linux-ext4 - Re: [PATCH 25/31] ext4: Convert ext4_block_write

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Date:   Mon, 06 Mar 2023 20:51:45 +0530
From:   Ritesh Harjani (IBM) <ritesh.list@...il.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Theodore Tso <tytso@....edu>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 25/31] ext4: Convert ext4_block_write_begin() to take a folio

Matthew Wilcox <willy@...radead.org> writes:

> On Mon, Mar 06, 2023 at 12:21:48PM +0530, Ritesh Harjani wrote:
>> "Matthew Wilcox (Oracle)" <willy@...radead.org> writes:
>>
>> > All the callers now have a folio, so pass that in and operate on folios.
>> > Removes four calls to compound_head().
>>
>> Why do you say four? Isn't it 3 calls of PageUptodate(page) which
>> removes calls to compound_head()? Which one did I miss?
>>
>> > -	BUG_ON(!PageLocked(page));
>> > +	BUG_ON(!folio_test_locked(folio));
>
> That one ;-)

__PAGEFLAG(Locked, locked, PF_NO_TAIL)

#define __PAGEFLAG(uname, lname, policy)				\
	TESTPAGEFLAG(uname, lname, policy)				\
	__SETPAGEFLAG(uname, lname, policy)				\
	__CLEARPAGEFLAG(uname, lname, policy)

#define TESTPAGEFLAG(uname, lname, policy)				\
static __always_inline bool folio_test_##lname(struct folio *folio)	\
{ return test_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); }	\
static __always_inline int Page##uname(struct page *page)		\
{ return test_bit(PG_##lname, &policy(page, 0)->flags); }

How? PageLocked(page) doesn't do any compount_head() calls no?

-ritesh

>
>> >  	} else if (fscrypt_inode_uses_fs_layer_crypto(inode)) {
>> >  		for (i = 0; i < nr_wait; i++) {
>> >  			int err2;
>> >
>> > -			err2 = fscrypt_decrypt_pagecache_blocks(page, blocksize,
>> > -								bh_offset(wait[i]));
>> > +			err2 = fscrypt_decrypt_pagecache_blocks(&folio->page,
>> > +						blocksize, bh_offset(wait[i]));
>>
>> folio_decrypt_pagecache_blocks() takes folio as it's argument now.
>>
>> Other than that it looks good to me. Please feel free to add -
>> Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@...il.com>
>
> Thanks.  I'll refresh this patchset next week.

Sure. Thanks!