ext4: close the external journal device in ->kill_sb

blkdev_put must not be called under sb->s_umount to avoid a lock order
reversal with disk->open_mutex.  Move closing the external journal device
into ->kill_sb to archive that.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Message-Id: <20230809220545.1308228-9-hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index b24f5b9..17c3e79 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -93,6 +93,7 @@ static int ext4_get_tree(struct fs_context *fc);
 static int ext4_reconfigure(struct fs_context *fc);
 static void ext4_fc_free(struct fs_context *fc);
 static int ext4_init_fs_context(struct fs_context *fc);
+static void ext4_kill_sb(struct super_block *sb);
 static const struct fs_parameter_spec ext4_param_specs[];
 
 /*
@@ -135,7 +136,7 @@ static struct file_system_type ext2_fs_type = {
        .name                   = "ext2",
        .init_fs_context        = ext4_init_fs_context,
        .parameters             = ext4_param_specs,
-       .kill_sb                = kill_block_super,
+       .kill_sb                = ext4_kill_sb,
        .fs_flags               = FS_REQUIRES_DEV,
 };
 MODULE_ALIAS_FS("ext2");
@@ -151,7 +152,7 @@ static struct file_system_type ext3_fs_type = {
        .name                   = "ext3",
        .init_fs_context        = ext4_init_fs_context,
        .parameters             = ext4_param_specs,
-       .kill_sb                = kill_block_super,
+       .kill_sb                = ext4_kill_sb,
        .fs_flags               = FS_REQUIRES_DEV,
 };
 MODULE_ALIAS_FS("ext3");
@@ -1125,25 +1126,6 @@ fail:
        return NULL;
 }
 
-/*
- * Release the journal device
- */
-static void ext4_blkdev_remove(struct ext4_sb_info *sbi)
-{
-       struct block_device *bdev;
-       bdev = sbi->s_journal_bdev;
-       if (bdev) {
-               /*
-                * Invalidate the journal device's buffers.  We don't want them
-                * floating about in memory - the physical journal device may
-                * hotswapped, and it breaks the `ro-after' testing code.
-                */
-               invalidate_bdev(bdev);
-               blkdev_put(bdev, sbi->s_sb);
-               sbi->s_journal_bdev = NULL;
-       }
-}
-
 static inline struct inode *orphan_list_entry(struct list_head *l)
 {
        return &list_entry(l, struct ext4_inode_info, i_orphan)->vfs_inode;
@@ -1339,8 +1321,13 @@ static void ext4_put_super(struct super_block *sb)
        sync_blockdev(sb->s_bdev);
        invalidate_bdev(sb->s_bdev);
        if (sbi->s_journal_bdev) {
+               /*
+                * Invalidate the journal device's buffers.  We don't want them
+                * floating about in memory - the physical journal device may
+                * hotswapped, and it breaks the `ro-after' testing code.
+                */
                sync_blockdev(sbi->s_journal_bdev);
-               ext4_blkdev_remove(sbi);
+               invalidate_bdev(sbi->s_journal_bdev);
        }
 
        ext4_xattr_destroy_cache(sbi->s_ea_inode_cache);
@@ -5663,9 +5650,11 @@ failed_mount:
                kfree(get_qf_name(sb, sbi, i));
 #endif
        fscrypt_free_dummy_policy(&sbi->s_dummy_enc_policy);
-       /* ext4_blkdev_remove() calls kill_bdev(), release bh before it. */
        brelse(sbi->s_sbh);
-       ext4_blkdev_remove(sbi);
+       if (sbi->s_journal_bdev) {
+               invalidate_bdev(sbi->s_journal_bdev);
+               blkdev_put(sbi->s_journal_bdev, sb);
+       }
 out_fail:
        invalidate_bdev(sb->s_bdev);
        sb->s_fs_info = NULL;
@@ -7272,12 +7261,23 @@ static inline int ext3_feature_set_ok(struct super_block *sb)
        return 1;
 }
 
+static void ext4_kill_sb(struct super_block *sb)
+{
+       struct ext4_sb_info *sbi = EXT4_SB(sb);
+       struct block_device *journal_bdev = sbi ? sbi->s_journal_bdev : NULL;
+
+       kill_block_super(sb);
+
+       if (journal_bdev)
+               blkdev_put(journal_bdev, sb);
+}
+
 static struct file_system_type ext4_fs_type = {
        .owner                  = THIS_MODULE,
        .name                   = "ext4",
        .init_fs_context        = ext4_init_fs_context,
        .parameters             = ext4_param_specs,
-       .kill_sb                = kill_block_super,
+       .kill_sb                = ext4_kill_sb,
        .fs_flags               = FS_REQUIRES_DEV | FS_ALLOW_IDMAP,
 };
 MODULE_ALIAS_FS("ext4");