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().

[akpm@linux-foundation.org: s/PAGE_SIZE/~0U/ per Linus and Matthew]
Link: http://lkml.kernel.org/r/20171006211541.GA7409@bombadil.infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Reported-by: Toshi Kani <toshi.kani@hpe.com>
Reported-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Tested-by: Toshi Kani <toshi.kani@hpe.com>
Acked-by: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 93d088f..789f55e 100644 (file)
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -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;
 }

diff --git a/fs/mpage.c b/fs/mpage.c
index 37bb77c..c991fae 100644 (file)
--- a/fs/mpage.c
+++ b/fs/mpage.c
@@ -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 @@ alloc_new:
        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);

diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index c8dae55..446b24c 100644 (file)
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -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 *);