Messages in this thread Patch in this message | | | Subject | [PATCH 3/4] statx: NFS: Return enhanced file attributes | From | David Howells <> | Date | Thu, 17 Nov 2016 13:35:17 +0000 |
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Return enhanced file atrributes from the NFS filesystem. This includes the following:
(1) The change attribute as stx_version if NFSv4.
(2) STATX_ATTR_AUTOMOUNT and STATX_ATTR_FABRICATED are set on referral or submount directories that are automounted upon. NFS shows one directory with a different FSID, but the local VFS has two: the mountpoint directory (fabricated) and the root of the filesystem mounted upon it.
(3) STATX_ATTR_REMOTE is set on files acquired over NFS.
Furthermore, what nfs_getattr() does can be controlled as follows:
(1) If AT_STATX_DONT_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_STATX_FORCE_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_STATX_FORCE_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@andromeda ~]# ./samples/statx/test-statx /warthog/ statx(/warthog/) = 0 results=17ff Size: 4096 Blocks: 8 IO Block: 1048576 directory Device: 00:26 Inode: 2 Links: 21 Access: (0555/dr-xr-xr-x) Uid: 0 Gid: 0 Access: 2016-11-14 11:49:14.582749262+0000 Modify: 2016-09-08 20:39:46.785788707+0100 Change: 2016-09-08 20:39:46.785788707+0100 Data version: 57d1be822ed62f23h Attributes: 0000000000002000 (-------- -------- -------- -------- -------- -------- --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 attributes. There is also a backup time that could be exposed.
Signed-off-by: David Howells <dhowells@redhat.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 bf4ec5ecc97e..73c4502d4abb 100644 --- a/fs/nfs/inode.c +++ b/fs/nfs/inode.c @@ -656,12 +656,23 @@ 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_STATX_FORCE_SYNC; + bool suppress_sync = stat->query_flags & AT_STATX_DONT_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))) + ) { err = filemap_write_and_wait(inode->i_mapping); if (err) goto out; @@ -676,11 +687,13 @@ 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) @@ -693,6 +706,20 @@ 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->attributes |= STATX_ATTR_FABRICATED; + + stat->attributes |= STATX_ATTR_REMOTE; + out: trace_nfs_getattr_exit(inode, err); return err;
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