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From: Matthew Wilcox <willy@infradead.org>
To: linux-fsdevel@vger.kernel.org
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	linux-btrfs@vger.kernel.org, linux-erofs@lists.ozlabs.org,
	linux-ext4@vger.kernel.org,
	linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com,
	ocfs2-devel@oss.oracle.com, linux-xfs@vger.kernel.org
Subject: [PATCH v6 01/19] mm: Return void from various readahead functions
Date: Mon, 17 Feb 2020 10:45:42 -0800	[thread overview]
Message-ID: <20200217184613.19668-2-willy@infradead.org> (raw)
In-Reply-To: <20200217184613.19668-1-willy@infradead.org>

From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

ondemand_readahead has two callers, neither of which use the return value.
That means that both ra_submit and __do_page_cache_readahead() can return
void, and we don't need to worry that a present page in the readahead
window causes us to return a smaller nr_pages than we ought to have.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/internal.h  |  8 ++++----
 mm/readahead.c | 24 ++++++++++--------------
 2 files changed, 14 insertions(+), 18 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index 3cf20ab3ca01..f779f058118b 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -49,18 +49,18 @@ void unmap_page_range(struct mmu_gather *tlb,
 			     unsigned long addr, unsigned long end,
 			     struct zap_details *details);
 
-extern unsigned int __do_page_cache_readahead(struct address_space *mapping,
+extern void __do_page_cache_readahead(struct address_space *mapping,
 		struct file *filp, pgoff_t offset, unsigned long nr_to_read,
 		unsigned long lookahead_size);
 
 /*
  * Submit IO for the read-ahead request in file_ra_state.
  */
-static inline unsigned long ra_submit(struct file_ra_state *ra,
+static inline void ra_submit(struct file_ra_state *ra,
 		struct address_space *mapping, struct file *filp)
 {
-	return __do_page_cache_readahead(mapping, filp,
-					ra->start, ra->size, ra->async_size);
+	__do_page_cache_readahead(mapping, filp,
+			ra->start, ra->size, ra->async_size);
 }
 
 /*
diff --git a/mm/readahead.c b/mm/readahead.c
index 2fe72cd29b47..8ce46d69e6ae 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -149,10 +149,8 @@ static int read_pages(struct address_space *mapping, struct file *filp,
  * the pages first, then submits them for I/O. This avoids the very bad
  * behaviour which would occur if page allocations are causing VM writeback.
  * We really don't want to intermingle reads and writes like that.
- *
- * Returns the number of pages requested, or the maximum amount of I/O allowed.
  */
-unsigned int __do_page_cache_readahead(struct address_space *mapping,
+void __do_page_cache_readahead(struct address_space *mapping,
 		struct file *filp, pgoff_t offset, unsigned long nr_to_read,
 		unsigned long lookahead_size)
 {
@@ -166,7 +164,7 @@ unsigned int __do_page_cache_readahead(struct address_space *mapping,
 	gfp_t gfp_mask = readahead_gfp_mask(mapping);
 
 	if (isize == 0)
-		goto out;
+		return;
 
 	end_index = ((isize - 1) >> PAGE_SHIFT);
 
@@ -211,8 +209,6 @@ unsigned int __do_page_cache_readahead(struct address_space *mapping,
 	if (nr_pages)
 		read_pages(mapping, filp, &page_pool, nr_pages, gfp_mask);
 	BUG_ON(!list_empty(&page_pool));
-out:
-	return nr_pages;
 }
 
 /*
@@ -378,11 +374,10 @@ static int try_context_readahead(struct address_space *mapping,
 /*
  * A minimal readahead algorithm for trivial sequential/random reads.
  */
-static unsigned long
-ondemand_readahead(struct address_space *mapping,
-		   struct file_ra_state *ra, struct file *filp,
-		   bool hit_readahead_marker, pgoff_t offset,
-		   unsigned long req_size)
+static void ondemand_readahead(struct address_space *mapping,
+		struct file_ra_state *ra, struct file *filp,
+		bool hit_readahead_marker, pgoff_t offset,
+		unsigned long req_size)
 {
 	struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
 	unsigned long max_pages = ra->ra_pages;
@@ -428,7 +423,7 @@ ondemand_readahead(struct address_space *mapping,
 		rcu_read_unlock();
 
 		if (!start || start - offset > max_pages)
-			return 0;
+			return;
 
 		ra->start = start;
 		ra->size = start - offset;	/* old async_size */
@@ -464,7 +459,8 @@ ondemand_readahead(struct address_space *mapping,
 	 * standalone, small random read
 	 * Read as is, and do not pollute the readahead state.
 	 */
-	return __do_page_cache_readahead(mapping, filp, offset, req_size, 0);
+	__do_page_cache_readahead(mapping, filp, offset, req_size, 0);
+	return;
 
 initial_readahead:
 	ra->start = offset;
@@ -489,7 +485,7 @@ ondemand_readahead(struct address_space *mapping,
 		}
 	}
 
-	return ra_submit(ra, mapping, filp);
+	ra_submit(ra, mapping, filp);
 }
 
 /**
-- 
2.25.0


  reply	other threads:[~2020-02-17 18:46 UTC|newest]

Thread overview: 111+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-17 18:45 [PATCH v6 00/19] Change readahead API Matthew Wilcox
2020-02-17 18:45 ` Matthew Wilcox [this message]
2020-02-18  4:47   ` [PATCH v6 01/19] mm: Return void from various readahead functions Dave Chinner
2020-02-18 21:05   ` John Hubbard
2020-02-18 21:21     ` Matthew Wilcox
2020-02-18 21:52       ` John Hubbard
2020-02-17 18:45 ` [PATCH v6 02/19] mm: Ignore return value of ->readpages Matthew Wilcox
2020-02-18  4:48   ` Dave Chinner
2020-02-18 21:33   ` John Hubbard
2020-02-17 18:45 ` [PATCH v6 03/19] mm: Use readahead_control to pass arguments Matthew Wilcox
2020-02-18  5:03   ` Dave Chinner
2020-02-18 13:56     ` Matthew Wilcox
2020-02-18 22:46       ` Dave Chinner
2020-02-18 22:52         ` Matthew Wilcox
2020-02-18 22:22   ` John Hubbard
2020-02-17 18:45 ` [PATCH v6 04/19] mm: Rearrange readahead loop Matthew Wilcox
2020-02-18  5:08   ` Dave Chinner
2020-02-18 13:57     ` Matthew Wilcox
2020-02-18 22:48       ` Dave Chinner
2020-02-18 22:33   ` John Hubbard
2020-02-17 18:45 ` [PATCH v6 04/16] mm: Tweak readahead loop slightly Matthew Wilcox
2020-02-18 22:57   ` John Hubbard
2020-02-18 23:00     ` John Hubbard
2020-02-17 18:45 ` [PATCH v6 05/16] mm: Put readahead pages in cache earlier Matthew Wilcox
2020-02-17 18:45 ` [PATCH v6 05/19] mm: Remove 'page_offset' from readahead loop Matthew Wilcox
2020-02-18  5:14   ` Dave Chinner
2020-02-18 23:08   ` John Hubbard
2020-02-17 18:45 ` [PATCH v6 06/16] mm: Add readahead address space operation Matthew Wilcox
2020-02-17 18:45 ` [PATCH v6 06/19] mm: rename readahead loop variable to 'i' Matthew Wilcox
2020-02-18  5:33   ` Dave Chinner
2020-02-18 23:11   ` John Hubbard
2020-02-17 18:45 ` [PATCH v6 07/16] mm: Add page_cache_readahead_limit Matthew Wilcox
2020-02-17 18:45 ` [PATCH v6 07/19] mm: Put readahead pages in cache earlier Matthew Wilcox
2020-02-18  6:14   ` Dave Chinner
2020-02-18 15:42     ` Matthew Wilcox
2020-02-19  0:59       ` Dave Chinner
2020-02-19  0:01   ` John Hubbard
2020-02-19  1:02     ` Matthew Wilcox
2020-02-19  1:13       ` John Hubbard
2020-02-19  3:24       ` John Hubbard
2020-02-19 14:41     ` Matthew Wilcox
2020-02-19 14:52       ` Christoph Hellwig
2020-02-19 15:01         ` Matthew Wilcox
2020-02-19 20:24           ` John Hubbard
2020-02-17 18:45 ` [PATCH v6 08/16] fs: Convert mpage_readpages to mpage_readahead Matthew Wilcox
2020-02-17 18:45 ` [PATCH v6 08/19] mm: Add readahead address space operation Matthew Wilcox
2020-02-18  6:21   ` Dave Chinner
2020-02-18 16:10     ` Matthew Wilcox
2020-02-19  1:04       ` Dave Chinner
2020-02-19  0:12   ` John Hubbard
2020-02-19  3:10   ` Eric Biggers
2020-02-19  3:35     ` Eric Biggers
2020-02-19 16:52     ` Matthew Wilcox
2020-02-17 18:45 ` [PATCH v6 09/16] btrfs: Convert from readpages to readahead Matthew Wilcox
2020-02-17 18:45 ` [PATCH v6 09/19] mm: Add page_cache_readahead_limit Matthew Wilcox
2020-02-18  6:31   ` Dave Chinner
2020-02-18 19:54     ` Matthew Wilcox
2020-02-19  1:08       ` Dave Chinner
2020-02-19  1:32   ` John Hubbard
2020-02-19  2:23     ` Matthew Wilcox
2020-02-19  2:46       ` John Hubbard
2020-02-17 18:45 ` [PATCH v6 10/16] erofs: Convert uncompressed files from readpages to readahead Matthew Wilcox
2020-02-17 18:45 ` [PATCH v6 10/19] fs: Convert mpage_readpages to mpage_readahead Matthew Wilcox
2020-02-18  1:51   ` [Ocfs2-devel] " Joseph Qi
2020-02-18  6:37   ` Dave Chinner
2020-02-19  2:48   ` John Hubbard
2020-02-19  3:28   ` Eric Biggers
2020-02-19  3:47     ` Matthew Wilcox
2020-02-19  3:55       ` Eric Biggers
2020-02-17 18:45 ` [PATCH v6 11/19] btrfs: Convert from readpages to readahead Matthew Wilcox
2020-02-18  6:57   ` Dave Chinner
2020-02-18 21:12     ` Matthew Wilcox
2020-02-19  1:23       ` Dave Chinner
2020-02-17 18:46 ` [PATCH v6 11/16] erofs: Convert compressed files " Matthew Wilcox
2020-02-19  2:34   ` Gao Xiang
2020-02-17 18:46 ` [PATCH v6 12/19] erofs: Convert uncompressed " Matthew Wilcox
2020-02-19  2:39   ` Gao Xiang
2020-02-19  3:04   ` Dave Chinner
2020-02-17 18:46 ` [PATCH v6 12/16] ext4: Convert " Matthew Wilcox
2020-02-17 18:46 ` [PATCH v6 13/19] erofs: Convert compressed files " Matthew Wilcox
2020-02-19  3:08   ` Dave Chinner
2020-02-17 18:46 ` [PATCH v6 13/16] f2fs: Convert " Matthew Wilcox
2020-02-17 18:46 ` [PATCH v6 14/19] ext4: " Matthew Wilcox
2020-02-19  3:16   ` Dave Chinner
2020-02-19  3:29   ` Eric Biggers
2020-02-17 18:46 ` [PATCH v6 14/16] fuse: " Matthew Wilcox
2020-02-17 18:46 ` [PATCH v6 15/19] f2fs: " Matthew Wilcox
2020-02-17 18:46 ` [PATCH v6 15/16] iomap: " Matthew Wilcox
2020-02-17 18:46 ` [PATCH v6 16/19] fuse: " Matthew Wilcox
2020-02-19  3:22   ` Dave Chinner
2020-02-17 18:46 ` [PATCH v6 16/16] mm: Use memalloc_nofs_save in readahead path Matthew Wilcox
2020-02-17 18:46 ` [PATCH v6 17/19] iomap: Restructure iomap_readpages_actor Matthew Wilcox
2020-02-19  3:17   ` John Hubbard
2020-02-19  5:35     ` Matthew Wilcox
2020-02-19  3:29   ` Dave Chinner
2020-02-19  6:04     ` Matthew Wilcox
2020-02-19  6:40       ` Dave Chinner
2020-02-19 17:06         ` Matthew Wilcox
2020-02-17 18:46 ` [PATCH v6 18/19] iomap: Convert from readpages to readahead Matthew Wilcox
2020-02-19  3:40   ` Dave Chinner
2020-02-17 18:46 ` [PATCH v6 19/19] mm: Use memalloc_nofs_save in readahead path Matthew Wilcox
2020-02-19  3:43   ` Dave Chinner
2020-02-19  5:22     ` Matthew Wilcox
2020-02-17 18:48 ` [PATCH v6 00/19] Change readahead API Matthew Wilcox
2020-02-18  4:56 ` Dave Chinner
2020-02-18 13:42   ` Matthew Wilcox
2020-02-18 21:26     ` Dave Chinner
2020-02-19  3:45       ` Dave Chinner
2020-02-19  3:48         ` Matthew Wilcox
2020-02-19  3:57           ` Dave Chinner
2020-02-18 20:49 ` John Hubbard

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