[ Upstream commit 0f28be64d1 ]
Lockdep reported the following issue when mounting erofs with a domain_id:
============================================
WARNING: possible recursive locking detected
6.8.0-rc7-xfstests #521 Not tainted
--------------------------------------------
mount/396 is trying to acquire lock:
ffff907a8aaaa0e0 (&type->s_umount_key#50/1){+.+.}-{3:3},
at: alloc_super+0xe3/0x3d0
but task is already holding lock:
ffff907a8aaa90e0 (&type->s_umount_key#50/1){+.+.}-{3:3},
at: alloc_super+0xe3/0x3d0
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&type->s_umount_key#50/1);
lock(&type->s_umount_key#50/1);
*** DEADLOCK ***
May be due to missing lock nesting notation
2 locks held by mount/396:
#0: ffff907a8aaa90e0 (&type->s_umount_key#50/1){+.+.}-{3:3},
at: alloc_super+0xe3/0x3d0
#1: ffffffffc00e6f28 (erofs_domain_list_lock){+.+.}-{3:3},
at: erofs_fscache_register_fs+0x3d/0x270 [erofs]
stack backtrace:
CPU: 1 PID: 396 Comm: mount Not tainted 6.8.0-rc7-xfstests #521
Call Trace:
<TASK>
dump_stack_lvl+0x64/0xb0
validate_chain+0x5c4/0xa00
__lock_acquire+0x6a9/0xd50
lock_acquire+0xcd/0x2b0
down_write_nested+0x45/0xd0
alloc_super+0xe3/0x3d0
sget_fc+0x62/0x2f0
vfs_get_super+0x21/0x90
vfs_get_tree+0x2c/0xf0
fc_mount+0x12/0x40
vfs_kern_mount.part.0+0x75/0x90
kern_mount+0x24/0x40
erofs_fscache_register_fs+0x1ef/0x270 [erofs]
erofs_fc_fill_super+0x213/0x380 [erofs]
This is because the file_system_type of both erofs and the pseudo-mount
point of domain_id is erofs_fs_type, so two successive calls to
alloc_super() are considered to be using the same lock and trigger the
warning above.
Therefore add a nodev file_system_type called erofs_anon_fs_type in
fscache.c to silence this complaint. Because kern_mount() takes a
pointer to struct file_system_type, not its (string) name. So we don't
need to call register_filesystem(). In addition, call init_pseudo() in
erofs_anon_init_fs_context() as suggested by Al Viro, so that we can
remove erofs_fc_fill_pseudo_super(), erofs_fc_anon_get_tree(), and
erofs_anon_context_ops.
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Fixes: a9849560c5 ("erofs: introduce a pseudo mnt to manage shared cookies")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-and-tested-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Yang Erkun <yangerkun@huawei.com>
Link: https://lore.kernel.org/r/20240307101018.2021925-1-libaokun1@huawei.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
b50efb417c