pe, 2022-05-20 kello 22:53 +0100, David Howells kirjoitti:
> If a callback break occurs (change notification), afs_getattr() needs
> to
> issue an FS.FetchStatus RPC operation to update the status of the
> file
> being examined by the stat-family of system calls.
>
> Fix afs_getattr() to do this if AFS_VNODE_CB_PROMISED has been
> cleared on a
> vnode by a callback break. Skip this if AT_STATX_DONT_SYNC is set.
>
> This can be tested by appending to a file on one AFS client and then
> using
> "stat -L" to examine its length on a machine running kafs. This can
> also
> be watched through tracing on the kafs machine. The callback break
> is
> seen:
>
> kworker/1:1-46 [001] ..... 978.910812: afs_cb_call:
> c=0000005f YFSCB.CallBack
> kworker/1:1-46 [001] ...1. 978.910829: afs_cb_break:
> 100058:23b4c:242d2c2 b=2 s=1 break-cb
> kworker/1:1-46 [001] ..... 978.911062: afs_call_done:
> c=0000005f ret=0 ab=0 [0000000082994ead]
>
> And then the stat command generated no traffic if unpatched, but with
> this
> change a call to fetch the status can be observed:
>
> stat-4471 [000] ..... 986.744122: afs_make_fs_call:
> c=000000ab 100058:023b4c:242d2c2 YFS.FetchStatus
> stat-4471 [000] ..... 986.745578: afs_call_done:
> c=000000ab ret=0 ab=0 [0000000087fc8c84]
>
> Fixes: 08e0e7c82eea ("[AF_RXRPC]: Make the in-kernel AFS filesystem
> use AF_RXRPC.")
> Reported-by: Markus Suvanto <markus.suvanto@xxxxxxxxx>
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> cc: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
> cc: linux-afs@xxxxxxxxxxxxxxxxxxx
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=216010
> ---
>
> fs/afs/inode.c | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/fs/afs/inode.c b/fs/afs/inode.c
> index 2fe402483ad5..30b066299d39 100644
> --- a/fs/afs/inode.c
> +++ b/fs/afs/inode.c
> @@ -740,10 +740,22 @@ int afs_getattr(struct user_namespace
> *mnt_userns, const struct path *path,
> {
> struct inode *inode = d_inode(path->dentry);
> struct afs_vnode *vnode = AFS_FS_I(inode);
> - int seq = 0;
> + struct key *key;
> + int ret, seq = 0;
>
> _enter("{ ino=%lu v=%u }", inode->i_ino, inode-
> >i_generation);
>
> + if (!(query_flags & AT_STATX_DONT_SYNC) &&
> + !test_bit(AFS_VNODE_CB_PROMISED, &vnode->flags)) {
> + key = afs_request_key(vnode->volume->cell);
> + if (IS_ERR(key))
> + return PTR_ERR(key);
> + ret = afs_validate(vnode, key);
> + key_put(key);
> + if (ret < 0)
> + return ret;
> + }
> +
> do {
> read_seqbegin_or_lock(&vnode->cb_lock, &seq);
> generic_fillattr(&init_user_ns, inode, stat);
>
>
Tested-by: Markus Suvanto <markus.suvanto@xxxxxxxxx>
-Markus
