[PATCH 6.12.y 2/3] f2fs: don't allow unaligned truncation to smaller/equal size on pinned file

[Sasha Levin <sashal@kernel.org>]

From: wangzijie <wangzijie1@honor.com>

[ Upstream commit d738f708564764ed591cb6ab50d55489f87c726a ]

To prevent scattered pin block generation, don't allow non-section aligned truncation
to smaller or equal size on pinned file. But for truncation to larger size, after
commit 3fdd89b452c2("f2fs: prevent writing without fallocate() for pinned files"),
we only support overwrite IO to pinned file, so we don't need to consider
attr->ia_size > i_size case.

Signed-off-by: wangzijie <wangzijie1@honor.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Stable-dep-of: d0a481fad5c7 ("f2fs: fix to avoid potential section-unaligned pinfile")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/f2fs/file.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 038b3f14b0a27..9cef43052f8b5 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1048,6 +1048,17 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 			!IS_ALIGNED(attr->ia_size,
 			F2FS_BLK_TO_BYTES(fi->i_cluster_size)))
 			return -EINVAL;
+		/*
+		 * To prevent scattered pin block generation, we don't allow
+		 * smaller/equal size unaligned truncation for pinned file.
+		 * We only support overwrite IO to pinned file, so don't
+		 * care about larger size truncation.
+		 */
+		if (f2fs_is_pinned_file(inode) &&
+			attr->ia_size <= i_size_read(inode) &&
+			!IS_ALIGNED(attr->ia_size,
+			F2FS_BLK_TO_BYTES(CAP_BLKS_PER_SEC(sbi))))
+			return -EINVAL;
 	}
 
 	if (is_quota_modification(idmap, inode, attr)) {
-- 
2.53.0