On Wed, Jun 25, 2025 at 5:27 AM Tomas Hlavaty wrote: > > Hi Ryusuke, > > I get the following error: > > NILFS error (device dm-0): nilfs_bmap_lookup_contig: > broken bmap (inode number=4023271) > > and the filesystem gets mounted read-only. > > I can remount the filesystem read-write again manually, but after an > operation which touches the broken part of the filesystem, it gets > remounted read-only again. > > I have identified the file of the inode: > sudo find / -inum 4023271 > as > /root/.cache/mesa_shader_cache_db/index > but remounting rw and trying to > rm -r /root/.cache > puts the filesystem to ro mode again. > (not sure why there is .cache dir and mesa_shader_cache_db dir in the > /root dir, I never use root account for GUI) > > I am in the process of upgrading the system from nixos24.11 to > nixos25.05 but this issue is preventing me from doing so. Is there a > way to fix the filesystem so that it stays read-write? Or do I have to > discard the whole filesystem? > > Also I have noticed since long time ago, that reboot or shutdown says > something about nilfs discarding stuff, which seems strange and those > messages were not there a year or more ago. Not sure if this is > related, but it should not be discarding anything I guess. I see these > messages on many machines so it is not related to a particular hardware. > > Log and stacktrace are bellow. > Please let me know if I can provide more info about the problem. > > Any help would be appreciated. > > Thank you, Sorry for the inconvenience, and thank you for reporting the details of the problem. The log suggests that the b-tree, which is the metadata of the file or directory with inode 4023271, is corrupted, making it impossible to read and, as a result, impossible to write. The /root/.cache/... directory is not created by nilfs, so it is probably an application directory. If the problem is only partial, first mount it read-only, and then try copying it to another device while excluding the directory from access, for example, by specifying the option "--exclude /root/.cache" in rsync. As for in-place repair, the conclusion is that there is currently no way to do it. The only thing we can do is mount the filesystem read-only and salvage as much data as possible (without touching the damage). If you have a backup, it may be quicker to retrieve important data from there (in any case, nilfs is powerless against block device corruption, so please make backups as frequently as necessary). syzbot started reporting a large number of automatically detected bugs a few years ago, so we have been fixing a lot of serious bugs over the past few years, and have also strengthened the detection of abnormal file system states. That is probably why the abnormal message from a few years ago (probably a message about dropping to read-only and discarding dirty data) has become a problem now. If there were no messages with the old kernel and there were no problems, you could use it to rescue your data, but since there is a high possibility that there is some abnormality that was not detected in the past, this method is generally not recommended. I hope this helps a little. Regards, Ryusuke Konishi > > Tomas > > $ uname -a > Linux buta 6.6.87 #1-NixOS SMP PREEMPT_DYNAMIC Thu Apr 10 12:37:44 UTC 2025 x86_64 GNU/Linux > > $ sudo dmesg | grep nilfs > [ 1.087780] stage-1-init: [Tue Jun 24 19:32:16 UTC 2025] loading module nilfs2... > [ 35.318251] NILFS error (device dm-0): nilfs_bmap_lookup_contig: broken bmap (inode number=4023271) > [ 35.319235] NILFS error (device dm-0): nilfs_bmap_lookup_contig: broken bmap (inode number=4023271) > [...] > [ 35.347872] NILFS error (device dm-0): nilfs_bmap_lookup_contig: > broken bmap (inode number=4023271) > [ 1733.401421] nilfs_segctor_do_construct+0xdd/0x2630 [nilfs2] > [ 1733.401747] ? nilfs_mdt_fetch_dirty+0x19/0x50 [nilfs2] > [ 1733.401899] ? nilfs_test_metadata_dirty.isra.0+0x50/0xb0 [nilfs2] > [ 1733.402059] nilfs_segctor_construct+0x170/0x2b0 [nilfs2] > [ 1733.402220] nilfs_segctor_thread+0x155/0x3f0 [nilfs2] > [ 1733.402385] ? __pfx_nilfs_segctor_thread+0x10/0x10 [nilfs2] > [ 1738.068626] NILFS error (device dm-0): nilfs_bmap_last_key: broken > bmap (inode number=4023271)
