Re: [PATCH 09/23] ocfs2: Convert w_pages to w_folios

[Joseph Qi <joseph.qi@linux.alibaba.com>]

On 2024/12/6 01:16, Matthew Wilcox (Oracle) wrote:
> From: Mark Tinguely <mark.tinguely@oracle.com>
> 
> Pass around an array of folios instead of an array of pages.
> Removes a few calls to compound_head().
> 
> Signed-off-by: Mark Tinguely <mark.tinguely@oracle.com>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Looks good.
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>

> ---
>  fs/ocfs2/aops.c | 118 ++++++++++++++++++++++++++----------------------
>  fs/ocfs2/aops.h |   1 +
>  2 files changed, 65 insertions(+), 54 deletions(-)
> 
> diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
> index 161f2dc00b00..afc20ab52b3e 100644
> --- a/fs/ocfs2/aops.c
> +++ b/fs/ocfs2/aops.c
> @@ -729,19 +729,19 @@ struct ocfs2_write_ctxt {
>  	unsigned int			w_large_pages;
>  
>  	/*
> -	 * Pages involved in this write.
> +	 * Folios involved in this write.
>  	 *
>  	 * w_target_folio is the folio being written to by the user.
>  	 *
> -	 * w_pages is an array of pages which always contains
> +	 * w_folios is an array of folios which always contains
>  	 * w_target_folio, and in the case of an allocating write with
>  	 * page_size < cluster size, it will contain zero'd and mapped
>  	 * pages adjacent to w_target_folio which need to be written
>  	 * out in so that future reads from that region will get
>  	 * zero's.
>  	 */
> -	unsigned int			w_num_pages;
> -	struct page			*w_pages[OCFS2_MAX_CTXT_PAGES];
> +	unsigned int			w_num_folios;
> +	struct folio			*w_folios[OCFS2_MAX_CTXT_PAGES];
>  	struct folio			*w_target_folio;
>  
>  	/*
> @@ -771,6 +771,19 @@ struct ocfs2_write_ctxt {
>  	unsigned int			w_unwritten_count;
>  };
>  
> +void ocfs2_unlock_and_free_folios(struct folio **folios, int num_folios)
> +{
> +	int i;
> +
> +	for(i = 0; i < num_folios; i++) {
> +		if (!folios[i])
> +			continue;
> +		folio_unlock(folios[i]);
> +		folio_mark_accessed(folios[i]);
> +		folio_put(folios[i]);
> +	}
> +}
> +
>  void ocfs2_unlock_and_free_pages(struct page **pages, int num_pages)
>  {
>  	int i;
> @@ -784,7 +797,7 @@ void ocfs2_unlock_and_free_pages(struct page **pages, int num_pages)
>  	}
>  }
>  
> -static void ocfs2_unlock_pages(struct ocfs2_write_ctxt *wc)
> +static void ocfs2_unlock_folios(struct ocfs2_write_ctxt *wc)
>  {
>  	int i;
>  
> @@ -795,16 +808,16 @@ static void ocfs2_unlock_pages(struct ocfs2_write_ctxt *wc)
>  	 */
>  	if (wc->w_target_locked) {
>  		BUG_ON(!wc->w_target_folio);
> -		for (i = 0; i < wc->w_num_pages; i++) {
> -			if (&wc->w_target_folio->page == wc->w_pages[i]) {
> -				wc->w_pages[i] = NULL;
> +		for (i = 0; i < wc->w_num_folios; i++) {
> +			if (wc->w_target_folio == wc->w_folios[i]) {
> +				wc->w_folios[i] = NULL;
>  				break;
>  			}
>  		}
>  		folio_mark_accessed(wc->w_target_folio);
>  		folio_put(wc->w_target_folio);
>  	}
> -	ocfs2_unlock_and_free_pages(wc->w_pages, wc->w_num_pages);
> +	ocfs2_unlock_and_free_folios(wc->w_folios, wc->w_num_folios);
>  }
>  
>  static void ocfs2_free_unwritten_list(struct inode *inode,
> @@ -826,7 +839,7 @@ static void ocfs2_free_write_ctxt(struct inode *inode,
>  				  struct ocfs2_write_ctxt *wc)
>  {
>  	ocfs2_free_unwritten_list(inode, &wc->w_unwritten_list);
> -	ocfs2_unlock_pages(wc);
> +	ocfs2_unlock_folios(wc);
>  	brelse(wc->w_di_bh);
>  	kfree(wc);
>  }
> @@ -922,8 +935,8 @@ static void ocfs2_write_failure(struct inode *inode,
>  	if (wc->w_target_folio)
>  		ocfs2_zero_new_buffers(wc->w_target_folio, from, to);
>  
> -	for(i = 0; i < wc->w_num_pages; i++) {
> -		tmppage = wc->w_pages[i];
> +	for (i = 0; i < wc->w_num_folios; i++) {
> +		tmppage = &wc->w_folios[i]->page;
>  
>  		if (tmppage && page_has_buffers(tmppage)) {
>  			if (ocfs2_should_order_data(inode))
> @@ -935,12 +948,11 @@ static void ocfs2_write_failure(struct inode *inode,
>  	}
>  }
>  
> -static int ocfs2_prepare_page_for_write(struct inode *inode, u64 *p_blkno,
> -					struct ocfs2_write_ctxt *wc,
> -					struct page *page, u32 cpos,
> -					loff_t user_pos, unsigned user_len,
> -					int new)
> +static int ocfs2_prepare_folio_for_write(struct inode *inode, u64 *p_blkno,
> +		struct ocfs2_write_ctxt *wc, struct folio *folio, u32 cpos,
> +		loff_t user_pos, unsigned user_len, int new)
>  {
> +	struct page *page = &folio->page;
>  	int ret;
>  	unsigned int map_from = 0, map_to = 0;
>  	unsigned int cluster_start, cluster_end;
> @@ -1019,11 +1031,9 @@ static int ocfs2_prepare_page_for_write(struct inode *inode, u64 *p_blkno,
>  /*
>   * This function will only grab one clusters worth of pages.
>   */
> -static int ocfs2_grab_pages_for_write(struct address_space *mapping,
> -				      struct ocfs2_write_ctxt *wc,
> -				      u32 cpos, loff_t user_pos,
> -				      unsigned user_len, int new,
> -				      struct folio *mmap_folio)
> +static int ocfs2_grab_folios_for_write(struct address_space *mapping,
> +		struct ocfs2_write_ctxt *wc, u32 cpos, loff_t user_pos,
> +		unsigned user_len, int new, struct folio *mmap_folio)
>  {
>  	int ret = 0, i;
>  	unsigned long start, target_index, end_index, index;
> @@ -1040,7 +1050,7 @@ static int ocfs2_grab_pages_for_write(struct address_space *mapping,
>  	 * last page of the write.
>  	 */
>  	if (new) {
> -		wc->w_num_pages = ocfs2_pages_per_cluster(inode->i_sb);
> +		wc->w_num_folios = ocfs2_pages_per_cluster(inode->i_sb);
>  		start = ocfs2_align_clusters_to_page_index(inode->i_sb, cpos);
>  		/*
>  		 * We need the index *past* the last page we could possibly
> @@ -1050,15 +1060,15 @@ static int ocfs2_grab_pages_for_write(struct address_space *mapping,
>  		last_byte = max(user_pos + user_len, i_size_read(inode));
>  		BUG_ON(last_byte < 1);
>  		end_index = ((last_byte - 1) >> PAGE_SHIFT) + 1;
> -		if ((start + wc->w_num_pages) > end_index)
> -			wc->w_num_pages = end_index - start;
> +		if ((start + wc->w_num_folios) > end_index)
> +			wc->w_num_folios = end_index - start;
>  	} else {
> -		wc->w_num_pages = 1;
> +		wc->w_num_folios = 1;
>  		start = target_index;
>  	}
>  	end_index = (user_pos + user_len - 1) >> PAGE_SHIFT;
>  
> -	for(i = 0; i < wc->w_num_pages; i++) {
> +	for(i = 0; i < wc->w_num_folios; i++) {
>  		index = start + i;
>  
>  		if (index >= target_index && index <= end_index &&
> @@ -1079,26 +1089,27 @@ static int ocfs2_grab_pages_for_write(struct address_space *mapping,
>  			}
>  
>  			folio_get(mmap_folio);
> -			wc->w_pages[i] = &mmap_folio->page;
> +			wc->w_folios[i] = mmap_folio;
>  			wc->w_target_locked = true;
>  		} else if (index >= target_index && index <= end_index &&
>  			   wc->w_type == OCFS2_WRITE_DIRECT) {
>  			/* Direct write has no mapping page. */
> -			wc->w_pages[i] = NULL;
> +			wc->w_folios[i] = NULL;
>  			continue;
>  		} else {
> -			wc->w_pages[i] = find_or_create_page(mapping, index,
> -							     GFP_NOFS);
> -			if (!wc->w_pages[i]) {
> -				ret = -ENOMEM;
> +			wc->w_folios[i] = __filemap_get_folio(mapping, index,
> +					FGP_LOCK | FGP_ACCESSED | FGP_CREAT,
> +					GFP_NOFS);
> +			if (IS_ERR(wc->w_folios[i])) {
> +				ret = PTR_ERR(wc->w_folios[i]);
>  				mlog_errno(ret);
>  				goto out;
>  			}
>  		}
> -		wait_for_stable_page(wc->w_pages[i]);
> +		folio_wait_stable(wc->w_folios[i]);
>  
>  		if (index == target_index)
> -			wc->w_target_folio = page_folio(wc->w_pages[i]);
> +			wc->w_target_folio = wc->w_folios[i];
>  	}
>  out:
>  	if (ret)
> @@ -1182,19 +1193,18 @@ static int ocfs2_write_cluster(struct address_space *mapping,
>  	if (!should_zero)
>  		p_blkno += (user_pos >> inode->i_sb->s_blocksize_bits) & (u64)(bpc - 1);
>  
> -	for(i = 0; i < wc->w_num_pages; i++) {
> +	for (i = 0; i < wc->w_num_folios; i++) {
>  		int tmpret;
>  
>  		/* This is the direct io target page. */
> -		if (wc->w_pages[i] == NULL) {
> +		if (wc->w_folios[i] == NULL) {
>  			p_blkno += (1 << (PAGE_SHIFT - inode->i_sb->s_blocksize_bits));
>  			continue;
>  		}
>  
> -		tmpret = ocfs2_prepare_page_for_write(inode, &p_blkno, wc,
> -						      wc->w_pages[i], cpos,
> -						      user_pos, user_len,
> -						      should_zero);
> +		tmpret = ocfs2_prepare_folio_for_write(inode, &p_blkno, wc,
> +				wc->w_folios[i], cpos, user_pos, user_len,
> +				should_zero);
>  		if (tmpret) {
>  			mlog_errno(tmpret);
>  			if (ret == 0)
> @@ -1493,12 +1503,12 @@ static int ocfs2_write_begin_inline(struct address_space *mapping,
>  		goto out;
>  	}
>  	/*
> -	 * If we don't set w_num_pages then this folio won't get unlocked
> +	 * If we don't set w_num_folios then this folio won't get unlocked
>  	 * and freed on cleanup of the write context.
>  	 */
>  	wc->w_target_folio = folio;
> -	wc->w_pages[0] = &folio->page;
> -	wc->w_num_pages = 1;
> +	wc->w_folios[0] = folio;
> +	wc->w_num_folios = 1;
>  
>  	ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), wc->w_di_bh,
>  				      OCFS2_JOURNAL_ACCESS_WRITE);
> @@ -1791,18 +1801,18 @@ int ocfs2_write_begin_nolock(struct address_space *mapping,
>  	}
>  
>  	/*
> -	 * Fill our page array first. That way we've grabbed enough so
> +	 * Fill our folio array first. That way we've grabbed enough so
>  	 * that we can zero and flush if we error after adding the
>  	 * extent.
>  	 */
> -	ret = ocfs2_grab_pages_for_write(mapping, wc, wc->w_cpos, pos, len,
> -					 cluster_of_pages, mmap_folio);
> +	ret = ocfs2_grab_folios_for_write(mapping, wc, wc->w_cpos, pos, len,
> +			cluster_of_pages, mmap_folio);
>  	if (ret) {
>  		/*
> -		 * ocfs2_grab_pages_for_write() returns -EAGAIN if it could not lock
> -		 * the target page. In this case, we exit with no error and no target
> -		 * page. This will trigger the caller, page_mkwrite(), to re-try
> -		 * the operation.
> +		 * ocfs2_grab_folios_for_write() returns -EAGAIN if it
> +		 * could not lock the target folio. In this case, we exit
> +		 * with no error and no target folio. This will trigger
> +		 * the caller, page_mkwrite(), to re-try the operation.
>  		 */
>  		if (type == OCFS2_WRITE_MMAP && ret == -EAGAIN) {
>  			BUG_ON(wc->w_target_folio);
> @@ -1997,8 +2007,8 @@ int ocfs2_write_end_nolock(struct address_space *mapping,
>  	if (wc->w_target_folio)
>  		flush_dcache_folio(wc->w_target_folio);
>  
> -	for(i = 0; i < wc->w_num_pages; i++) {
> -		tmppage = wc->w_pages[i];
> +	for (i = 0; i < wc->w_num_folios; i++) {
> +		tmppage = &wc->w_folios[i]->page;
>  
>  		/* This is the direct io target page. */
>  		if (tmppage == NULL)
> @@ -2059,7 +2069,7 @@ int ocfs2_write_end_nolock(struct address_space *mapping,
>  	 * this lock and will ask for the page lock when flushing the data.
>  	 * put it here to preserve the unlock order.
>  	 */
> -	ocfs2_unlock_pages(wc);
> +	ocfs2_unlock_folios(wc);
>  
>  	if (handle)
>  		ocfs2_commit_trans(osb, handle);
> diff --git a/fs/ocfs2/aops.h b/fs/ocfs2/aops.h
> index 1cb46072ad84..dcf4b0dc82c4 100644
> --- a/fs/ocfs2/aops.h
> +++ b/fs/ocfs2/aops.h
> @@ -17,6 +17,7 @@ int ocfs2_map_page_blocks(struct page *page, u64 *p_blkno,
>  			  struct inode *inode, unsigned int from,
>  			  unsigned int to, int new);
>  
> +void ocfs2_unlock_and_free_folios(struct folio **folios, int num_folios);
>  void ocfs2_unlock_and_free_pages(struct page **pages, int num_pages);
>  
>  int walk_page_buffers(	handle_t *handle,