1. Please describe the problem:

I check log from fstrim.service from time to time and I could not see trimming /home in last few days.

I tried manually and it returned fstrim: /home: the discard operation is not supported.

sh# fstrim -v /home 
fstrim: /home: the discard operation is not supported

sh#  strace -Z fstrim /home 
arch_prctl(0x3001 /* ARCH_??? */, 0x7fffdfe2c5c0) = -1 EINVAL (Invalid argument)
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
ioctl(3, FITRIM, {start=0, len=0xffffffffffffffff, minlen=0}) = -1 EOPNOTSUPP (Operation not supported)

It still work on /boot which is ext4 as well and also with "root" / whihc is luks + btrfs

sh-5.0# fstrim -va
/boot: 24.4 MiB (25550848 bytes) trimmed on /dev/nvme0n1p1
/: 3.7 GiB (3988697088 bytes) trimmed on /dev/mapper/luks-0f8d83fa-5cf9-43e7-82da-8fb5a81a0621


 sh-5.0# lsblk 
NAME                                          MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
nvme0n1                                       259:0    0 238.5G  0 disk  
├─nvme0n1p1                                   259:1    0     3G  0 part  /boot
├─nvme0n1p2                                   259:2    0   100G  0 part  
│ └─luks-0f8d83fa-5cf9-43e7-82da-8fb5a81a0621 253:1    0   100G  0 crypt /
└─nvme0n1p3                                   259:3    0 135.5G  0 part  
  └─luks-38c8cdbc-292c-4bcd-9275-404d5ba2a119 253:0    0 135.5G  0 crypt 
    ├─fedora-home                             253:2    0   100G  0 lvm   /home
    └─fedora-swap                             253:3    0  35.5G  0 lvm   [SWAP]

sh-5.0# blkid 
/dev/nvme0n1p1: UUID="9d4311d8-acfa-4657-af5f-d9ccabb4a7c2" BLOCK_SIZE="4096" TYPE="ext4" PARTUUID="00012ec8-01"
/dev/nvme0n1p2: UUID="0f8d83fa-5cf9-43e7-82da-8fb5a81a0621" TYPE="crypto_LUKS" PARTUUID="00012ec8-02"
/dev/nvme0n1p3: UUID="38c8cdbc-292c-4bcd-9275-404d5ba2a119" TYPE="crypto_LUKS" PARTUUID="00012ec8-03"
/dev/mapper/luks-38c8cdbc-292c-4bcd-9275-404d5ba2a119: UUID="N7IqF5-PITu-vlne-HD6e-YYjO-iVrI-FiKhJQ" TYPE="LVM2_member"
/dev/mapper/luks-0f8d83fa-5cf9-43e7-82da-8fb5a81a0621: UUID="391bb71d-f1d7-41c1-b2dd-446843be9ee8" UUID_SUB="b9f06d72-33a9-4122-8c0b-12d15ac3c2f0" BLOCK_SIZE="4096" TYPE="btrfs"
/dev/mapper/fedora-home: LABEL="home" UUID="87d8dfc3-7012-42ff-ac6c-24242c05ffc5" BLOCK_SIZE="4096" TYPE="ext4"
/dev/mapper/fedora-swap: LABEL="swap" UUID="28fde753-295c-4a9c-b9ee-7844de277d4b" TYPE="swap"


2. What is the Version-Release number of the kernel:

sh-5.0# uname -a
Linux localhost.localdomain 5.8.15-201.fc32.x86_64 #1 SMP Thu Oct 15 15:56:44 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

3. Did it work previously in Fedora? If so, what kernel version did the issue
   *first* appear?  Old kernels are available for download at
   https://koji.fedoraproject.org/koji/packageinfo?packageID=8 :

I cannot reproduce with latest 5.7 from koji (kernel-core-5.7.17-200.fc32.x86_64)

4. Can you reproduce this issue? If so, please provide the steps to reproduce
   the issue below:

I can reproduce on my laptop; did not try in VM. 

6. Are you running any modules that not shipped with directly Fedora's kernel?:

No

7. Please attach the kernel logs. You can get the complete kernel log
   for a boot with ``journalctl --no-hostname -k > dmesg.txt``. If the
   issue occurred on a previous boot, use the journalctl ``-b`` flag.

There is nothing in journal or dmesg  for problematic "fstrim -v /home/"