diff mbox series

[RFC,v2,for-6.8/block,17/18] ext4: remove block_device_ejected()

Message ID 20231211140833.975935-1-yukuai1@huaweicloud.com (mailing list archive)
State New, archived
Headers show
Series block: don't access bd_inode directly from other modules | expand

Commit Message

Yu Kuai Dec. 11, 2023, 2:08 p.m. UTC 
From: Yu Kuai <yukuai3@huawei.com>

block_device_ejected() is added by commit bdfe0cbd746a ("Revert
"ext4: remove block_device_ejected"") in 2015. At that time 'bdi->wb'
is destroyed synchronized from del_gendisk(), hence if ext4 is still
mounted, and then mark_buffer_dirty() will reference destroyed 'wb'.
However, such problem doesn't exist anymore:

- commit d03f6cdc1fc4 ("block: Dynamically allocate and refcount
backing_dev_info") switch bdi to use refcounting;
- commit 13eec2363ef0 ("fs: Get proper reference for s_bdi"), will grab
additional reference of bdi while mounting, so that 'bdi->wb' will not
be destroyed until generic_shutdown_super().

Hence remove this dead function block_device_ejected().

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
 fs/ext4/super.c | 18 ------------------
 1 file changed, 18 deletions(-)

Comments

Jan Kara Dec. 11, 2023, 5:04 p.m. UTC | #1 
On Mon 11-12-23 22:08:33, Yu Kuai wrote:
> From: Yu Kuai <yukuai3@huawei.com>
> 
> block_device_ejected() is added by commit bdfe0cbd746a ("Revert
> "ext4: remove block_device_ejected"") in 2015. At that time 'bdi->wb'
> is destroyed synchronized from del_gendisk(), hence if ext4 is still
> mounted, and then mark_buffer_dirty() will reference destroyed 'wb'.
> However, such problem doesn't exist anymore:
> 
> - commit d03f6cdc1fc4 ("block: Dynamically allocate and refcount
> backing_dev_info") switch bdi to use refcounting;
> - commit 13eec2363ef0 ("fs: Get proper reference for s_bdi"), will grab
> additional reference of bdi while mounting, so that 'bdi->wb' will not
> be destroyed until generic_shutdown_super().
> 
> Hence remove this dead function block_device_ejected().
> 
> Signed-off-by: Yu Kuai <yukuai3@huawei.com>

Agreed, this should not be needed anymore. We'll see whether this is true
also in practice :). Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza
Christoph Hellwig Dec. 12, 2023, 1:22 p.m. UTC | #2 
Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>
diff mbox series

Patch

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index ae41204f52d4..3b5e2b557488 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -467,22 +467,6 @@  static void ext4_maybe_update_superblock(struct super_block *sb)
 		schedule_work(&EXT4_SB(sb)->s_sb_upd_work);
 }
 
-/*
- * The del_gendisk() function uninitializes the disk-specific data
- * structures, including the bdi structure, without telling anyone
- * else.  Once this happens, any attempt to call mark_buffer_dirty()
- * (for example, by ext4_commit_super), will cause a kernel OOPS.
- * This is a kludge to prevent these oops until we can put in a proper
- * hook in del_gendisk() to inform the VFS and file system layers.
- */
-static int block_device_ejected(struct super_block *sb)
-{
-	struct inode *bd_inode = sb->s_bdev->bd_inode;
-	struct backing_dev_info *bdi = inode_to_bdi(bd_inode);
-
-	return bdi->dev == NULL;
-}
-
 static void ext4_journal_commit_callback(journal_t *journal, transaction_t *txn)
 {
 	struct super_block		*sb = journal->j_private;
@@ -6162,8 +6146,6 @@  static int ext4_commit_super(struct super_block *sb)
 
 	if (!sbh)
 		return -EINVAL;
-	if (block_device_ejected(sb))
-		return -ENODEV;
 
 	ext4_update_super(sb);