[PATCH v2 14/18] btrfs: switch to the new mount API

[Josef Bacik <josef@toxicpanda.com>]

Now that we have all of the parts in place to use the new mount API,
switch our fs_type to use the new callbacks.

There are a few things that have to be done at the same time because of
the order of operations changes that come along with the new mount API.
These must be done in the same patch otherwise things will go wrong.

1. Export and use btrfs_check_options in open_ctree().  This is because
   the options are done ahead of time, and we need to check them once we
   have the feature flags loaded.
2. Update the free space cache settings.  Since we're coming in with the
   options already set we need to make sure we don't undo what the user
   has asked for.
3. Set our sb_flags at init_fs_context time, the fs_context stuff is
   trying to manage the sb_flagss itself, so move that into
   init_fs_context and out of the fill super part.

Additionally I've marked the unused functions with __maybe_unused and
will remove them in a future patch.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
 fs/btrfs/disk-io.c |  5 +--
 fs/btrfs/super.c   | 88 ++++++++++++++++++++++++++--------------------
 fs/btrfs/super.h   |  2 ++
 3 files changed, 54 insertions(+), 41 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index c70e507a28d0..ce861f4baf47 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3295,9 +3295,10 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 	 */
 	btrfs_set_free_space_cache_settings(fs_info);
 
-	ret = btrfs_parse_options(fs_info, options, sb->s_flags);
-	if (ret)
+	if (!btrfs_check_options(fs_info, &fs_info->mount_opt, sb->s_flags)) {
+		ret = -EINVAL;
 		goto fail_alloc;
+	}
 
 	ret = btrfs_check_features(fs_info, !sb_rdonly(sb));
 	if (ret < 0)
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 7a49a61fc50a..4ce07d255497 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -304,7 +304,7 @@ static const struct constant_table btrfs_parameter_fragment[] = {
 };
 #endif
 
-static const struct fs_parameter_spec btrfs_fs_parameters[] __maybe_unused = {
+static const struct fs_parameter_spec btrfs_fs_parameters[] = {
 	fsparam_flag_no("acl", Opt_acl),
 	fsparam_flag("clear_cache", Opt_clear_cache),
 	fsparam_u32("commit", Opt_commit_interval),
@@ -747,8 +747,8 @@ static bool check_ro_option(struct btrfs_fs_info *fs_info,
 	return false;
 }
 
-static bool check_options(struct btrfs_fs_info *info, unsigned long *mount_opt,
-			  unsigned long flags)
+bool btrfs_check_options(struct btrfs_fs_info *info, unsigned long *mount_opt,
+			 unsigned long flags)
 {
 	if (!(flags & SB_RDONLY) &&
 	    (check_ro_option(info, *mount_opt, BTRFS_MOUNT_NOLOGREPLAY, "nologreplay") ||
@@ -783,18 +783,6 @@ static bool check_options(struct btrfs_fs_info *info, unsigned long *mount_opt,
 
 void btrfs_set_free_space_cache_settings(struct btrfs_fs_info *fs_info)
 {
-	if (btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE))
-		btrfs_set_opt(fs_info->mount_opt, FREE_SPACE_TREE);
-	else if (btrfs_free_space_cache_v1_active(fs_info)) {
-		if (btrfs_is_zoned(fs_info)) {
-			btrfs_info(fs_info,
-			"zoned: clearing existing space cache");
-			btrfs_set_super_cache_generation(fs_info->super_copy, 0);
-		} else {
-			btrfs_set_opt(fs_info->mount_opt, SPACE_CACHE);
-		}
-	}
-
 	if (fs_info->sectorsize < PAGE_SIZE) {
 		btrfs_clear_opt(fs_info->mount_opt, SPACE_CACHE);
 		if (!btrfs_test_opt(fs_info, FREE_SPACE_TREE)) {
@@ -804,6 +792,35 @@ void btrfs_set_free_space_cache_settings(struct btrfs_fs_info *fs_info)
 			btrfs_set_opt(fs_info->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))
+		return;
+
+	if (btrfs_is_zoned(fs_info) &&
+	    btrfs_free_space_cache_v1_active(fs_info)) {
+		btrfs_info(fs_info, "zoned: clearing existing space cache");
+		btrfs_set_super_cache_generation(fs_info->super_copy, 0);
+		return;
+	}
+
+	if (btrfs_test_opt(fs_info, SPACE_CACHE))
+		return;
+
+	if (btrfs_test_opt(fs_info, NOSPACECACHE))
+		return;
+
+	/*
+	 * At this point we don't have explicit options set by the user, set
+	 * 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);
+	else if (btrfs_free_space_cache_v1_active(fs_info))
+		btrfs_set_opt(fs_info->mount_opt, SPACE_CACHE);
 }
 
 static int parse_rescue_options(struct btrfs_fs_info *info, const char *options)
@@ -1340,7 +1357,7 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
 		}
 	}
 out:
-	if (!ret && !check_options(info, &info->mount_opt, new_flags))
+	if (!ret && !btrfs_check_options(info, &info->mount_opt, new_flags))
 		ret = -EINVAL;
 	return ret;
 }
@@ -1641,10 +1658,6 @@ static int btrfs_fill_super(struct super_block *sb,
 #endif
 	sb->s_xattr = btrfs_xattr_handlers;
 	sb->s_time_gran = 1;
-#ifdef CONFIG_BTRFS_FS_POSIX_ACL
-	sb->s_flags |= SB_POSIXACL;
-#endif
-	sb->s_flags |= SB_I_VERSION;
 	sb->s_iflags |= SB_I_CGROUPWB;
 
 	err = super_setup_bdi(sb);
@@ -1924,7 +1937,7 @@ static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
  * Note: This is based on mount_bdev from fs/super.c with a few additions
  *       for multiple device setup.  Make sure to keep it in sync.
  */
-static struct dentry *btrfs_mount_root(struct file_system_type *fs_type,
+static __maybe_unused struct dentry *btrfs_mount_root(struct file_system_type *fs_type,
 		int flags, const char *device_name, void *data)
 {
 	struct block_device *bdev = NULL;
@@ -2057,7 +2070,7 @@ static struct dentry *btrfs_mount_root(struct file_system_type *fs_type,
  *   3. Call mount_subvol() to get the dentry of subvolume. Since there is
  *      "btrfs subvolume set-default", mount_subvol() is called always.
  */
-static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
+static __maybe_unused struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
 		const char *device_name, void *data)
 {
 	struct vfsmount *mnt_root;
@@ -2521,7 +2534,7 @@ static int btrfs_reconfigure(struct fs_context *fc)
 	set_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
 
 	if (!mount_reconfigure &&
-	    !check_options(fs_info, &ctx->mount_opt, fc->sb_flags))
+	    !btrfs_check_options(fs_info, &ctx->mount_opt, fc->sb_flags))
 		return -EINVAL;
 
 	ret = btrfs_check_features(fs_info, !(fc->sb_flags & SB_RDONLY));
@@ -3189,7 +3202,7 @@ static const struct fs_context_operations btrfs_fs_context_ops = {
 	.free		= btrfs_free_fs_context,
 };
 
-static int __maybe_unused btrfs_init_fs_context(struct fs_context *fc)
+static int btrfs_init_fs_context(struct fs_context *fc)
 {
 	struct btrfs_fs_context *ctx;
 
@@ -3210,24 +3223,22 @@ static int __maybe_unused btrfs_init_fs_context(struct fs_context *fc)
 		ctx->commit_interval = BTRFS_DEFAULT_COMMIT_INTERVAL;
 	}
 
+#ifdef CONFIG_BTRFS_FS_POSIX_ACL
+	fc->sb_flags |= SB_POSIXACL;
+#endif
+	fc->sb_flags |= SB_I_VERSION;
+
 	return 0;
 }
 
 static struct file_system_type btrfs_fs_type = {
-	.owner		= THIS_MODULE,
-	.name		= "btrfs",
-	.mount		= btrfs_mount,
-	.kill_sb	= btrfs_kill_super,
-	.fs_flags	= FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA,
-};
-
-static struct file_system_type btrfs_root_fs_type = {
-	.owner		= THIS_MODULE,
-	.name		= "btrfs",
-	.mount		= btrfs_mount_root,
-	.kill_sb	= btrfs_kill_super,
-	.fs_flags	= FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA | FS_ALLOW_IDMAP,
-};
+	.owner			= THIS_MODULE,
+	.name			= "btrfs",
+	.init_fs_context	= btrfs_init_fs_context,
+	.parameters		= btrfs_fs_parameters,
+	.kill_sb		= btrfs_kill_super,
+	.fs_flags		= FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA | FS_ALLOW_IDMAP,
+ };
 
 MODULE_ALIAS_FS("btrfs");
 
@@ -3440,7 +3451,6 @@ static const struct super_operations btrfs_super_ops = {
 	.destroy_inode	= btrfs_destroy_inode,
 	.free_inode	= btrfs_free_inode,
 	.statfs		= btrfs_statfs,
-	.remount_fs	= btrfs_remount,
 	.freeze_fs	= btrfs_freeze,
 	.unfreeze_fs	= btrfs_unfreeze,
 };
diff --git a/fs/btrfs/super.h b/fs/btrfs/super.h
index 7c1cd7527e76..7f6577d69902 100644
--- a/fs/btrfs/super.h
+++ b/fs/btrfs/super.h
@@ -3,6 +3,8 @@
 #ifndef BTRFS_SUPER_H
 #define BTRFS_SUPER_H
 
+bool btrfs_check_options(struct btrfs_fs_info *info, unsigned long *mount_opt,
+			 unsigned long flags);
 int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
 			unsigned long new_flags);
 int btrfs_sync_fs(struct super_block *sb, int wait);
-- 
2.41.0