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FAILED: patch "[PATCH] fs/mpage.c: fix mpage_writepage() for pages with buffers" failed to apply to 4.4-stable tree

PATCH [email protected] 1 participant 1 message Oct 15, 2017

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The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

Quoted 1 line

From f892760aa66a2d657deaf59538fb69433036767c Mon Sep 17 00:00:00 2001

From: Matthew Wilcox <[email protected]>
Date: Fri, 13 Oct 2017 15:58:15 -0700
Subject: [PATCH] fs/mpage.c: fix mpage_writepage() for pages with buffers

When using FAT on a block device which supports rw_page, we can hit BUG_ON(!PageLocked(page)) in try_to_free_buffers(). This is because we call clean_buffers() after unlocking the page we've written. Introduce a new clean_page_buffers() which cleans all buffers associated with a page and call it from within bdev_write_page().

[[email protected]: s/PAGE_SIZE/~0U/ per Linus and Matthew]
Link http://lkml.kernel.org/r/[email protected] open here
Signed-off-by Matthew Wilcox <[email protected]>
Reported-by Toshi Kani <[email protected]>
Reported-by OGAWA Hirofumi <[email protected]>
Tested-by Toshi Kani <[email protected]>
Acked-by Johannes Thumshirn <[email protected]>
Cc Ross Zwisler <[email protected]>
Cc <[email protected]>
Signed-off-by Andrew Morton <[email protected]>
Signed-off-by Linus Torvalds <[email protected]>
fs/block_dev.c +4 -2
index 93d088ffc05c..789f55e851ae 100644
@@ -716,10 +716,12 @@ int bdev_write_page(struct block_device *bdev, sector_t sector,
 
 	set_page_writeback(page);
 	result = ops->rw_page(bdev, sector + get_start_sect(bdev), page, true);
-	if (result)
+	if (result) {
 		end_page_writeback(page);
-	else
+	} else {
+		clean_page_buffers(page);
 		unlock_page(page);
+	}
 	blk_queue_exit(bdev->bd_queue);
 	return result;
 }
fs/mpage.c +11 -3
index 37bb77c1302c..c991faec70b9 100644
@@ -468,6 +468,16 @@ static void clean_buffers(struct page *page, unsigned first_unmapped)
 		try_to_free_buffers(page);
 }
 
+/*
+ * For situations where we want to clean all buffers attached to a page.
+ * We don't need to calculate how many buffers are attached to the page,
+ * we just need to specify a number larger than the maximum number of buffers.
+ */
+void clean_page_buffers(struct page *page)
+{
+	clean_buffers(page, ~0U);
+}
+
 static int __mpage_writepage(struct page *page, struct writeback_control *wbc,
 		      void *data)
 {

@@ -605,10 +615,8 @@ static int __mpage_writepage(struct page *page, struct writeback_control *wbc,
 	if (bio == NULL) {
 		if (first_unmapped == blocks_per_page) {
 			if (!bdev_write_page(bdev, blocks[0] << (blkbits - 9),
-								page, wbc)) {
-				clean_buffers(page, first_unmapped);
+								page, wbc))
 				goto out;
-			}
 		}
 		bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
 				BIO_MAX_PAGES, GFP_NOFS|__GFP_HIGH);
include/linux/buffer_head.h +1 -0
index c8dae555eccf..446b24cac67d 100644
@@ -232,6 +232,7 @@ int generic_write_end(struct file *, struct address_space *,
 				loff_t, unsigned, unsigned,
 				struct page *, void *);
 void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
+void clean_page_buffers(struct page *page);
 int cont_write_begin(struct file *, struct address_space *, loff_t,
 			unsigned, unsigned, struct page **, void **,
 			get_block_t *, loff_t *);