The patch below does not apply to the 6.17-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.17.y git checkout FETCH_HEAD git cherry-pick -x 8e7e265d558e0257d6dacc78ec64aff4ba75f61e # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025101559-usher-corroding-5b5a@gregkh' --subject-prefix 'PATCH 6.17.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 8e7e265d558e0257d6dacc78ec64aff4ba75f61e Mon Sep 17 00:00:00 2001 From: Charalampos Mitrodimas charmitro@posteo.net Date: Sat, 16 Aug 2025 14:14:37 +0000 Subject: [PATCH] debugfs: fix mount options not being applied

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 parsed options were never applied to the superblock when it was reused. As a result, the mount options were ignored when debugfs was mounted.

Fix this by following the same pattern as the tracefs fix in commit e4d32142d1de ("tracing: Fix tracefs mount options"). Call debugfs_reconfigure() in debugfs_get_tree() to apply the mount options to the superblock after it has been created or reused.

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

With the fix applied, it works as expected:

$ mount -o mode=0666 -t debugfs debugfs /tmp/debugfs_test $ mount | grep debugfs_test debugfs on /tmp/debugfs_test type debugfs (rw,relatime,mode=666) $ ls -ld /tmp/debugfs_test drw-rw-rw- 37 root root 0 Aug 2 17:28 /tmp/debugfs_test

Fixes: a20971c18752 ("vfs: Convert debugfs to use the new mount API") Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220406 Cc: stable@vger.kernel.org Reviewed-by: Eric Sandeen sandeen@redhat.com Signed-off-by: Charalampos Mitrodimas charmitro@posteo.net Link: https://lore.kernel.org/20250816-debugfs-mount-opts-v3-1-d271dad57b5b@posteo... Signed-off-by: Christian Brauner brauner@kernel.org

diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c index a0357b0cf362..c12d649df6a5 100644 --- a/fs/debugfs/inode.c +++ b/fs/debugfs/inode.c @@ -183,6 +183,9 @@ static int debugfs_reconfigure(struct fs_context *fc) struct debugfs_fs_info *sb_opts = sb->s_fs_info; struct debugfs_fs_info *new_opts = fc->s_fs_info;

+ if (!new_opts) + return 0; + sync_filesystem(sb);

/* structure copy of new mount options to sb */ @@ -282,10 +285,16 @@ static int debugfs_fill_super(struct super_block *sb, struct fs_context *fc)

static int debugfs_get_tree(struct fs_context *fc) { + int err; + if (!(debugfs_allow & DEBUGFS_ALLOW_API)) return -EPERM;

- return get_tree_single(fc, debugfs_fill_super); + err = get_tree_single(fc, debugfs_fill_super); + if (err) + return err; + + return debugfs_reconfigure(fc); }

static void debugfs_free_fc(struct fs_context *fc)