Hi Ted, Thanks for the response. Really appreciate it. Some questions: a) This issue is observed on one of the customer board and hence a fix is a must for us or at least I will need to do a work-around so other customer boards do not face this issue. As I mentioned my script relies on df -h output of used percentage. In the case of the board reporting 16Z of used space and size, the available space is somehow reported correctly. Should my script rely on available space and not on the used space% output of df. Will that be a reliable work-around? Do you see any issue in using the partition from then or some where down the line the overhead blocks number would create a problem and my partition would end up misbehaving or any sort of data loss could occur? Data loss would be a concern for us. Please guide. //* More info on my script: I have a script which monitors the used percentage of the partition using df -h command and when the used percentage is greater than 70%, it deletes files until the used percentage comes down. Considering df is reporting all the time 100% usage, all my files get deleted.*// b) Any other suggestions of a work-around so even if the overhead blocks reports more blocks than actual blocks on the partition, i am able to use the partition reliably or do you think it would be a better suggestion to wait for the fix in e2fsprogs? I think apart from the fix in e2fsprogs tool, a kernel fix is also required, wherein it performs check that the overhead blocks should not be greater than the actual blocks on the partition. Regards On Sat, Mar 26, 2022 at 3:41 AM Theodore Ts'o <tytso@xxxxxxx> wrote: > > On Fri, Mar 25, 2022 at 12:12:30PM +0530, Fariya F wrote: > > The output dumpe2fs returns the following > > > > Block count: 102400 > > Reserved block count: 5120 > > Overhead blocks: 50343939 > > Yeah, that value is obviously wrong; I'm not sure how it got > corrupted, but that's the cause of the your problem. > > > a) Where does overhead blocks get set? > > The kernel can calculate the overhead value, but it can be slow for > very large file systems. For that reason, it is cached in the > superblock. So if the s_overhead_clusters is zero, the kernel will > calculate the overhead value, and then update the superblock. > > In newer versions of e2fsprogs, mkfs.ext4 / mke2fs will write the > overhead value into the superblock. > > > b) Why is this value huge for my partition and how to correct it > > considering fsck is also not correcting this > > The simpleest way is to run the following command with the file system > unmounted: > > debugfs -w -R "set_super_value overhead_clusters 0" /dev/sdXX > > Then the next time you mount the file system, the correct value should > get caluclated and filled in. > > It's a bug that fsck isn't notcing the problem and correcting it. > I'll work on getting that fixed in a future version of e2fsprogs. > > My apologies for the inconvenience. > > Cheers, > > - Ted
