Executive summary: Every tool I've tried confirms lots of inodes in use on this ext4 partitionEvery tool I've tried shows me that there are no files on the partitionIt's not files held open and it's not an overlay mountLong story:I have an SSD with a single ext4 partition.  This drive was being used to continually store video from cameras, in short clips, and a cron job would periodically delete the oldest clips (in a C application, which deleted them by calling remove()).  After a while someone noticed that while there should have been about 5 days' worth of video backed up, there was hardly any, but the drive was almost full.I took a look and naively tried just removing lost+found, but the drive was still full.  So, I deleted everything (rm -rf *), but df -i tells me that 91230 inodes are in use, even though ls and du show nothing at all.e2fsck -fv found no errors to fix (aside from creating lost+found again), and dumpe2fs and tune2fs -l both agree with df -i on the number of used inodes.  I've tried e2fsck -b with a couple of the backup super-blocks and it didn't seem to make any difference.baobab shows the same used space as df in the summary view, but when I click on the partition to see where the space is used, it only shows the 4.1kB used by  the empty lost+found directory.The problem is not that deleted file handles that are still open - nothing is open.  I've mounted and unmounted this partition multiple times, and even taken the drive out and put it in a completely different machine.I know I could just re-format the partition and start fresh, but I would really like to understand what's going on here and whether there's any proper way to fix this - I don't care whether it brings the files for those inodes back or it makes them properly deleted so they don't use up all the space.Edit:Running dump creates a backup file roughly equal in size to the used space reported by df et al.  Then running restore to a different drive created a chain of directories that's clearly wrong (/media/usb0/20150426/10/1_20150426_100125.264/20150426/10/1_20150426_100125.264/ and it continues many levels deep, the same structure repeating), before printing a bunch of lines like:expected next file 7823361, got 7610674expected next file 7823361, got 7610675(second number incrementing - it goes back well beyond my terminal's buffer) before finally:cannot find directory inode 11abort? [yn]Choosing n results in more cannot find directory node x, so I aborted.Giving up and writing this off as a freak file-system corruption which hopefully won't happen again.
ext4 inodes in use for files that are missing
ext4