On Wed, 2021-06-16 at 20:44 +0800, Gao Xiang wrote:
> When testing fstests with ext4 over nfs 4.2, I found generic/486
> failed. The root cause is that the length of its xattr value is
> min(st_blksize * 3 / 4, XATTR_SIZE_MAX)
>
> which is 4096 * 3 / 4 = 3072 for underlayfs ext4 rather than
> XATTR_SIZE_MAX = 65536 for nfs since the block size would be wsize
> (=131072) if bsize is not specified.
>
> Let's use pnfs_blksize first instead of using wsize directly if
> bsize isn't specified. And the testcase itself can pass now.
>
> Cc: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> Cc: Anna Schumaker <anna.schumaker@xxxxxxxxxx>
> Cc: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx>
> ---
> Considering bsize is not specified, we might use pnfs_blksize
> directly first rather than wsize.
>
> fs/nfs/super.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/fs/nfs/super.c b/fs/nfs/super.c
> index fe58525cfed4..5015edf0cd9a 100644
> --- a/fs/nfs/super.c
> +++ b/fs/nfs/super.c
> @@ -1068,9 +1068,13 @@ static void nfs_fill_super(struct super_block
> *sb, struct nfs_fs_context *ctx)
> snprintf(sb->s_id, sizeof(sb->s_id),
> "%u:%u", MAJOR(sb->s_dev), MINOR(sb->s_dev));
>
> - if (sb->s_blocksize == 0)
> - sb->s_blocksize = nfs_block_bits(server->wsize,
> + if (sb->s_blocksize == 0) {
> + unsigned int blksize = server->pnfs_blksize ?
> + server->pnfs_blksize : server->wsize;
NACK. The pnfs block size is a layout driver-specific quantity, and
should not be used to substitute for the server-advertised block size.
It only applies to I/O _if_ the client is holding a layout for a
specific file and is using pNFS to do I/O to that file.
It has nothing to do with xattrs at all.
> +
> + sb->s_blocksize = nfs_block_bits(blksize,
> &sb-
> >s_blocksize_bits);
> + }
>
> nfs_super_set_maxbytes(sb, server->maxfilesize);
> server->has_sec_mnt_opts = ctx->has_sec_mnt_opts;
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@xxxxxxxxxxxxxxx
