linux-kernel - Re: [V2] btrfs: drop inode reference count on error path

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Date:   Thu, 18 Apr 2019 10:07:54 -0400
From:   Josef Bacik <josef@...icpanda.com>
To:     Nikolay Borisov <nborisov@...e.com>
Cc:     Pan Bian <bianpan2016@....com>, Chris Mason <clm@...com>,
        Josef Bacik <josef@...icpanda.com>,
        David Sterba <dsterba@...e.com>, linux-btrfs@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [V2] btrfs: drop inode reference count on error path

On Thu, Apr 18, 2019 at 03:50:00PM +0300, Nikolay Borisov wrote:
> 
> 
> On 18.04.19 г. 14:06 ч., Pan Bian wrote:
> > The reference count of inode is incremented by ihold. It should be
> > dropped if not used. However, the reference count is not dropped if
> > error occurs during updating the inode or deleting orphan items. This
> > patch fixes the bug.
> > 
> > Signed-off-by: Pan Bian <bianpan2016@....com>
> > ---
> > V2: move ihold just before device_initialize to make code clearer
> > ---
> >  fs/btrfs/inode.c | 54 +++++++++++++++++++++++++-----------------------------
> >  1 file changed, 25 insertions(+), 29 deletions(-)
> > 
> > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> > index 82fdda8..d6630df 100644
> > --- a/fs/btrfs/inode.c
> > +++ b/fs/btrfs/inode.c
> > @@ -6579,7 +6579,7 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
> >  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
> >  	u64 index;
> >  	int err;
> > -	int drop_inode = 0;
> > +	int log_mode;
> >  
> >  	/* do not allow sys_link's with other subvols of the same device */
> >  	if (root->root_key.objectid != BTRFS_I(inode)->root->root_key.objectid)
> > @@ -6616,41 +6616,37 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
> >  	err = btrfs_add_nondir(trans, BTRFS_I(dir), dentry, BTRFS_I(inode),
> >  			1, index);
> >  
> > -	if (err) {
> > -		drop_inode = 1;
> > -	} else {
> > -		struct dentry *parent = dentry->d_parent;
> > -		int ret;
> > +	if (err)
> > +		goto err_link;
> >  
> > -		err = btrfs_update_inode(trans, root, inode);
> > +	err = btrfs_update_inode(trans, root, inode);
> > +	if (err)
> > +		goto err_link;
> > +	if (inode->i_nlink == 1) {
> > +		/*
> > +		 * If new hard link count is 1, it's a file created
> > +		 * with open(2) O_TMPFILE flag.
> > +		 */
> > +		err = btrfs_orphan_del(trans, BTRFS_I(inode));
> >  		if (err)
> > -			goto fail;
> > -		if (inode->i_nlink == 1) {
> > -			/*
> > -			 * If new hard link count is 1, it's a file created
> > -			 * with open(2) O_TMPFILE flag.
> > -			 */
> > -			err = btrfs_orphan_del(trans, BTRFS_I(inode));
> > -			if (err)
> > -				goto fail;
> > -		}
> > -		BTRFS_I(inode)->last_link_trans = trans->transid;
> > -		d_instantiate(dentry, inode);
> > -		ret = btrfs_log_new_name(trans, BTRFS_I(inode), NULL, parent,
> > -					 true, NULL);
> > -		if (ret == BTRFS_NEED_TRANS_COMMIT) {
> > -			err = btrfs_commit_transaction(trans);
> > -			trans = NULL;
> > -		}
> > +			goto err_link;
> > +	}
> > +	BTRFS_I(inode)->last_link_trans = trans->transid;
> > +	ihold(inode);

Where is the iput for this ihold?

Josef