Re: [PATCH] xfs: Set xfs_buf type flag when growing summary/bitmap files

[Christoph Hellwig <hch@infradead.org>]

On Sat, Sep 12, 2020 at 06:30:15PM +0530, Chandan Babu R wrote:
> The following sequence of commands,
> 
>   mkfs.xfs -f -m reflink=0 -r rtdev=/dev/loop1,size=10M /dev/loop0
>   mount -o rtdev=/dev/loop1 /dev/loop0 /mnt
>   xfs_growfs  /mnt
> 
> ... causes the following call trace to be printed on the console,
> 
> XFS: Assertion failed: (bip->bli_flags & XFS_BLI_STALE) || (xfs_blft_from_flags(&bip->__bli_format) > XFS_BLFT_UNKNOWN_BUF && xfs_blft_from_flags(&bip->__bli_format) < XFS_BLFT_MAX_BUF), file: fs/xfs/xfs_buf_item.c, line: 331
> Call Trace:
>  xfs_buf_item_format+0x632/0x680
>  ? kmem_alloc_large+0x29/0x90
>  ? kmem_alloc+0x70/0x120
>  ? xfs_log_commit_cil+0x132/0x940
>  xfs_log_commit_cil+0x26f/0x940
>  ? xfs_buf_item_init+0x1ad/0x240
>  ? xfs_growfs_rt_alloc+0x1fc/0x280
>  __xfs_trans_commit+0xac/0x370
>  xfs_growfs_rt_alloc+0x1fc/0x280
>  xfs_growfs_rt+0x1a0/0x5e0
>  xfs_file_ioctl+0x3fd/0xc70
>  ? selinux_file_ioctl+0x174/0x220
>  ksys_ioctl+0x87/0xc0
>  __x64_sys_ioctl+0x16/0x20
>  do_syscall_64+0x3e/0x70
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
> This occurs because the buffer being formatted has the value of
> XFS_BLFT_UNKNOWN_BUF assigned to the 'type' subfield of
> bip->bli_formats->blf_flags.
> 
> This commit fixes the issue by assigning one of XFS_BLFT_RTSUMMARY_BUF
> and XFS_BLFT_RTBITMAP_BUF to the 'type' subfield of
> bip->bli_formats->blf_flags before committing the corresponding
> transaction.
> 
> Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
> ---
>  fs/xfs/xfs_rtalloc.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
> index 6209e7b6b895..192a69f307d7 100644
> --- a/fs/xfs/xfs_rtalloc.c
> +++ b/fs/xfs/xfs_rtalloc.c
> @@ -767,8 +767,12 @@ xfs_growfs_rt_alloc(
>  	struct xfs_bmbt_irec	map;		/* block map output */
>  	int			nmap;		/* number of block maps */
>  	int			resblks;	/* space reservation */
> +	enum xfs_blft		buf_type;
>  	struct xfs_trans	*tp;
>  
> +	buf_type = (ip == mp->m_rsumip) ?
> +		XFS_BLFT_RTSUMMARY_BUF : XFS_BLFT_RTBITMAP_BUF;

Nit:  can you turn this into a normal if / else?

Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>