Commit 3b672e3a authored by Zhang Yi's avatar Zhang Yi Committed by Theodore Ts'o
Browse files

ext4: remove bdev_try_to_free_page() callback 



After we introduce a jbd2 shrinker to release checkpointed buffer's
journal head, we could free buffer without bdev_try_to_free_page()
under memory pressure. So this patch remove the whole
bdev_try_to_free_page() callback directly. It also remove many
use-after-free issues relate to it together.

Signed-off-by: default avatarZhang Yi <yi.zhang@huawei.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20210610112440.3438139-8-yi.zhang@huawei.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent dbf2bab7

fs/ext4/super.c

+0 −21
Original line number Diff line number Diff line
@@ -1442,26 +1442,6 @@ static int ext4_nfs_commit_metadata(struct inode *inode) 
	return ext4_write_inode(inode, &wbc);

}



/*

 * Try to release metadata pages (indirect blocks, directories) which are

 * mapped via the block device.  Since these pages could have journal heads

 * which would prevent try_to_free_buffers() from freeing them, we must use

 * jbd2 layer's try_to_free_buffers() function to release them.

 */

static int bdev_try_to_free_page(struct super_block *sb, struct page *page,

				 gfp_t wait)

{

	journal_t *journal = EXT4_SB(sb)->s_journal;



	WARN_ON(PageChecked(page));

	if (!page_has_buffers(page))

		return 0;

	if (journal)

		return jbd2_journal_try_to_free_buffers(journal, page);



	return try_to_free_buffers(page);

}



#ifdef CONFIG_FS_ENCRYPTION

static int ext4_get_context(struct inode *inode, void *ctx, size_t len)

{
@@ -1656,7 +1636,6 @@ static const struct super_operations ext4_sops = { 
	.quota_write	= ext4_quota_write,

	.get_dquots	= ext4_get_dquots,

#endif

	.bdev_try_to_free_page = bdev_try_to_free_page,

};



static const struct export_operations ext4_export_ops = {