by Jaegeuk Kim

[permalink] [raw]

Subject: Re: [f2fs-dev] [PATCH v2] f2fs: fix deadlock in i_xattr_sem and inode page lock and fix the original issue

On 06/28, Jaegeuk Kim wrote:
> On 06/28, Chao Yu wrote:
> > On 2023/6/28 16:08, Jaegeuk Kim wrote:
> > > Thread #1:
> > >
> > > [122554.641906][ T92] f2fs_getxattr+0xd4/0x5fc
> > > -> waiting for f2fs_down_read(&F2FS_I(inode)->i_xattr_sem);
> > >
> > > [122554.641927][ T92] __f2fs_get_acl+0x50/0x284
> > > [122554.641948][ T92] f2fs_init_acl+0x84/0x54c
> > > [122554.641969][ T92] f2fs_init_inode_metadata+0x460/0x5f0
> > > [122554.641990][ T92] f2fs_add_inline_entry+0x11c/0x350
> > > -> Locked dir->inode_page by f2fs_get_node_page()
> > >
> > > [122554.642009][ T92] f2fs_do_add_link+0x100/0x1e4
> > > [122554.642025][ T92] f2fs_create+0xf4/0x22c
> > > [122554.642047][ T92] vfs_create+0x130/0x1f4
> > >
> > > Thread #2:
> > >
> > > [123996.386358][ T92] __get_node_page+0x8c/0x504
> > > -> waiting for dir->inode_page lock
> > >
> > > [123996.386383][ T92] read_all_xattrs+0x11c/0x1f4
> > > [123996.386405][ T92] __f2fs_setxattr+0xcc/0x528
> > > [123996.386424][ T92] f2fs_setxattr+0x158/0x1f4
> > > -> f2fs_down_write(&F2FS_I(inode)->i_xattr_sem);
> > >
> > > [123996.386443][ T92] __f2fs_set_acl+0x328/0x430
> > > [123996.386618][ T92] f2fs_set_acl+0x38/0x50
> > > [123996.386642][ T92] posix_acl_chmod+0xc8/0x1c8
> > > [123996.386669][ T92] f2fs_setattr+0x5e0/0x6bc
> > > [123996.386689][ T92] notify_change+0x4d8/0x580
> > > [123996.386717][ T92] chmod_common+0xd8/0x184
> > > [123996.386748][ T92] do_fchmodat+0x60/0x124
> > > [123996.386766][ T92] __arm64_sys_fchmodat+0x28/0x3c
> >
> > Back to the race condition, my question is why we can chmod on inode before
> > it has been created?
>
> This is touching the directory.

Chao,

Do you have other concern? Otherwise, I'll include this into the next pull
request.

Thanks,

>
> >
> > Thanks,
> >
> > >
> > > Fixes: 27161f13e3c3 "f2fs: avoid race in between read xattr & write xattr"
> > > Cc: <[email protected]>
> > > Signed-off-by: Jaegeuk Kim <[email protected]>
> > > ---
> > > fs/f2fs/dir.c | 9 ++++++++-
> > > fs/f2fs/xattr.c | 6 ++++--
> > > 2 files changed, 12 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
> > > index 887e55988450..d635c58cf5a3 100644
> > > --- a/fs/f2fs/dir.c
> > > +++ b/fs/f2fs/dir.c
> > > @@ -775,8 +775,15 @@ int f2fs_add_dentry(struct inode *dir, const struct f2fs_filename *fname,
> > > {
> > > int err = -EAGAIN;
> > > - if (f2fs_has_inline_dentry(dir))
> > > + if (f2fs_has_inline_dentry(dir)) {
> > > + /*
> > > + * Should get i_xattr_sem to keep the lock order:
> > > + * i_xattr_sem -> inode_page lock used by f2fs_setxattr.
> > > + */
> > > + f2fs_down_read(&F2FS_I(dir)->i_xattr_sem);
> > > err = f2fs_add_inline_entry(dir, fname, inode, ino, mode);
> > > + f2fs_up_read(&F2FS_I(dir)->i_xattr_sem);
> > > + }
> > > if (err == -EAGAIN)
> > > err = f2fs_add_regular_entry(dir, fname, inode, ino, mode);
> > > diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c
> > > index 213805d3592c..476b186b90a6 100644
> > > --- a/fs/f2fs/xattr.c
> > > +++ b/fs/f2fs/xattr.c
> > > @@ -528,10 +528,12 @@ int f2fs_getxattr(struct inode *inode, int index, const char *name,
> > > if (len > F2FS_NAME_LEN)
> > > return -ERANGE;
> > > - f2fs_down_read(&F2FS_I(inode)->i_xattr_sem);
> > > + if (!ipage)
> > > + f2fs_down_read(&F2FS_I(inode)->i_xattr_sem);
> > > error = lookup_all_xattrs(inode, ipage, index, len, name,
> > > &entry, &base_addr, &base_size, &is_inline);
> > > - f2fs_up_read(&F2FS_I(inode)->i_xattr_sem);
> > > + if (!ipage)
> > > + f2fs_up_read(&F2FS_I(inode)->i_xattr_sem);
> > > if (error)
> > > return error;
>
>
> _______________________________________________
> Linux-f2fs-devel mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel

2023-06-30 23:56:17

by Chao Yu

[permalink] [raw]

Subject: Re: [f2fs-dev] [PATCH v2] f2fs: fix deadlock in i_xattr_sem and inode page lock and fix the original issue

On 2023/7/1 5:59, Jaegeuk Kim wrote:
> On 06/28, Jaegeuk Kim wrote:
>> On 06/28, Chao Yu wrote:
>>> On 2023/6/28 16:08, Jaegeuk Kim wrote:
>>>> Thread #1:
>>>>
>>>> [122554.641906][ T92] f2fs_getxattr+0xd4/0x5fc
>>>> -> waiting for f2fs_down_read(&F2FS_I(inode)->i_xattr_sem);
>>>>
>>>> [122554.641927][ T92] __f2fs_get_acl+0x50/0x284
>>>> [122554.641948][ T92] f2fs_init_acl+0x84/0x54c
>>>> [122554.641969][ T92] f2fs_init_inode_metadata+0x460/0x5f0
>>>> [122554.641990][ T92] f2fs_add_inline_entry+0x11c/0x350
>>>> -> Locked dir->inode_page by f2fs_get_node_page()
>>>>
>>>> [122554.642009][ T92] f2fs_do_add_link+0x100/0x1e4
>>>> [122554.642025][ T92] f2fs_create+0xf4/0x22c
>>>> [122554.642047][ T92] vfs_create+0x130/0x1f4
>>>>
>>>> Thread #2:
>>>>
>>>> [123996.386358][ T92] __get_node_page+0x8c/0x504
>>>> -> waiting for dir->inode_page lock
>>>>
>>>> [123996.386383][ T92] read_all_xattrs+0x11c/0x1f4
>>>> [123996.386405][ T92] __f2fs_setxattr+0xcc/0x528
>>>> [123996.386424][ T92] f2fs_setxattr+0x158/0x1f4
>>>> -> f2fs_down_write(&F2FS_I(inode)->i_xattr_sem);
>>>>
>>>> [123996.386443][ T92] __f2fs_set_acl+0x328/0x430
>>>> [123996.386618][ T92] f2fs_set_acl+0x38/0x50
>>>> [123996.386642][ T92] posix_acl_chmod+0xc8/0x1c8
>>>> [123996.386669][ T92] f2fs_setattr+0x5e0/0x6bc
>>>> [123996.386689][ T92] notify_change+0x4d8/0x580
>>>> [123996.386717][ T92] chmod_common+0xd8/0x184
>>>> [123996.386748][ T92] do_fchmodat+0x60/0x124
>>>> [123996.386766][ T92] __arm64_sys_fchmodat+0x28/0x3c
>>>
>>> Back to the race condition, my question is why we can chmod on inode before
>>> it has been created?
>>
>> This is touching the directory.
>
> Chao,
>
> Do you have other concern? Otherwise, I'll include this into the next pull
> request.

Jaegeuk,

Sorry for late reply, I was misled by "dir->inode_page" and "inode" words in commit
message, it should be "dir->inode_page" and "dir_inode".

Anyway, the patch looks good to me.

Reviewed-by: Chao Yu <[email protected]>

Thanks,

>
> Thanks,
>
>>
>>>
>>> Thanks,
>>>
>>>>
>>>> Fixes: 27161f13e3c3 "f2fs: avoid race in between read xattr & write xattr"
>>>> Cc: <[email protected]>
>>>> Signed-off-by: Jaegeuk Kim <[email protected]>
>>>> ---
>>>> fs/f2fs/dir.c | 9 ++++++++-
>>>> fs/f2fs/xattr.c | 6 ++++--
>>>> 2 files changed, 12 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
>>>> index 887e55988450..d635c58cf5a3 100644
>>>> --- a/fs/f2fs/dir.c
>>>> +++ b/fs/f2fs/dir.c
>>>> @@ -775,8 +775,15 @@ int f2fs_add_dentry(struct inode *dir, const struct f2fs_filename *fname,
>>>> {
>>>> int err = -EAGAIN;
>>>> - if (f2fs_has_inline_dentry(dir))
>>>> + if (f2fs_has_inline_dentry(dir)) {
>>>> + /*
>>>> + * Should get i_xattr_sem to keep the lock order:
>>>> + * i_xattr_sem -> inode_page lock used by f2fs_setxattr.
>>>> + */
>>>> + f2fs_down_read(&F2FS_I(dir)->i_xattr_sem);
>>>> err = f2fs_add_inline_entry(dir, fname, inode, ino, mode);
>>>> + f2fs_up_read(&F2FS_I(dir)->i_xattr_sem);
>>>> + }
>>>> if (err == -EAGAIN)
>>>> err = f2fs_add_regular_entry(dir, fname, inode, ino, mode);
>>>> diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c
>>>> index 213805d3592c..476b186b90a6 100644
>>>> --- a/fs/f2fs/xattr.c
>>>> +++ b/fs/f2fs/xattr.c
>>>> @@ -528,10 +528,12 @@ int f2fs_getxattr(struct inode *inode, int index, const char *name,
>>>> if (len > F2FS_NAME_LEN)
>>>> return -ERANGE;
>>>> - f2fs_down_read(&F2FS_I(inode)->i_xattr_sem);
>>>> + if (!ipage)
>>>> + f2fs_down_read(&F2FS_I(inode)->i_xattr_sem);
>>>> error = lookup_all_xattrs(inode, ipage, index, len, name,
>>>> &entry, &base_addr, &base_size, &is_inline);
>>>> - f2fs_up_read(&F2FS_I(inode)->i_xattr_sem);
>>>> + if (!ipage)
>>>> + f2fs_up_read(&F2FS_I(inode)->i_xattr_sem);
>>>> if (error)
>>>> return error;
>>
>>
>> _______________________________________________
>> Linux-f2fs-devel mailing list
>> [email protected]
>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel