nilfs2: fix lockdep warnings during disk space reclamation

During disk space reclamation, nilfs2 still emits the following lockdep
warning due to page/folio operations on shadowed page caches that nilfs2
uses to get a snapshot of DAT file in memory:

  WARNING: CPU: 0 PID: 2643 at include/linux/backing-dev.h:272 __folio_mark_dirty+0x645/0x670
  ...
  RIP: 0010:__folio_mark_dirty+0x645/0x670
  ...
  Call Trace:
    filemap_dirty_folio+0x74/0xd0
    __set_page_dirty_nobuffers+0x85/0xb0
    nilfs_copy_dirty_pages+0x288/0x510 [nilfs2]
    nilfs_mdt_save_to_shadow_map+0x50/0xe0 [nilfs2]
    nilfs_clean_segments+0xee/0x5d0 [nilfs2]
    nilfs_ioctl_clean_segments.isra.19+0xb08/0xf40 [nilfs2]
    nilfs_ioctl+0xc52/0xfb0 [nilfs2]
    __x64_sys_ioctl+0x11d/0x170

This fixes the remaining warning by using inode objects to hold those
page caches.

Link: https://lkml.kernel.org/r/1647867427-30498-3-git-send-email-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hao Sun <sunhao.th@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 26 insertions, 12 deletions

diff --git a/fs/nilfs2/mdt.c b/fs/nilfs2/mdt.c
index a8274d0efa37..d29a0f2b9c16 100644
--- a/fs/nilfs2/mdt.c
+++ b/fs/nilfs2/mdt.c
@@ -471,9 +471,18 @@ int nilfs_mdt_init(struct inode *inode, gfp_t gfp_mask, size_t objsz)
 void nilfs_mdt_clear(struct inode *inode)
 {
 	struct nilfs_mdt_info *mdi = NILFS_MDT(inode);
+	struct nilfs_shadow_map *shadow = mdi->mi_shadow;
 
 	if (mdi->mi_palloc_cache)
 		nilfs_palloc_destroy_cache(inode);
+
+	if (shadow) {
+		struct inode *s_inode = shadow->inode;
+
+		shadow->inode = NULL;
+		iput(s_inode);
+		mdi->mi_shadow = NULL;
+	}
 }
 
 /**
@@ -507,12 +516,15 @@ int nilfs_mdt_setup_shadow_map(struct inode *inode,
 			       struct nilfs_shadow_map *shadow)
 {
 	struct nilfs_mdt_info *mi = NILFS_MDT(inode);
+	struct inode *s_inode;
 
 	INIT_LIST_HEAD(&shadow->frozen_buffers);
-	address_space_init_once(&shadow->frozen_data);
-	nilfs_mapping_init(&shadow->frozen_data, inode);
-	address_space_init_once(&shadow->frozen_btnodes);
-	nilfs_mapping_init(&shadow->frozen_btnodes, inode);
+
+	s_inode = nilfs_iget_for_shadow(inode);
+	if (IS_ERR(s_inode))
+		return PTR_ERR(s_inode);
+
+	shadow->inode = s_inode;
 	mi->mi_shadow = shadow;
 	return 0;
 }
@@ -526,13 +538,14 @@ int nilfs_mdt_save_to_shadow_map(struct inode *inode)
 	struct nilfs_mdt_info *mi = NILFS_MDT(inode);
 	struct nilfs_inode_info *ii = NILFS_I(inode);
 	struct nilfs_shadow_map *shadow = mi->mi_shadow;
+	struct inode *s_inode = shadow->inode;
 	int ret;
 
-	ret = nilfs_copy_dirty_pages(&shadow->frozen_data, inode->i_mapping);
+	ret = nilfs_copy_dirty_pages(s_inode->i_mapping, inode->i_mapping);
 	if (ret)
 		goto out;
 
-	ret = nilfs_copy_dirty_pages(&shadow->frozen_btnodes,
+	ret = nilfs_copy_dirty_pages(NILFS_I(s_inode)->i_assoc_inode->i_mapping,
 				     ii->i_assoc_inode->i_mapping);
 	if (ret)
 		goto out;
@@ -549,7 +562,7 @@ int nilfs_mdt_freeze_buffer(struct inode *inode, struct buffer_head *bh)
 	struct page *page;
 	int blkbits = inode->i_blkbits;
 
-	page = grab_cache_page(&shadow->frozen_data, bh->b_page->index);
+	page = grab_cache_page(shadow->inode->i_mapping, bh->b_page->index);
 	if (!page)
 		return -ENOMEM;
 
@@ -581,7 +594,7 @@ nilfs_mdt_get_frozen_buffer(struct inode *inode, struct buffer_head *bh)
 	struct page *page;
 	int n;
 
-	page = find_lock_page(&shadow->frozen_data, bh->b_page->index);
+	page = find_lock_page(shadow->inode->i_mapping, bh->b_page->index);
 	if (page) {
 		if (page_has_buffers(page)) {
 			n = bh_offset(bh) >> inode->i_blkbits;
@@ -622,11 +635,11 @@ void nilfs_mdt_restore_from_shadow_map(struct inode *inode)
 		nilfs_palloc_clear_cache(inode);
 
 	nilfs_clear_dirty_pages(inode->i_mapping, true);
-	nilfs_copy_back_pages(inode->i_mapping, &shadow->frozen_data);
+	nilfs_copy_back_pages(inode->i_mapping, shadow->inode->i_mapping);
 
 	nilfs_clear_dirty_pages(ii->i_assoc_inode->i_mapping, true);
 	nilfs_copy_back_pages(ii->i_assoc_inode->i_mapping,
-			      &shadow->frozen_btnodes);
+			      NILFS_I(shadow->inode)->i_assoc_inode->i_mapping);
 
 	nilfs_bmap_restore(ii->i_bmap, &shadow->bmap_store);
 
@@ -641,10 +654,11 @@ void nilfs_mdt_clear_shadow_map(struct inode *inode)
 {
 	struct nilfs_mdt_info *mi = NILFS_MDT(inode);
 	struct nilfs_shadow_map *shadow = mi->mi_shadow;
+	struct inode *shadow_btnc_inode = NILFS_I(shadow->inode)->i_assoc_inode;
 
 	down_write(&mi->mi_sem);
 	nilfs_release_frozen_buffers(shadow);
-	truncate_inode_pages(&shadow->frozen_data, 0);
-	truncate_inode_pages(&shadow->frozen_btnodes, 0);
+	truncate_inode_pages(shadow->inode->i_mapping, 0);
+	truncate_inode_pages(shadow_btnc_inode->i_mapping, 0);
 	up_write(&mi->mi_sem);
 }