On Wed, Jan 16, 2019 at 10:34:23PM +0100, Etienne Buira wrote: > For the background: i've hit defect sectors (on part of md array), and i > want to rewrite those sectors to force hdd reallocation, so i need to > figure out what they are used for. Hi, I could resolve my issue, i was wrong on block number. What's left is the weird behaviour of debugfs, which reports a given block as "in use", and not linked to any inode (although it is in data part): > Unrolling the layers under fs, i'm interested in a 4K blocks range that > starts at 2035, here starts the trouble: > debugfs 1.43.9 (8-Feb-2018) > debugfs: testb 2035 > Block 2035 marked in use > debugfs: icheck 2035 > Block Inode number > 2035 <block not found> > > From this result, i tried to figure out if this block were used for fs > internal structures. > Using dumpe2fs, i see that this block belongs to group 0, and falls > beyond fs structures (last block for inode table is reported as 1568). > Block 2035 is not reported as free blocks. The debugfs queries have been done multiple times, so it is quite unprobable fs allocated this block everytime before i issued testb, and released it by the time i issued icheck. Regards.
