Re: [PATCH] nfs: set invalid blocks after NFSv4 writes

[Trond Myklebust <trondmy@hammerspace.com>]

On Wed, 2020-05-20 at 09:30 +0800, Zheng Bin wrote:
> Use the following command to test nfsv4(size of file1M is 1MB):
> mount -t nfs -o vers=4.0,actimeo=60 127.0.0.1/dir1 /mnt
> cp file1M /mnt
> du -h /mnt/file1M  -->0 within 60s, then 1M
> 
> When write is done(cp file1M /mnt), will call this:
> nfs_writeback_done
>   nfs4_write_done
>     nfs4_write_done_cb
>       nfs_writeback_update_inode
>         nfs_post_op_update_inode_force_wcc_locked(change, ctime,
> mtime
> nfs_post_op_update_inode_force_wcc_locked
>    nfs_set_cache_invalid
>    nfs_refresh_inode_locked
>      nfs_update_inode
> 
> nfsd write response contains change, ctime, mtime, the flag will be
> clear after nfs_update_inode. Howerver, write response does not
> contain
> space_used, previous open response contains space_used whose value is
> 0,
> so inode->i_blocks is still 0.
> 
> nfs_getattr  -->called by "du -h"
>   do_update |= force_sync || nfs_attribute_cache_expired -->false in
> 60s
>   cache_validity = READ_ONCE(NFS_I(inode)->cache_validity)
>   do_update |= cache_validity & (NFS_INO_INVALID_ATTR    -->false
>   if (do_update) {
>         __nfs_revalidate_inode
>   }
> 
> Within 60s, does not send getattr request to nfsd, thus "du -h
> /mnt/file1M"
> is 0.
> 
> Add a NFS_INO_INVALID_BLOCKS flag, set it when nfsv4 write is done.
> 
> Fixes: 16e143751727 ("NFS: More fine grained attribute tracking")
> Signed-off-by: Zheng Bin <zhengbin13@huawei.com>
> ---
>  fs/nfs/inode.c         | 9 +++++++--
>  include/linux/nfs_fs.h | 6 ++++--
>  2 files changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
> index b9d0921cb4fe..2d743e42fee1 100644
> --- a/fs/nfs/inode.c
> +++ b/fs/nfs/inode.c
> @@ -1764,7 +1764,8 @@ int
> nfs_post_op_update_inode_force_wcc_locked(struct inode *inode, struct
> nfs_fa
>  	status = nfs_post_op_update_inode_locked(inode, fattr,
>  			NFS_INO_INVALID_CHANGE
>  			| NFS_INO_INVALID_CTIME
> -			| NFS_INO_INVALID_MTIME);
> +			| NFS_INO_INVALID_MTIME
> +			| NFS_INO_INVALID_BLOCKS);
>  	return status;
>  }
> 
> @@ -2033,8 +2034,12 @@ static int nfs_update_inode(struct inode
> *inode, struct nfs_fattr *fattr)
>  		inode->i_blocks = nfs_calc_block_size(fattr-
> >du.nfs3.used);
>  	} else if (fattr->valid & NFS_ATTR_FATTR_BLOCKS_USED)
>  		inode->i_blocks = fattr->du.nfs2.blocks;
> -	else
> +	else {
> +		nfsi->cache_validity |= save_cache_validity &
> +				(NFS_INO_INVALID_BLOCKS
> +				| NFS_INO_REVAL_FORCED);
>  		cache_revalidated = false;
> +	}
> 
>  	/* Update attrtimeo value if we're out of the unstable period
> */
>  	if (attr_changed) {
> diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
> index 73eda45f1cfd..77efdca12cab 100644
> --- a/include/linux/nfs_fs.h
> +++ b/include/linux/nfs_fs.h
> @@ -227,14 +227,16 @@ struct nfs4_copy_state {
>  #define NFS_INO_INVALID_CTIME	BIT(9)		/* cached
> ctime is invalid */
>  #define NFS_INO_INVALID_MTIME	BIT(10)		/* cached
> mtime is invalid */
>  #define NFS_INO_INVALID_SIZE	BIT(11)		/* cached size is
> invalid */
> -#define NFS_INO_INVALID_OTHER	BIT(12)		/* other
> attrs are invalid */
> +#define NFS_INO_INVALID_BLOCKS	BIT(12)         /* cached
> blocks are invalid */
> +#define NFS_INO_INVALID_OTHER	BIT(13)		/* other
> attrs are invalid */
>  #define NFS_INO_DATA_INVAL_DEFER	\
> -				BIT(13)		/* Deferred cache
> invalidation */
> +				BIT(14)		/* Deferred cache
> invalidation */
> 
>  #define NFS_INO_INVALID_ATTR	(NFS_INO_INVALID_CHANGE \
>  		| NFS_INO_INVALID_CTIME \
>  		| NFS_INO_INVALID_MTIME \
>  		| NFS_INO_INVALID_SIZE \
> +		| NFS_INO_INVALID_BLOCKS \

Can we please replace this with an explicit check for STATX_BLOCKS in
nfs_getattr()? The above would just mean we always revalidate
independently of whether or not the user cares.

>  		| NFS_INO_INVALID_OTHER)	/* inode metadata is invalid
> */
> 
>  /*
> --
> 2.26.0.106.g9fadedd
> 
-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com