Re: [PATCH -next v5 24/32] ext4: advance i_disksize to i_size upon disksize-grow I/O completion

On 8/14/2026 6:25 PM, [email protected] wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [High] The EXT4_STATE_DISKSIZE_GROW_PENDING state bit is never set anywhere in the codebase, rendering the entire disksize-grow logic and safety mechanism inert.
> --
> 

This is a false positive. EXT4_STATE_DISKSIZE_GROW_PENDING is set
in patch 28. This patch is just preparing for that functionality.

Thanks,
Yi.


> --- Patch [24]: [PATCH -next v5 24/32] ext4: advance i_disksize to i_size upon disksize-grow I/O completion ---
> commit d834c25602b493451d52cc75b3ae8fd40461bce9
> Author: Zhang Yi <[email protected]>
> 
> ext4: advance i_disksize to i_size upon disksize-grow I/O completion
> 
> This commit updates the iomap writeback path to advance i_disksize to i_size
> upon completion of a disksize-grow I/O. It introduces an is_disksize_grow flag
> to ext4_iomap_wb_update_disksize() to trigger this update safely.
> 
>> diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
>> index 955ff88045db6..4f1176b9332f2 100644
>> --- a/fs/ext4/page-io.c
>> +++ b/fs/ext4/page-io.c
> [ ... ]
>> @@ -589,9 +589,36 @@ static int ext4_iomap_wb_update_disksize(handle_t *handle, struct inode *inode,
>>   	 * i_data_sem.
>>   	 */
>>   	down_write(&ei->i_data_sem);
>> -	new_disksize = min(new_disksize, i_size_read(inode));
>> +	i_size = i_size_read(inode);
>> +
>> +	/*
>> +	 * EXT4_STATE_DISKSIZE_GROW_PENDING is cleared when the pending
>> +	 * I/O completes. However, another thread may have re-set the bit
>> +	 * between that point and here, meaning i_disksize has already
>> +	 * been advanced and a new EOF zeroing has been initiated. In that
>> +	 * case, do not advance i_disksize to i_size; leave it to the
>> +	 * next pending grow ioend.
>> +	 */
>> +	if (is_disksize_grow &&
>> +	    ext4_test_inode_state(inode, EXT4_STATE_DISKSIZE_GROW_PENDING))
>> +		is_disksize_grow = false;
> 
> [Severity: High]
> Is EXT4_STATE_DISKSIZE_GROW_PENDING actually set anywhere in the codebase?
> 
> It appears this state bit is never set, such as during EOF zeroing in
> ext4_block_zero_eof() where there is a TODO comment about tracking the
> ordered range.
> 
> If the bit is never set, ext4_test_inode_state() will always return false
> and this safety check will be bypassed during concurrent fallocate and
> truncate operations.
> 
> [ ... ]
>> @@ -607,6 +634,8 @@ static void ext4_iomap_finish_ioend(struct iomap_ioend *ioend)
>>   	loff_t pos = ioend->io_offset;
>>   	size_t size = ioend->io_size;
>>   	loff_t end = pos + size;
>> +	unsigned long io_mode = (unsigned long)ioend->io_private;
>> +	bool is_disksize_grow = (io_mode == EXT4_IOMAP_IOEND_DISKSIZE_GROW_IO);
> 
> [Severity: High]
> Is EXT4_IOMAP_IOEND_DISKSIZE_GROW_IO ever assigned to ioend->io_private?
> 
> Because the EXT4_STATE_DISKSIZE_GROW_PENDING bit is never set, it seems
> ext4_iomap_get_disksize_pending_range() will always return 0, meaning this
> io_mode flag is never assigned.
> 
> Does this render the entire disksize-grow logic inert?
>