Re: [PATCH v6 1/1] xfs: prevent close() from hanging on frozen filesystems

["Darrick J. Wong" <djwong@kernel.org>]

On Mon, Sep 14, 2026 at 09:31:51AM +0000, Aditya Prakash Srivastava wrote:
> When a file is closed, xfs_file_release() attempts to trim speculative
> post-EOF blocks. This requires allocating a transaction, which blocks
> indefinitely if the filesystem is frozen.
> 
> Fix the hang by wrapping the preallocation cleanup block with
> sb_start_write_trylock() and xfs_ilock_nowait() to bypass the trim
> best-effort when the filesystem is frozen or locking fails.
> 
> Suggested-by: Darrick J. Wong <djwong@kernel.org>
> Signed-off-by: Aditya Prakash Srivastava <aditya.ansh182@gmail.com>

Looks great, can't wait to see how the integration testing goes ;)
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> ---
>  fs/xfs/xfs_file.c | 22 +++++++++++++---------
>  1 file changed, 13 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index d8202da15aca..dd6d2e08faff 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -1872,17 +1872,21 @@ xfs_file_release(
>  		return 0;
>  
>  	/*
> -	 * If we can't get the iolock just skip truncating the blocks past EOF
> -	 * because we could deadlock with the mmap_lock otherwise. We'll get
> -	 * another chance to drop them once the last reference to the inode is
> -	 * dropped, so we'll never leak blocks permanently.
> +	 * If we can't get the iolock or if the filesystem is frozen, just skip
> +	 * truncating the blocks past EOF because we could deadlock with the
> +	 * mmap_lock or hang the close() call. We'll get another chance to drop
> +	 * them once the last reference to the inode is dropped, so we'll never
> +	 * leak blocks permanently.
>  	 */
>  	if (!xfs_iflags_test(ip, XFS_EOFBLOCKS_RELEASED) &&
> -	    xfs_ilock_nowait(ip, XFS_IOLOCK_EXCL)) {
> -		if (xfs_can_free_eofblocks(ip) &&
> -		    !xfs_iflags_test_and_set(ip, XFS_EOFBLOCKS_RELEASED))
> -			xfs_free_eofblocks(ip);
> -		xfs_iunlock(ip, XFS_IOLOCK_EXCL);
> +	    sb_start_write_trylock(mp->m_super)) {
> +		if (xfs_ilock_nowait(ip, XFS_IOLOCK_EXCL)) {
> +			if (xfs_can_free_eofblocks(ip) &&
> +			    !xfs_iflags_test_and_set(ip, XFS_EOFBLOCKS_RELEASED))
> +				xfs_free_eofblocks(ip);
> +			xfs_iunlock(ip, XFS_IOLOCK_EXCL);
> +		}
> +		sb_end_write(mp->m_super);
>  	}
>  
>  	return 0;
> -- 
> 2.47.3
> 
>