btrfs: move space cache settings into open_ctree

Currently we pre-load the space cache settings in btrfs_parse_options,
however when we switch to the new mount API the mount option parsing
will happen before we have the super block loaded.  Add a helper to set
the appropriate options based on the fs settings, this will allow us to
have consistent free space cache settings.

This also folds in the space cache related decisions we make for subpage
sectorsize support, so all of this is done in one place.

Since this was being called by parse options it looks like we're
changing the behavior of remount, but in fact we aren't.  The
pre-loading of the free space cache settings is done because we want to
handle the case of users not using any space_cache options, we'll derive
the appropriate mount option based on the on disk state.  On remount
this wouldn't reset anything as we'll have cleared the v1 cache
generation if we mounted -o nospace_cache.  Similarly it's impossible to
turn off the free space tree without specifically saying -o
nospace_cache,clear_cache, which will delete the free space tree and
clear the compat_ro option.  Again in this case calling this code in
remount wouldn't result in any change.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 6 insertions, 11 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 969887b2f8fe..33e48e3865c5 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3305,6 +3305,12 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 	fs_info->csums_per_leaf = BTRFS_MAX_ITEM_SIZE(fs_info) / fs_info->csum_size;
 	fs_info->stripesize = stripesize;
 
+	/*
+	 * Handle the space caching options appropriately now that we have the
+	 * super block loaded and validated.
+	 */
+	btrfs_set_free_space_cache_settings(fs_info);
+
 	ret = btrfs_parse_options(fs_info, options, sb->s_flags);
 	if (ret)
 		goto fail_alloc;
@@ -3316,17 +3322,6 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 	if (sectorsize < PAGE_SIZE) {
 		struct btrfs_subpage_info *subpage_info;
 
-		/*
-		 * V1 space cache has some hardcoded PAGE_SIZE usage, and is
-		 * going to be deprecated.
-		 *
-		 * Force to use v2 cache for subpage case.
-		 */
-		btrfs_clear_opt(fs_info->mount_opt, SPACE_CACHE);
-		btrfs_set_and_info(fs_info, FREE_SPACE_TREE,
-			"forcing free space tree for sector size %u with page size %lu",
-			sectorsize, PAGE_SIZE);
-
 		btrfs_warn(fs_info,
 		"read-write for sector size %u with page size %lu is experimental",
 			   sectorsize, PAGE_SIZE);