Read errors after an UBIFS update

Question

I am encountering the messages below after creating an UBIFS filesystem in a new UBI volume on an existing UBI partition.

This happens while reading all the files on the UBI fs via tar -cf /dev/null *:

UBIFS error (pid 1810): ubifs_read_node: bad node type (255 but expected 1)
UBIFS error (pid 1810): ubifs_read_node: bad node at LEB 33:967120, LEB mapping status 0
Not a node, first 24 bytes:
00000000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
CPU: 0 PID: 1810 Comm: tar Tainted: P           O   3.18.80 #3
Backtrace:
 [<8001b664>] (dump_backtrace) from [<8001b880>] (show_stack+0x18/0x1c)
 r7:00000000 r6:00000000 r5:80000013 r4:80566cbc
 [<8001b868>] (show_stack) from [<801d77e0>] (dump_stack+0x88/0xa4)
 [<801d7758>] (dump_stack) from [<80171608>] (ubifs_read_node+0x1fc/0x2b8)
  r7:00000021 r6:00000712 r5:000ec1d0 r4:bd59d000
 [<8017140c>] (ubifs_read_node) from [<8018b654>](ubifs_tnc_read_node+0x88/0x124)
  r10:00000000 r9:b4f9fdb0 r8:bd59d264 r7:00000001 r6:b71e6000 r5:bd59d000
  r4:b6126148
 [<8018b5cc>] (ubifs_tnc_read_node) from [<80174690>](ubifs_tnc_locate+0x108/0x1e0)
  r7:00000001 r6:b71e6000 r5:00000001 r4:bd59d000
 [<80174588>] (ubifs_tnc_locate) from [<80168200>] (do_readpage+0x1c0/0x39c)
  r10:bd59d000 r9:000005b1 r8:00000000 r7:bd258710 r6:a5914000 r5:b71e6000
  r4:be09e280
 [<80168040>] (do_readpage) from [<80169398>] (ubifs_readpage+0x44/0x424)
  r10:00000000 r9:00000000 r8:bd59d000 r7:be09e280 r6:00000000 r5:bd258710
  r4:00000000
 [<80169354>] (ubifs_readpage) from [<80089654>](generic_file_read_iter+0x48c/0x5d8)
  r10:00000000 r9:00000000 r8:00000000 r7:be09e280 r6:bd2587d4 r5:bd5379e0
  r4:00000000
 [<800891c8>] (generic_file_read_iter) from [<800bbd60>](new_sync_read+0x84/0xa8)
  r10:00000000 r9:b4f9e000 r8:80008e24 r7:bd6437a0 r6:bd5379e0 r5:b4f9ff80
  r4:00001000
 [<800bbcdc>] (new_sync_read) from [<800bc85c>] (__vfs_read+0x20/0x54)
  r7:b4f9ff80 r6:7ec2d800 r5:00001000 r4:800bbcdc
 [<800bc83c>] (__vfs_read) from [<800bc91c>] (vfs_read+0x8c/0xf4)
  r5:00001000 r4:bd5379e0
 [<800bc890>] (vfs_read) from [<800bc9cc>] (SyS_read+0x48/0x80)
  r9:b4f9e000 r8:80008e24 r7:00001000 r6:7ec2d800 r5:bd5379e0 r4:bd5379e0
 [<800bc984>] (SyS_read) from [<80008c80>] (ret_fast_syscall+0x0/0x3c)
  r7:00000003 r6:7ec2d800 r5:00000008 r4:00082a08
UBIFS error (pid 1811): do_readpage: cannot read page 0 of inode 1457, error -22

Mounting looks like this:

UBI-0: ubi_attach_mtd_dev:default fastmap pool size: 190
UBI-0: ubi_attach_mtd_dev:default fastmap WL pool size: 25
UBI-0: ubi_attach_mtd_dev:attaching mtd3 to ubi0
UBI-0: scan_all:scanning is finished
UBI-0: ubi_attach_mtd_dev:attached mtd3 (name "data", size 3824 MiB)
UBI-0: ubi_attach_mtd_dev:PEB size: 1048576 bytes (1024 KiB), LEB size: 1040384 bytes
UBI-0: ubi_attach_mtd_dev:min./max. I/O unit sizes: 4096/4096, sub-page size 4096
UBI-0: ubi_attach_mtd_dev:VID header offset: 4096 (aligned 4096), data offset: 8192
UBI-0: ubi_attach_mtd_dev:good PEBs: 3816, bad PEBs: 8, corrupted PEBs: 0
UBI-0: ubi_attach_mtd_dev:user volume: 6, internal volumes: 1, max. volumes count: 128
UBI-0: ubi_attach_mtd_dev:max/mean erase counter: 4/2, WL threshold: 4096, image sequence number: 1362948729
UBI-0: ubi_attach_mtd_dev:available PEBs: 2313, total reserved PEBs: 1503, PEBs reserved for bad PEB handling: 72
UBI-0: ubi_thread:background thread "ubi_bgt0d" started, PID 419
UBIFS: mounted UBI device 0, volume 6, name "slot1", R/O mode
UBIFS: LEB size: 1040384 bytes (1016 KiB), min./max. I/O unit sizes: 4096 bytes/4096 bytes
UBIFS: FS size: 259055616 bytes (247 MiB, 249 LEBs), journal size 12484608 bytes (11 MiB, 12 LEBs)
UBIFS: reserved for root: 4952683 bytes (4836 KiB)
UBIFS: media format: w4/r0 (latest is w4/r0), UUID 92C7B251-2666-4717-B735-5539900FE749, small LPT model

The rate of reproduction is one in about 20 sequences of: ubirmvol, ubimkvol (256MB), unpack a rootfs.tgz (20MB, 40MB unpacked) in the mounted UBIFS, umount, ubidetach, sync, reboot. There are no xattrs created. No power cuts happen during the tests.

The board runs a 3.18.80 kernel on an ARM board. I tested other identical test boards where only the NAND chip manufacturer was different.

I had CONFIG_MTD_UBI_FASTMAP enabled when the error occured, but I used no explicit fastmap boot cmdline option. I tried mounting the ubifs with a rebuilt kernel that had the config option disabled after the issue reproduced, but the read error still occured.

I also tried mounting with a kernel that had "ubifs: Fix journal replay w.r.t. xattr nodes" patch [1] applied, after reading older similar error reports, but once reproduced on a NAND, the read error persisted.

[1] https://patchwork.ozlabs.org/patch/713213/

Is there some special requirement except just umount, ubidetach and sync before running reboot, or regarding free space fixup ? Would creating the fs image offline with mkfs.ubifs instead of unpacking it via tar make a difference here ? Would it help to test with cherry picked commits from linux v4.14 that touch fs/ubifs ?