From: Kent Overstreet <kent.overstreet@linux.dev>
Date: Sat, 24 May 2025 19:29:50 +0000 (-0400)
Subject: bcachefs: Fix lost rebalance wakeups
X-Git-Tag: v6.16-rc1~48^2~64
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=9e2c3c2ed4772cb0e2ad5b0def08c2c943483445;p=thirdparty%2Fkernel%2Flinux.git

bcachefs: Fix lost rebalance wakeups

Fix a missing wakeup in

'bcachefs set-file-option' -> xattr option update -> inode_write

this was missing because the wakeup needs to happen after transaction
commit. Also, add a 'kick' counter, to make sure we don't miss a wakeup
that occured right after we finished checking the rebalance_work btree.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---

diff --git a/fs/bcachefs/fs.c b/fs/bcachefs/fs.c
index ddfe89d849666..adae43223bce3 100644
--- a/fs/bcachefs/fs.c
+++ b/fs/bcachefs/fs.c
@@ -124,8 +124,9 @@ retry:
 		goto err;
 
 	struct bch_extent_rebalance new_r = bch2_inode_rebalance_opts_get(c, &inode_u);
+	bool rebalance_changed = memcmp(&old_r, &new_r, sizeof(new_r));
 
-	if (memcmp(&old_r, &new_r, sizeof(new_r))) {
+	if (rebalance_changed) {
 		ret = bch2_set_rebalance_needs_scan_trans(trans, inode_u.bi_inum);
 		if (ret)
 			goto err;
@@ -146,6 +147,9 @@ err:
 	if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 		goto retry;
 
+	if (rebalance_changed)
+		bch2_rebalance_wakeup(c);
+
 	bch2_fs_fatal_err_on(bch2_err_matches(ret, ENOENT), c,
 			     "%s: inode %llu:%llu not found when updating",
 			     bch2_err_str(ret),
diff --git a/fs/bcachefs/rebalance.c b/fs/bcachefs/rebalance.c
index de1ec9e0caa0f..dbaabaad1986b 100644
--- a/fs/bcachefs/rebalance.c
+++ b/fs/bcachefs/rebalance.c
@@ -527,7 +527,7 @@ static void rebalance_wait(struct bch_fs *c)
 		r->state		= BCH_REBALANCE_waiting;
 	}
 
-	bch2_kthread_io_clock_wait(clock, r->wait_iotime_end, MAX_SCHEDULE_TIMEOUT);
+	bch2_kthread_io_clock_wait_once(clock, r->wait_iotime_end, MAX_SCHEDULE_TIMEOUT);
 }
 
 static bool bch2_rebalance_enabled(struct bch_fs *c)
@@ -544,6 +544,7 @@ static int do_rebalance(struct moving_context *ctxt)
 	struct bch_fs_rebalance *r = &c->rebalance;
 	struct btree_iter rebalance_work_iter, extent_iter = {};
 	struct bkey_s_c k;
+	u32 kick = r->kick;
 	int ret = 0;
 
 	bch2_trans_begin(trans);
@@ -593,7 +594,8 @@ static int do_rebalance(struct moving_context *ctxt)
 	if (!ret &&
 	    !kthread_should_stop() &&
 	    !atomic64_read(&r->work_stats.sectors_seen) &&
-	    !atomic64_read(&r->scan_stats.sectors_seen)) {
+	    !atomic64_read(&r->scan_stats.sectors_seen) &&
+	    kick == r->kick) {
 		bch2_moving_ctxt_flush_all(ctxt);
 		bch2_trans_unlock_long(trans);
 		rebalance_wait(c);
diff --git a/fs/bcachefs/rebalance.h b/fs/bcachefs/rebalance.h
index 5d9214fe1a22b..7a565ea7dbfcc 100644
--- a/fs/bcachefs/rebalance.h
+++ b/fs/bcachefs/rebalance.h
@@ -39,13 +39,11 @@ int bch2_set_fs_needs_rebalance(struct bch_fs *);
 
 static inline void bch2_rebalance_wakeup(struct bch_fs *c)
 {
-	struct task_struct *p;
-
-	rcu_read_lock();
-	p = rcu_dereference(c->rebalance.thread);
+	c->rebalance.kick++;
+	guard(rcu)();
+	struct task_struct *p = rcu_dereference(c->rebalance.thread);
 	if (p)
 		wake_up_process(p);
-	rcu_read_unlock();
 }
 
 void bch2_rebalance_status_to_text(struct printbuf *, struct bch_fs *);
diff --git a/fs/bcachefs/rebalance_types.h b/fs/bcachefs/rebalance_types.h
index 33d77286f1d56..c659da149fa3c 100644
--- a/fs/bcachefs/rebalance_types.h
+++ b/fs/bcachefs/rebalance_types.h
@@ -18,6 +18,7 @@ enum bch_rebalance_states {
 
 struct bch_fs_rebalance {
 	struct task_struct __rcu	*thread;
+	u32				kick;
 	struct bch_pd_controller pd;
 
 	enum bch_rebalance_states	state;