bcachefs: Ensure that fpunch updates inode timestamps

Fixes xfstests generic/059
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/fs-io.c

@@ -2407,6 +2407,15 @@ int bch2_truncate(struct bch_inode_info *inode, struct iattr *iattr)
 
 /* fallocate: */
 
+static int inode_update_times_fn(struct bch_inode_info *inode,
+				 struct bch_inode_unpacked *bi, void *p)
+{
+	struct bch_fs *c = inode->v.i_sb->s_fs_info;
+
+	bi->bi_mtime = bi->bi_ctime = bch2_current_time(c);
+	return 0;
+}
+
 static long bchfs_fpunch(struct bch_inode_info *inode, loff_t offset, loff_t len)
 {
 	struct bch_fs *c = inode->v.i_sb->s_fs_info;
@@ -2444,6 +2453,11 @@ static long bchfs_fpunch(struct bch_inode_info *inode, loff_t offset, loff_t len
 				  &i_sectors_delta);
 		i_sectors_acct(c, inode, NULL, i_sectors_delta);
 	}
+
+	mutex_lock(&inode->ei_update_lock);
+	ret = bch2_write_inode(c, inode, inode_update_times_fn, NULL,
+			       ATTR_MTIME|ATTR_CTIME) ?: ret;
+	mutex_unlock(&inode->ei_update_lock);
 err:
 	bch2_pagecache_block_put(&inode->ei_pagecache_lock);
 	inode_unlock(&inode->v);

fs/bcachefs/fs.c

@@ -145,7 +145,7 @@ int __must_check bch2_write_inode(struct bch_fs *c,
 	struct bch_inode_unpacked inode_u;
 	int ret;
 
-	bch2_trans_init(&trans, c, 0, 0);
+	bch2_trans_init(&trans, c, 0, 256);
 retry:
 	bch2_trans_begin(&trans);