On Tue, Jan 09 2018, Trond Myklebust wrote:
> Support the query flags AT_STATX_FORCE_SYNC by forcing an attribute
> revalidation, and AT_STATX_DONT_SYNC by returning cached attributes
> only.
>
> Use the mask to optimise away server revalidation for attributes
> that are not being requested by the user.
>
> Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> ---
> v2:
> - Respect the attribute cache timeout.
> - Unless AT_STATX_DONT_SYNC is set, we must only return attributes
> that have been duly revalidated.
This looks good, thanks.
It handles _FORCE_SYNC and _DONT_SYNC and avoids the flush if
CTIME/MTIME aren't requested.
I note that you no longer call nfs_need_revalidate_inode().
Most of the checks in there you have included in a different form,
but I don't see a test for NFS_INO_INVALID_LABEL. Is there a reason
that we don't need that test any more? Was it redundant previously?
Thanks,
NeilBrown
>
> fs/nfs/inode.c | 51 ++++++++++++++++++++++++++++++++++++++-------------
> 1 file changed, 38 insertions(+), 13 deletions(-)
>
> diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
> index b112002dbdb2..c2c8bb7755ad 100644
> --- a/fs/nfs/inode.c
> +++ b/fs/nfs/inode.c
> @@ -735,12 +735,20 @@ int nfs_getattr(const struct path *path, struct kstat *stat,
> u32 request_mask, unsigned int query_flags)
> {
> struct inode *inode = d_inode(path->dentry);
> - int need_atime = NFS_I(inode)->cache_validity & NFS_INO_INVALID_ATIME;
> + struct nfs_server *server = NFS_SERVER(inode);
> + unsigned long cache_validity;
> int err = 0;
> + bool force_sync = query_flags & AT_STATX_FORCE_SYNC;
> + bool do_update = false;
>
> trace_nfs_getattr_enter(inode);
> +
> + if ((query_flags & AT_STATX_DONT_SYNC) && !force_sync)
> + goto out_no_update;
> +
> /* Flush out writes to the server in order to update c/mtime. */
> - if (S_ISREG(inode->i_mode)) {
> + if ((request_mask & (STATX_CTIME|STATX_MTIME)) &&
> + S_ISREG(inode->i_mode)) {
> err = filemap_write_and_wait(inode->i_mapping);
> if (err)
> goto out;
> @@ -757,24 +765,41 @@ int nfs_getattr(const struct path *path, struct kstat *stat,
> */
> if ((path->mnt->mnt_flags & MNT_NOATIME) ||
> ((path->mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode)))
> - need_atime = 0;
> -
> - if (need_atime || nfs_need_revalidate_inode(inode)) {
> - struct nfs_server *server = NFS_SERVER(inode);
> -
> + request_mask &= ~STATX_ATIME;
> +
> + /* Is the user requesting attributes that might need revalidation? */
> + if (!(request_mask & (STATX_MODE|STATX_NLINK|STATX_ATIME|STATX_CTIME|
> + STATX_MTIME|STATX_UID|STATX_GID|
> + STATX_SIZE|STATX_BLOCKS)))
> + goto out_no_revalidate;
> +
> + /* Check whether the cached attributes are stale */
> + do_update |= force_sync || nfs_attribute_cache_expired(inode);
> + cache_validity = READ_ONCE(NFS_I(inode)->cache_validity);
> + do_update |= cache_validity & NFS_INO_INVALID_ATTR;
> + if (request_mask & STATX_ATIME)
> + do_update |= cache_validity & NFS_INO_INVALID_ATIME;
> + if (request_mask & (STATX_CTIME|STATX_MTIME))
> + do_update |= cache_validity & NFS_INO_REVAL_PAGECACHE;
> + if (do_update) {
> + /* Update the attribute cache */
> if (!(server->flags & NFS_MOUNT_NOAC))
> nfs_readdirplus_parent_cache_miss(path->dentry);
> else
> nfs_readdirplus_parent_cache_hit(path->dentry);
> err = __nfs_revalidate_inode(server, inode);
> + if (err)
> + goto out;
> } else
> nfs_readdirplus_parent_cache_hit(path->dentry);
> - if (!err) {
> - generic_fillattr(inode, stat);
> - stat->ino = nfs_compat_user_ino64(NFS_FILEID(inode));
> - if (S_ISDIR(inode->i_mode))
> - stat->blksize = NFS_SERVER(inode)->dtsize;
> - }
> +out_no_revalidate:
> + /* Only return attributes that were revalidated. */
> + stat->result_mask &= request_mask;
> +out_no_update:
> + generic_fillattr(inode, stat);
> + stat->ino = nfs_compat_user_ino64(NFS_FILEID(inode));
> + if (S_ISDIR(inode->i_mode))
> + stat->blksize = NFS_SERVER(inode)->dtsize;
> out:
> trace_nfs_getattr_exit(inode, err);
> return err;
> --
> 2.14.3
>
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