On 8/4/25 12:22 PM, Eric Sandeen wrote: > On 8/4/25 9:30 AM, Charalampos Mitrodimas wrote: >> Mount options (uid, gid, mode) are silently ignored when debugfs is >> mounted. This is a regression introduced during the conversion to the >> new mount API. >> >> When the mount API conversion was done, the line that sets >> sb->s_fs_info to the parsed options was removed. This causes >> debugfs_apply_options() to operate on a NULL pointer. >> >> As an example, with the bug the "mode" mount option is ignored: >> >> $ mount -o mode=0666 -t debugfs debugfs /tmp/debugfs_test >> $ mount | grep debugfs_test >> debugfs on /tmp/debugfs_test type debugfs (rw,relatime) >> $ ls -ld /tmp/debugfs_test >> drwx------ 25 root root 0 Aug 4 14:16 /tmp/debugfs_test > > Argh. So, this looks a lot like the issue that got fixed for tracefs in: > > e4d32142d1de tracing: Fix tracefs mount options > > Let me look at this; tracefs & debugfs are quite similar, so perhaps > keeping the fix consistent would make sense as well but I'll dig > into it a bit more. So, yes - a fix following the pattern of e4d32142d1de does seem to resolve this issue. However, I think we might be playing whack-a-mole here (fixing one fs at a time, when the problem is systemic) among filesystems that use get_tree_single() and have configurable options. For example, pstore: # umount /sys/fs/pstore # mount -t pstore -o kmsg_bytes=65536 none /sys/fs/pstore # mount | grep pstore none on /sys/fs/pstore type pstore (rw,relatime,seclabel) # mount -o remount,kmsg_bytes=65536 /sys/fs/pstore # mount | grep pstore none on /sys/fs/pstore type pstore (rw,relatime,seclabel,kmsg_bytes=65536) # I think gadgetfs most likely has the same problem but I'm not yet sure how to test that. I have no real objection to merging your patch, though I like the consistency of following e4d32142d1de a bit more. But I think we should find a graceful solution so that any filesystem using get_tree_single can avoid this pitfall, if possible. -Eric
