Re: [PATCH v2 2/2] generic/486: adjust the max xattr size

[Xiubo Li <xiubli@redhat.com>]

On 6/9/22 6:53 PM, Luís Henriques wrote:
> CephFS doesn't have a maximum xattr size.  Instead, it imposes a maximum
> size for the full set of xattrs names+values, which by default is 64K.
> And since ceph reports 4M as the blocksize (the default ceph object size),
> generic/486 will fail in this filesystem because it will end up using
> XATTR_SIZE_MAX to set the size of the 2nd (big) xattr value.
>
> The fix is to adjust the max size in attr_replace_test so that it takes
> into account the initial xattr name and value lengths.
>
> Signed-off-by: Luís Henriques <lhenriques@suse.de>
> ---
>   src/attr_replace_test.c | 7 ++++++-
>   1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/src/attr_replace_test.c b/src/attr_replace_test.c
> index cca8dcf8ff60..1c8d1049a1d8 100644
> --- a/src/attr_replace_test.c
> +++ b/src/attr_replace_test.c
> @@ -29,6 +29,11 @@ int main(int argc, char *argv[])
>   	char *value;
>   	struct stat sbuf;
>   	size_t size = sizeof(value);
> +	/*
> +	 * Take into account the initial (small) xattr name and value sizes and
> +	 * subtract them from the XATTR_SIZE_MAX maximum.
> +	 */
> +	size_t maxsize = XATTR_SIZE_MAX - strlen(name) - 1;

Why not use the statfs to get the filesystem type first ? And then just 
minus the strlen(name) for ceph only ?


>   
>   	if (argc != 2)
>   		fail("Usage: %s <file>\n", argv[0]);
> @@ -46,7 +51,7 @@ int main(int argc, char *argv[])
>   	size = sbuf.st_blksize * 3 / 4;
>   	if (!size)
>   		fail("Invalid st_blksize(%ld)\n", sbuf.st_blksize);
> -	size = MIN(size, XATTR_SIZE_MAX);
> +	size = MIN(size, maxsize);
>   	value = malloc(size);
>   	if (!value)
>   		fail("Failed to allocate memory\n");
>