Re: [f2fs-dev] [PATCH 6/6] f2fs: set I_LINKABLE early to avoid wrong access by vfs

From: Jaegeuk Kim
Date: Tue Dec 10 2019 - 20:31:27 EST


On 12/11, Chao Yu wrote:
> On 2019/12/11 9:21, Jaegeuk Kim wrote:
> > On 12/10, Chao Yu wrote:
> >> On 2019/12/10 6:23, Jaegeuk Kim wrote:
> >>> This patch moves setting I_LINKABLE early in rename2(whiteout) to avoid the
> >>> below warning.
> >>>
> >>> [ 3189.163385] WARNING: CPU: 3 PID: 59523 at fs/inode.c:358 inc_nlink+0x32/0x40
> >>> [ 3189.246979] Call Trace:
> >>> [ 3189.248707] f2fs_init_inode_metadata+0x2d6/0x440 [f2fs]
> >>> [ 3189.251399] f2fs_add_inline_entry+0x162/0x8c0 [f2fs]
> >>> [ 3189.254010] f2fs_add_dentry+0x69/0xe0 [f2fs]
> >>> [ 3189.256353] f2fs_do_add_link+0xc5/0x100 [f2fs]
> >>> [ 3189.258774] f2fs_rename2+0xabf/0x1010 [f2fs]
> >>> [ 3189.261079] vfs_rename+0x3f8/0xaa0
> >>> [ 3189.263056] ? tomoyo_path_rename+0x44/0x60
> >>> [ 3189.265283] ? do_renameat2+0x49b/0x550
> >>> [ 3189.267324] do_renameat2+0x49b/0x550
> >>> [ 3189.269316] __x64_sys_renameat2+0x20/0x30
> >>> [ 3189.271441] do_syscall_64+0x5a/0x230
> >>> [ 3189.273410] entry_SYSCALL_64_after_hwframe+0x49/0xbe
> >>> [ 3189.275848] RIP: 0033:0x7f270b4d9a49
> >>>
> >>> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> >>> ---
> >>> fs/f2fs/namei.c | 27 +++++++++++++--------------
> >>> 1 file changed, 13 insertions(+), 14 deletions(-)
> >>>
> >>> diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
> >>> index a1c507b0b4ac..5d9584281935 100644
> >>> --- a/fs/f2fs/namei.c
> >>> +++ b/fs/f2fs/namei.c
> >>> @@ -797,6 +797,7 @@ static int __f2fs_tmpfile(struct inode *dir, struct dentry *dentry,
> >>>
> >>> if (whiteout) {
> >>> f2fs_i_links_write(inode, false);
> >>> + inode->i_state |= I_LINKABLE;
> >>> *whiteout = inode;
> >>> } else {
> >>> d_tmpfile(dentry, inode);
> >>> @@ -867,6 +868,12 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
> >>> F2FS_I(old_dentry->d_inode)->i_projid)))
> >>> return -EXDEV;
> >>>
> >>> + if (flags & RENAME_WHITEOUT) {
> >>> + err = f2fs_create_whiteout(old_dir, &whiteout);
> >>> + if (err)
> >>> + return err;
> >>> + }
> >>
> >> To record quota info correctly, we need to create whiteout inode after
> >> dquot_initialize(old_dir)?
> >
> > __f2fs_tmpfile() will do it.
>
> Okay.
>
> Any comments on below question?
>
> >
> >>
> >>> +
> >>> err = dquot_initialize(old_dir);
> >>> if (err)
> >>> goto out;
> >>> @@ -898,17 +905,11 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
> >>> }
> >>> }
> >>>
> >>> - if (flags & RENAME_WHITEOUT) {
> >>> - err = f2fs_create_whiteout(old_dir, &whiteout);
> >>> - if (err)
> >>> - goto out_dir;
> >>> - }
> >>> -
> >>> if (new_inode) {
> >>>
> >>> err = -ENOTEMPTY;
> >>> if (old_dir_entry && !f2fs_empty_dir(new_inode))
> >>> - goto out_whiteout;
> >>> + goto out_dir;
> >>>
> >>> err = -ENOENT;
> >>> new_entry = f2fs_find_entry(new_dir, &new_dentry->d_name,
> >>> @@ -916,7 +917,7 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
> >>> if (!new_entry) {
> >>> if (IS_ERR(new_page))
> >>> err = PTR_ERR(new_page);
> >>> - goto out_whiteout;
> >>> + goto out_dir;
> >>> }
> >>>
> >>> f2fs_balance_fs(sbi, true);
> >>> @@ -948,7 +949,7 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
> >>> err = f2fs_add_link(new_dentry, old_inode);
> >>> if (err) {
> >>> f2fs_unlock_op(sbi);
> >>> - goto out_whiteout;
> >>> + goto out_dir;
> >>> }
> >>>
> >>> if (old_dir_entry)
> >>> @@ -972,7 +973,7 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
> >>> if (IS_ERR(old_page))
> >>> err = PTR_ERR(old_page);
> >>> f2fs_unlock_op(sbi);
> >>> - goto out_whiteout;
> >>> + goto out_dir;
> >>> }
> >>> }
> >>> }
> >>> @@ -991,7 +992,6 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
> >>> f2fs_delete_entry(old_entry, old_page, old_dir, NULL);
> >>>
> >>> if (whiteout) {
> >>> - whiteout->i_state |= I_LINKABLE;
> >>> set_inode_flag(whiteout, FI_INC_LINK);
> >>> err = f2fs_add_link(old_dentry, whiteout);
> >>
> >> [ 3189.256353] f2fs_do_add_link+0xc5/0x100 [f2fs]
> >> [ 3189.258774] f2fs_rename2+0xabf/0x1010 [f2fs]
> >>
> >> Does the call stack point here? if so, we have set I_LINKABLE before
> >> f2fs_add_link(), why the warning still be triggered?
>
> Am I missing something?

Not sure exactly tho, I suspect some races before/after unlock_new_inode().

>
> Thanks,
>
> >>
> >> Thanks,
> >>
> >>> if (err)
> >>> @@ -1027,15 +1027,14 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
> >>> f2fs_unlock_op(sbi);
> >>> if (new_page)
> >>> f2fs_put_page(new_page, 0);
> >>> -out_whiteout:
> >>> - if (whiteout)
> >>> - iput(whiteout);
> >>> out_dir:
> >>> if (old_dir_entry)
> >>> f2fs_put_page(old_dir_page, 0);
> >>> out_old:
> >>> f2fs_put_page(old_page, 0);
> >>> out:
> >>> + if (whiteout)
> >>> + iput(whiteout);
> >>> return err;
> >>> }
> >>>
> >>>
> > .
> >