Long mount time of ESP FAT partition

From: Paul Menzel
Date: Tue Feb 28 2023 - 08:00:15 EST


Dear Linux folks,


On a Dell Precision 3540 with Debian sid/unstable, Linux 6.1.12 takes 1.5 seconds to mount the 128 MB FAT partition `/dev/nvme0n1p1` to `/boot/efi`.

```
$ lsblk --fs
NAME FSTYPE FSVER LABEL UUID FSAVAIL FSUSE% MOUNTPOINTS
nvme0n1
├─nvme0n1p1 vfat FAT32 ESP 381C-FF6C 49.2M 61% /boot/efi
├─nvme0n1p2 crypto_LUKS 2 b88be798-13e3-4884-9748-bf7a23f0ae87
│ └─nvme0n1p2_crypt ext4 1.0 c9342a55-b747-4442-b2f4-bc03eb7a51cf 733G 17% /
└─nvme0n1p3 ext4 1.0 boot 16743b63-5a4f-404e-a46e-2db5add63980 303.6M 10% /boot
$ more /etc/fstab
[…]
/dev/disk/by-uuid/c9342a55-b747-4442-b2f4-bc03eb7a51cf / auto defaults,errors=remount-ro 0 1
/dev/disk/by-uuid/16743b63-5a4f-404e-a46e-2db5add63980 /boot auto defaults,errors=remount-ro 0 1
UUID=381C-FF6C /boot/efi vfat umask=0022 0 1
$ journalctl -b -u boot.mount -o short-precise
Feb 28 11:19:14.006616 morley systemd[1]: Mounting boot.mount - /boot...
Feb 28 11:19:14.013246 morley systemd[1]: Mounted boot.mount - /boot.
$ journalctl -b -u boot-efi.mount -o short-precise
Feb 28 11:19:14.014469 morley systemd[1]: Mounting boot-efi.mount - /boot/efi...
Feb 28 11:19:15.550770 morley systemd[1]: Mounted boot-efi.mount - /boot/efi.
```

On a Dell Latitude E7250 mounting a 128 MB FAT partition `/dev/sda1` (SAMSUNG SSD PM851 mSATA 256GB) only takes 90 ms.

```
$ journalctl -u boot-efi.mount -o short-monotonic -b
[ 10.693263] ersatz systemd[1]: Mounting boot-efi.mount - /boot/efi...
[ 10.783176] ersatz systemd[1]: Mounted boot-efi.mount - /boot/efi.
```


Kind regards,

Paul