f2fs: don't allow unaligned truncation to smaller/equal size on pinned file

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 3fdd89b("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 <[email protected]>
Reviewed-by: Chao Yu <[email protected]>
Signed-off-by: Jaegeuk Kim <[email protected]>

Author: wangzijie

fs/f2fs/file.c

@@ -1064,6 +1064,17 @@ 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;
 	}
 
 	err = setattr_prepare(idmap, dentry, attr);