *glock_waitqueue(struct lm_lockname *name) +{ + u32 hash = jhash2((u32 *)name, ht_parms.key_len / 4, 0); + + return glock_wait_table + hash_32(hash, GLOCK_WAIT_TABLE_BITS); +} + +/** + * wake_up_glock - Wake up waiters on a glock + * @gl: the glock + */ +static void wake_up_glock(struct gfs2_glock *gl) +{ + wait_queue_head_t *wq = glock_waitqueue(&gl->gl_name); + + if (waitqueue_active(wq)) + __wake_up(wq, TASK_NORMAL, 1, &gl->gl_name); +} + +static void gfs2_glock_dealloc(struct rcu_head *rcu) +{ + struct gfs2_glock *gl = container_of(rcu, struct gfs2_glock, gl_rcu); + + if (gl->gl_ops->go_flags & GLOF_ASPACE) { + kmem_cache_free(gfs2_glock_aspace_cachep, gl); + } else { + kfree(gl->gl_lksb.sb_lvbptr); + kmem_cache_free(gfs2_glock_cachep, gl); + } +} + +void gfs2_glock_free(struct gfs2_glock *gl) +{ + struct gfs2_sbd *sdp = gl->gl_name.ln_sbd; + + BUG_ON(atomic_read(&gl->gl_revokes)); + rhashtable_remove_fast(&gl_hash_table, &gl->gl_node, ht_parms); + smp_mb(); + wake_up_glock(gl); + call_rcu(&gl->gl_rcu, gfs2_glock_dealloc); + if (atomic_dec_and_test(&sdp->sd_glock_disposal)) + wake_up(&sdp->sd_glock_wait); +} + +/** + * gfs2_glock_hold() - increment reference count on glock + * @gl: The glock to hold + * + */ + +void gfs2_glock_hold(struct gfs2_glock *gl) +{ + GLOCK_BUG_ON(gl, __lockref_is_dead(&gl->gl_lockref)); + lockref_get(&gl->gl_lockref); +} + +/** + * demote_ok - Check to see if it's ok to unlock a glock + * @gl: the glock + * + * Returns: 1 if it's ok + */ + +static int demote_ok(const struct gfs2_glock *gl) +{ + const struct gfs2_glock_operations *glops = gl->gl_ops; + + if (gl->gl_state == LM_ST_UNLOCKED) + return 0; + if (!list_empty(&gl->gl_holders)) + return 0; + if (glops->go_demote_ok) + return glops->go_demote_ok(gl); + return 1; +} + + +void gfs2_glock_add_to_lru(struct gfs2_glock *gl) +{ + if (!(gl->gl_ops->go_flags & GLOF_LRU)) + return; + + spin_lock(&lru_lock); + + list_del(&gl->gl_lru); + list_add_tail(&gl->gl_lru, &lru_list); + + if (!test_bit(GLF_LRU, &gl->gl_flags)) { + set_bit(GLF_LRU, &gl->gl_flags); + atomic_inc(&lru_count); + } + + spin_unlock(&lru_lock); +} + +static void gfs2_glock_remove_from_lru(struct gfs2_glock *gl) +{ + if (!(gl->gl_ops->go_flags & GLOF_LRU)) + return; + + spin_lock(&lru_lock); + if (test_bit(GLF_LRU, &gl->gl_flags)) { + list_del_init(&gl->gl_lru); + atomic_dec(&lru_count); + clear_bit(GLF_LRU, &gl->gl_flags); + } + spin_unlock(&lru_lock); +} + +/* + * Enqueue the glock on the work queue. Passes one glock reference on to the + * work queue. + */ +static void __gfs2_glock_queue_work(struct gfs2_glock *gl, unsigned long delay) { + if (!queue_delayed_work(glock_workqueue, &gl->gl_work, delay)) { + /* + * We are holding the lockref spinlock, and the work was still + * queued above. The queued work (glock_work_func) takes that + * spinlock before dropping its glock reference(s), so it + * cannot have dropped them in the meantime. + */ + GLOCK_BUG_ON(gl, gl->gl_lockref.count < 2); + gl->gl_lockref.count--; + } +} + +static void gfs2_glock_queue_work(struct gfs2_glock *gl, unsigned long delay) { + spin_lock(&gl->gl_lockref.lock); + __gfs2_glock_queue_work(gl, delay); + spin_unlock(&gl->gl_lockref.lock); +} + +static void __gfs2_glock_put(struct gfs2_glock *gl) +{ + struct gfs2_sbd *sdp = gl->gl_name.ln_sbd; + struct address_space *mapping = gfs2_glock2aspace(gl); + + lockref_mark_dead(&gl->gl_lockref); + + gfs2_glock_remove_from_lru(gl); + spin_unlock(&gl->gl_lockref.lock); + GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders)); + GLOCK_BUG_ON(gl, mapping && mapping->nrpages); + trace_gfs2_glock_put(gl); + sdp->sd_lockstruct.ls_ops->lm_put_lock(gl); +} + +/* + * Cause the glock to be put in work queue context. + */ +void gfs2_glock_queue_put(struct gfs2_glock *gl) +{ + gfs2_glock_queue_work(gl, 0); +} + +/** + * gfs2_glock_put() - Decrement reference count on glock + * @gl: The glock to put + * + */ + +void gfs2_glock_put(struct gfs2_glock *gl) +{ + if (lockref_put_or_lock(&gl->gl_lockref)) + return; + + __gfs2_glock_put(gl); +} + +/** + * may_grant - check if its ok to grant a new lock + * @gl: The glock + * @gh: The lock request which we wish to grant + * + * Returns: true if its ok to grant the lock + */ + +static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh) +{ + const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list); + if ((gh->gh_state == LM_ST_EXCLUSIVE || + gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head) + return 0; + if (gl->gl_state == gh->gh_state) + return 1; + if (gh->gh_flags & GL_EXACT) + return 0; + if (gl->gl_state == LM_ST_EXCLUSIVE) { + if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED) + return 1; + if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED) + return 1; + } + if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY)) + return 1; + return 0; +} + +static void gfs2_holder_wake(struct gfs2_holder *gh) +{ + clear_bit(HIF_WAIT, &gh->gh_iflags); + smp_mb__after_atomic(); + wake_up_bit(&gh->gh_iflags, HIF_WAIT); +} + +/** + * do_error - Something unexpected has happened during a lock request + * + */ + +static void do_error(struct gfs2_glock *gl, const int ret) +{ + struct gfs2_holder *gh, *tmp; + + list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) { + if (test_bit(HIF_HOLDER, &gh->gh_iflags)) + continue; + if (ret & LM_OUT_ERROR) + gh->gh_error = -EIO; + else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) + gh->gh_error = GLR_TRYFAILED; + else + continue; + list_del_init(&gh->gh_list); + trace_gfs2_glock_queue(gh, 0); + gfs2_holder_wake(gh); + } +} + +/** + * do_promote - promote as many requests as possible on the current queue + * @gl: The glock + * + * Returns: 1 if there is a blocked holder at the head of the list, or 2 + * if a type specific operation is underway. + */ + +static int do_promote(struct gfs2_glock *gl) +__releases(&gl->gl_lockref.lock) +__acquires(&gl->gl_lockref.lock) +{ + const struct gfs2_glock_operations *glops = gl->gl_ops; + struct gfs2_holder *gh, *tmp; + int ret; + +restart: + list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) { + if (test_bit(HIF_HOLDER, &gh->gh_iflags)) + continue; + if (may_grant(gl, gh)) { + if (gh->gh_list.prev == &gl->gl_holders && + glops->go_lock) { + spin_unlock(&gl->gl_lockref.lock); + /* FIXME: eliminate this eventually */ + ret = glops->go_lock(gh); + spin_lock(&gl->gl_lockref.lock); + if (ret) { + if (ret == 1) + return 2; + gh->gh_error = ret; + list_del_init(&gh->gh_list); + trace_gfs2_glock_queue(gh, 0); + gfs2_holder_wake(gh); + goto restart; + } + set_bit(HIF_HOLDER, &gh->gh_iflags); + trace_gfs2_promote(gh, 1); + gfs2_holder_wake(gh); + goto restart; + } + set_bit(HIF_HOLDER, &gh->gh_iflags); + trace_gfs2_promote(gh, 0); + gfs2_holder_wake(gh); + continue; + } + if (gh->gh_list.prev == &gl->gl_holders) + return 1; + do_error(gl, 0); + break; + } + return 0; +} + +/** + * find_first_waiter - find the first gh that's waiting for the glock + * @gl: the glock + */ + +static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl) +{ + struct gfs2_holder *gh; + + list_for_each_entry(gh, &gl->gl_holders, gh_list) { + if (!test_bit(HIF_HOLDER, &gh->gh_iflags)) + return gh; + } + return NULL; +} + +/** + * state_change - record that the glock is now in a different state + * @gl: the glock + * @new_state the new state + * + */ + +static void state_change(struct gfs2_glock *gl, unsigned int new_state) +{ + int held1, held2; + + held1 = (gl->gl_state != LM_ST_UNLOCKED); + held2 = (new_state != LM_ST_UNLOCKED); + + if (held1 != held2) { + GLOCK_BUG_ON(gl, __lockref_is_dead(&gl->gl_lockref)); + if (held2) + gl->gl_lockref.count++; + else + gl->gl_lockref.count--; + } + if (held1 && held2 && list_empty(&gl->gl_holders)) + clear_bit(GLF_QUEUED, &gl->gl_flags); + + if (new_state != gl->gl_target) + /* shorten our minimum hold time */ + gl->gl_hold_time = max(gl->gl_hold_time - GL_GLOCK_HOLD_DECR, + GL_GLOCK_MIN_HOLD); + gl->gl_state = new_state; + gl->gl_tchange = jiffies; +} + +static void gfs2_demote_wake(struct gfs2_glock *gl) +{ + gl->gl_demote_state = LM_ST_EXCLUSIVE; + clear_bit(GLF_DEMOTE, &gl->gl_flags); + smp_mb__after_atomic(); + wake_up_bit(&gl->gl_flags, GLF_DEMOTE); +} + +/** + * finish_xmote - The DLM has replied to one of our lock requests + * @gl: The glock + * @ret: The status from the DLM + * + */ + +static void finish_xmote(struct gfs2_glock *gl, unsigned int ret) +{ + const struct gfs2_glock_operations *glops = gl->gl_ops; + struct gfs2_holder *gh; + unsigned state = ret & LM_OUT_ST_MASK; + int rv; + + spin_lock(&gl->gl_lockref.lock); + trace_gfs2_glock_state_change(gl, state); + state_change(gl, state); + gh = find_first_waiter(gl); + + /* Demote to UN request arrived during demote to SH or DF */ + if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) && + state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED) + gl->gl_target = LM_ST_UNLOCKED; + + /* Check for state != intended state */ + if (unlikely(state != gl->gl_target)) { + if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) { + /* move to back of queue and try next entry */ + if (ret & LM_OUT_CANCELED) { + if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0) + list_move_tail(&gh->gh_list, &gl->gl_holders); + gh = find_first_waiter(gl); + gl->gl_target = gh->gh_state; + goto retry; + } + /* Some error or failed "try lock" - report it */ + if ((ret & LM_OUT_ERROR) || + (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) { + gl->gl_target = gl->gl_state; + do_error(gl, ret); + goto out; + } + } + switch(state) { + /* Unlocked due to conversion deadlock, try again */ + case LM_ST_UNLOCKED: +retry: + do_xmote(gl, gh, gl->gl_target); + break; + /* Conversion fails, unlock and try again */ + case LM_ST_SHARED: + case LM_ST_DEFERRED: + do_xmote(gl, gh, LM_ST_UNLOCKED); + break; + default: /* Everything else */ + pr_err("wanted %u got %u\n", gl->gl_target, state); + GLOCK_BUG_ON(gl, 1); + } + spin_unlock(&gl->gl_lockref.lock); + return; + } + + /* Fast path - we got what we asked for */ + if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) + gfs2_demote_wake(gl); + if (state != LM_ST_UNLOCKED) { + if (glops->go_xmote_bh) { + spin_unlock(&gl->gl_lockref.lock); + rv = glops->go_xmote_bh(gl, gh); + spin_lock(&gl->gl_lockref.lock); + if (rv) { + do_error(gl, rv); + goto out; + } + } + rv = do_promote(gl); + if (rv == 2) + goto out_locked; + } +out: + clear_bit(GLF_LOCK, &gl->gl_flags); +out_locked: + spin_unlock(&gl->gl_lockref.lock); +} + +/** + * do_xmote - Calls the DLM to change the state of a lock + * @gl: The lock state + * @gh: The holder (only for promotes) + * @target: The target lock state + * + */ + +static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target) +__releases(&gl->gl_lockref.lock) +__acquires(&gl->gl_lockref.lock) +{ + const struct gfs2_glock_operations *glops = gl->gl_ops; + struct gfs2_sbd *sdp = gl->gl_name.ln_sbd; + unsigned int lck_flags = (unsigned int)(gh ? gh->gh_flags : 0); + int ret; + + if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)) && + target != LM_ST_UNLOCKED) + return; + lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP | + LM_FLAG_PRIORITY); + GLOCK_BUG_ON(gl, gl->gl_state == target); + GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target); + if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) && + glops->go_inval) { + set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags); + do_error(gl, 0); /* Fail queued try locks */ + } + gl->gl_req = target; + set_bit(GLF_BLOCKING, &gl->gl_flags); + if ((gl->gl_req == LM_ST_UNLOCKED) || + (gl->gl_state == LM_ST_EXCLUSIVE) || + (lck_flags & (LM_FLAG_TRY|LM_FLAG_TRY_1CB))) + clear_bit(GLF_BLOCKING, &gl->gl_flags); + spin_unlock(&gl->gl_lockref.lock); + if (glops->go_sync) + glops->go_sync(gl); + if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags)) + glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA); + clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags); + + gfs2_glock_hold(gl); + if (sdp->sd_lockstruct.ls_ops->lm_lock) { + /* lock_dlm */ + ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags); + if (ret == -EINVAL && gl->gl_target == LM_ST_UNLOCKED && + target == LM_ST_UNLOCKED && + test_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags)) { + finish_xmote(gl, target); + gfs2_glock_queue_work(gl, 0); + } + else if (ret) { + pr_err("lm_lock ret %d\n", ret); + GLOCK_BUG_ON(gl, !test_bit(SDF_SHUTDOWN, + &sdp->sd_flags)); + } + } else { /* lock_nolock */ + finish_xmote(gl, target); + gfs2_glock_queue_work(gl, 0); + } + + spin_lock(&gl->gl_lockref.lock); +} + +/** + * find_first_holder - find the first "holder" gh + * @gl: the glock + */ + +static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl) +{ + struct gfs2_holder *gh; + + if (!list_empty(&gl->gl_holders)) { + gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list); + if (test_bit(HIF_HOLDER, &gh->gh_iflags)) + return gh; + } + return NULL; +} + +/** + * run_queue - do all outstanding tasks related to a glock + * @gl: The glock in question + * @nonblock: True if we must not block in run_queue + * + */ + +static void run_queue(struct gfs2_glock *gl, const int nonblock) +__releases(&gl->gl_lockref.lock) +__acquires(&gl->gl_lockref.lock) +{ + struct gfs2_holder *gh = NULL; + int ret; + + if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) + return; + + GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)); + + if (test_bit(GLF_DEMOTE, &gl->gl_flags) && + gl->gl_demote_state != gl->gl_state) { + if (find_first_holder(gl)) + goto out_unlock; + if (nonblock) + goto out_sched; + set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags); + GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE); + gl->gl_target = gl->gl_demote_state; + } else { + if (test_bit(GLF_DEMOTE, &gl->gl_flags)) + gfs2_demote_wake(gl); + ret = do_promote(gl); + if (ret == 0) + goto out_unlock; + if (ret == 2) + goto out; + gh = find_first_waiter(gl); + gl->gl_target = gh->gh_state; + if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) + do_error(gl, 0); /* Fail queued try locks */ + } + do_xmote(gl, gh, gl->gl_target); +out: + return; + +out_sched: + clear_bit(GLF_LOCK, &gl->gl_flags); + smp_mb__after_atomic(); + gl->gl_lockref.count++; + __gfs2_glock_queue_work(gl, 0); + return; + +out_unlock: + clear_bit(GLF_LOCK, &gl->gl_flags); + smp_mb__after_atomic(); + return; +} + +static void delete_work_func(struct work_struct *work) +{ + struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete); + struct gfs2_sbd *sdp = gl->gl_name.ln_sbd; + struct inode *inode; + u64 no_addr = gl->gl_name.ln_number; + + /* If someone's using this glock to create a new dinode, the block must + have been freed by another node, then re-used, in which case our + iopen callback is too late after the fact. Ignore it. */ + if (test_bit(GLF_INODE_CREATING, &gl->gl_flags)) + goto out; + + inode = gfs2_lookup_by_inum(sdp, no_addr, NULL, GFS2_BLKST_UNLINKED); + if (inode && !IS_ERR(inode)) { + d_prune_aliases(inode); + iput(inode); + } +out: + gfs2_glock_put(gl); +} + +static void glock_work_func(struct work_struct *work) +{ + unsigned long delay = 0; + struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work); + unsigned int drop_refs = 1; + + if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) { + finish_xmote(gl, gl->gl_reply); + drop_refs++; + } + spin_lock(&gl->gl_lockref.lock); + if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) && + gl->gl_state != LM_ST_UNLOCKED && + gl->gl_demote_state != LM_ST_EXCLUSIVE) { + unsigned long holdtime, now = jiffies; + + holdtime = gl->gl_tchange + gl->gl_hold_time; + if (time_before(now, holdtime)) + delay = holdtime - now; + + if (!delay) { + clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags); + set_bit(GLF_DEMOTE, &gl->gl_flags); + } + } + run_queue(gl, 0); + if (delay) { + /* Keep one glock reference for the work we requeue. */ + drop_refs--; + if (gl->gl_name.ln_type != LM_TYPE_INODE) + delay = 0; + __gfs2_glock_queue_work(gl, delay); + } + + /* + * Drop the remaining glock references manually here. (Mind that + * __gfs2_glock_queue_work depends on the lockref spinlock begin held + * here as well.) + */ + gl->gl_lockref.count -= drop_refs; + if (!gl->gl_lockref.count) { + __gfs2_glock_put(gl); + return; + } + spin_unlock(&gl->gl_lockref.lock); +} + +static struct gfs2_glock *find_insert_glock(struct lm_lockname *name, + struct gfs2_glock *new) +{ + struct wait_glock_queue wait; + wait_queue_head_t *wq = glock_waitqueue(name); + struct gfs2_glock *gl; + + wait.name = name; + init_wait(&wait.wait); + wait.wait.func = glock_wake_function; + +again: + prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE); + rcu_read_lock(); + if (new) { + gl = rhashtable_lookup_get_insert_fast(&gl_hash_table, + &new->gl_node, ht_parms); + if (IS_ERR(gl)) + goto out; + } else { + gl = rhashtable_lookup_fast(&gl_hash_table, + name, ht_parms); + } + if (gl && !lockref_get_not_dead(&gl->gl_lockref)) { + rcu_read_unlock(); + schedule(); + goto again; + } +out: + rcu_read_unlock(); + finish_wait(wq, &wait.wait); + return gl; +} + +/** + * gfs2_glock_get() - Get a glock, or create one if one doesn't exist + * @sdp: The GFS2 superblock + * @number: the lock number + * @glops: The glock_operations to use + * @create: If 0, don't create the glock if it doesn't exist + * @glp: the glock is returned here + * + * This does not lock a glock, just finds/creates structures for one. + * + * Returns: errno + */ + +int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number, + const struct gfs2_glock_operations *glops, int create, + struct gfs2_glock **glp) +{ + struct super_block *s = sdp->sd_vfs; + struct lm_lockname name = { .ln_number = number, + .ln_type = glops->go_type, + .ln_sbd = sdp }; + struct gfs2_glock *gl, *tmp; + struct address_space *mapping; + struct kmem_cache *cachep; + int ret = 0; + + gl = find_insert_glock(&name, NULL); + if (gl) { + *glp = gl; + return 0; + } + if (!create) + return -ENOENT; + + if (glops->go_flags & GLOF_ASPACE) + cachep = gfs2_glock_aspace_cachep; + else + cachep = gfs2_glock_cachep; + gl = kmem_cache_alloc(cachep, GFP_NOFS); + if (!gl) + return -ENOMEM; + + memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb)); + + if (glops->go_flags & GLOF_LVB) { + gl->gl_lksb.sb_lvbptr = kzalloc(GFS2_MIN_LVB_SIZE, GFP_NOFS); + if (!gl->gl_lksb.sb_lvbptr) { + kmem_cache_free(cachep, gl); + return -ENOMEM; + } + } + + atomic_inc(&sdp->sd_glock_disposal); + gl->gl_node.next = NULL; + gl->gl_flags = 0; + gl->gl_name = name; + gl->gl_lockref.count = 1; + gl->gl_state = LM_ST_UNLOCKED; + gl->gl_target = LM_ST_UNLOCKED; + gl->gl_demote_state = LM_ST_EXCLUSIVE; + gl->gl_ops = glops; + gl->gl_dstamp = 0; + preempt_disable(); + /* We use the global stats to estimate the initial per-glock stats */ + gl->gl_stats = this_cpu_ptr(sdp->sd_lkstats)->lkstats[glops->go_type]; + preempt_enable(); + gl->gl_stats.stats[GFS2_LKS_DCOUNT] = 0; + gl->gl_stats.stats[GFS2_LKS_QCOUNT] = 0; + gl->gl_tchange = jiffies; + gl->gl_object = NULL; + gl->gl_hold_time = GL_GLOCK_DFT_HOLD; + INIT_DELAYED_WORK(&gl->gl_work, glock_work_func); + INIT_WORK(&gl->gl_delete, delete_work_func); + + mapping = gfs2_glock2aspace(gl); + if (mapping) { + mapping->a_ops = &gfs2_meta_aops; + mapping->host = s->s_bdev->bd_inode; + mapping->flags = 0; + mapping_set_gfp_mask(mapping, GFP_NOFS); + mapping->private_data = NULL; + mapping->writeback_index = 0; + } + + tmp = find_insert_glock(&name, gl); + if (!tmp) { + *glp = gl; + goto out; + } + if (IS_ERR(tmp)) { + ret = PTR_ERR(tmp); + goto out_free; + } + *glp = tmp; + +out_free: + kfree(gl->gl_lksb.sb_lvbptr); + kmem_cache_free(cachep, gl); + if (atomic_dec_and_test(&sdp->sd_glock_disposal)) + wake_up(&sdp->sd_glock_wait); + +out: + return ret; +} + +/** + * gfs2_holder_init - initialize a struct gfs2_holder in the default way + * @gl: the glock + * @state: the state we're requesting + * @flags: the modifier flags + * @gh: the holder structure + * + */ + +void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, u16 flags, + struct gfs2_holder *gh) +{ + INIT_LIST_HEAD(&gh->gh_list); + gh->gh_gl = gl; + gh->gh_ip = _RET_IP_; + gh->gh_owner_pid = get_pid(task_pid(current)); + gh->gh_state = state; + gh->gh_flags = flags; + gh->gh_error = 0; + gh->gh_iflags = 0; + gfs2_glock_hold(gl); +} + +/** + * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it + * @state: the state we're requesting + * @flags: the modifier flags + * @gh: the holder structure + * + * Don't mess with the glock. + * + */ + +void gfs2_holder_reinit(unsigned int state, u16 flags, struct gfs2_holder *gh) +{ + gh->gh_state = state; + gh->gh_flags = flags; + gh->gh_iflags = 0; + gh->gh_ip = _RET_IP_; + put_pid(gh->gh_owner_pid); + gh->gh_owner_pid = get_pid(task_pid(current)); +} + +/** + * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference) + * @gh: the holder structure + * + */ + +void gfs2_holder_uninit(struct gfs2_holder *gh) +{ + put_pid(gh->gh_owner_pid); + gfs2_glock_put(gh->gh_gl); + gfs2_holder_mark_uninitialized(gh); + gh->gh_ip = 0; +} + +/** + * gfs2_glock_wait - wait on a glock acquisition + * @gh: the glock holder + * + * Returns: 0 on success + */ + +int gfs2_glock_wait(struct gfs2_holder *gh) +{ + unsigned long time1 = jiffies; + + might_sleep(); + wait_on_bit(&gh->gh_iflags, HIF_WAIT, TASK_UNINTERRUPTIBLE); + if (time_after(jiffies, time1 + HZ)) /* have we waited > a second? */ + /* Lengthen the minimum hold time. */ + gh->gh_gl->gl_hold_time = min(gh->gh_gl->gl_hold_time + + GL_GLOCK_HOLD_INCR, + GL_GLOCK_MAX_HOLD); + return gh->gh_error; +} + +/** + * handle_callback - process a demote request + * @gl: the glock + * @state: the state the caller wants us to change to + * + * There are only two requests that we are going to see in actual + * practise: LM_ST_SHARED and LM_ST_UNLOCKED + */ + +static void handle_callback(struct gfs2_glock *gl, unsigned int state, + unsigned long delay, bool remote) +{ + int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE; + + set_bit(bit, &gl->gl_flags); + if (gl->gl_demote_state == LM_ST_EXCLUSIVE) { + gl->gl_demote_state = state; + gl->gl_demote_time = jiffies; + } else if (gl->gl_demote_state != LM_ST_UNLOCKED && + gl->gl_demote_state != state) { + gl->gl_demote_state = LM_ST_UNLOCKED; + } + if (gl->gl_ops->go_callback) + gl->gl_ops->go_callback(gl, remote); + trace_gfs2_demote_rq(gl, remote); +} + +void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...) +{ + struct va_format vaf; + va_list args; + + va_start(args, fmt); + + if (seq) { + seq_vprintf(seq, fmt, args); + } else { + vaf.fmt = fmt; + vaf.va = &args; + + pr_err("%pV", &vaf); + } + + va_end(args); +} + +/** + * add_to_queue - Add a holder to the wait queue (but look for recursion) + * @gh: the holder structure to add + * + * Eventually we should move the recursive locking trap to a + * debugging option or something like that. This is the fast + * path and needs to have the minimum number of distractions. + * + */ + +static inline void add_to_queue(struct gfs2_holder *gh) +__releases(&gl->gl_lockref.lock) +__acquires(&gl->gl_lockref.lock) +{ + struct gfs2_glock *gl = gh->gh_gl; + struct gfs2_sbd *sdp = gl->gl_name.ln_sbd; + struct list_head *insert_pt = NULL; + struct gfs2_holder *gh2; + int try_futile = 0; + + BUG_ON(gh->gh_owner_pid == NULL); + if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags)) + BUG(); + + if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) { + if (test_bit(GLF_LOCK, &gl->gl_flags)) + try_futile = !may_grant(gl, gh); + if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags)) + goto fail; + } + + list_for_each_entry(gh2, &gl->gl_holders, gh_list) { + if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid && + (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK))) + goto trap_recursive; + if (try_futile && + !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) { +fail: + gh->gh_error = GLR_TRYFAILED; + gfs2_holder_wake(gh); + return; + } + if (test_bit(HIF_HOLDER, &gh2->gh_iflags)) + continue; + if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt)) + insert_pt = &gh2->gh_list; + } + set_bit(GLF_QUEUED, &gl->gl_flags); + trace_gfs2_glock_queue(gh, 1); + gfs2_glstats_inc(gl, GFS2_LKS_QCOUNT); + gfs2_sbstats_inc(gl, GFS2_LKS_QCOUNT); + if (likely(insert_pt == NULL)) { + list_add_tail(&gh->gh_list, &gl->gl_holders); + if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY)) + goto do_cancel; + return; + } + list_add_tail(&gh->gh_list, insert_pt); +do_cancel: + gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list); + if (!(gh->gh_flags & LM_FLAG_PRIORITY)) { + spin_unlock(&gl->gl_lockref.lock); + if (sdp->sd_lockstruct.ls_ops->lm_cancel) + sdp->sd_lockstruct.ls_ops->lm_cancel(gl); + spin_lock(&gl->gl_lockref.lock); + } + return; + +trap_recursive: + pr_err("original: %pSR\n", (void *)gh2->gh_ip); + pr_err("pid: %d\n", pid_nr(gh2->gh_owner_pid)); + pr_err("lock type: %d req lock state : %d\n", + gh2->gh_gl->gl_name.ln_type, gh2->gh_state); + pr_err("new: %pSR\n", (void *)gh->gh_ip); + pr_err("pid: %d\n", pid_nr(gh->gh_owner_pid)); + pr_err("lock type: %d req lock state : %d\n", + gh->gh_gl->gl_name.ln_type, gh->gh_state); + gfs2_dump_glock(NULL, gl); + BUG(); +} + +/** + * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock) + * @gh: the holder structure + * + * if (gh->gh_flags & GL_ASYNC), this never returns an error + * + * Returns: 0, GLR_TRYFAILED, or errno on failure + */ + +int gfs2_glock_nq(struct gfs2_holder *gh) +{ + struct gfs2_glock *gl = gh->gh_gl; + struct gfs2_sbd *sdp = gl->gl_name.ln_sbd; + int error = 0; + + if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) + return -EIO; + + if (test_bit(GLF_LRU, &gl->gl_flags)) + gfs2_glock_remove_from_lru(gl); + + spin_lock(&gl->gl_lockref.lock); + add_to_queue(gh); + if (unlikely((LM_FLAG_NOEXP & gh->gh_flags) && + test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))) { + set_bit(GLF_REPLY_PENDING, &gl->gl_flags); + gl->gl_lockref.count++; + __gfs2_glock_queue_work(gl, 0); + } + run_queue(gl, 1); + spin_unlock(&gl->gl_lockref.lock); + + if (!(gh->gh_flags & GL_ASYNC)) + error = gfs2_glock_wait(gh); + + return error; +} + +/** + * gfs2_glock_poll - poll to see if an async request has been completed + * @gh: the holder + * + * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on + */ + +int gfs2_glock_poll(struct gfs2_holder *gh) +{ + return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1; +} + +/** + * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock) + * @gh: the glock holder + * + */ + +void gfs2_glock_dq(struct gfs2_holder *gh) +{ + struct gfs2_glock *gl = gh->gh_gl; + const struct gfs2_glock_operations *glops = gl->gl_ops; + unsigned delay = 0; + int fast_path = 0; + + spin_lock(&gl->gl_lockref.lock); + if (gh->gh_flags & GL_NOCACHE) + handle_callback(gl, LM_ST_UNLOCKED, 0, false); + + list_del_init(&gh->gh_list); + clear_bit(HIF_HOLDER, &gh->gh_iflags); + if (find_first_holder(gl) == NULL) { + if (glops->go_unlock) { + GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags)); + spin_unlock(&gl->gl_lockref.lock); + glops->go_unlock(gh); + spin_lock(&gl->gl_lockref.lock); + clear_bit(GLF_LOCK, &gl->gl_flags); + } + if (list_empty(&gl->gl_holders) && + !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) && + !test_bit(GLF_DEMOTE, &gl->gl_flags)) + fast_path = 1; + } + if (!test_bit(GLF_LFLUSH, &gl->gl_flags) && demote_ok(gl)) + gfs2_glock_add_to_lru(gl); + + trace_gfs2_glock_queue(gh, 0); + if (unlikely(!fast_path)) { + gl->gl_lockref.count++; + if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) && + !test_bit(GLF_DEMOTE, &gl->gl_flags) && + gl->gl_name.ln_type == LM_TYPE_INODE) + delay = gl->gl_hold_time; + __gfs2_glock_queue_work(gl, delay); + } + spin_unlock(&gl->gl_lockref.lock); +} + +void gfs2_glock_dq_wait(struct gfs2_holder *gh) +{ + struct gfs2_glock *gl = gh->gh_gl; + gfs2_glock_dq(gh); + might_sleep(); + wait_on_bit(&gl->gl_flags, GLF_DEMOTE, TASK_UNINTERRUPTIBLE); +} + +/** + * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it + * @gh: the holder structure + * + */ + +void gfs2_glock_dq_uninit(struct gfs2_holder *gh) +{ + gfs2_glock_dq(gh); + gfs2_holder_uninit(gh); +} + +/** + * gfs2_glock_nq_num - acquire a glock based on lock number + * @sdp: the filesystem + * @number: the lock number + * @glops: the glock operations for the type of glock + * @state: the state to acquire the glock in + * @flags: modifier flags for the acquisition + * @gh: the struct gfs2_holder + * + * Returns: errno + */ + +int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number, + const struct gfs2_glock_operations *glops, + unsigned int state, u16 flags, struct gfs2_holder *gh) +{ + struct gfs2_glock *gl; + int error; + + error = gfs2_glock_get(sdp, number, glops, CREATE, &gl); + if (!error) { + error = gfs2_glock_nq_init(gl, state, flags, gh); + gfs2_glock_put(gl); + } + + return error; +} + +/** + * glock_compare - Compare two struct gfs2_glock structures for sorting + * @arg_a: the first structure + * @arg_b: the second structure + * + */ + +static int glock_compare(const void *arg_a, const void *arg_b) +{ + const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a; + const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b; + const struct lm_lockname *a = &gh_a->gh_gl->gl_name; + const struct lm_lockname *b = &gh_b->gh_gl->gl_name; + + if (a->ln_number > b->ln_number) + return 1; + if (a->ln_number < b->ln_number) + return -1; + BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type); + return 0; +} + +/** + * nq_m_sync - synchonously acquire more than one glock in deadlock free order + * @num_gh: the number of structures + * @ghs: an array of struct gfs2_holder structures + * + * Returns: 0 on success (all glocks acquired), + * errno on failure (no glocks acquired) + */ + +static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs, + struct gfs2_holder **p) +{ + unsigned int x; + int error = 0; + + for (x = 0; x < num_gh; x++) + p[x] = &ghs[x]; + + sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL); + + for (x = 0; x < num_gh; x++) { + p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC); + + error = gfs2_glock_nq(p[x]); + if (error) { + while (x--) + gfs2_glock_dq(p[x]); + break; + } + } + + return error; +} + +/** + * gfs2_glock_nq_m - acquire multiple glocks + * @num_gh: the number of structures + * @ghs: an array of struct gfs2_holder structures + * + * + * Returns: 0 on success (all glocks acquired), + * errno on failure (no glocks acquired) + */ + +int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs) +{ + struct gfs2_holder *tmp[4]; + struct gfs2_holder **pph = tmp; + int error = 0; + + switch(num_gh) { + case 0: + return 0; + case 1: + ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC); + return gfs2_glock_nq(ghs); + default: + if (num_gh <= 4) + break; + pph = kmalloc_array(num_gh, sizeof(struct gfs2_holder *), + GFP_NOFS); + if (!pph) + return -ENOMEM; + } + + error = nq_m_sync(num_gh, ghs, pph); + + if (pph != tmp) + kfree(pph); + + return error; +} + +/** + * gfs2_glock_dq_m - release multiple glocks + * @num_gh: the number of structures + * @ghs: an array of struct gfs2_holder structures + * + */ + +void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs) +{ + while (num_gh--) + gfs2_glock_dq(&ghs[num_gh]); +} + +void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state) +{ + unsigned long delay = 0; + unsigned long holdtime; + unsigned long now = jiffies; + + gfs2_glock_hold(gl); + holdtime = gl->gl_tchange + gl->gl_hold_time; + if (test_bit(GLF_QUEUED, &gl->gl_flags) && + gl->gl_name.ln_type == LM_TYPE_INODE) { + if (time_before(now, holdtime)) + delay = holdtime - now; + if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags)) + delay = gl->gl_hold_time; + } + + spin_lock(&gl->gl_lockref.lock); + handle_callback(gl, state, delay, true); + __gfs2_glock_queue_work(gl, delay); + spin_unlock(&gl->gl_lockref.lock); +} + +/** + * gfs2_should_freeze - Figure out if glock should be frozen + * @gl: The glock in question + * + * Glocks are not frozen if (a) the result of the dlm operation is + * an error, (b) the locking operation was an unlock operation or + * (c) if there is a "noexp" flagged request anywhere in the queue + * + * Returns: 1 if freezing should occur, 0 otherwise + */ + +static int gfs2_should_freeze(const struct gfs2_glock *gl) +{ + const struct gfs2_holder *gh; + + if (gl->gl_reply & ~LM_OUT_ST_MASK) + return 0; + if (gl->gl_target == LM_ST_UNLOCKED) + return 0; + + list_for_each_entry(gh, &gl->gl_holders, gh_list) { + if (test_bit(HIF_HOLDER, &gh->gh_iflags)) + continue; + if (LM_FLAG_NOEXP & gh->gh_flags) + return 0; + } + + return 1; +} + +/** + * gfs2_glock_complete - Callback used by locking + * @gl: Pointer to the glock + * @ret: The return value from the dlm + * + * The gl_reply field is under the gl_lockref.lock lock so that it is ok + * to use a bitfield shared with other glock state fields. + */ + +void gfs2_glock_complete(struct gfs2_glock *gl, int ret) +{ + struct lm_lockstruct *ls = &gl->gl_name.ln_sbd->sd_lockstruct; + + spin_lock(&gl->gl_lockref.lock); + gl->gl_reply = ret; + + if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags))) { + if (gfs2_should_freeze(gl)) { + set_bit(GLF_FROZEN, &gl->gl_flags); + spin_unlock(&gl->gl_lockref.lock); + return; + } + } + + gl->gl_lockref.count++; + set_bit(GLF_REPLY_PENDING, &gl->gl_flags); + __gfs2_glock_queue_work(gl, 0); + spin_unlock(&gl->gl_lockref.lock); +} + +static int glock_cmp(void *priv, struct list_head *a, struct list_head *b) +{ + struct gfs2_glock *gla, *glb; + + gla = list_entry(a, struct gfs2_glock, gl_lru); + glb = list_entry(b, struct gfs2_glock, gl_lru); + + if (gla->gl_name.ln_number > glb->gl_name.ln_number) + return 1; + if (gla->gl_name.ln_number < glb->gl_name.ln_number) + return -1; + + return 0; +} + +/** + * gfs2_dispose_glock_lru - Demote a list of glocks + * @list: The list to dispose of + * + * Disposing of glocks may involve disk accesses, so that here we sort + * the glocks by number (i.e. disk location of the inodes) so that if + * there are any such accesses, they'll be sent in order (mostly). + * + * Must be called under the lru_lock, but may drop and retake this + * lock. While the lru_lock is dropped, entries may vanish from the + * list, but no new entries will appear on the list (since it is + * private) + */ + +static void gfs2_dispose_glock_lru(struct list_head *list) +__releases(&lru_lock) +__acquires(&lru_lock) +{ + struct gfs2_glock *gl; + + list_sort(NULL, list, glock_cmp); + + while(!list_empty(list)) { + gl = list_entry(list->next, struct gfs2_glock, gl_lru); + list_del_init(&gl->gl_lru); + clear_bit(GLF_LRU, &gl->gl_flags); + if (!spin_trylock(&gl->gl_lockref.lock)) { +add_back_to_lru: + list_add(&gl->gl_lru, &lru_list); + set_bit(GLF_LRU, &gl->gl_flags); + atomic_inc(&lru_count); + continue; + } + if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) { + spin_unlock(&gl->gl_lockref.lock); + goto add_back_to_lru; + } + gl->gl_lockref.count++; + if (demote_ok(gl)) + handle_callback(gl, LM_ST_UNLOCKED, 0, false); + WARN_ON(!test_and_clear_bit(GLF_LOCK, &gl->gl_flags)); + __gfs2_glock_queue_work(gl, 0); + spin_unlock(&gl->gl_lockref.lock); + cond_resched_lock(&lru_lock); + } +} + +/** + * gfs2_scan_glock_lru - Scan the LRU looking for locks to demote + * @nr: The number of entries to scan + * + * This function selects the entries on the LRU which are able to + * be demoted, and then kicks off the process by calling + * gfs2_dispose_glock_lru() above. + */ + +static long gfs2_scan_glock_lru(int nr) +{ + struct gfs2_glock *gl; + LIST_HEAD(skipped); + LIST_HEAD(dispose); + long freed = 0; + + spin_lock(&lru_lock); + while ((nr-- >= 0) && !list_empty(&lru_list)) { + gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru); + + /* Test for being demotable */ + if (!test_bit(GLF_LOCK, &gl->gl_flags)) { + list_move(&gl->gl_lru, &dispose); + atomic_dec(&lru_count); + freed++; + continue; + } + + list_move(&gl->gl_lru, &skipped); + } + list_splice(&skipped, &lru_list); + if (!list_empty(&dispose)) + gfs2_dispose_glock_lru(&dispose); + spin_unlock(&lru_lock); + + return freed; +} + +static unsigned long gfs2_glock_shrink_scan(struct shrinker *shrink, + struct shrink_control *sc) +{ + if (!(sc->gfp_mask & __GFP_FS)) + return SHRINK_STOP; + return gfs2_scan_glock_lru(sc->nr_to_scan); +} + +static unsigned long gfs2_glock_shrink_count(struct shrinker *shrink, + struct shrink_control *sc) +{ + return vfs_pressure_ratio(atomic_read(&lru_count)); +} + +static struct shrinker glock_shrinker = { + .seeks = DEFAULT_SEEKS, + .count_objects = gfs2_glock_shrink_count, + .scan_objects = gfs2_glock_shrink_scan, +}; + +/** + * examine_bucket - Call a function for glock in a hash bucket + * @examiner: the function + * @sdp: the filesystem + * @bucket: the bucket + * + * Note that the function can be called multiple times on the same + * object. So the user must ensure that the function can cope with + * that. + */ + +static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp) +{ + struct gfs2_glock *gl; + struct rhashtable_iter iter; + + rhashtable_walk_enter(&gl_hash_table, &iter); + + do { + rhashtable_walk_start(&iter); + + while ((gl = rhashtable_walk_next(&iter)) && !IS_ERR(gl)) + if (gl->gl_name.ln_sbd == sdp && + lockref_get_not_dead(&gl->gl_lockref)) + examiner(gl); + + rhashtable_walk_stop(&iter); + } while (cond_resched(), gl == ERR_PTR(-EAGAIN)); + + rhashtable_walk_exit(&iter); +} + +/** + * thaw_glock - thaw out a glock which has an unprocessed reply waiting + * @gl: The glock to thaw + * + */ + +static void thaw_glock(struct gfs2_glock *gl) +{ + if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags)) { + gfs2_glock_put(gl); + return; + } + set_bit(GLF_REPLY_PENDING, &gl->gl_flags); + gfs2_glock_queue_work(gl, 0); +} + +/** + * clear_glock - look at a glock and see if we can free it from glock cache + * @gl: the glock to look at + * + */ + +static void clear_glock(struct gfs2_glock *gl) +{ + gfs2_glock_remove_from_lru(gl); + + spin_lock(&gl->gl_lockref.lock); + if (gl->gl_state != LM_ST_UNLOCKED) + handle_callback(gl, LM_ST_UNLOCKED, 0, false); + __gfs2_glock_queue_work(gl, 0); + spin_unlock(&gl->gl_lockref.lock); +} + +/** + * gfs2_glock_thaw - Thaw any frozen glocks + * @sdp: The super block + * + */ + +void gfs2_glock_thaw(struct gfs2_sbd *sdp) +{ + glock_hash_walk(thaw_glock, sdp); +} + +static void dump_glock(struct seq_file *seq, struct gfs2_glock *gl) +{ + spin_lock(&gl->gl_lockref.lock); + gfs2_dump_glock(seq, gl); + spin_unlock(&gl->gl_lockref.lock); +} + +static void dump_glock_func(struct gfs2_glock *gl) +{ + dump_glock(NULL, gl); +} + +/** + * gfs2_gl_hash_clear - Empty out the glock hash table + * @sdp: the filesystem + * @wait: wait until it's all gone + * + * Called when unmounting the filesystem. + */ + +void gfs2_gl_hash_clear(struct gfs2_sbd *sdp) +{ + set_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags); + flush_workqueue(glock_workqueue); + glock_hash_walk(clear_glock, sdp); + flush_workqueue(glock_workqueue); + wait_event_timeout(sdp->sd_glock_wait, + atomic_read(&sdp->sd_glock_disposal) == 0, + HZ * 600); + glock_hash_walk(dump_glock_func, sdp); +} + +void gfs2_glock_finish_truncate(struct gfs2_inode *ip) +{ + struct gfs2_glock *gl = ip->i_gl; + int ret; + + ret = gfs2_truncatei_resume(ip); + gfs2_assert_withdraw(gl->gl_name.ln_sbd, ret == 0); + + spin_lock(&gl->gl_lockref.lock); + clear_bit(GLF_LOCK, &gl->gl_flags); + run_queue(gl, 1); + spin_unlock(&gl->gl_lockref.lock); +} + +static const char *state2str(unsigned state) +{ + switch(state) { + case LM_ST_UNLOCKED: + return "UN"; + case LM_ST_SHARED: + return "SH"; + case LM_ST_DEFERRED: + return "DF"; + case LM_ST_EXCLUSIVE: + return "EX"; + } + return "??"; +} + +static const char *hflags2str(char *buf, u16 flags, unsigned long iflags) +{ + char *p = buf; + if (flags & LM_FLAG_TRY) + *p++ = 't'; + if (flags & LM_FLAG_TRY_1CB) + *p++ = 'T'; + if (flags & LM_FLAG_NOEXP) + *p++ = 'e'; + if (flags & LM_FLAG_ANY) + *p++ = 'A'; + if (flags & LM_FLAG_PRIORITY) + *p++ = 'p'; + if (flags & GL_ASYNC) + *p++ = 'a'; + if (flags & GL_EXACT) + *p++ = 'E'; + if (flags & GL_NOCACHE) + *p++ = 'c'; + if (test_bit(HIF_HOLDER, &iflags)) + *p++ = 'H'; + if (test_bit(HIF_WAIT, &iflags)) + *p++ = 'W'; + if (test_bit(HIF_FIRST, &iflags)) + *p++ = 'F'; + *p = 0; + return buf; +} + +/** + * dump_holder - print information about a glock holder + * @seq: the seq_file struct + * @gh: the glock holder + * + */ + +static void dump_holder(struct seq_file *seq, const struct gfs2_holder *gh) +{ + struct task_struct *gh_owner = NULL; + char flags_buf[32]; + + rcu_read_lock(); + if (gh->gh_owner_pid) + gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID); + gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %pS\n", + state2str(gh->gh_state), + hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags), + gh->gh_error, + gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1, + gh_owner ? gh_owner->comm : "(ended)", + (void *)gh->gh_ip); + rcu_read_unlock(); +} + +static const char *gflags2str(char *buf, const struct gfs2_glock *gl) +{ + const unsigned long *gflags = &gl->gl_flags; + char *p = buf; + + if (test_bit(GLF_LOCK, gflags)) + *p++ = 'l'; + if (test_bit(GLF_DEMOTE, gflags)) + *p++ = 'D'; + if (test_bit(GLF_PENDING_DEMOTE, gflags)) + *p++ = 'd'; + if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags)) + *p++ = 'p'; + if (test_bit(GLF_DIRTY, gflags)) + *p++ = 'y'; + if (test_bit(GLF_LFLUSH, gflags)) + *p++ = 'f'; + if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags)) + *p++ = 'i'; + if (test_bit(GLF_REPLY_PENDING, gflags)) + *p++ = 'r'; + if (test_bit(GLF_INITIAL, gflags)) + *p++ = 'I'; + if (test_bit(GLF_FROZEN, gflags)) + *p++ = 'F'; + if (test_bit(GLF_QUEUED, gflags)) + *p++ = 'q'; + if (test_bit(GLF_LRU, gflags)) + *p++ = 'L'; + if (gl->gl_object) + *p++ = 'o'; + if (test_bit(GLF_BLOCKING, gflags)) + *p++ = 'b'; + *p = 0; + return buf; +} + +/** + * gfs2_dump_glock - print information about a glock + * @seq: The seq_file struct + * @gl: the glock + * + * The file format is as follows: + * One line per object, capital letters are used to indicate objects + * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented, + * other objects are indented by a single space and follow the glock to + * which they are related. Fields are indicated by lower case letters + * followed by a colon and the field value, except for strings which are in + * [] so that its possible to see if they are composed of spaces for + * example. The field's are n = number (id of the object), f = flags, + * t = type, s = state, r = refcount, e = error, p = pid. + * + */ + +void gfs2_dump_glock(struct seq_file *seq, const struct gfs2_glock *gl) +{ + const struct gfs2_glock_operations *glops = gl->gl_ops; + unsigned long long dtime; + const struct gfs2_holder *gh; + char gflags_buf[32]; + + dtime = jiffies - gl->gl_demote_time; + dtime *= 1000000/HZ; /* demote time in uSec */ + if (!test_bit(GLF_DEMOTE, &gl->gl_flags)) + dtime = 0; + gfs2_print_dbg(seq, "G: s:%s n:%u/%llx f:%s t:%s d:%s/%llu a:%d v:%d r:%d m:%ld\n", + state2str(gl->gl_state), + gl->gl_name.ln_type, + (unsigned long long)gl->gl_name.ln_number, + gflags2str(gflags_buf, gl), + state2str(gl->gl_target), + state2str(gl->gl_demote_state), dtime, + atomic_read(&gl->gl_ail_count), + atomic_read(&gl->gl_revokes), + (int)gl->gl_lockref.count, gl->gl_hold_time); + + list_for_each_entry(gh, &gl->gl_holders, gh_list) + dump_holder(seq, gh); + + if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump) + glops->go_dump(seq, gl); +} + +static int gfs2_glstats_seq_show(struct seq_file *seq, void *iter_ptr) +{ + struct gfs2_glock *gl = iter_ptr; + + seq_printf(seq, "G: n:%u/%llx rtt:%llu/%llu rttb:%llu/%llu irt:%llu/%llu dcnt: %llu qcnt: %llu\n", + gl->gl_name.ln_type, + (unsigned long long)gl->gl_name.ln_number, + (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTT], + (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTTVAR], + (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTTB], + (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTTVARB], + (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SIRT], + (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SIRTVAR], + (unsigned long long)gl->gl_stats.stats[GFS2_LKS_DCOUNT], + (unsigned long long)gl->gl_stats.stats[GFS2_LKS_QCOUNT]); + return 0; +} + +static const char *gfs2_gltype[] = { + "type", + "reserved", + "nondisk", + "inode", + "rgrp", + "meta", + "iopen", + "flock", + "plock", + "quota", + "journal", +}; + +static const char *gfs2_stype[] = { + [GFS2_LKS_SRTT] = "srtt", + [GFS2_LKS_SRTTVAR] = "srttvar", + [GFS2_LKS_SRTTB] = "srttb", + [GFS2_LKS_SRTTVARB] = "srttvarb", + [GFS2_LKS_SIRT] = "sirt", + [GFS2_LKS_SIRTVAR] = "sirtvar", + [GFS2_LKS_DCOUNT] = "dlm", + [GFS2_LKS_QCOUNT] = "queue", +}; + +#define GFS2_NR_SBSTATS (ARRAY_SIZE(gfs2_gltype) * ARRAY_SIZE(gfs2_stype)) + +static int gfs2_sbstats_seq_show(struct seq_file *seq, void *iter_ptr) +{ + struct gfs2_sbd *sdp = seq->private; + loff_t pos = *(loff_t *)iter_ptr; + unsigned index = pos >> 3; + unsigned subindex = pos & 0x07; + int i; + + if (index == 0 && subindex != 0) + return 0; + + seq_printf(seq, "%-10s %8s:", gfs2_gltype[index], + (index == 0) ? "cpu": gfs2_stype[subindex]); + + for_each_possible_cpu(i) { + const struct gfs2_pcpu_lkstats *lkstats = per_cpu_ptr(sdp->sd_lkstats, i); + + if (index == 0) + seq_printf(seq, " %15u", i); + else + seq_printf(seq, " %15llu", (unsigned long long)lkstats-> + lkstats[index - 1].stats[subindex]); + } + seq_putc(seq, '\n'); + return 0; +} + +int __init gfs2_glock_init(void) +{ + int i, ret; + + ret = rhashtable_init(&gl_hash_table, &ht_parms); + if (ret < 0) + return ret; + + glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM | + WQ_HIGHPRI | WQ_FREEZABLE, 0); + if (!glock_workqueue) { + rhashtable_destroy(&gl_hash_table); + return -ENOMEM; + } + gfs2_delete_workqueue = alloc_workqueue("delete_workqueue", + WQ_MEM_RECLAIM | WQ_FREEZABLE, + 0); + if (!gfs2_delete_workqueue) { + destroy_workqueue(glock_workqueue); + rhashtable_destroy(&gl_hash_table); + return -ENOMEM; + } + + ret = register_shrinker(&glock_shrinker); + if (ret) { + destroy_workqueue(gfs2_delete_workqueue); + destroy_workqueue(glock_workqueue); + rhashtable_destroy(&gl_hash_table); + return ret; + } + + for (i = 0; i < GLOCK_WAIT_TABLE_SIZE; i++) + init_waitqueue_head(glock_wait_table + i); + + return 0; +} + +void gfs2_glock_exit(void) +{ + unregister_shrinker(&glock_shrinker); + rhashtable_destroy(&gl_hash_table); + destroy_workqueue(glock_workqueue); + destroy_workqueue(gfs2_delete_workqueue); +} + +static void gfs2_glock_iter_next(struct gfs2_glock_iter *gi, loff_t n) +{ + struct gfs2_glock *gl = gi->gl; + + if (gl) { + if (n == 0) + return; + if (!lockref_put_not_zero(&gl->gl_lockref)) + gfs2_glock_queue_put(gl); + } + for (;;) { + gl = rhashtable_walk_next(&gi->hti); + if (IS_ERR_OR_NULL(gl)) { + if (gl == ERR_PTR(-EAGAIN)) { + n = 1; + continue; + } + gl = NULL; + break; + } + if (gl->gl_name.ln_sbd != gi->sdp) + continue; + if (n <= 1) { + if (!lockref_get_not_dead(&gl->gl_lockref)) + continue; + break; + } else { + if (__lockref_is_dead(&gl->gl_lockref)) + continue; + n--; + } + } + gi->gl = gl; +} + +static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos) + __acquires(RCU) +{ + struct gfs2_glock_iter *gi = seq->private; + loff_t n; + + /* + * We can either stay where we are, skip to the next hash table + * entry, or start from the beginning. + */ + if (*pos < gi->last_pos) { + rhashtable_walk_exit(&gi->hti); + rhashtable_walk_enter(&gl_hash_table, &gi->hti); + n = *pos + 1; + } else { + n = *pos - gi->last_pos; + } + + rhashtable_walk_start(&gi->hti); + + gfs2_glock_iter_next(gi, n); + gi->last_pos = *pos; + return gi->gl; +} + +static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr, + loff_t *pos) +{ + struct gfs2_glock_iter *gi = seq->private; + + (*pos)++; + gi->last_pos = *pos; + gfs2_glock_iter_next(gi, 1); + return gi->gl; +} + +static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr) + __releases(RCU) +{ + struct gfs2_glock_iter *gi = seq->private; + + rhashtable_walk_stop(&gi->hti); +} + +static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr) +{ + dump_glock(seq, iter_ptr); + return 0; +} + +static void *gfs2_sbstats_seq_start(struct seq_file *seq, loff_t *pos) +{ + preempt_disable(); + if (*pos >= GFS2_NR_SBSTATS) + return NULL; + return pos; +} + +static void *gfs2_sbstats_seq_next(struct seq_file *seq, void *iter_ptr, + loff_t *pos) +{ + (*pos)++; + if (*pos >= GFS2_NR_SBSTATS) + return NULL; + return pos; +} + +static void gfs2_sbstats_seq_stop(struct seq_file *seq, void *iter_ptr) +{ + preempt_enable(); +} + +static const struct seq_operations gfs2_glock_seq_ops = { + .start = gfs2_glock_seq_start, + .next = gfs2_glock_seq_next, + .stop = gfs2_glock_seq_stop, + .show = gfs2_glock_seq_show, +}; + +static const struct seq_operations gfs2_glstats_seq_ops = { + .start = gfs2_glock_seq_start, + .next = gfs2_glock_seq_next, + .stop = gfs2_glock_seq_stop, + .show = gfs2_glstats_seq_show, +}; + +static const struct seq_operations gfs2_sbstats_seq_ops = { + .start = gfs2_sbstats_seq_start, + .next = gfs2_sbstats_seq_next, + .stop = gfs2_sbstats_seq_stop, + .show = gfs2_sbstats_seq_show, +}; + +#define GFS2_SEQ_GOODSIZE min(PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER, 65536UL) + +static int __gfs2_glocks_open(struct inode *inode, struct file *file, + const struct seq_operations *ops) +{ + int ret = seq_open_private(file, ops, sizeof(struct gfs2_glock_iter)); + if (ret == 0) { + struct seq_file *seq = file->private_data; + struct gfs2_glock_iter *gi = seq->private; + + gi->sdp = inode->i_private; + seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN); + if (seq->buf) + seq->size = GFS2_SEQ_GOODSIZE; + /* + * Initially, we are "before" the first hash table entry; the + * first call to rhashtable_walk_next gets us the first entry. + */ + gi->last_pos = -1; + gi->gl = NULL; + rhashtable_walk_enter(&gl_hash_table, &gi->hti); + } + return ret; +} + +static int gfs2_glocks_open(struct inode *inode, struct file *file) +{ + return __gfs2_glocks_open(inode, file, &gfs2_glock_seq_ops); +} + +static int gfs2_glocks_release(struct inode *inode, struct file *file) +{ + struct seq_file *seq = file->private_data; + struct gfs2_glock_iter *gi = seq->private; + + if (gi->gl) + gfs2_glock_put(gi->gl); + rhashtable_walk_exit(&gi->hti); + return seq_release_private(inode, file); +} + +static int gfs2_glstats_open(struct inode *inode, struct file *file) +{ + return __gfs2_glocks_open(inode, file, &gfs2_glstats_seq_ops); +} + +static int gfs2_sbstats_open(struct inode *inode, struct file *file) +{ + int ret = seq_open(file, &gfs2_sbstats_seq_ops); + if (ret == 0) { + struct seq_file *seq = file->private_data; + seq->private = inode->i_private; /* sdp */ + } + return ret; +} + +static const struct file_operations gfs2_glocks_fops = { + .owner = THIS_MODULE, + .open = gfs2_glocks_open, + .read = seq_read, + .llseek = seq_lseek, + .release = gfs2_glocks_release, +}; + +static const struct file_operations gfs2_glstats_fops = { + .owner = THIS_MODULE, + .open = gfs2_glstats_open, + .read = seq_read, + .llseek = seq_lseek, + .release = gfs2_glocks_release, +}; + +static const struct file_operations gfs2_sbstats_fops = { + .owner = THIS_MODULE, + .open = gfs2_sbstats_open, + .read = seq_read, + .llseek = seq_lseek, + .release = seq_release, +}; + +int gfs2_create_debugfs_file(struct gfs2_sbd *sdp) +{ + struct dentry *dent; + + dent = debugfs_create_dir(sdp->sd_table_name, gfs2_root); + if (IS_ERR_OR_NULL(dent)) + goto fail; + sdp->debugfs_dir = dent; + + dent = debugfs_create_file("glocks", + S_IFREG | S_IRUGO, + sdp->debugfs_dir, sdp, + &gfs2_glocks_fops); + if (IS_ERR_OR_NULL(dent)) + goto fail; + sdp->debugfs_dentry_glocks = dent; + + dent = debugfs_create_file("glstats", + S_IFREG | S_IRUGO, + sdp->debugfs_dir, sdp, + &gfs2_glstats_fops); + if (IS_ERR_OR_NULL(dent)) + goto fail; + sdp->debugfs_dentry_glstats = dent; + + dent = debugfs_create_file("sbstats", + S_IFREG | S_IRUGO, + sdp->debugfs_dir, sdp, + &gfs2_sbstats_fops); + if (IS_ERR_OR_NULL(dent)) + goto fail; + sdp->debugfs_dentry_sbstats = dent; + + return 0; +fail: + gfs2_delete_debugfs_file(sdp); + return dent ? PTR_ERR(dent) : -ENOMEM; +} + +void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp) +{ + if (sdp->debugfs_dir) { + if (sdp->debugfs_dentry_glocks) { + debugfs_remove(sdp->debugfs_dentry_glocks); + sdp->debugfs_dentry_glocks = NULL; + } + if (sdp->debugfs_dentry_glstats) { + debugfs_remove(sdp->debugfs_dentry_glstats); + sdp->debugfs_dentry_glstats = NULL; + } + if (sdp->debugfs_dentry_sbstats) { + debugfs_remove(sdp->debugfs_dentry_sbstats); + sdp->debugfs_dentry_sbstats = NULL; + } + debugfs_remove(sdp->debugfs_dir); + sdp->debugfs_dir = NULL; + } +} + +int gfs2_register_debugfs(void) +{ + gfs2_root = debugfs_create_dir("gfs2", NULL); + if (IS_ERR(gfs2_root)) + return PTR_ERR(gfs2_root); + return gfs2_root ? 0 : -ENOMEM; +} + +void gfs2_unregister_debugfs(void) +{ + debugfs_remove(gfs2_root); + gfs2_root = NULL; +} |