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From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org,
	Kent Overstreet <kent.overstreet@gmail.com>,
	Christoph Hellwig <hch@lst.de>
Subject: [PATCH v5 09/18] mm/filemap: Change filemap_read_page calling conventions
Date: Fri, 22 Jan 2021 16:01:31 +0000
Message-ID: <20210122160140.223228-10-willy@infradead.org> (raw)
In-Reply-To: <20210122160140.223228-1-willy@infradead.org>

Make this function more generic by passing the file instead of the iocb.
Check in the callers whether we should call readpage or not.  Also make
it return an errno / 0 / AOP_TRUNCATED_PAGE, and make calling put_page()
the caller's responsibility.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Kent Overstreet <kent.overstreet@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 mm/filemap.c | 89 +++++++++++++++++++++++++---------------------------
 1 file changed, 42 insertions(+), 47 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index ee1255a88106f..ceb2931f5725f 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2212,56 +2212,38 @@ static void filemap_get_read_batch(struct address_space *mapping,
 	rcu_read_unlock();
 }
 
-static struct page *filemap_read_page(struct kiocb *iocb, struct file *filp,
-		struct address_space *mapping, struct page *page)
+static int filemap_read_page(struct file *file, struct address_space *mapping,
+		struct page *page)
 {
-	struct file_ra_state *ra = &filp->f_ra;
 	int error;
 
-	if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT | IOCB_WAITQ)) {
-		unlock_page(page);
-		put_page(page);
-		return ERR_PTR(-EAGAIN);
-	}
-
 	/*
-	 * A previous I/O error may have been due to temporary
-	 * failures, eg. multipath errors.
-	 * PG_error will be set again if readpage fails.
+	 * A previous I/O error may have been due to temporary failures,
+	 * eg. multipath errors.  PG_error will be set again if readpage
+	 * fails.
 	 */
 	ClearPageError(page);
 	/* Start the actual read. The read will unlock the page. */
-	error = mapping->a_ops->readpage(filp, page);
-
-	if (unlikely(error)) {
-		put_page(page);
-		return error != AOP_TRUNCATED_PAGE ? ERR_PTR(error) : NULL;
-	}
+	error = mapping->a_ops->readpage(file, page);
+	if (error)
+		return error;
+	if (PageUptodate(page))
+		return 0;
 
+	error = lock_page_killable(page);
+	if (error)
+		return error;
 	if (!PageUptodate(page)) {
-		error = lock_page_killable(page);
-		if (unlikely(error)) {
-			put_page(page);
-			return ERR_PTR(error);
-		}
-		if (!PageUptodate(page)) {
-			if (page->mapping == NULL) {
-				/*
-				 * invalidate_mapping_pages got it
-				 */
-				unlock_page(page);
-				put_page(page);
-				return NULL;
-			}
-			unlock_page(page);
-			shrink_readahead_size_eio(ra);
-			put_page(page);
-			return ERR_PTR(-EIO);
+		if (page->mapping == NULL) {
+			/* page truncated */
+			error = AOP_TRUNCATED_PAGE;
+		} else {
+			shrink_readahead_size_eio(&file->f_ra);
+			error = -EIO;
 		}
-		unlock_page(page);
 	}
-
-	return page;
+	unlock_page(page);
+	return error;
 }
 
 static struct page *filemap_update_page(struct kiocb *iocb, struct file *filp,
@@ -2303,7 +2285,18 @@ static struct page *filemap_update_page(struct kiocb *iocb, struct file *filp,
 	return page;
 
 readpage:
-	return filemap_read_page(iocb, filp, mapping, page);
+	if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT | IOCB_WAITQ)) {
+		unlock_page(page);
+		put_page(page);
+		return ERR_PTR(-EAGAIN);
+	}
+	error = filemap_read_page(iocb->ki_filp, mapping, page);
+	if (!error)
+		return page;
+	put_page(page);
+	if (error == AOP_TRUNCATED_PAGE)
+		return NULL;
+	return ERR_PTR(error);
 truncated:
 	unlock_page(page);
 	put_page(page);
@@ -2319,7 +2312,7 @@ static struct page *filemap_create_page(struct kiocb *iocb,
 	struct page *page;
 	int error;
 
-	if (iocb->ki_flags & IOCB_NOIO)
+	if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT | IOCB_WAITQ))
 		return ERR_PTR(-EAGAIN);
 
 	page = page_cache_alloc(mapping);
@@ -2328,12 +2321,14 @@ static struct page *filemap_create_page(struct kiocb *iocb,
 
 	error = add_to_page_cache_lru(page, mapping, index,
 				      mapping_gfp_constraint(mapping, GFP_KERNEL));
-	if (error) {
-		put_page(page);
-		return error != -EEXIST ? ERR_PTR(error) : NULL;
-	}
-
-	return filemap_read_page(iocb, filp, mapping, page);
+	if (!error)
+		error = filemap_read_page(iocb->ki_filp, mapping, page);
+	if (!error)
+		return page;
+	put_page(page);
+	if (error == -EEXIST || error == AOP_TRUNCATED_PAGE)
+		return NULL;
+	return ERR_PTR(error);
 }
 
 static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter,
-- 
2.29.2


  parent reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-22 16:01 [PATCH v5 00/18] Refactor generic_file_buffered_read Matthew Wilcox (Oracle)
2021-01-22 16:01 ` [PATCH v5 01/18] mm/filemap: Rename generic_file_buffered_read subfunctions Matthew Wilcox (Oracle)
2021-01-22 16:01 ` [PATCH v5 02/18] mm/filemap: Remove dynamically allocated array from filemap_read Matthew Wilcox (Oracle)
2021-01-22 16:01 ` [PATCH v5 03/18] mm/filemap: Convert filemap_get_pages to take a pagevec Matthew Wilcox (Oracle)
2021-01-22 16:01 ` [PATCH v5 04/18] mm/filemap: Use head pages in generic_file_buffered_read Matthew Wilcox (Oracle)
2021-01-22 16:01 ` [PATCH v5 05/18] mm/filemap: Pass a sleep state to put_and_wait_on_page_locked Matthew Wilcox (Oracle)
2021-01-22 16:01 ` [PATCH v5 06/18] mm/filemap: Support readpage splitting a page Matthew Wilcox (Oracle)
2021-01-22 16:01 ` [PATCH v5 07/18] mm/filemap: Inline __wait_on_page_locked_async into caller Matthew Wilcox (Oracle)
2021-01-22 16:01 ` [PATCH v5 08/18] mm/filemap: Don't call ->readpage if IOCB_WAITQ is set Matthew Wilcox (Oracle)
2021-01-22 16:01 ` Matthew Wilcox (Oracle) [this message]
2021-01-22 16:01 ` [PATCH v5 10/18] mm/filemap: Change filemap_create_page calling conventions Matthew Wilcox (Oracle)
2021-01-22 16:01 ` [PATCH v5 11/18] mm/filemap: Convert filemap_update_page to return an errno Matthew Wilcox (Oracle)
2021-01-22 16:01 ` [PATCH v5 12/18] mm/filemap: Move the iocb checks into filemap_update_page Matthew Wilcox (Oracle)
2021-01-22 16:01 ` [PATCH v5 13/18] mm/filemap: Add filemap_range_uptodate Matthew Wilcox (Oracle)
2021-01-22 16:01 ` [PATCH v5 14/18] mm/filemap: Split filemap_readahead out of filemap_get_pages Matthew Wilcox (Oracle)
2021-01-22 16:01 ` [PATCH v5 15/18] mm/filemap: Restructure filemap_get_pages Matthew Wilcox (Oracle)
2021-01-22 16:01 ` [PATCH v5 16/18] mm/filemap: Don't relock the page after calling readpage Matthew Wilcox (Oracle)
2021-01-22 16:01 ` [PATCH v5 17/18] mm/filemap: Rename generic_file_buffered_read to filemap_read Matthew Wilcox (Oracle)
2021-01-22 16:01 ` [PATCH v5 18/18] mm/filemap: Simplify generic_file_read_iter Matthew Wilcox (Oracle)

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