Messages in this thread | | | Date | Sat, 26 Nov 2022 11:20:49 +0800 | Subject | Re: [PATCH v2] erofs: check the uniqueness of fsid in shared domain in advance | From | Jingbo Xu <> |
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Hi Tao,
Thanks for catching this!
On 11/25/22 7:08 PM, Hou Tao wrote: > From: Hou Tao <houtao1@huawei.com> > > When shared domain is enabled, doing mount twice with the same fsid and > domain_id will trigger sysfs warning as shown below: > > sysfs: cannot create duplicate filename '/fs/erofs/d0,meta.bin' > CPU: 15 PID: 1051 Comm: mount Not tainted 6.1.0-rc6+ #1 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) > Call Trace: > <TASK> > dump_stack_lvl+0x38/0x49 > dump_stack+0x10/0x12 > sysfs_warn_dup.cold+0x17/0x27 > sysfs_create_dir_ns+0xb8/0xd0 > kobject_add_internal+0xb1/0x240 > kobject_init_and_add+0x71/0xa0 > erofs_register_sysfs+0x89/0x110 > erofs_fc_fill_super+0x98c/0xaf0 > vfs_get_super+0x7d/0x100 > get_tree_nodev+0x16/0x20 > erofs_fc_get_tree+0x20/0x30 > vfs_get_tree+0x24/0xb0 > path_mount+0x2fa/0xa90 > do_mount+0x7c/0xa0 > __x64_sys_mount+0x8b/0xe0 > do_syscall_64+0x30/0x60 > entry_SYSCALL_64_after_hwframe+0x46/0xb0 > > The reason is erofs_fscache_register_cookie() doesn't guarantee the primary > data blob (aka fsid) is unique in the shared domain and > erofs_register_sysfs() invoked by the second mount will fail due to the > duplicated fsid in the shared domain and report warning. > > It would be better to check the uniqueness of fsid before doing > erofs_register_sysfs(), so adding a new flags parameter for > erofs_fscache_register_cookie() and doing the uniqueness check if > EROFS_REG_COOKIE_NEED_NOEXIST is enabled. > > After the patch, the error in dmesg for the duplicated mount would be: > > erofs: ...: erofs_domain_register_cookie: XX already exists in domain YY > > Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com> > Signed-off-by: Hou Tao <houtao1@huawei.com>
LGTM.
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
-- Thanks, Jingbo
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