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From: Christoph Hellwig <hch@lst.de>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Kent Overstreet <kent.overstreet@gmail.com>,
	Matthew Wilcox <willy@infradead.org>,
	linux-mm@kvack.org, linux-fsdevel@vger.kernel.org
Subject: [PATCH 11/13] mm: streamline the partially uptodate checks in filemap_make_page_uptodate
Date: Sat, 31 Oct 2020 10:00:02 +0100	[thread overview]
Message-ID: <20201031090004.452516-12-hch@lst.de> (raw)
In-Reply-To: <20201031090004.452516-1-hch@lst.de>

Unwind the goto mess a bit.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/filemap.c | 42 +++++++++++++++++-------------------------
 1 file changed, 17 insertions(+), 25 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 000f75cd359d1c..904b0a4fb9e008 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2218,7 +2218,6 @@ static int filemap_make_page_uptodate(struct kiocb *iocb, struct iov_iter *iter,
 	struct address_space *mapping = file->f_mapping;
 	loff_t last = iocb->ki_pos + iter->count;
 	pgoff_t last_index = (last + PAGE_SIZE - 1) >> PAGE_SHIFT;
-	loff_t pos = max(iocb->ki_pos, (loff_t)pg_index << PAGE_SHIFT);
 	int error;
 
 	if (PageReadahead(page)) {
@@ -2251,32 +2250,22 @@ static int filemap_make_page_uptodate(struct kiocb *iocb, struct iov_iter *iter,
 	if (PageUptodate(page))
 		return 0;
 
-	if (mapping->host->i_blkbits == PAGE_SHIFT ||
-	    !mapping->a_ops->is_partially_uptodate)
-		goto page_not_up_to_date;
-	/* pipes can't handle partially uptodate pages */
-	if (unlikely(iov_iter_is_pipe(iter)))
-		goto page_not_up_to_date;
-	if (!trylock_page(page))
-		goto page_not_up_to_date;
-	/* Did it get truncated before we got the lock? */
-	if (!page->mapping)
-		goto page_not_up_to_date_locked;
-	if (!mapping->a_ops->is_partially_uptodate(page, pos & ~PAGE_MASK,
-			last - pos))
-		goto page_not_up_to_date_locked;
-
-unlock_page:
-	unlock_page(page);
-	return 0;
+	if (mapping->host->i_blkbits <= PAGE_SHIFT &&
+	    mapping->a_ops->is_partially_uptodate &&
+	    !iov_iter_is_pipe(iter) &&
+	    trylock_page(page)) {
+		loff_t pos = max(iocb->ki_pos, (loff_t)pg_index << PAGE_SHIFT);
 
-page_not_up_to_date:
-	/* Get exclusive access to the page ... */
-	error = lock_page_for_iocb(iocb, page);
-	if (unlikely(error))
-		return error;
+		if (page->mapping &&
+		    mapping->a_ops->is_partially_uptodate(page,
+				pos & ~PAGE_MASK, last - pos))
+			goto unlock_page;
+	} else {
+		error = lock_page_for_iocb(iocb, page);
+		if (unlikely(error))
+			return error;
+	}
 
-page_not_up_to_date_locked:
 	/* Did it get truncated before we got the lock? */
 	if (!page->mapping) {
 		unlock_page(page);
@@ -2287,6 +2276,9 @@ static int filemap_make_page_uptodate(struct kiocb *iocb, struct iov_iter *iter,
 	if (PageUptodate(page))
 		goto unlock_page;
 	return filemap_readpage(iocb, page);
+unlock_page:
+	unlock_page(page);
+	return 0;
 }
 
 static int filemap_new_page(struct kiocb *iocb, struct iov_iter *iter,
-- 
2.28.0


  parent reply	other threads:[~2020-10-31  9:26 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-31  8:59 clean up the generic pagecache read helpers Christoph Hellwig
2020-10-31  8:59 ` [PATCH 01/13] mm: simplify generic_file_buffered_read_readpage Christoph Hellwig
2020-10-31  8:59 ` [PATCH 02/13] mm: simplify generic_file_buffered_read_pagenotuptodate Christoph Hellwig
2020-10-31  8:59 ` [PATCH 03/13] mm: lift the nowait checks into generic_file_buffered_read_pagenotuptodate Christoph Hellwig
2020-10-31  8:59 ` [PATCH 04/13] mm: handle readahead in generic_file_buffered_read_pagenotuptodate Christoph Hellwig
2020-10-31 17:06   ` Matthew Wilcox
2020-11-01 10:31     ` Christoph Hellwig
2020-11-01 10:49       ` Matthew Wilcox
2020-11-01 10:51         ` Christoph Hellwig
2020-11-01 10:51           ` Christoph Hellwig
2020-11-01 11:04             ` Matthew Wilcox
2020-11-01 11:52               ` Christoph Hellwig
2020-11-01 14:55                 ` Matthew Wilcox
2020-11-02  8:18                   ` Christoph Hellwig
2020-10-31  8:59 ` [PATCH 05/13] mm: simplify generic_file_buffered_read_no_cached_page Christoph Hellwig
2020-10-31 16:20   ` Matthew Wilcox
2020-10-31 16:28   ` Matthew Wilcox
2020-11-01 10:29     ` Christoph Hellwig
2020-10-31  8:59 ` [PATCH 06/13] mm: factor out a filemap_find_get_pages helper Christoph Hellwig
2020-10-31  8:59 ` [PATCH 07/13] mm: refactor generic_file_buffered_read_get_pages Christoph Hellwig
2020-11-01 11:18   ` Matthew Wilcox
2020-10-31  8:59 ` [PATCH 08/13] mm: move putting the page on error out of filemap_readpage Christoph Hellwig
2020-10-31  9:00 ` [PATCH 09/13] mm: move putting the page on error out of filemap_make_page_uptodate Christoph Hellwig
2020-10-31  9:00 ` [PATCH 10/13] mm: open code readahead in filemap_new_page Christoph Hellwig
2020-11-01 11:20   ` Matthew Wilcox
2020-10-31  9:00 ` Christoph Hellwig [this message]
2020-11-01 11:23   ` [PATCH 11/13] mm: streamline the partially uptodate checks in filemap_make_page_uptodate Matthew Wilcox
2020-10-31  9:00 ` [PATCH 12/13] mm: rename generic_file_buffered_read to filemap_read Christoph Hellwig
2020-10-31  9:00 ` [PATCH 13/13] mm: simplify generic_file_read_iter Christoph Hellwig
2020-10-31 15:42 ` clean up the generic pagecache read helpers Matthew Wilcox

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