Retry zn_flush_cached_data on ERESTART

`zfs_putpage` sometimes fails on `dmu_tx_assign`, and looping prevents
writeback flush from missing any pages needed to detect dirty records.

Also fix zn_has_cached_data bounds.

Signed-off-by: Robert Evans <evansr@google.com>

module/os/linux/zfs/zpl_file.c

@@ -720,23 +720,23 @@ zpl_putpage(struct page *pp, struct writeback_control *wbc, void *data)
 {
 	boolean_t *for_sync = data;
 	fstrans_cookie_t cookie;
+	int ret;
 
 	ASSERT(PageLocked(pp));
 	ASSERT(!PageWriteback(pp));
 
 	cookie = spl_fstrans_mark();
-	(void) zfs_putpage(pp->mapping->host, pp, wbc, *for_sync);
+	ret = zfs_putpage(pp->mapping->host, pp, wbc, *for_sync);
 	spl_fstrans_unmark(cookie);
 
-	return (0);
+	return (ret);
 }
 
 #ifdef HAVE_WRITEPAGE_T_FOLIO
 static int
 zpl_putfolio(struct folio *pp, struct writeback_control *wbc, void *data)
 {
-	(void) zpl_putpage(&pp->page, wbc, data);
-	return (0);
+	return (zpl_putpage(&pp->page, wbc, data));
 }
 #endif
 

module/zfs/zfs_vnops.c

@@ -122,8 +122,13 @@ zfs_holey_common(znode_t *zp, ulong_t cmd, loff_t *off)
 		hole = B_FALSE;
 
 	/* Flush any mmap()'d data to disk */
-	if (zn_has_cached_data(zp, 0, file_sz - 1))
-		zn_flush_cached_data(zp, B_FALSE);
+	if (zn_has_cached_data(zp, 0, file_sz - 1)) {
+		do {
+			error = zn_flush_cached_data(zp, B_TRUE);
+		} while (error == ERESTART);
+		if (error != 0)
+			return (error);
+	}
 
 	lr = zfs_rangelock_enter(&zp->z_rangelock, 0, UINT64_MAX, RL_READER);
 	error = dmu_offset_next(ZTOZSB(zp)->z_os, zp->z_id, hole, &noff);
@@ -1190,9 +1195,15 @@ zfs_clone_range(znode_t *inzp, uint64_t *inoffp, znode_t *outzp,
 	/*
 	 * Flush mmap'ed pages to disk before cloning.
 	 */
-	if (zn_has_cached_data(inzp, inoff, len)) {
+	if (zn_has_cached_data(inzp, inoff, inoff + len - 1)) {
 		// FIXME: flush only the cloned range
-		zn_flush_cached_data(inzp, B_FALSE);
+		do {
+			error = zn_flush_cached_data(inzp, B_TRUE);
+		} while (error == ERESTART);
+		if (error != 0) {
+			zfs_exit_two(inzfsvfs, outzfsvfs, FTAG);
+			return (error);
+		}
 	}
 
 	/*