Re: [PATCH v3 1/2] filemap: find_lock_entries() now updates start offset

[Matthew Wilcox <willy@infradead.org>]

On Mon, Oct 17, 2022 at 09:17:59AM -0700, Vishal Moola (Oracle) wrote:
> +++ b/mm/shmem.c
> @@ -932,21 +932,18 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
>  
>  	folio_batch_init(&fbatch);
>  	index = start;
> -	while (index < end && find_lock_entries(mapping, index, end - 1,
> +	while (index < end && find_lock_entries(mapping, &index, end - 1,

Sorry for not spotting this in earlier revisions, but this is wrong.
Before, find_lock_entries() would go up to (end - 1) and then the
index++ at the end of the loop would increment index to "end", causing
the loop to terminate.  Now we don't increment index any more, so the
condition is wrong.

I suggest just removing the 'index < end" half of the condition.

> @@ -361,9 +361,8 @@ void truncate_inode_pages_range(struct address_space *mapping,
>  
>  	folio_batch_init(&fbatch);
>  	index = start;
> -	while (index < end && find_lock_entries(mapping, index, end - 1,
> +	while (index < end && find_lock_entries(mapping, &index, end - 1,
>  			&fbatch, indices)) {

Similarly here.

> @@ -510,20 +509,17 @@ unsigned long invalidate_mapping_pagevec(struct address_space *mapping,
>  	int i;
>  
>  	folio_batch_init(&fbatch);
> -	while (find_lock_entries(mapping, index, end, &fbatch, indices)) {
> +	while (find_lock_entries(mapping, &index, end, &fbatch, indices)) {

While this one had the check removed already, so is fine ;-)