wip: do custom zpl_writepages on syncfs(2)

Signed-off-by: Pavel Snajdr <[email protected]>

Author: snajpa

include/os/linux/zfs/sys/zpl.h

@@ -49,6 +49,8 @@ extern const struct inode_operations zpl_special_inode_operations;
 extern const struct address_space_operations zpl_address_space_operations;
 extern const struct file_operations zpl_file_operations;
 extern const struct file_operations zpl_dir_file_operations;
+extern int zpl_writepages(struct address_space *mapping,
+    struct writeback_control *wbc);
 
 /* zpl_super.c */
 extern void zpl_prune_sb(uint64_t nr_to_scan, void *arg);

module/os/linux/zfs/zpl_file.c

@@ -546,7 +546,7 @@ zpl_write_cache_pages(struct address_space *mapping,
 	return (result);
 }
 
-static int
+int
 zpl_writepages(struct address_space *mapping, struct writeback_control *wbc)
 {
 	znode_t		*zp = ITOZ(mapping->host);

module/os/linux/zfs/zpl_super.c

@@ -111,6 +111,12 @@ zpl_sync_fs(struct super_block *sb, int wait)
 	cred_t *cr = CRED();
 	znode_t *zp;
 	zfsvfs_t *zfsvfs = sb->s_fs_info;
+	struct writeback_control wbc = {
+		.sync_mode = wait ? WB_SYNC_ALL : WB_SYNC_NONE,
+		.nr_to_write = LONG_MAX,
+		.range_start = 0,
+		.range_end = LLONG_MAX,
+	};
 	int error;
 
 	crhold(cr);
@@ -119,7 +125,7 @@ zpl_sync_fs(struct super_block *sb, int wait)
 	for (zp = list_head(&zfsvfs->z_all_znodes); zp;
 	    zp = list_next(&zfsvfs->z_all_znodes, zp)) {
 		if (zp->z_sa_hdl)
-			error = filemap_write_and_wait(ZTOI(zp)->i_mapping);
+			error = zpl_writepages(ZTOI(zp)->i_mapping, &wbc);
 		if (error != 0)
 			break;
 	}