Re: [PATCH -next] ext4: fix bug_on in ext4_writepages

[yebin <yebin10@huawei.com>]

On 2022/5/5 23:47, Jan Kara wrote:
> On Thu 05-05-22 21:57:08, Ye Bin wrote:
>> we got issue as follows:
>> EXT4-fs error (device loop0): ext4_mb_generate_buddy:1141: group 0, block bitmap and bg descriptor inconsistent: 25 vs 31513 free cls
>> ------------[ cut here ]------------
>> kernel BUG at fs/ext4/inode.c:2708!
>> invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
>> CPU: 2 PID: 2147 Comm: rep Not tainted 5.18.0-rc2-next-20220413+ #155
>> RIP: 0010:ext4_writepages+0x1977/0x1c10
>> RSP: 0018:ffff88811d3e7880 EFLAGS: 00010246
>> RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffff88811c098000
>> RDX: 0000000000000000 RSI: ffff88811c098000 RDI: 0000000000000002
>> RBP: ffff888128140f50 R08: ffffffffb1ff6387 R09: 0000000000000000
>> R10: 0000000000000007 R11: ffffed10250281ea R12: 0000000000000001
>> R13: 00000000000000a4 R14: ffff88811d3e7bb8 R15: ffff888128141028
>> FS:  00007f443aed9740(0000) GS:ffff8883aef00000(0000) knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 0000000020007200 CR3: 000000011c2a4000 CR4: 00000000000006e0
>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> Call Trace:
>>   <TASK>
>>   do_writepages+0x130/0x3a0
>>   filemap_fdatawrite_wbc+0x83/0xa0
>>   filemap_flush+0xab/0xe0
>>   ext4_alloc_da_blocks+0x51/0x120
>>   __ext4_ioctl+0x1534/0x3210
>>   __x64_sys_ioctl+0x12c/0x170
>>   do_syscall_64+0x3b/0x90
>>
>> It may happen as follows:
>> 1. write inline_data inode
>> vfs_write
>>    new_sync_write
>>      ext4_file_write_iter
>>        ext4_buffered_write_iter
>>          generic_perform_write
>> 	  ext4_da_write_begin
>> 	    ext4_da_write_inline_data_begin -> If inline data size too
>> 	    small will allocate block to write, then mapping will has
>> 	    dirty page
>> 	    	ext4_da_convert_inline_data_to_extent ->clear EXT4_STATE_MAY_INLINE_DATA
>> 2. fallocate
>> do_vfs_ioctl
>>    ioctl_preallocate
>>      vfs_fallocate
>>        ext4_fallocate
>>          ext4_convert_inline_data
>> 	  ext4_convert_inline_data_nolock
>> 	    ext4_map_blocks -> fail will goto restore data
>> 	    ext4_restore_inline_data
>> 	      ext4_create_inline_data
>> 	      ext4_write_inline_data
>> 	      ext4_set_inode_state -> set inode EXT4_STATE_MAY_INLINE_DATA
>> 3. writepages
>> __ext4_ioctl
>>    ext4_alloc_da_blocks
>>      filemap_flush
>>        filemap_fdatawrite_wbc
>>          do_writepages
>> 	  ext4_writepages
>> 	    if (ext4_has_inline_data(inode))
>> 	      BUG_ON(ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA))
>>
>> To solved this issue, record origin 'EXT4_STATE_MAY_INLINE_DATA' flag, then pass
>> value to 'ext4_restore_inline_data', 'ext4_restore_inline_data' will
>> decide to if recovery 'EXT4_STATE_MAY_INLINE_DATA' flag according to parameter.
>>
>> Signed-off-by: Ye Bin <yebin10@huawei.com>
> I think this will get also fixed by a patch from your colleague I've
> reviewed here [1], won't it?
>
> [1] https://lore.kernel.org/all/20220428165725.mvjh6mx7gr5vekqe@quack3.lan
>
> 								Honza
The issue I fixed is not the same as the isuue my colleague fixed.
>> ---
>>   fs/ext4/inline.c | 13 +++++++++----
>>   1 file changed, 9 insertions(+), 4 deletions(-)
>>
>> diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
>> index 9c076262770d..407061c79adc 100644
>> --- a/fs/ext4/inline.c
>> +++ b/fs/ext4/inline.c
>> @@ -1125,8 +1125,8 @@ static int ext4_update_inline_dir(handle_t *handle, struct inode *dir,
>>   }
>>   
>>   static void ext4_restore_inline_data(handle_t *handle, struct inode *inode,
>> -				     struct ext4_iloc *iloc,
>> -				     void *buf, int inline_size)
>> +				     struct ext4_iloc *iloc, void *buf,
>> +				     int inline_size, bool has_data)
>>   {
>>   	int ret;
>>   
>> @@ -1138,7 +1138,8 @@ static void ext4_restore_inline_data(handle_t *handle, struct inode *inode,
>>   		return;
>>   	}
>>   	ext4_write_inline_data(inode, iloc, buf, 0, inline_size);
>> -	ext4_set_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA);
>> +	if (has_data)
>> +		ext4_set_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA);
>>   }
>>   
>>   static int ext4_finish_convert_inline_dir(handle_t *handle,
>> @@ -1194,6 +1195,7 @@ static int ext4_convert_inline_data_nolock(handle_t *handle,
>>   	struct buffer_head *data_bh = NULL;
>>   	struct ext4_map_blocks map;
>>   	int inline_size;
>> +	bool has_data;
>>   
>>   	inline_size = ext4_get_inline_size(inode);
>>   	buf = kmalloc(inline_size, GFP_NOFS);
>> @@ -1222,6 +1224,8 @@ static int ext4_convert_inline_data_nolock(handle_t *handle,
>>   	if (error)
>>   		goto out;
>>   
>> +	has_data = !!ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA);
>> +
>>   	map.m_lblk = 0;
>>   	map.m_len = 1;
>>   	map.m_flags = 0;
>> @@ -1262,7 +1266,8 @@ static int ext4_convert_inline_data_nolock(handle_t *handle,
>>   	unlock_buffer(data_bh);
>>   out_restore:
>>   	if (error)
>> -		ext4_restore_inline_data(handle, inode, iloc, buf, inline_size);
>> +		ext4_restore_inline_data(handle, inode, iloc, buf,
>> +					 inline_size, has_data);
>>   
>>   out:
>>   	brelse(data_bh);
>> -- 
>> 2.31.1
>>