linux-kernel - Re: [PATCH] fs: make insert_inode_locked() wait for inode destruction

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Message-ID: <o2ypypbtb6jjlditunp67nir52qb3q7jr262nawh4cn5hfxlca@cgg3mshbsg77>
Date: Mon, 12 Jan 2026 12:47:21 +0100
From: Jan Kara <jack@...e.cz>
To: Mateusz Guzik <mjguzik@...il.com>
Cc: brauner@...nel.org, viro@...iv.linux.org.uk, jack@...e.cz, 
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH] fs: make insert_inode_locked() wait for inode destruction

On Sun 11-01-26 09:38:42, Mateusz Guzik wrote:
> This is the only routine which instead skipped instead of waiting.
> 
> The current behavior is arguably a bug as it results in a corner case
> where the inode hash can have *two* matching inodes, one of which is on
> its way out.
> 
> Ironing out this difference is an incremental step towards sanitizing
> the API.
> 
> Signed-off-by: Mateusz Guzik <mjguzik@...il.com>

Agreed, it's an odd difference between the two inode insertion apis. Feel
free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  fs/inode.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/inode.c b/fs/inode.c
> index f8904f813372..3b838f07cb40 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -1832,16 +1832,13 @@ int insert_inode_locked(struct inode *inode)
>  	while (1) {
>  		struct inode *old = NULL;
>  		spin_lock(&inode_hash_lock);
> +repeat:
>  		hlist_for_each_entry(old, head, i_hash) {
>  			if (old->i_ino != ino)
>  				continue;
>  			if (old->i_sb != sb)
>  				continue;
>  			spin_lock(&old->i_lock);
> -			if (inode_state_read(old) & (I_FREEING | I_WILL_FREE)) {
> -				spin_unlock(&old->i_lock);
> -				continue;
> -			}
>  			break;
>  		}
>  		if (likely(!old)) {
> @@ -1852,6 +1849,11 @@ int insert_inode_locked(struct inode *inode)
>  			spin_unlock(&inode_hash_lock);
>  			return 0;
>  		}
> +		if (inode_state_read(old) & (I_FREEING | I_WILL_FREE)) {
> +			__wait_on_freeing_inode(old, true);
> +			old = NULL;
> +			goto repeat;
> +		}
>  		if (unlikely(inode_state_read(old) & I_CREATING)) {
>  			spin_unlock(&old->i_lock);
>  			spin_unlock(&inode_hash_lock);
> -- 
> 2.48.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR