[PATCH 1/3] bcachefs: bch2_copygc_wakeup()

[PATCH 1/3] bcachefs: bch2_copygc_wakeup()

[Kent Overstreet]

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---
 fs/bcachefs/movinggc.h  | 9 +++++++++
 fs/bcachefs/rebalance.c | 4 ++--
 fs/bcachefs/rebalance.h | 2 +-
 fs/bcachefs/super.c     | 4 ++--
 fs/bcachefs/sysfs.c     | 7 +++----
 5 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/fs/bcachefs/movinggc.h b/fs/bcachefs/movinggc.h
index ea181fef5bc9..d1885cf67a45 100644
--- a/fs/bcachefs/movinggc.h
+++ b/fs/bcachefs/movinggc.h
@@ -5,6 +5,15 @@
 unsigned long bch2_copygc_wait_amount(struct bch_fs *);
 void bch2_copygc_wait_to_text(struct printbuf *, struct bch_fs *);
 
+static inline void bch2_copygc_wakeup(struct bch_fs *c)
+{
+	rcu_read_lock();
+	struct task_struct *p = rcu_dereference(c->copygc_thread);
+	if (p)
+		wake_up_process(p);
+	rcu_read_unlock();
+}
+
 void bch2_copygc_stop(struct bch_fs *);
 int bch2_copygc_start(struct bch_fs *);
 void bch2_fs_copygc_init(struct bch_fs *);
diff --git a/fs/bcachefs/rebalance.c b/fs/bcachefs/rebalance.c
index 63f013496687..d63de50f6323 100644
--- a/fs/bcachefs/rebalance.c
+++ b/fs/bcachefs/rebalance.c
@@ -268,7 +268,7 @@ int bch2_set_rebalance_needs_scan(struct bch_fs *c, u64 inum)
 	int ret = bch2_trans_commit_do(c, NULL, NULL,
 				       BCH_TRANS_COMMIT_no_enospc,
 			    bch2_set_rebalance_needs_scan_trans(trans, inum));
-	rebalance_wakeup(c);
+	bch2_rebalance_wakeup(c);
 	return ret;
 }
 
@@ -670,7 +670,7 @@ void bch2_rebalance_stop(struct bch_fs *c)
 	c->rebalance.thread = NULL;
 
 	if (p) {
-		/* for sychronizing with rebalance_wakeup() */
+		/* for sychronizing with bch2_rebalance_wakeup() */
 		synchronize_rcu();
 
 		kthread_stop(p);
diff --git a/fs/bcachefs/rebalance.h b/fs/bcachefs/rebalance.h
index 62a3859d3823..e5e8eb4a2dd1 100644
--- a/fs/bcachefs/rebalance.h
+++ b/fs/bcachefs/rebalance.h
@@ -37,7 +37,7 @@ int bch2_set_rebalance_needs_scan_trans(struct btree_trans *, u64);
 int bch2_set_rebalance_needs_scan(struct bch_fs *, u64 inum);
 int bch2_set_fs_needs_rebalance(struct bch_fs *);
 
-static inline void rebalance_wakeup(struct bch_fs *c)
+static inline void bch2_rebalance_wakeup(struct bch_fs *c)
 {
 	struct task_struct *p;
 
diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index 222b31f23799..72e001e4c151 100644
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -1526,7 +1526,7 @@ static int bch2_dev_attach_bdev(struct bch_fs *c, struct bch_sb_handle *sb)
 	strscpy(ca->name, name.buf, sizeof(ca->name));
 	printbuf_exit(&name);
 
-	rebalance_wakeup(c);
+	bch2_rebalance_wakeup(c);
 	return 0;
 }
 
@@ -1672,7 +1672,7 @@ int __bch2_dev_set_state(struct bch_fs *c, struct bch_dev *ca,
 	if (new_state == BCH_MEMBER_STATE_rw)
 		__bch2_dev_read_write(c, ca);
 
-	rebalance_wakeup(c);
+	bch2_rebalance_wakeup(c);
 
 	return ret;
 }
diff --git a/fs/bcachefs/sysfs.c b/fs/bcachefs/sysfs.c
index fff675edef4e..00405372af5e 100644
--- a/fs/bcachefs/sysfs.c
+++ b/fs/bcachefs/sysfs.c
@@ -766,11 +766,10 @@ static ssize_t sysfs_opt_store(struct bch_fs *c,
 		bch2_set_rebalance_needs_scan(c, 0);
 
 	if (v && id == Opt_rebalance_enabled)
-		rebalance_wakeup(c);
+		bch2_rebalance_wakeup(c);
 
-	if (v && id == Opt_copygc_enabled &&
-	    c->copygc_thread)
-		wake_up_process(c->copygc_thread);
+	if (v && id == Opt_copygc_enabled)
+		bch2_copygc_wakeup(c);
 
 	if (id == Opt_discard && !ca) {
 		mutex_lock(&c->sb_lock);
-- 
2.49.0

[PATCH 2/3] bcachefs: Clean up option pre/post hooks, small fixes

[Kent Overstreet]

The helpers are now:
- bch2_opt_hook_pre_set()
- bch2_opts_hooks_pre_set()
- bch2_opt_hook_post_set

Fix a bug where the filesystem discard option would incorrectly be
changed when setting the device option, and don't trigger rebalance
scans unnecessarily (when options aren't changing).

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---
 fs/bcachefs/inode.h |  2 +-
 fs/bcachefs/opts.c  | 81 +++++++++++++++++++++++++++++++++++++++------
 fs/bcachefs/opts.h  | 11 +++---
 fs/bcachefs/super.c |  2 +-
 fs/bcachefs/sysfs.c | 29 ++++------------
 fs/bcachefs/xattr.c |  2 +-
 6 files changed, 87 insertions(+), 40 deletions(-)

diff --git a/fs/bcachefs/inode.h b/fs/bcachefs/inode.h
index f82cfbf460d0..1b2fc902af1c 100644
--- a/fs/bcachefs/inode.h
+++ b/fs/bcachefs/inode.h
@@ -284,7 +284,7 @@ static inline bool bch2_inode_should_have_single_bp(struct bch_inode_unpacked *i
 struct bch_opts bch2_inode_opts_to_opts(struct bch_inode_unpacked *);
 void bch2_inode_opts_get(struct bch_io_opts *, struct bch_fs *,
 			 struct bch_inode_unpacked *);
-int bch2_inum_opts_get(struct btree_trans*, subvol_inum, struct bch_io_opts *);
+int bch2_inum_opts_get(struct btree_trans *, subvol_inum, struct bch_io_opts *);
 
 #include "rebalance.h"
 
diff --git a/fs/bcachefs/opts.c b/fs/bcachefs/opts.c
index b3fcffc91d6f..386482ff8e7b 100644
--- a/fs/bcachefs/opts.c
+++ b/fs/bcachefs/opts.c
@@ -7,7 +7,9 @@
 #include "compress.h"
 #include "disk_groups.h"
 #include "error.h"
+#include "movinggc.h"
 #include "opts.h"
+#include "rebalance.h"
 #include "recovery_passes.h"
 #include "super-io.h"
 #include "util.h"
@@ -516,7 +518,7 @@ void bch2_opts_to_text(struct printbuf *out,
 	}
 }
 
-int bch2_opt_check_may_set(struct bch_fs *c, struct bch_dev *ca, int id, u64 v)
+int bch2_opt_hook_pre_set(struct bch_fs *c, struct bch_dev *ca, enum bch_opt_id id, u64 v)
 {
 	int ret = 0;
 
@@ -534,15 +536,17 @@ int bch2_opt_check_may_set(struct bch_fs *c, struct bch_dev *ca, int id, u64 v)
 		if (v)
 			bch2_check_set_feature(c, BCH_FEATURE_ec);
 		break;
+	default:
+		break;
 	}
 
 	return ret;
 }
 
-int bch2_opts_check_may_set(struct bch_fs *c)
+int bch2_opts_hooks_pre_set(struct bch_fs *c)
 {
 	for (unsigned i = 0; i < bch2_opts_nr; i++) {
-		int ret = bch2_opt_check_may_set(c, NULL, i, bch2_opt_get_by_id(&c->opts, i));
+		int ret = bch2_opt_hook_pre_set(c, NULL, i, bch2_opt_get_by_id(&c->opts, i));
 		if (ret)
 			return ret;
 	}
@@ -550,6 +554,52 @@ int bch2_opts_check_may_set(struct bch_fs *c)
 	return 0;
 }
 
+void bch2_opt_hook_post_set(struct bch_fs *c, struct bch_dev *ca, u64 inum,
+			    struct bch_opts *new_opts, enum bch_opt_id id)
+{
+	switch (id) {
+	case Opt_foreground_target:
+		if (new_opts->foreground_target &&
+		    !new_opts->background_target)
+			bch2_set_rebalance_needs_scan(c, inum);
+		break;
+	case Opt_compression:
+		if (new_opts->compression &&
+		    !new_opts->background_compression)
+			bch2_set_rebalance_needs_scan(c, inum);
+		break;
+	case Opt_background_target:
+		if (new_opts->background_target)
+			bch2_set_rebalance_needs_scan(c, inum);
+		break;
+	case Opt_background_compression:
+		if (new_opts->background_compression)
+			bch2_set_rebalance_needs_scan(c, inum);
+		break;
+	case Opt_rebalance_enabled:
+		bch2_rebalance_wakeup(c);
+		break;
+	case Opt_copygc_enabled:
+		bch2_copygc_wakeup(c);
+		break;
+	case Opt_discard:
+		if (!ca) {
+			mutex_lock(&c->sb_lock);
+			for_each_member_device(c, ca) {
+				struct bch_member *m =
+					bch2_members_v2_get_mut(ca->disk_sb.sb, ca->dev_idx);
+				SET_BCH_MEMBER_DISCARD(m, c->opts.discard);
+			}
+
+			bch2_write_super(c);
+			mutex_unlock(&c->sb_lock);
+		}
+		break;
+	default:
+		break;
+	}
+}
+
 int bch2_parse_one_mount_opt(struct bch_fs *c, struct bch_opts *opts,
 			     struct printbuf *parse_later,
 			     const char *name, const char *val)
@@ -709,9 +759,11 @@ int bch2_opts_from_sb(struct bch_opts *opts, struct bch_sb *sb)
 	return 0;
 }
 
-void __bch2_opt_set_sb(struct bch_sb *sb, int dev_idx,
+bool __bch2_opt_set_sb(struct bch_sb *sb, int dev_idx,
 		       const struct bch_option *opt, u64 v)
 {
+	bool changed = false;
+
 	if (opt->flags & OPT_SB_FIELD_SECTORS)
 		v >>= 9;
 
@@ -721,26 +773,35 @@ void __bch2_opt_set_sb(struct bch_sb *sb, int dev_idx,
 	if (opt->flags & OPT_SB_FIELD_ONE_BIAS)
 		v++;
 
-	if ((opt->flags & OPT_FS) && opt->set_sb && dev_idx < 0)
+	if ((opt->flags & OPT_FS) && opt->set_sb && dev_idx < 0) {
+		changed = v != opt->get_sb(sb);
+
 		opt->set_sb(sb, v);
+	}
 
 	if ((opt->flags & OPT_DEVICE) && opt->set_member && dev_idx >= 0) {
 		if (WARN(!bch2_member_exists(sb, dev_idx),
 			 "tried to set device option %s on nonexistent device %i",
 			 opt->attr.name, dev_idx))
-			return;
+			return false;
 
-		opt->set_member(bch2_members_v2_get_mut(sb, dev_idx), v);
+		struct bch_member *m = bch2_members_v2_get_mut(sb, dev_idx);
+		changed = v != opt->get_member(m);
+		opt->set_member(m, v);
 	}
+
+	return changed;
 }
 
-void bch2_opt_set_sb(struct bch_fs *c, struct bch_dev *ca,
+bool bch2_opt_set_sb(struct bch_fs *c, struct bch_dev *ca,
 		     const struct bch_option *opt, u64 v)
 {
 	mutex_lock(&c->sb_lock);
-	__bch2_opt_set_sb(c->disk_sb.sb, ca ? ca->dev_idx : -1, opt, v);
-	bch2_write_super(c);
+	bool changed = __bch2_opt_set_sb(c->disk_sb.sb, ca ? ca->dev_idx : -1, opt, v);
+	if (changed)
+		bch2_write_super(c);
 	mutex_unlock(&c->sb_lock);
+	return changed;
 }
 
 /* io opts: */
diff --git a/fs/bcachefs/opts.h b/fs/bcachefs/opts.h
index 4be0634eae80..f69ba5e63e15 100644
--- a/fs/bcachefs/opts.h
+++ b/fs/bcachefs/opts.h
@@ -607,10 +607,10 @@ void bch2_opt_set_by_id(struct bch_opts *, enum bch_opt_id, u64);
 
 u64 bch2_opt_from_sb(struct bch_sb *, enum bch_opt_id, int);
 int bch2_opts_from_sb(struct bch_opts *, struct bch_sb *);
-void __bch2_opt_set_sb(struct bch_sb *, int, const struct bch_option *, u64);
+bool __bch2_opt_set_sb(struct bch_sb *, int, const struct bch_option *, u64);
 
 struct bch_dev;
-void bch2_opt_set_sb(struct bch_fs *, struct bch_dev *, const struct bch_option *, u64);
+bool bch2_opt_set_sb(struct bch_fs *, struct bch_dev *, const struct bch_option *, u64);
 
 int bch2_opt_lookup(const char *);
 int bch2_opt_validate(const struct bch_option *, u64, struct printbuf *);
@@ -627,8 +627,11 @@ void bch2_opts_to_text(struct printbuf *,
 		       struct bch_fs *, struct bch_sb *,
 		       unsigned, unsigned, unsigned);
 
-int bch2_opt_check_may_set(struct bch_fs *, struct bch_dev *, int, u64);
-int bch2_opts_check_may_set(struct bch_fs *);
+int bch2_opt_hook_pre_set(struct bch_fs *, struct bch_dev *, enum bch_opt_id, u64);
+int bch2_opts_hooks_pre_set(struct bch_fs *);
+void bch2_opt_hook_post_set(struct bch_fs *, struct bch_dev *, u64,
+			    struct bch_opts *, enum bch_opt_id);
+
 int bch2_parse_one_mount_opt(struct bch_fs *, struct bch_opts *,
 			     struct printbuf *, const char *, const char *);
 int bch2_parse_mount_opts(struct bch_fs *, struct bch_opts *, struct printbuf *,
diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index 72e001e4c151..1d27a306938d 100644
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -1099,7 +1099,7 @@ int bch2_fs_start(struct bch_fs *c)
 	if (ret)
 		goto err;
 
-	ret = bch2_opts_check_may_set(c);
+	ret = bch2_opts_hooks_pre_set(c);
 	if (ret)
 		goto err;
 
diff --git a/fs/bcachefs/sysfs.c b/fs/bcachefs/sysfs.c
index 00405372af5e..455c6ae9a494 100644
--- a/fs/bcachefs/sysfs.c
+++ b/fs/bcachefs/sysfs.c
@@ -749,36 +749,19 @@ static ssize_t sysfs_opt_store(struct bch_fs *c,
 
 	u64 v;
 	ret =   bch2_opt_parse(c, opt, strim(tmp), &v, NULL) ?:
-		bch2_opt_check_may_set(c, ca, id, v);
+		bch2_opt_hook_pre_set(c, ca, id, v);
 	kfree(tmp);
 
 	if (ret < 0)
 		goto err;
 
-	bch2_opt_set_sb(c, ca, opt, v);
-	bch2_opt_set_by_id(&c->opts, id, v);
+	bool changed = bch2_opt_set_sb(c, ca, opt, v);
 
-	if (v &&
-	    (id == Opt_background_target ||
-	     (id == Opt_foreground_target && !c->opts.background_target) ||
-	     id == Opt_background_compression ||
-	     (id == Opt_compression && !c->opts.background_compression)))
-		bch2_set_rebalance_needs_scan(c, 0);
+	if (!ca)
+		bch2_opt_set_by_id(&c->opts, id, v);
 
-	if (v && id == Opt_rebalance_enabled)
-		bch2_rebalance_wakeup(c);
-
-	if (v && id == Opt_copygc_enabled)
-		bch2_copygc_wakeup(c);
-
-	if (id == Opt_discard && !ca) {
-		mutex_lock(&c->sb_lock);
-		for_each_member_device(c, ca)
-			opt->set_member(bch2_members_v2_get_mut(ca->disk_sb.sb, ca->dev_idx), v);
-
-		bch2_write_super(c);
-		mutex_unlock(&c->sb_lock);
-	}
+	if (changed)
+		bch2_opt_hook_post_set(c, ca, 0, &c->opts, id);
 
 	ret = size;
 err:
diff --git a/fs/bcachefs/xattr.c b/fs/bcachefs/xattr.c
index 651da52b2cbc..3d324e485ee9 100644
--- a/fs/bcachefs/xattr.c
+++ b/fs/bcachefs/xattr.c
@@ -523,7 +523,7 @@ static int bch2_xattr_bcachefs_set(const struct xattr_handler *handler,
 		if (ret < 0)
 			goto err_class_exit;
 
-		ret = bch2_opt_check_may_set(c, NULL, opt_id, v);
+		ret = bch2_opt_hook_pre_set(c, NULL, opt_id, v);
 		if (ret < 0)
 			goto err_class_exit;
 
-- 
2.49.0

[PATCH 3/3] bcachefs: Incompatible features may now be enabled at runtime

[Kent Overstreet]

version_upgrade is now a runtime option.

In the future we'll want to add compatible upgrades at runtime, and call
the full check_version_upgrade() when the option changes, but we don't
have compatible optional upgrades just yet.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---
 fs/bcachefs/opts.c     |  9 +++++++++
 fs/bcachefs/opts.h     |  2 +-
 fs/bcachefs/recovery.c |  4 ++--
 fs/bcachefs/super-io.c | 25 +++++++++++++++++++++++++
 fs/bcachefs/super-io.h |  1 +
 5 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/fs/bcachefs/opts.c b/fs/bcachefs/opts.c
index 386482ff8e7b..b1cf88905b81 100644
--- a/fs/bcachefs/opts.c
+++ b/fs/bcachefs/opts.c
@@ -595,6 +595,15 @@ void bch2_opt_hook_post_set(struct bch_fs *c, struct bch_dev *ca, u64 inum,
 			mutex_unlock(&c->sb_lock);
 		}
 		break;
+	case Opt_version_upgrade:
+		/*
+		 * XXX: in the future we'll likely want to do compatible
+		 * upgrades at runtime as well, but right now there's nothing
+		 * that does that:
+		 */
+		if (new_opts->version_upgrade == BCH_VERSION_UPGRADE_incompatible)
+			bch2_sb_upgrade_incompat(c);
+		break;
 	default:
 		break;
 	}
diff --git a/fs/bcachefs/opts.h b/fs/bcachefs/opts.h
index f69ba5e63e15..5cdb18802138 100644
--- a/fs/bcachefs/opts.h
+++ b/fs/bcachefs/opts.h
@@ -445,7 +445,7 @@ enum fsck_err_opts {
 	  BCH2_NO_SB_OPT,		false,				\
 	  NULL,		"Reconstruct alloc btree")			\
 	x(version_upgrade,		u8,				\
-	  OPT_FS|OPT_MOUNT,						\
+	  OPT_FS|OPT_MOUNT|OPT_RUNTIME,					\
 	  OPT_STR(bch2_version_upgrade_opts),				\
 	  BCH_SB_VERSION_UPGRADE,	BCH_VERSION_UPGRADE_compatible,	\
 	  NULL,		"Set superblock to latest version,\n"		\
diff --git a/fs/bcachefs/recovery.c b/fs/bcachefs/recovery.c
index 606d684e6f23..58ee1ebdcbaa 100644
--- a/fs/bcachefs/recovery.c
+++ b/fs/bcachefs/recovery.c
@@ -666,7 +666,7 @@ static bool check_version_upgrade(struct bch_fs *c)
 				     bch2_recovery_passes_from_stable(le64_to_cpu(passes)));
 		}
 
-		bch_info(c, "%s", buf.buf);
+		bch_notice(c, "%s", buf.buf);
 		printbuf_exit(&buf);
 
 		ret = true;
@@ -682,7 +682,7 @@ static bool check_version_upgrade(struct bch_fs *c)
 		bch2_version_to_text(&buf, c->sb.version_incompat_allowed);
 		prt_newline(&buf);
 
-		bch_info(c, "%s", buf.buf);
+		bch_notice(c, "%s", buf.buf);
 		printbuf_exit(&buf);
 
 		ret = true;
diff --git a/fs/bcachefs/super-io.c b/fs/bcachefs/super-io.c
index fa4d323ddada..791dee30f042 100644
--- a/fs/bcachefs/super-io.c
+++ b/fs/bcachefs/super-io.c
@@ -1273,6 +1273,31 @@ void bch2_sb_upgrade(struct bch_fs *c, unsigned new_version, bool incompat)
 	}
 }
 
+void bch2_sb_upgrade_incompat(struct bch_fs *c)
+{
+	mutex_lock(&c->sb_lock);
+	if (c->sb.version == c->sb.version_incompat_allowed)
+		goto unlock;
+
+	struct printbuf buf = PRINTBUF;
+
+	prt_str(&buf, "Now allowing incompatible features up to ");
+	bch2_version_to_text(&buf, c->sb.version);
+	prt_str(&buf, ", previously allowed up to ");
+	bch2_version_to_text(&buf, c->sb.version_incompat_allowed);
+	prt_newline(&buf);
+
+	bch_notice(c, "%s", buf.buf);
+	printbuf_exit(&buf);
+
+	c->disk_sb.sb->features[0] |= cpu_to_le64(BCH_SB_FEATURES_ALL);
+	SET_BCH_SB_VERSION_INCOMPAT_ALLOWED(c->disk_sb.sb,
+			max(BCH_SB_VERSION_INCOMPAT_ALLOWED(c->disk_sb.sb), c->sb.version));
+	bch2_write_super(c);
+unlock:
+	mutex_unlock(&c->sb_lock);
+}
+
 static int bch2_sb_ext_validate(struct bch_sb *sb, struct bch_sb_field *f,
 				enum bch_validate_flags flags, struct printbuf *err)
 {
diff --git a/fs/bcachefs/super-io.h b/fs/bcachefs/super-io.h
index 78f708a6fbcd..a3b7a90f2533 100644
--- a/fs/bcachefs/super-io.h
+++ b/fs/bcachefs/super-io.h
@@ -107,6 +107,7 @@ static inline void bch2_check_set_feature(struct bch_fs *c, unsigned feat)
 
 bool bch2_check_version_downgrade(struct bch_fs *);
 void bch2_sb_upgrade(struct bch_fs *, unsigned, bool);
+void bch2_sb_upgrade_incompat(struct bch_fs *);
 
 void __bch2_sb_field_to_text(struct printbuf *, struct bch_sb *,
 			     struct bch_sb_field *);
-- 
2.49.0

[PATCH 2/3] bcachefs: Clean up option pre/post hooks, small fixes

[Kent Overstreet]

The helpers are now:
- bch2_opt_hook_pre_set()
- bch2_opts_hooks_pre_set()
- bch2_opt_hook_post_set

Fix a bug where the filesystem discard option would incorrectly be
changed when setting the device option, and don't trigger rebalance
scans unnecessarily (when options aren't changing).

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---
 fs/bcachefs/inode.h |  2 +-
 fs/bcachefs/opts.c  | 81 +++++++++++++++++++++++++++++++++++++++------
 fs/bcachefs/opts.h  | 11 +++---
 fs/bcachefs/super.c |  2 +-
 fs/bcachefs/sysfs.c | 29 ++++------------
 fs/bcachefs/xattr.c |  2 +-
 6 files changed, 87 insertions(+), 40 deletions(-)

diff --git a/fs/bcachefs/inode.h b/fs/bcachefs/inode.h
index f82cfbf460d0..1b2fc902af1c 100644
--- a/fs/bcachefs/inode.h
+++ b/fs/bcachefs/inode.h
@@ -284,7 +284,7 @@ static inline bool bch2_inode_should_have_single_bp(struct bch_inode_unpacked *i
 struct bch_opts bch2_inode_opts_to_opts(struct bch_inode_unpacked *);
 void bch2_inode_opts_get(struct bch_io_opts *, struct bch_fs *,
 			 struct bch_inode_unpacked *);
-int bch2_inum_opts_get(struct btree_trans*, subvol_inum, struct bch_io_opts *);
+int bch2_inum_opts_get(struct btree_trans *, subvol_inum, struct bch_io_opts *);
 
 #include "rebalance.h"
 
diff --git a/fs/bcachefs/opts.c b/fs/bcachefs/opts.c
index b3fcffc91d6f..386482ff8e7b 100644
--- a/fs/bcachefs/opts.c
+++ b/fs/bcachefs/opts.c
@@ -7,7 +7,9 @@
 #include "compress.h"
 #include "disk_groups.h"
 #include "error.h"
+#include "movinggc.h"
 #include "opts.h"
+#include "rebalance.h"
 #include "recovery_passes.h"
 #include "super-io.h"
 #include "util.h"
@@ -516,7 +518,7 @@ void bch2_opts_to_text(struct printbuf *out,
 	}
 }
 
-int bch2_opt_check_may_set(struct bch_fs *c, struct bch_dev *ca, int id, u64 v)
+int bch2_opt_hook_pre_set(struct bch_fs *c, struct bch_dev *ca, enum bch_opt_id id, u64 v)
 {
 	int ret = 0;
 
@@ -534,15 +536,17 @@ int bch2_opt_check_may_set(struct bch_fs *c, struct bch_dev *ca, int id, u64 v)
 		if (v)
 			bch2_check_set_feature(c, BCH_FEATURE_ec);
 		break;
+	default:
+		break;
 	}
 
 	return ret;
 }
 
-int bch2_opts_check_may_set(struct bch_fs *c)
+int bch2_opts_hooks_pre_set(struct bch_fs *c)
 {
 	for (unsigned i = 0; i < bch2_opts_nr; i++) {
-		int ret = bch2_opt_check_may_set(c, NULL, i, bch2_opt_get_by_id(&c->opts, i));
+		int ret = bch2_opt_hook_pre_set(c, NULL, i, bch2_opt_get_by_id(&c->opts, i));
 		if (ret)
 			return ret;
 	}
@@ -550,6 +554,52 @@ int bch2_opts_check_may_set(struct bch_fs *c)
 	return 0;
 }
 
+void bch2_opt_hook_post_set(struct bch_fs *c, struct bch_dev *ca, u64 inum,
+			    struct bch_opts *new_opts, enum bch_opt_id id)
+{
+	switch (id) {
+	case Opt_foreground_target:
+		if (new_opts->foreground_target &&
+		    !new_opts->background_target)
+			bch2_set_rebalance_needs_scan(c, inum);
+		break;
+	case Opt_compression:
+		if (new_opts->compression &&
+		    !new_opts->background_compression)
+			bch2_set_rebalance_needs_scan(c, inum);
+		break;
+	case Opt_background_target:
+		if (new_opts->background_target)
+			bch2_set_rebalance_needs_scan(c, inum);
+		break;
+	case Opt_background_compression:
+		if (new_opts->background_compression)
+			bch2_set_rebalance_needs_scan(c, inum);
+		break;
+	case Opt_rebalance_enabled:
+		bch2_rebalance_wakeup(c);
+		break;
+	case Opt_copygc_enabled:
+		bch2_copygc_wakeup(c);
+		break;
+	case Opt_discard:
+		if (!ca) {
+			mutex_lock(&c->sb_lock);
+			for_each_member_device(c, ca) {
+				struct bch_member *m =
+					bch2_members_v2_get_mut(ca->disk_sb.sb, ca->dev_idx);
+				SET_BCH_MEMBER_DISCARD(m, c->opts.discard);
+			}
+
+			bch2_write_super(c);
+			mutex_unlock(&c->sb_lock);
+		}
+		break;
+	default:
+		break;
+	}
+}
+
 int bch2_parse_one_mount_opt(struct bch_fs *c, struct bch_opts *opts,
 			     struct printbuf *parse_later,
 			     const char *name, const char *val)
@@ -709,9 +759,11 @@ int bch2_opts_from_sb(struct bch_opts *opts, struct bch_sb *sb)
 	return 0;
 }
 
-void __bch2_opt_set_sb(struct bch_sb *sb, int dev_idx,
+bool __bch2_opt_set_sb(struct bch_sb *sb, int dev_idx,
 		       const struct bch_option *opt, u64 v)
 {
+	bool changed = false;
+
 	if (opt->flags & OPT_SB_FIELD_SECTORS)
 		v >>= 9;
 
@@ -721,26 +773,35 @@ void __bch2_opt_set_sb(struct bch_sb *sb, int dev_idx,
 	if (opt->flags & OPT_SB_FIELD_ONE_BIAS)
 		v++;
 
-	if ((opt->flags & OPT_FS) && opt->set_sb && dev_idx < 0)
+	if ((opt->flags & OPT_FS) && opt->set_sb && dev_idx < 0) {
+		changed = v != opt->get_sb(sb);
+
 		opt->set_sb(sb, v);
+	}
 
 	if ((opt->flags & OPT_DEVICE) && opt->set_member && dev_idx >= 0) {
 		if (WARN(!bch2_member_exists(sb, dev_idx),
 			 "tried to set device option %s on nonexistent device %i",
 			 opt->attr.name, dev_idx))
-			return;
+			return false;
 
-		opt->set_member(bch2_members_v2_get_mut(sb, dev_idx), v);
+		struct bch_member *m = bch2_members_v2_get_mut(sb, dev_idx);
+		changed = v != opt->get_member(m);
+		opt->set_member(m, v);
 	}
+
+	return changed;
 }
 
-void bch2_opt_set_sb(struct bch_fs *c, struct bch_dev *ca,
+bool bch2_opt_set_sb(struct bch_fs *c, struct bch_dev *ca,
 		     const struct bch_option *opt, u64 v)
 {
 	mutex_lock(&c->sb_lock);
-	__bch2_opt_set_sb(c->disk_sb.sb, ca ? ca->dev_idx : -1, opt, v);
-	bch2_write_super(c);
+	bool changed = __bch2_opt_set_sb(c->disk_sb.sb, ca ? ca->dev_idx : -1, opt, v);
+	if (changed)
+		bch2_write_super(c);
 	mutex_unlock(&c->sb_lock);
+	return changed;
 }
 
 /* io opts: */
diff --git a/fs/bcachefs/opts.h b/fs/bcachefs/opts.h
index 4be0634eae80..f69ba5e63e15 100644
--- a/fs/bcachefs/opts.h
+++ b/fs/bcachefs/opts.h
@@ -607,10 +607,10 @@ void bch2_opt_set_by_id(struct bch_opts *, enum bch_opt_id, u64);
 
 u64 bch2_opt_from_sb(struct bch_sb *, enum bch_opt_id, int);
 int bch2_opts_from_sb(struct bch_opts *, struct bch_sb *);
-void __bch2_opt_set_sb(struct bch_sb *, int, const struct bch_option *, u64);
+bool __bch2_opt_set_sb(struct bch_sb *, int, const struct bch_option *, u64);
 
 struct bch_dev;
-void bch2_opt_set_sb(struct bch_fs *, struct bch_dev *, const struct bch_option *, u64);
+bool bch2_opt_set_sb(struct bch_fs *, struct bch_dev *, const struct bch_option *, u64);
 
 int bch2_opt_lookup(const char *);
 int bch2_opt_validate(const struct bch_option *, u64, struct printbuf *);
@@ -627,8 +627,11 @@ void bch2_opts_to_text(struct printbuf *,
 		       struct bch_fs *, struct bch_sb *,
 		       unsigned, unsigned, unsigned);
 
-int bch2_opt_check_may_set(struct bch_fs *, struct bch_dev *, int, u64);
-int bch2_opts_check_may_set(struct bch_fs *);
+int bch2_opt_hook_pre_set(struct bch_fs *, struct bch_dev *, enum bch_opt_id, u64);
+int bch2_opts_hooks_pre_set(struct bch_fs *);
+void bch2_opt_hook_post_set(struct bch_fs *, struct bch_dev *, u64,
+			    struct bch_opts *, enum bch_opt_id);
+
 int bch2_parse_one_mount_opt(struct bch_fs *, struct bch_opts *,
 			     struct printbuf *, const char *, const char *);
 int bch2_parse_mount_opts(struct bch_fs *, struct bch_opts *, struct printbuf *,
diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index 72e001e4c151..1d27a306938d 100644
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -1099,7 +1099,7 @@ int bch2_fs_start(struct bch_fs *c)
 	if (ret)
 		goto err;
 
-	ret = bch2_opts_check_may_set(c);
+	ret = bch2_opts_hooks_pre_set(c);
 	if (ret)
 		goto err;
 
diff --git a/fs/bcachefs/sysfs.c b/fs/bcachefs/sysfs.c
index 82ee333ddd21..bfdadeae970e 100644
--- a/fs/bcachefs/sysfs.c
+++ b/fs/bcachefs/sysfs.c
@@ -637,36 +637,19 @@ static ssize_t sysfs_opt_store(struct bch_fs *c,
 
 	u64 v;
 	ret =   bch2_opt_parse(c, opt, strim(tmp), &v, NULL) ?:
-		bch2_opt_check_may_set(c, ca, id, v);
+		bch2_opt_hook_pre_set(c, ca, id, v);
 	kfree(tmp);
 
 	if (ret < 0)
 		goto err;
 
-	bch2_opt_set_sb(c, ca, opt, v);
-	bch2_opt_set_by_id(&c->opts, id, v);
+	bool changed = bch2_opt_set_sb(c, ca, opt, v);
 
-	if (v &&
-	    (id == Opt_background_target ||
-	     (id == Opt_foreground_target && !c->opts.background_target) ||
-	     id == Opt_background_compression ||
-	     (id == Opt_compression && !c->opts.background_compression)))
-		bch2_set_rebalance_needs_scan(c, 0);
+	if (!ca)
+		bch2_opt_set_by_id(&c->opts, id, v);
 
-	if (v && id == Opt_rebalance_enabled)
-		bch2_rebalance_wakeup(c);
-
-	if (v && id == Opt_copygc_enabled)
-		bch2_copygc_wakeup(c);
-
-	if (id == Opt_discard && !ca) {
-		mutex_lock(&c->sb_lock);
-		for_each_member_device(c, ca)
-			opt->set_member(bch2_members_v2_get_mut(ca->disk_sb.sb, ca->dev_idx), v);
-
-		bch2_write_super(c);
-		mutex_unlock(&c->sb_lock);
-	}
+	if (changed)
+		bch2_opt_hook_post_set(c, ca, 0, &c->opts, id);
 
 	ret = size;
 err:
diff --git a/fs/bcachefs/xattr.c b/fs/bcachefs/xattr.c
index 651da52b2cbc..3d324e485ee9 100644
--- a/fs/bcachefs/xattr.c
+++ b/fs/bcachefs/xattr.c
@@ -523,7 +523,7 @@ static int bch2_xattr_bcachefs_set(const struct xattr_handler *handler,
 		if (ret < 0)
 			goto err_class_exit;
 
-		ret = bch2_opt_check_may_set(c, NULL, opt_id, v);
+		ret = bch2_opt_hook_pre_set(c, NULL, opt_id, v);
 		if (ret < 0)
 			goto err_class_exit;
 
-- 
2.49.0