[PATCH] ceph: fix NULL vs IS_ERR() bug in ceph_zero_partial_page()

[Dan Carpenter <dan.carpenter@xxxxxxxxxx>]

The filemap_lock_folio() never returns NULL.  It returns error pointers.
Update the checking to match.

Fixes: 483239f03149 ("ceph: convert ceph_zero_partial_page() to use a folio")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
 fs/ceph/file.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index d5c674d2ba8a..f6e63265c516 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -2536,12 +2536,13 @@ static inline void ceph_zero_partial_page(struct inode *inode,
 	struct folio *folio;
 
 	folio = filemap_lock_folio(inode->i_mapping, offset >> PAGE_SHIFT);
-	if (folio) {
-		folio_wait_writeback(folio);
-		folio_zero_range(folio, offset_in_folio(folio, offset), size);
-		folio_unlock(folio);
-		folio_put(folio);
-	}
+	if (IS_ERR(folio))
+		return;
+
+	folio_wait_writeback(folio);
+	folio_zero_range(folio, offset_in_folio(folio, offset), size);
+	folio_unlock(folio);
+	folio_put(folio);
 }
 
 static void ceph_zero_pagecache_range(struct inode *inode, loff_t offset,
-- 
2.47.2