[PATCH xfsprogs] Document current limitation of shrinking fs

[PATCH xfsprogs] Document current limitation of shrinking fs

[Xavier Claude]

Hello,

If I understand the code correctly[1], shrinking more than one AG is not
supported. So I propose to add it to the manpage, like for the log
shrinking option.

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/xfs/xfs_fsops.c?h=v6.17-rc2#n152
-- >8 --

Current implementation in the kernel doesn't allow to shrink more that
one AG

Signed-off-by: Xavier Claude <contact@xavierclaude.be>
---
 man/man8/xfs_growfs.8 | 1 +
 1 file changed, 1 insertion(+)

diff --git a/man/man8/xfs_growfs.8 b/man/man8/xfs_growfs.8
index a0126927..2e329fa6 100644
--- a/man/man8/xfs_growfs.8
+++ b/man/man8/xfs_growfs.8
@@ -70,6 +70,7 @@ otherwise the data section is grown to the largest size possible with the
 option. The size is expressed in filesystem blocks. A filesystem with only
 1 AG cannot be shrunk further, and a filesystem cannot be shrunk to the point
 where it would only have 1 AG.
+.B [NOTE: Only shrinking the last AG without removing it is implemented]
 .TP
 .B \-e
 Allows the real-time extent size to be specified. In
-- 
2.50.1

Re: [PATCH xfsprogs] Document current limitation of shrinking fs

[Darrick J. Wong]

On Mon, Aug 18, 2025 at 03:19:10PM +0000, Xavier Claude wrote:
> Hello,
> 
> If I understand the code correctly[1], shrinking more than one AG is not
> supported. So I propose to add it to the manpage, like for the log
> shrinking option.
> 
> [1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/xfs/xfs_fsops.c?h=v6.17-rc2#n152
> -- >8 --
> 
> Current implementation in the kernel doesn't allow to shrink more that
> one AG
> 
> Signed-off-by: Xavier Claude <contact@xavierclaude.be>
> ---
>  man/man8/xfs_growfs.8 | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/man/man8/xfs_growfs.8 b/man/man8/xfs_growfs.8
> index a0126927..2e329fa6 100644
> --- a/man/man8/xfs_growfs.8
> +++ b/man/man8/xfs_growfs.8
> @@ -70,6 +70,7 @@ otherwise the data section is grown to the largest size possible with the
>  option. The size is expressed in filesystem blocks. A filesystem with only
>  1 AG cannot be shrunk further, and a filesystem cannot be shrunk to the point
>  where it would only have 1 AG.
> +.B [NOTE: Only shrinking the last AG without removing it is implemented]

That's my understanding of where growfs is right now wrt shrinking

Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

>  .TP
>  .B \-e
>  Allows the real-time extent size to be specified. In
> -- 
> 2.50.1
> 
> 
>