[PATCH v6 39/43] btrfs: set the appropriate free space settings in reconfigure

[Daniel Vacek <neelx@suse.com>]

From: Josef Bacik <josef@toxicpanda.com>

btrfs/330 uncovered a problem where we were accidentally turning off the
free space tree when we do the transition from ro->rw.  This happens
because we don't update

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Daniel Vacek <neelx@suse.com>
---

v5: https://lore.kernel.org/linux-btrfs/325598eeb1d23f9ae04f675b4ee218f7e98e3ff0.1706116485.git.josef@toxicpanda.com/
 * Re-wrapped comments.
 * Fixed argument type.  mount_opt is now ull.
---
 fs/btrfs/disk-io.c |  2 +-
 fs/btrfs/super.c   | 28 +++++++++++++++-------------
 fs/btrfs/super.h   |  3 ++-
 3 files changed, 18 insertions(+), 15 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index f47a20976b53..993d2080fcbf 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3416,7 +3416,7 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 	 * Handle the space caching options appropriately now that we have the
 	 * super block loaded and validated.
 	 */
-	btrfs_set_free_space_cache_settings(fs_info);
+	btrfs_set_free_space_cache_settings(fs_info, &fs_info->mount_opt);
 
 	if (!btrfs_check_options(fs_info, &fs_info->mount_opt, sb->s_flags)) {
 		ret = -EINVAL;
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 06788b27a870..4a2887147ead 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -745,10 +745,10 @@ bool btrfs_check_options(const struct btrfs_fs_info *info,
 }
 
 /*
- * This is subtle, we only call this during open_ctree().  We need to pre-load
- * the mount options with the on-disk settings.  Before the new mount API took
- * effect we would do this on mount and remount.  With the new mount API we'll
- * only do this on the initial mount.
+ * Because we have an odd set of behavior with turning on and off the space cache
+ * and free space tree we have to call this before we start the mount operation
+ * after we load the super, or before we start remount.  This is to make sure we
+ * have the proper free space settings in place if the user didn't specify any.
  *
  * This isn't a change in behavior, because we're using the current state of the
  * file system to set the current mount options.  If you mounted with special
@@ -756,21 +756,22 @@ bool btrfs_check_options(const struct btrfs_fs_info *info,
  * settings, because mounting without these features cleared the on-disk
  * settings, so this being called on re-mount is not needed.
  */
-void btrfs_set_free_space_cache_settings(struct btrfs_fs_info *fs_info)
+void btrfs_set_free_space_cache_settings(struct btrfs_fs_info *fs_info,
+					 unsigned long long *mount_opt)
 {
-	if (fs_info->sectorsize != PAGE_SIZE && btrfs_test_opt(fs_info, SPACE_CACHE)) {
+	if (fs_info->sectorsize != PAGE_SIZE && btrfs_raw_test_opt(*mount_opt, SPACE_CACHE)) {
 		btrfs_info(fs_info,
 			   "forcing free space tree for sector size %u with page size %lu",
 			   fs_info->sectorsize, PAGE_SIZE);
-		btrfs_clear_opt(fs_info->mount_opt, SPACE_CACHE);
-		btrfs_set_opt(fs_info->mount_opt, FREE_SPACE_TREE);
+		btrfs_clear_opt(*mount_opt, SPACE_CACHE);
+		btrfs_set_opt(*mount_opt, FREE_SPACE_TREE);
 	}
 
 	/*
 	 * At this point our mount options are populated, so we only mess with
 	 * these settings if we don't have any settings already.
 	 */
-	if (btrfs_test_opt(fs_info, FREE_SPACE_TREE))
+	if (btrfs_raw_test_opt(*mount_opt, FREE_SPACE_TREE))
 		return;
 
 	if (btrfs_is_zoned(fs_info) &&
@@ -780,10 +781,10 @@ void btrfs_set_free_space_cache_settings(struct btrfs_fs_info *fs_info)
 		return;
 	}
 
-	if (btrfs_test_opt(fs_info, SPACE_CACHE))
+	if (btrfs_raw_test_opt(*mount_opt, SPACE_CACHE))
 		return;
 
-	if (btrfs_test_opt(fs_info, NOSPACECACHE))
+	if (btrfs_raw_test_opt(*mount_opt, NOSPACECACHE))
 		return;
 
 	/*
@@ -791,9 +792,9 @@ void btrfs_set_free_space_cache_settings(struct btrfs_fs_info *fs_info)
 	 * them ourselves based on the state of the file system.
 	 */
 	if (btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE))
-		btrfs_set_opt(fs_info->mount_opt, FREE_SPACE_TREE);
+		btrfs_set_opt(*mount_opt, FREE_SPACE_TREE);
 	else if (btrfs_free_space_cache_v1_active(fs_info))
-		btrfs_set_opt(fs_info->mount_opt, SPACE_CACHE);
+		btrfs_set_opt(*mount_opt, SPACE_CACHE);
 }
 
 static void set_device_specific_options(struct btrfs_fs_info *fs_info)
@@ -1573,6 +1574,7 @@ static int btrfs_reconfigure(struct fs_context *fc)
 
 	sync_filesystem(sb);
 	set_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
+	btrfs_set_free_space_cache_settings(fs_info, &ctx->mount_opt);
 
 	if (!btrfs_check_options(fs_info, &ctx->mount_opt, fc->sb_flags))
 		return -EINVAL;
diff --git a/fs/btrfs/super.h b/fs/btrfs/super.h
index d80a86acfbbe..584f428d36e2 100644
--- a/fs/btrfs/super.h
+++ b/fs/btrfs/super.h
@@ -16,7 +16,8 @@ bool btrfs_check_options(const struct btrfs_fs_info *info,
 int btrfs_sync_fs(struct super_block *sb, int wait);
 char *btrfs_get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info,
 					  u64 subvol_objectid);
-void btrfs_set_free_space_cache_settings(struct btrfs_fs_info *fs_info);
+void btrfs_set_free_space_cache_settings(struct btrfs_fs_info *fs_info,
+					 unsigned long long *mount_opt);
 
 static inline struct btrfs_fs_info *btrfs_sb(struct super_block *sb)
 {
-- 
2.51.0