On Mon, Apr 15, 2024 at 08:17:46PM +0800, Baokun Li wrote: > When erofs_kill_sb() is called in block dev based mode, s_bdev may not have > been initialised yet, and if CONFIG_EROFS_FS_ONDEMAND is enabled, it will > be mistaken for fscache mode, and then attempt to free an anon_dev that has > never been allocated, triggering the following warning: > > ============================================ > ida_free called for id=0 which is not allocated. > WARNING: CPU: 14 PID: 926 at lib/idr.c:525 ida_free+0x134/0x140 > Modules linked in: > CPU: 14 PID: 926 Comm: mount Not tainted 6.9.0-rc3-dirty #630 > RIP: 0010:ida_free+0x134/0x140 > Call Trace: > <TASK> > erofs_kill_sb+0x81/0x90 > deactivate_locked_super+0x35/0x80 > get_tree_bdev+0x136/0x1e0 > vfs_get_tree+0x2c/0xf0 > do_new_mount+0x190/0x2f0 > [...] > ============================================ > > To avoid this problem, add SB_NODEV to fc->sb_flags after successfully > parsing the fsid, and then the superblock inherits this flag when it is > allocated, so that the sb_flags can be used to distinguish whether it is > in block dev based mode when calling erofs_kill_sb(). > > Signed-off-by: Baokun Li <libaok...@huawei.com> > --- > fs/erofs/super.c | 7 +++---- > 1 file changed, 3 insertions(+), 4 deletions(-) > > diff --git a/fs/erofs/super.c b/fs/erofs/super.c > index b21bd8f78dc1..7539ce7d64bc 100644 > --- a/fs/erofs/super.c > +++ b/fs/erofs/super.c > @@ -520,6 +520,7 @@ static int erofs_fc_parse_param(struct fs_context *fc, > ctx->fsid = kstrdup(param->string, GFP_KERNEL); > if (!ctx->fsid) > return -ENOMEM; > + fc->sb_flags |= SB_NODEV;
Hm, I wouldn't do it this way. That's an abuse of that flag imho. Record the information in the erofs_fs_context if you need to.