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Re: [PATCH 17/30] db: rewrite IO engine to use libxfs

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: [PATCH 17/30] db: rewrite IO engine to use libxfs
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Thu, 31 Oct 2013 08:10:46 -0700
Cc: xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1383107481-28937-18-git-send-email-david@xxxxxxxxxxxxx>
References: <1383107481-28937-1-git-send-email-david@xxxxxxxxxxxxx> <1383107481-28937-18-git-send-email-david@xxxxxxxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Wed, Oct 30, 2013 at 03:31:08PM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
> 
> Now that we have buffers and xfs_buf_maps, it is relatively easy to
> convert the IO engine to use libxfs routines. This gets rid of the
> most of the differences between mapped and straight buffer reads,
> and tracks xfs_bufs directly in the IO context that is being used.
> 
> This is not yet a perfect solution, as xfs_db does different sized
> IOs for the same block range which will throw warnings like:
> 
> xfs_db> inode 64
> 7ffff7fde740: Badness in key lookup (length)
> bp=(bno 0x40, len 8192 bytes) key=(bno 0x40, len 4096 bytes)
> xfs_db>

Maybe we should use uncached buffer I/O in xfs_db, similar to what we do
in the mount path in the kernel?

>       mp->m_flags = (LIBXFS_MOUNT_32BITINODES|LIBXFS_MOUNT_32BITINOOPT);
> +     if (flags & LIBXFS_MOUNT_ROOTINOS)
> +             mp->m_flags |= LIBXFS_MOUNT_ROOTINOS;
> +
>       mp->m_sb = *sb;
>       INIT_RADIX_TREE(&mp->m_perag_tree, GFP_KERNEL);
>       sbp = &(mp->m_sb);
> @@ -866,6 +869,8 @@ libxfs_umount(xfs_mount_t *mp)
>       int                     agno;
>  
>       libxfs_rtmount_destroy(mp);
> +     if ((mp->m_flags & LIBXFS_MOUNT_ROOTINOS) && mp->m_rootip)
> +             libxfs_iput(mp->m_rootip, 0);

Seems like the patch to remove m_rootip should go before this one?

> -struct xfs_buf *
> -libxfs_readbuf_map(struct xfs_buftarg *btp, struct xfs_buf_map *map, int 
> nmaps,
> -             int flags, const struct xfs_buf_ops *ops)
> +int
> +libxfs_readbufr_map(struct xfs_buftarg *btp, struct xfs_buf *bp,
> +                 struct xfs_buf_map *map, int nmaps, int flags)

Shouldn't these sort of changes go into a separate patch?


Otherwise looks good to me.

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