From c4f68a130fc1795e4a75ec5bdaf9e85d86c22419 Mon Sep 17 00:00:00 2001 From: Benjamin Marzinski Date: Thu, 23 Aug 2007 13:19:05 -0500 Subject: [PATCH] [GFS2] delay glock demote for a minimum hold time When a lot of IO, with some distributed mmap IO, is run on a GFS2 filesystem in a cluster, it will deadlock. The reason is that do_no_page() will repeatedly call gfs2_sharewrite_nopage(), because each node keeps giving up the glock too early, and is forced to call unmap_mapping_range(). This bumps the mapping->truncate_count sequence count, forcing do_no_page() to retry. This patch institutes a minimum glock hold time a tenth a second. This insures that even in heavy contention cases, the node has enough time to get some useful work done before it gives up the glock. A second issue is that when gfs2_glock_dq() is called from within a page fault to demote a lock, and the associated page needs to be written out, it will try to acqire a lock on it, but it has already been locked at a higher level. This patch puts makes gfs2_glock_dq() use the work queue as well, to avoid this issue. This is the same patch as Steve Whitehouse originally proposed to fix this issue, execpt that gfs2_glock_dq() now grabs a reference to the glock before it queues up the work on it. Signed-off-by: Benjamin E. Marzinski Signed-off-by: Steven Whitehouse --- fs/gfs2/glock.c | 75 +++++++++++++++++++++++++++++++++++++----------- fs/gfs2/glops.c | 2 ++ fs/gfs2/incore.h | 5 ++++ 3 files changed, 66 insertions(+), 16 deletions(-) diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 3d949187fed0..931368a385c8 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -27,6 +27,8 @@ #include #include #include +#include +#include #include "gfs2.h" #include "incore.h" @@ -58,10 +60,13 @@ static int gfs2_dump_lockstate(struct gfs2_sbd *sdp); static int dump_glock(struct glock_iter *gi, struct gfs2_glock *gl); static void gfs2_glock_xmote_th(struct gfs2_glock *gl, struct gfs2_holder *gh); static void gfs2_glock_drop_th(struct gfs2_glock *gl); +static void run_queue(struct gfs2_glock *gl); + static DECLARE_RWSEM(gfs2_umount_flush_sem); static struct dentry *gfs2_root; static struct task_struct *scand_process; static unsigned int scand_secs = 5; +static struct workqueue_struct *glock_workqueue; #define GFS2_GL_HASH_SHIFT 15 #define GFS2_GL_HASH_SIZE (1 << GFS2_GL_HASH_SHIFT) @@ -277,6 +282,18 @@ static struct gfs2_glock *gfs2_glock_find(const struct gfs2_sbd *sdp, return gl; } +static void glock_work_func(struct work_struct *work) +{ + struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work); + + spin_lock(&gl->gl_spin); + if (test_and_clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags)) + set_bit(GLF_DEMOTE, &gl->gl_flags); + run_queue(gl); + spin_unlock(&gl->gl_spin); + gfs2_glock_put(gl); +} + /** * gfs2_glock_get() - Get a glock, or create one if one doesn't exist * @sdp: The GFS2 superblock @@ -316,6 +333,7 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number, gl->gl_name = name; atomic_set(&gl->gl_ref, 1); gl->gl_state = LM_ST_UNLOCKED; + gl->gl_demote_state = LM_ST_EXCLUSIVE; gl->gl_hash = hash; gl->gl_owner_pid = 0; gl->gl_ip = 0; @@ -324,10 +342,12 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number, gl->gl_req_bh = NULL; gl->gl_vn = 0; gl->gl_stamp = jiffies; + gl->gl_tchange = jiffies; gl->gl_object = NULL; gl->gl_sbd = sdp; gl->gl_aspace = NULL; lops_init_le(&gl->gl_le, &gfs2_glock_lops); + INIT_DELAYED_WORK(&gl->gl_work, glock_work_func); /* If this glock protects actual on-disk data or metadata blocks, create a VFS inode to manage the pages/buffers holding them. */ @@ -441,6 +461,8 @@ static void wait_on_holder(struct gfs2_holder *gh) static void gfs2_demote_wake(struct gfs2_glock *gl) { + BUG_ON(!spin_is_locked(&gl->gl_spin)); + gl->gl_demote_state = LM_ST_EXCLUSIVE; clear_bit(GLF_DEMOTE, &gl->gl_flags); smp_mb__after_clear_bit(); wake_up_bit(&gl->gl_flags, GLF_DEMOTE); @@ -682,10 +704,14 @@ static void gfs2_glmutex_unlock(struct gfs2_glock *gl) * practise: LM_ST_SHARED and LM_ST_UNLOCKED */ -static void handle_callback(struct gfs2_glock *gl, unsigned int state, int remote) +static void handle_callback(struct gfs2_glock *gl, unsigned int state, + int remote, unsigned long delay) { + int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE; + spin_lock(&gl->gl_spin); - if (test_and_set_bit(GLF_DEMOTE, &gl->gl_flags) == 0) { + set_bit(bit, &gl->gl_flags); + if (gl->gl_demote_state == LM_ST_EXCLUSIVE) { gl->gl_demote_state = state; gl->gl_demote_time = jiffies; if (remote && gl->gl_ops->go_type == LM_TYPE_IOPEN && @@ -727,6 +753,7 @@ static void state_change(struct gfs2_glock *gl, unsigned int new_state) } gl->gl_state = new_state; + gl->gl_tchange = jiffies; } /** @@ -813,7 +840,6 @@ static void xmote_bh(struct gfs2_glock *gl, unsigned int ret) gl->gl_req_gh = NULL; gl->gl_req_bh = NULL; clear_bit(GLF_LOCK, &gl->gl_flags); - run_queue(gl); spin_unlock(&gl->gl_spin); } @@ -885,7 +911,6 @@ static void drop_bh(struct gfs2_glock *gl, unsigned int ret) gfs2_assert_warn(sdp, !ret); state_change(gl, LM_ST_UNLOCKED); - gfs2_demote_wake(gl); if (glops->go_inval) glops->go_inval(gl, DIO_METADATA); @@ -898,10 +923,10 @@ static void drop_bh(struct gfs2_glock *gl, unsigned int ret) } spin_lock(&gl->gl_spin); + gfs2_demote_wake(gl); gl->gl_req_gh = NULL; gl->gl_req_bh = NULL; clear_bit(GLF_LOCK, &gl->gl_flags); - run_queue(gl); spin_unlock(&gl->gl_spin); gfs2_glock_put(gl); @@ -1209,9 +1234,10 @@ 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; if (gh->gh_flags & GL_NOCACHE) - handle_callback(gl, LM_ST_UNLOCKED, 0); + handle_callback(gl, LM_ST_UNLOCKED, 0, 0); gfs2_glmutex_lock(gl); @@ -1229,8 +1255,14 @@ void gfs2_glock_dq(struct gfs2_holder *gh) } clear_bit(GLF_LOCK, &gl->gl_flags); - run_queue(gl); spin_unlock(&gl->gl_spin); + + gfs2_glock_hold(gl); + if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) && + !test_bit(GLF_DEMOTE, &gl->gl_flags)) + delay = gl->gl_ops->go_min_hold_time; + if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0) + gfs2_glock_put(gl); } void gfs2_glock_dq_wait(struct gfs2_holder *gh) @@ -1457,18 +1489,21 @@ static void blocking_cb(struct gfs2_sbd *sdp, struct lm_lockname *name, unsigned int state) { struct gfs2_glock *gl; + unsigned long delay = 0; + unsigned long holdtime; + unsigned long now = jiffies; gl = gfs2_glock_find(sdp, name); if (!gl) return; - handle_callback(gl, state, 1); + holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time; + if (time_before(now, holdtime)) + delay = holdtime - now; - spin_lock(&gl->gl_spin); - run_queue(gl); - spin_unlock(&gl->gl_spin); - - gfs2_glock_put(gl); + handle_callback(gl, state, 1, delay); + if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0) + gfs2_glock_put(gl); } /** @@ -1509,7 +1544,8 @@ void gfs2_glock_cb(void *cb_data, unsigned int type, void *data) return; if (!gfs2_assert_warn(sdp, gl->gl_req_bh)) gl->gl_req_bh(gl, async->lc_ret); - gfs2_glock_put(gl); + if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0) + gfs2_glock_put(gl); up_read(&gfs2_umount_flush_sem); return; } @@ -1602,7 +1638,7 @@ void gfs2_reclaim_glock(struct gfs2_sbd *sdp) if (gfs2_glmutex_trylock(gl)) { if (list_empty(&gl->gl_holders) && gl->gl_state != LM_ST_UNLOCKED && demote_ok(gl)) - handle_callback(gl, LM_ST_UNLOCKED, 0); + handle_callback(gl, LM_ST_UNLOCKED, 0, 0); gfs2_glmutex_unlock(gl); } @@ -1702,7 +1738,7 @@ static void clear_glock(struct gfs2_glock *gl) if (gfs2_glmutex_trylock(gl)) { if (list_empty(&gl->gl_holders) && gl->gl_state != LM_ST_UNLOCKED) - handle_callback(gl, LM_ST_UNLOCKED, 0); + handle_callback(gl, LM_ST_UNLOCKED, 0, 0); gfs2_glmutex_unlock(gl); } } @@ -2009,11 +2045,18 @@ int __init gfs2_glock_init(void) if (IS_ERR(scand_process)) return PTR_ERR(scand_process); + glock_workqueue = create_workqueue("glock_workqueue"); + if (IS_ERR(glock_workqueue)) { + kthread_stop(scand_process); + return PTR_ERR(glock_workqueue); + } + return 0; } void gfs2_glock_exit(void) { + destroy_workqueue(glock_workqueue); kthread_stop(scand_process); } diff --git a/fs/gfs2/glops.c b/fs/gfs2/glops.c index 88342e0b4bc7..7ef6b23bb38a 100644 --- a/fs/gfs2/glops.c +++ b/fs/gfs2/glops.c @@ -454,6 +454,7 @@ const struct gfs2_glock_operations gfs2_inode_glops = { .go_lock = inode_go_lock, .go_unlock = inode_go_unlock, .go_type = LM_TYPE_INODE, + .go_min_hold_time = HZ / 10, }; const struct gfs2_glock_operations gfs2_rgrp_glops = { @@ -464,6 +465,7 @@ const struct gfs2_glock_operations gfs2_rgrp_glops = { .go_lock = rgrp_go_lock, .go_unlock = rgrp_go_unlock, .go_type = LM_TYPE_RGRP, + .go_min_hold_time = HZ / 10, }; const struct gfs2_glock_operations gfs2_trans_glops = { diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h index 1390b30daf19..23b611aa70d2 100644 --- a/fs/gfs2/incore.h +++ b/fs/gfs2/incore.h @@ -11,6 +11,7 @@ #define __INCORE_DOT_H__ #include +#include #define DIO_WAIT 0x00000010 #define DIO_METADATA 0x00000020 @@ -130,6 +131,7 @@ struct gfs2_glock_operations { int (*go_lock) (struct gfs2_holder *gh); void (*go_unlock) (struct gfs2_holder *gh); const int go_type; + const unsigned long go_min_hold_time; }; enum { @@ -161,6 +163,7 @@ enum { GLF_LOCK = 1, GLF_STICKY = 2, GLF_DEMOTE = 3, + GLF_PENDING_DEMOTE = 4, GLF_DIRTY = 5, }; @@ -193,6 +196,7 @@ struct gfs2_glock { u64 gl_vn; unsigned long gl_stamp; + unsigned long gl_tchange; void *gl_object; struct list_head gl_reclaim; @@ -203,6 +207,7 @@ struct gfs2_glock { struct gfs2_log_element gl_le; struct list_head gl_ail_list; atomic_t gl_ail_count; + struct delayed_work gl_work; }; struct gfs2_alloc {