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* can I change NAME_MAX limit
@ 2019-05-07  9:48 litaibaichina
  2019-05-07 10:57 ` David Sterba
  0 siblings, 1 reply; 2+ messages in thread
From: litaibaichina @ 2019-05-07  9:48 UTC (permalink / raw)
  To: linux-btrfs@vger.kernel.org


Hi Guys,

I am running btrfs on a 4.4.178 kernel,  I want to support a longer file name, now the NAME_MAX is 255,  can I just increase the NAME_MAX macro and recompile the kernel to support longer file name ?  I guess I will break sth,  but I am not sure what part will be broken.

Thanks.

^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: can I change NAME_MAX limit
  2019-05-07  9:48 can I change NAME_MAX limit litaibaichina
@ 2019-05-07 10:57 ` David Sterba
  0 siblings, 0 replies; 2+ messages in thread
From: David Sterba @ 2019-05-07 10:57 UTC (permalink / raw)
  To: litaibaichina@gmail.com; +Cc: linux-btrfs@vger.kernel.org

On Tue, May 07, 2019 at 05:48:47PM +0800, litaibaichina@gmail.com wrote:
> I am running btrfs on a 4.4.178 kernel,  I want to support a longer
> file name, now the NAME_MAX is 255,  can I just increase the NAME_MAX
> macro and recompile the kernel to support longer file name ?  I guess
> I will break sth,  but I am not sure what part will be broken.

NAME_MAX is system-wide and defined in limits.h. This is not btrfs
specific, you'd need to recompile the whole userspace too and who knows
what would break.

255 fits into a byte and I think some filesystems use that as maximum
that can be stored in their metdata, ie. not possible to change without
wider thanges.

Btrfs has space in btrfs_dir_item as it stores the name as 16bit number.

^ permalink raw reply	[flat|nested] 2+ messages in thread

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2019-05-07  9:48 can I change NAME_MAX limit litaibaichina
2019-05-07 10:57 ` David Sterba

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