From: Kent Overstreet <kent.overstreet@gmail.com>
Date: Thu, 28 Oct 2021 22:22:25 +0000 (-0400)
Subject: bcachefs: Ensure journal doesn't get stuck in nochanges mode
X-Git-Tag: v6.7-rc1~201^2~1323
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=fae1157d184084f1716a10273423f8e949d8471f;p=thirdparty%2Fkernel%2Flinux.git

bcachefs: Ensure journal doesn't get stuck in nochanges mode

This tweaks the journal code to always act as if there's space available
in nochanges mode, when we're not going to be doing any writes. This
helps in recovering filesystems that won't mount because they need
journal replay and the journal has gotten stuck.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
---

diff --git a/fs/bcachefs/journal.h b/fs/bcachefs/journal.h
index 1d556790b38ee..99fd253648bf6 100644
--- a/fs/bcachefs/journal.h
+++ b/fs/bcachefs/journal.h
@@ -446,6 +446,7 @@ static inline int bch2_journal_preres_get_fast(struct journal *j,
 		ret = 0;
 
 		if ((flags & JOURNAL_RES_GET_RESERVED) ||
+		    test_bit(JOURNAL_NOCHANGES, &j->flags) ||
 		    new.reserved + d < new.remaining) {
 			new.reserved += d;
 			ret = 1;
diff --git a/fs/bcachefs/journal_io.c b/fs/bcachefs/journal_io.c
index e797d6376a824..ed8d7f90b6071 100644
--- a/fs/bcachefs/journal_io.c
+++ b/fs/bcachefs/journal_io.c
@@ -1512,7 +1512,7 @@ retry_alloc:
 
 	w->devs_written = bch2_bkey_devs(bkey_i_to_s_c(&w->key));
 
-	if (c->opts.nochanges)
+	if (test_bit(JOURNAL_NOCHANGES, &j->flags))
 		goto no_io;
 
 	for_each_rw_member(ca, c, i)
diff --git a/fs/bcachefs/journal_reclaim.c b/fs/bcachefs/journal_reclaim.c
index 0bc4681ccc24a..3f417af16e590 100644
--- a/fs/bcachefs/journal_reclaim.c
+++ b/fs/bcachefs/journal_reclaim.c
@@ -34,8 +34,10 @@ unsigned bch2_journal_dev_buckets_available(struct journal *j,
 					    struct journal_device *ja,
 					    enum journal_space_from from)
 {
-	unsigned available = (journal_space_from(ja, from) -
-			      ja->cur_idx - 1 + ja->nr) % ja->nr;
+	unsigned available = !test_bit(JOURNAL_NOCHANGES, &j->flags)
+		? ((journal_space_from(ja, from) -
+		    ja->cur_idx - 1 + ja->nr) % ja->nr)
+		: ja->nr;
 
 	/*
 	 * Don't use the last bucket unless writing the new last_seq
diff --git a/fs/bcachefs/journal_types.h b/fs/bcachefs/journal_types.h
index cce02bad850cc..0647a53eb35c0 100644
--- a/fs/bcachefs/journal_types.h
+++ b/fs/bcachefs/journal_types.h
@@ -154,6 +154,7 @@ enum {
 	JOURNAL_NEED_WRITE,
 	JOURNAL_MAY_GET_UNRESERVED,
 	JOURNAL_MAY_SKIP_FLUSH,
+	JOURNAL_NOCHANGES,
 };
 
 /* Embedded in struct bch_fs */
diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index ca2acb7c6134c..501fe129ea9c5 100644
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -801,6 +801,9 @@ static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts)
 	    bch2_fs_fsio_init(c))
 		goto err;
 
+	if (c->opts.nochanges)
+		set_bit(JOURNAL_NOCHANGES, &c->journal.flags);
+
 	mi = bch2_sb_get_members(c->disk_sb.sb);
 	for (i = 0; i < c->sb.nr_devices; i++)
 		if (bch2_dev_exists(c->disk_sb.sb, mi, i) &&