On Thursday, July 11, 2019 5:23 AM, Jan Kara <jack@xxxxxxx> wrote: > On Wed 26-06-19 11:17:54, Thomas Walker wrote: > > Sorry to revive a rather old thread, but Elana mentioned that there might > > have been a related fix recently? Possibly something to do with > > truncate? A quick scan of the last month or so turned up > > https://www.spinics.net/lists/linux-ext4/msg65772.html but none of these > > seemed obviously applicable to me. We do still experience this phantom > > space usage quite frequently (although the remount workaround below has > > lowered the priority). > > I don't recall any fix for this. But seeing that remount "fixes" the issue > for you can you try whether one of the following has a similar effect? > > 1) Try "sync" > 2) Try "fsfreeze -f / && fsfreeze -u /" > 3) Try "echo 3 >/proc/sys/vm/drop_caches" > > Also what is the contents of > /sys/fs/ext4/<problematic-device>/delayed_allocation_blocks > when the issue happens? We just had one of these today, and no luck from any of those. delayed_allocation_blocks is 1: # df -h / Filesystem Size Used Avail Use% Mounted on /dev/disk/by-uuid/523c8243-5a25-40eb-8627-f3bbf98ec299 50G 47G 455M 100% / # ls -l /dev/disk/by-uuid/523c8243-5a25-40eb-8627-f3bbf98ec299 lrwxrwxrwx 1 root root 10 Mar 8 16:03 /dev/disk/by-uuid/523c8243-5a25-40eb-8627-f3bbf98ec299 -> ../../sda3 # cat /sys/fs/ext4/sda3/delayed_allocation_blocks 1 # sync; sync; sync # df -h / Filesystem Size Used Avail Use% Mounted on /dev/disk/by-uuid/523c8243-5a25-40eb-8627-f3bbf98ec299 50G 47G 455M 100% / # fsfreeze -f /; fsfreeze -u / # df -h / Filesystem Size Used Avail Use% Mounted on /dev/disk/by-uuid/523c8243-5a25-40eb-8627-f3bbf98ec299 50G 47G 455M 100% / # echo 3 > /proc/sys/vm/drop_caches [blocks for about 10 seconds] # df -h / Filesystem Size Used Avail Use% Mounted on /dev/disk/by-uuid/523c8243-5a25-40eb-8627-f3bbf98ec299 50G 47G 454M 100% / # umount / [blocks for about 2 seconds] umount: /: device is busy. (In some cases useful info about processes that use the device is found by lsof(8) or fuser(1)) # df -h / Filesystem Size Used Avail Use% Mounted on /dev/disk/by-uuid/523c8243-5a25-40eb-8627-f3bbf98ec299 50G 16G 32G 33% / # uname -r 4.14.67-ts1 -- Geoffrey Thomas geofft@xxxxxxxxxxxx
