linux-kernel - Re: [PATCH v2 4/7] btrfs: Convert process_page_range() to use filemap_get_folios

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Message-ID: <20220823203825.GT13489@twin.jikos.cz>
Date:   Tue, 23 Aug 2022 22:38:25 +0200
From:   David Sterba <dsterba@...e.cz>
To:     "Vishal Moola (Oracle)" <vishal.moola@...il.com>
Cc:     linux-fsdevel@...r.kernel.org, linux-btrfs@...r.kernel.org,
        linux-nilfs@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/7] btrfs: Convert process_page_range() to use
 filemap_get_folios_contig()

On Tue, Aug 16, 2022 at 10:52:43AM -0700, Vishal Moola (Oracle) wrote:
> Converted function to use folios throughout. This is in preparation for
> the removal of find_get_pages_contig(). Now also supports large folios.
> 
> Since we may receive more than nr_pages pages, nr_pages may underflow.
> Since nr_pages > 0 is equivalent to index <= end_index, we replaced it
> with this check instead.
> 
> Also minor comment renaming for consistency in subpage.
> 
> Signed-off-by: Vishal Moola (Oracle) <vishal.moola@...il.com>

Acked-by: David Sterba <dsterba@...e.com>

> --- a/fs/btrfs/tests/extent-io-tests.c
> +++ b/fs/btrfs/tests/extent-io-tests.c
> @@ -4,6 +4,7 @@
>   */
>  
>  #include <linux/pagemap.h>
> +#include <linux/pagevec.h>
>  #include <linux/sched.h>
>  #include <linux/slab.h>
>  #include <linux/sizes.h>
> @@ -20,39 +21,39 @@ static noinline int process_page_range(struct inode *inode, u64 start, u64 end,
>  				       unsigned long flags)
>  {
>  	int ret;
> -	struct page *pages[16];
> +	struct folio_batch fbatch;
>  	unsigned long index = start >> PAGE_SHIFT;
>  	unsigned long end_index = end >> PAGE_SHIFT;
> -	unsigned long nr_pages = end_index - index + 1;
>  	int i;
>  	int count = 0;
>  	int loops = 0;
>  
> -	while (nr_pages > 0) {
> -		ret = find_get_pages_contig(inode->i_mapping, index,
> -				     min_t(unsigned long, nr_pages,
> -				     ARRAY_SIZE(pages)), pages);
> +	folio_batch_init(&fbatch);
> +
> +	while (index <= end_index) {
> +		ret = filemap_get_folios_contig(inode->i_mapping, &index,
> +				end_index, &fbatch);
>  		for (i = 0; i < ret; i++) {
> +			struct folio *folio = fbatch.folios[i];

Add a newline please

>  			if (flags & PROCESS_TEST_LOCKED &&
> -			    !PageLocked(pages[i]))
> +			    !folio_test_locked(folio))
>  				count++;
> -			if (flags & PROCESS_UNLOCK && PageLocked(pages[i]))
> -				unlock_page(pages[i]);
> -			put_page(pages[i]);
> +			if (flags & PROCESS_UNLOCK && folio_test_locked(folio))
> +				folio_unlock(folio);
>  			if (flags & PROCESS_RELEASE)
> -				put_page(pages[i]);
> +				folio_put(folio);
>  		}
> -		nr_pages -= ret;
> -		index += ret;
> +		folio_batch_release(&fbatch);
>  		cond_resched();
>  		loops++;
>  		if (loops > 100000) {
>  			printk(KERN_ERR
> -		"stuck in a loop, start %llu, end %llu, nr_pages %lu, ret %d\n",
> -				start, end, nr_pages, ret);
> +		"stuck in a loop, start %llu, end %llu, ret %d\n",
> +				start, end, ret);
>  			break;
>  		}
>  	}
> +
>  	return count;
>  }
>  
> -- 
> 2.36.1