ext4: warn when page is dirtied without buffers

Warn when a page is dirtied without buffers (as that will likely lead to
a crash in ext4_writepages()) or when it gets newly dirtied without the
page being locked (as there is nothing that prevents buffers to get
stripped just before calling set_page_dirty() under memory pressure).

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 9 insertions, 0 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 861f848159e8..7d95b6174980 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3714,6 +3714,13 @@ static int ext4_journalled_set_page_dirty(struct page *page)
         return __set_page_dirty_nobuffers(page);
 }
 
+static int ext4_set_page_dirty(struct page *page)
+{
+        WARN_ON_ONCE(!PageLocked(page) && !PageDirty(page));
+        WARN_ON_ONCE(!page_has_buffers(page));
+        return __set_page_dirty_buffers(page);
+}
+
 static const struct address_space_operations ext4_aops = {
         .readpage               = ext4_readpage,
         .readpages              = ext4_readpages,
@@ -3721,6 +3728,7 @@ static const struct address_space_operations ext4_aops = {
         .writepages             = ext4_writepages,
         .write_begin            = ext4_write_begin,
         .write_end              = ext4_write_end,
+        .set_page_dirty         = ext4_set_page_dirty,
         .bmap                   = ext4_bmap,
         .invalidatepage         = ext4_invalidatepage,
         .releasepage            = ext4_releasepage,
@@ -3753,6 +3761,7 @@ static const struct address_space_operations ext4_da_aops = {
         .writepages             = ext4_writepages,
         .write_begin            = ext4_da_write_begin,
         .write_end              = ext4_da_write_end,
+        .set_page_dirty         = ext4_set_page_dirty,
         .bmap                   = ext4_bmap,
         .invalidatepage         = ext4_da_invalidatepage,
         .releasepage            = ext4_releasepage,