On Sat, May 26, 2018 at 07:42:46AM -0400, Jeff Layton wrote:
>On Sat, 2018-05-26 at 10:42 +0800, Lu Fengqi wrote:
>> Creating a file reuses the inode object by kmem_cache_alloc without
>> initializing maping->wb_err. If it contains an unseen writeback error,
>> fsync will report an error on the file, even if no error has ever occurred
>> after the file was created.
>>
>> Before commit b4678df184b3 ("errseq: Always report a writeback error
>> once"), any errors that occur before the file descriptor is opened will be
>> ignored, causing the issue not to be found. Afterward, any unseen writeback
>> error will be reported once, including, of course, the uninitialized
>> maping->wb_err, which exposes this problem.
>>
>> Signed-off-by: Lu Fengqi <lufq.fnst@xxxxxxxxxxxxxx>
>> ---
>> fs/inode.c | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/fs/inode.c b/fs/inode.c
>> index 13ceb98c3bd3..bf02dc9d1837 100644
>> --- a/fs/inode.c
>> +++ b/fs/inode.c
>> @@ -182,6 +182,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
>> mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
>> mapping->private_data = NULL;
>> mapping->writeback_index = 0;
>> + mapping->wb_err = 0;
>> inode->i_private = NULL;
>> inode->i_mapping = mapping;
>> INIT_HLIST_HEAD(&inode->i_dentry); /* buggered by rcu freeing */
>
>(cc'ing Darrick)
>
>I think Darrick had a similar patch that also fixed up some related
>inode reuse issues in xfs. Darrick, were you planning to get that
>merged for v4.17?
Oh, I missed Darrick's patch. Thanks for your reminder.
--
Thanks,
Lu
>--
>Jeff Layton <jlayton@xxxxxxxxxx>
>
>
