[PATCH v4 1/9] ext4: use FGP_WRITEBEGIN for tail block zeroing

[Zhang Yi]

From: Zhang Yi <yi.zhang@xxxxxxxxxx>

ext4_load_tail_bh() returns a locked folio that callers immediately
mutate through folio_zero_range() and mark_buffer_dirty().  Use
FGP_WRITEBEGIN so that, on backing devices that require stable writes,
__filemap_get_folio() waits for writeback to finish before returning
the folio; on regular devices the wait is a no-op.

Signed-off-by: Zhang Yi <yi.zhang@xxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
---
 fs/ext4/inode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index c2c2d6ac7f3d..7b2face041ef 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4037,7 +4037,7 @@ static struct buffer_head *ext4_load_tail_bh(struct inode *inode, loff_t from)
 	int err = 0;
 
 	folio = __filemap_get_folio(mapping, from >> PAGE_SHIFT,
-				    FGP_LOCK | FGP_ACCESSED | FGP_CREAT,
+				    FGP_WRITEBEGIN | FGP_ACCESSED,
 				    mapping_gfp_constraint(mapping, ~__GFP_FS));
 	if (IS_ERR(folio))
 		return ERR_CAST(folio);
-- 
2.52.0