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Date: Mon, 2 May 2016 16:48:50 -0600
From: Andreas Dilger <adilger@...ger.ca>
To: David Howells <dhowells@...hat.com>
Cc: linux-fsdevel@...r.kernel.org, linux-afs@...r.kernel.org,
linux-nfs@...r.kernel.org, samba-technical@...ts.samba.org,
linux-kernel@...r.kernel.org, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 4/6] statx: NFS: Return enhanced file attributes
On Apr 29, 2016, at 6:58 AM, David Howells <dhowells@...hat.com> wrote:
>
> Return enhanced file atrributes from the NFS filesystem. This includes the
> following:
>
> (1) The change attribute as st_version if NFSv4.
>
> (2) STATX_INFO_AUTOMOUNT and STATX_INFO_FABRICATED are set on referral or
> submount directories that are automounted upon. NFS shows one
> directory with a different FSID, but the local filesystem has two: the
> mountpoint directory and the root of the filesystem mounted upon it.
>
> (3) STATX_INFO_REMOTE is set on files acquired over NFS.
>
> (4) STATX_IOC_FLAGS is set and if the atime is unavailable on a file,
> st_ioc_flags will have FL_NOATIME_FL set in it.
This is not implemented in this patch, and should removed from the commit
message. The generic_fillattr() change in [1/6] will clear the STATX_ATIME
flag if IS_NOATIME() is true, so maybe that is enough for what you intended?
Cheers, Andreas
> Furthermore, what nfs_getattr() does can be controlled as follows:
>
> (1) If AT_NO_ATTR_SYNC is indicated then this will suppress the flushing
> of outstanding writes and the rereading of the inode's attributes with
> the server as detailed below.
>
> (2) Otherwise:
>
> (a) If AT_FORCE_ATTR_SYNC is indicated, or mtime, ctime or
> data_version (NFSv4 only) are requested then the outstanding
> writes will be written to the server first.
>
> (b) The inode's attributes will be reread from the server:
>
> (i) if AT_FORCE_ATTR_SYNC is indicated;
>
> (ii) if atime is requested (and atime updating is not suppressed by
> a mount flag); or
>
> (iii) if the cached attributes have expired;
>
> If the inode isn't synchronised, then the cached attributes will be used -
> even if expired - without reference to the server.
>
> Example output:
>
> [root@...romeda ~]# ./samples/statx/test-statx /warthog/
> statx(/warthog/) = 0
> results=37ef
> Size: 4096 Blocks: 8 IO Block: 1048576 directory
> Device: 00:26 Inode: 2 Links: 122
> Access: (3777/drwxrwxrwx) Uid: 0 Gid: 4041
> Access: 2015-10-30 16:15:41.730925545+0000
> Modify: 2015-10-07 10:33:19.896108112+0100
> Change: 2015-10-07 10:33:19.896108112+0100
> Data version: 5614e6df35698650h
> Inode flags: 00000000 (-------- -------- -------- --------)
> Information: 00000010 (-------- -------- -------- ---r----)
> IO-blocksize: blksize=1048576
>
> Note that the NFS4 protocol potentially provides a creation time that could
> be passed through this interface and system, hidden and archive values that
> could be passed as IOC flags. There is also a backup time that could be
> added.
>
> Signed-off-by: David Howells <dhowells@...hat.com>
> ---
>
> fs/nfs/inode.c | 41 ++++++++++++++++++++++++++++++++++-------
> 1 file changed, 34 insertions(+), 7 deletions(-)
>
> diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
> index 738c84a42eb0..8637236bca0c 100644
> --- a/fs/nfs/inode.c
> +++ b/fs/nfs/inode.c
> @@ -655,12 +655,23 @@ static bool nfs_need_revalidate_inode(struct inode *inode)
> int nfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
> {
> struct inode *inode = d_inode(dentry);
> - int need_atime = NFS_I(inode)->cache_validity & NFS_INO_INVALID_ATIME;
> + bool force_sync = stat->query_flags & AT_FORCE_ATTR_SYNC;
> + bool suppress_sync = stat->query_flags & AT_NO_ATTR_SYNC;
> + bool need_atime = NFS_I(inode)->cache_validity & NFS_INO_INVALID_ATIME;
> int err = 0;
>
> trace_nfs_getattr_enter(inode);
> - /* Flush out writes to the server in order to update c/mtime. */
> - if (S_ISREG(inode->i_mode)) {
> +
> + if (NFS_SERVER(inode)->nfs_client->rpc_ops->version < 4)
> + stat->request_mask &= ~STATX_VERSION;
> +
> + /* Flush out writes to the server in order to update c/mtime or data
> + * version if the user wants them.
> + */
> + if (S_ISREG(inode->i_mode) && !suppress_sync &&
> + (force_sync || (stat->request_mask &
> + (STATX_MTIME | STATX_CTIME | STATX_VERSION)))
> + ) {
> inode_lock(inode);
> err = nfs_sync_inode(inode);
> inode_unlock(inode);
> @@ -677,11 +688,13 @@ int nfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
> * - NFS never sets MS_NOATIME or MS_NODIRATIME so there is
> * no point in checking those.
> */
> - if ((mnt->mnt_flags & MNT_NOATIME) ||
> - ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode)))
> - need_atime = 0;
> + if (!(stat->request_mask & STATX_ATIME) ||
> + (mnt->mnt_flags & MNT_NOATIME) ||
> + ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode)))
> + need_atime = false;
>
> - if (need_atime || nfs_need_revalidate_inode(inode)) {
> + if (!suppress_sync &&
> + (force_sync || need_atime || nfs_need_revalidate_inode(inode))) {
> struct nfs_server *server = NFS_SERVER(inode);
>
> if (server->caps & NFS_CAP_READDIRPLUS)
> @@ -694,6 +707,20 @@ int nfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
> if (S_ISDIR(inode->i_mode))
> stat->blksize = NFS_SERVER(inode)->dtsize;
> }
> +
> + generic_fillattr(inode, stat);
> + stat->ino = nfs_compat_user_ino64(NFS_FILEID(inode));
> +
> + if (stat->request_mask & STATX_VERSION) {
> + stat->version = inode->i_version;
> + stat->result_mask |= STATX_VERSION;
> + }
> +
> + if (IS_AUTOMOUNT(inode))
> + stat->information |= STATX_INFO_FABRICATED;
> +
> + stat->information |= STATX_INFO_REMOTE;
> +
> out:
> trace_nfs_getattr_exit(inode, err);
> return err;
>
> --
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Cheers, Andreas
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