Bug 1009546

Description of problem:

On a thinly-provisioned logical volume, when you run fstrim AFTER the first time, it only trims 124 MB of data even when you delete GB's of data.



Version-Release number of selected component (if applicable):


kernel-3.10.11-200.fc19.x86_64
kernel-modules-extra-3.10.11-200.fc19.x86_64
lvm2-2.02.98-12.fc19.x86_64
lvm2-libs-2.02.98-12.fc19.x86_64
util-linux-2.23.2-4.fc19.x86_64



How reproducible: Always


Steps to Reproduce:

This is a 100GB partition:

# pvcreate /dev/sda3
# vgcreate vgthin1
# lvcreate --thinpool lvthinpool -l 25774 vgthin1
# lvcreate --name lvol1 --virtualsize 100.78GB --thin vgthin1/lvthinpool
# mkfs.ext4 /dev/vgthin1/lvol1
# mount /dev/vgthin1/lvol1 /var/lib/libvirt/images
# restorecon -R /var/lib/libvirt/images


Actual results:

# mount /var/lib/libvirt/images
# fstrim -v /var/lib/libvirt/images
/var/lib/libvirt/images: 99 GiB (106316812288 bytes) trimmed

# dd if=/dev/zero of=/var/lib/libvirt/images/tempfile bs=1M count=7000
7000+0 records in
7000+0 records out
7340032000 bytes (7.3 GB) copied, 17.1512 s, 428 MB/s

# rm /var/lib/libvirt/images/tempfile
# sync
# fstrim -v /var/lib/libvirt/images/tempfile
/var/lib/libvirt/images: 124 MiB (130019328 bytes) trimmed


Expected results:

# fstrim -v /var/lib/libvirt/images/tempfile
/var/lib/libvirt/images: 7 GiB (7516192768 bytes) trimmed


Additional info:

When I monitor the above steps (using "lvs vgthin1") I see the Data% usage grow as I create files but almost never shrinks back. I need to unmount & mount the filesystem so I can run fstrim for the first time so that it discards all free space (and eventually I'll see the thinpool data-usage statistics reflect that).

As a side note:  when I perform the steps described in this bug report using logical volumes (not thinly provisioned) I get the expected result.  

Finally, more info here:


# ls -l /dev/mapper/vgthin1-lvol1 
lrwxrwxrwx. 1 root root 8 Sep 18 10:41 /dev/mapper/vgthin1-lvol1 -> ../dm-14

# grep . /sys/block/dm-14/queue/*

/sys/block/dm-14/queue/add_random:0
/sys/block/dm-14/queue/discard_granularity:512
/sys/block/dm-14/queue/discard_max_bytes:65536
/sys/block/dm-14/queue/discard_zeroes_data:0
/sys/block/dm-14/queue/hw_sector_size:512
/sys/block/dm-14/queue/iostats:0
/sys/block/dm-14/queue/logical_block_size:512
/sys/block/dm-14/queue/max_hw_sectors_kb:32767
/sys/block/dm-14/queue/max_integrity_segments:0
/sys/block/dm-14/queue/max_sectors_kb:512
/sys/block/dm-14/queue/max_segments:168
/sys/block/dm-14/queue/max_segment_size:65536
/sys/block/dm-14/queue/minimum_io_size:512
/sys/block/dm-14/queue/nomerges:0
/sys/block/dm-14/queue/nr_requests:128
/sys/block/dm-14/queue/optimal_io_size:65536
/sys/block/dm-14/queue/physical_block_size:512
/sys/block/dm-14/queue/read_ahead_kb:128
/sys/block/dm-14/queue/rotational:0
/sys/block/dm-14/queue/rq_affinity:0
/sys/block/dm-14/queue/scheduler:none
/sys/block/dm-14/queue/write_same_max_bytes:0