[RFC PATCH 32/79] fs/block: do not rely on page->mapping get it from the context

[jglisse]

From: Jérôme Glisse <jgli...@redhat.com>

This patch remove most dereference of page->mapping and get the mapping
from the call context (either already available in the function or by
adding it to function arguments).

Signed-off-by: Jérôme Glisse <jgli...@redhat.com>
Cc: Jens Axboe <ax...@kernel.dk>
CC: Andrew Morton <a...@linux-foundation.org>
Cc: Alexander Viro <v...@zeniv.linux.org.uk>
Cc: linux-fsde...@vger.kernel.org
Cc: Tejun Heo <t...@kernel.org>
Cc: Jan Kara <j...@suse.cz>
Cc: Josef Bacik <jba...@fb.com>
Cc: Mel Gorman <mgor...@techsingularity.net>
---
 fs/block_dev.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 502b6643bc74..dd9da97615e3 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -564,14 +564,14 @@ EXPORT_SYMBOL(thaw_bdev);
 static int blkdev_writepage(struct address_space *mapping, struct page *page,
                            struct writeback_control *wbc)
 {
-       return block_write_full_page(page->mapping->host, page,
+       return block_write_full_page(mapping->host, page,
                                     blkdev_get_block, wbc);
 }
 
 static int blkdev_readpage(struct file * file, struct address_space *mapping,
                           struct page * page)
 {
-       return block_read_full_page(page->mapping->host,page,blkdev_get_block);
+       return block_read_full_page(mapping->host,page,blkdev_get_block);
 }
 
 static int blkdev_readpages(struct file *file, struct address_space *mapping,
@@ -1941,7 +1941,7 @@ EXPORT_SYMBOL_GPL(blkdev_read_iter);
 static int blkdev_releasepage(struct address_space *mapping,
                              struct page *page, gfp_t wait)
 {
-       struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super;
+       struct super_block *super = BDEV_I(mapping->host)->bdev.bd_super;
 
        if (super && super->s_op->bdev_try_to_free_page)
                return super->s_op->bdev_try_to_free_page(super, page, wait);
-- 
2.14.3