mm: remove nrexceptional from inode

mainline inclusion
from mainline-v5.13-rc1
commit 8bc3c481
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I3ZE5V
CVE: NA

-------------------------------------------------

We no longer track anything in nrexceptional, so remove it, saving 8 bytes
per inode.

Link: https://lkml.kernel.org/r/20201026151849.24232-5-willy@infradead.orgSigned-off-by: NMatthew Wilcox (Oracle) <willy@infradead.org>
Tested-by: NVishal Verma <vishal.l.verma@intel.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NLiu Shixin <liushixin2@huawei.com>
Reviewed-by: NTong Tiangen <tongtiangen@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

fs/inode.c

@@ -530,7 +530,7 @@ void clear_inode(struct inode *inode)
 	 */
 	xa_lock_irq(&inode->i_data.i_pages);
 	BUG_ON(inode->i_data.nrpages);
-	BUG_ON(inode->i_data.nrexceptional);
+	BUG_ON(!mapping_empty(&inode->i_data));
 	xa_unlock_irq(&inode->i_data.i_pages);
 	BUG_ON(!list_empty(&inode->i_data.private_list));
 	BUG_ON(!(inode->i_state & I_FREEING));

include/linux/fs.h

@@ -439,7 +439,6 @@ int pagecache_write_end(struct file *, struct address_space *mapping,
  * @i_mmap: Tree of private and shared mappings.
  * @i_mmap_rwsem: Protects @i_mmap and @i_mmap_writable.
  * @nrpages: Number of page entries, protected by the i_pages lock.
- * @nrexceptional: Shadow or DAX entries, protected by the i_pages lock.
  * @writeback_index: Writeback starts here.
  * @a_ops: Methods.
  * @flags: Error bits and flags (AS_*).
@@ -460,7 +459,6 @@ struct address_space {
 	struct rb_root_cached	i_mmap;
 	struct rw_semaphore	i_mmap_rwsem;
 	unsigned long		nrpages;
-	unsigned long		nrexceptional;
 	pgoff_t			writeback_index;
 	const struct address_space_operations *a_ops;
 	unsigned long		flags;