Re: [PATCH] xfs_db: Scan entire file system when using 'frag'

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On 4/26/19 5:59 PM, Jorge Guerra wrote:
> From: Jorge Guerra <jorgeguerra@xxxxxx>
> 
> While running the 'frag' command of 'xfs_db' we noticed that the
> tool is not scanning all the files in the file system.  We noticed
> this when we modified the tool to print the inodes of all the files
> scanned.  For example:
> 
>  $ find /mnt/xfsdisk -type f | wc -l
>  1782674
>  $ xfs_db -r -c frag /dev/sdXX  | grep MB | awk '{print $5}' | paste -s -d+ | bc
>  656818
> 
> Upon inspecting the code we noticed that the scanfunc_ino function
> stops processing a given inode block once it encounters a free leaf.
> However, in practice we see that inodes are necessarily always layed
> out contiguously on the leaf node.  This resulted in the 'frag'
> command skipping some valid inodes.
> 
> In this change we modify the scanfunc_ino function to skip freed
> inodes.  With the change in place we ran the same experiment again
> and noticed a more accurate file count:
> 
>  $ find /mnt/d0 -type f | wc -l
>  1810442
>  $ xfs_db -r -c frag /dev/sdXX  | grep MB | awk '{print $5}' | paste -s -d+ | bc
>  1810442
> 
> Signed-off-by: Jorge Guerra <jorgeguerra@xxxxxx>

This looks right, but I'll warn you that xfs_db's frag command is largely
useless in the first place.  ;)

Also, I think:

Fixes: 2a5eb70c ("xfs_db: teach the frag command about sparse inode chunks")

Reviewed-by: Eric Sandeen <sandeen@xxxxxxxxxx>

Thanks!

> ---
>  db/frag.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/db/frag.c b/db/frag.c
> index 5f33cb73..91395234 100644
> --- a/db/frag.c
> +++ b/db/frag.c
> @@ -507,7 +507,7 @@ scanfunc_ino(
>  
>  				for (j = 0; j < inodes_per_buf; j++) {
>  					if (XFS_INOBT_IS_FREE_DISK(&rp[i], ioff + j))
> -						goto next_buf;
> +						continue;
>  					dip = (xfs_dinode_t *)((char *)iocur_top->data +
>  						((off + j) << mp->m_sb.sb_inodelog));
>  					process_inode(agf, agino + ioff + j, dip);
> 



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