On Fri, 2020-01-17 at 21:28 +0800, Yan, Zheng wrote:
> On 1/16/20 4:59 AM, Jeff Layton wrote:
> > With the Octopus release, the MDS will hand out directory create caps.
> >
> > If we have Fxc caps on the directory, and complete directory information
> > or a known negative dentry, then we can return without waiting on the
> > reply, allowing the open() call to return very quickly to userland.
> >
> > We use the normal ceph_fill_inode() routine to fill in the inode, so we
> > have to gin up some reply inode information with what we'd expect the
> > newly-created inode to have. The client assumes that it has a full set
> > of caps on the new inode, and that the MDS will revoke them when there
> > is conflicting access.
> >
> > This functionality is gated on the enable_async_dirops module option,
> > along with async unlinks, and on the server supporting the necessary
> > CephFS feature bit.
> >
> > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> > ---
> > fs/ceph/file.c | 196 +++++++++++++++++++++++++++++++++--
> > include/linux/ceph/ceph_fs.h | 3 +
> > 2 files changed, 190 insertions(+), 9 deletions(-)
> >
> > diff --git a/fs/ceph/file.c b/fs/ceph/file.c
> > index b44ccbc85fe4..2742417fa5ec 100644
> > --- a/fs/ceph/file.c
> > +++ b/fs/ceph/file.c
> > @@ -448,6 +448,169 @@ cache_file_layout(struct inode *dst, struct inode *src)
> > spin_unlock(&cdst->i_ceph_lock);
> > }
> >
> > +/*
> > + * Try to set up an async create. We need caps, a file layout, and inode number,
> > + * and either a lease on the dentry or complete dir info. If any of those
> > + * criteria are not satisfied, then return false and the caller can go
> > + * synchronous.
> > + */
> > +static bool try_prep_async_create(struct inode *dir, struct dentry *dentry,
> > + struct ceph_file_layout *lo,
> > + unsigned long *pino)
> > +{
> > + struct ceph_inode_info *ci = ceph_inode(dir);
> > + bool ret = false;
> > + unsigned long ino;
> > +
> > + spin_lock(&ci->i_ceph_lock);
> > + /* No auth cap means no chance for Dc caps */
> > + if (!ci->i_auth_cap)
> > + goto no_async;
> > +
> > + /* Any delegated inos? */
> > + if (xa_empty(&ci->i_auth_cap->session->s_delegated_inos))
> > + goto no_async;
> > +
> > + if (!ceph_file_layout_is_valid(&ci->i_cached_layout))
> > + goto no_async;
> > +
> > + /* Use LOOKUP_RCU since we're under i_ceph_lock */
> > + if (!__ceph_dir_is_complete(ci) &&
> > + !dentry_lease_is_valid(dentry, LOOKUP_RCU))
> > + goto no_async;
>
> dentry_lease_is_valid() checks dentry lease. When directory inode has
> Fsx caps, mds does not issue lease for individual dentry. Check here
> should be something like dir_lease_is_valid()
Ok, I think I get it. The catch here is that we're calling this from
atomic_open, so we may be dealing with a dentry that is brand new and
has never had a lookup. I think we have to handle those two cases
differently.
This is what I'm thinking:
---
fs/ceph/file.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index 7b14dba92266..a3eb38fac68a 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -459,6 +459,7 @@ static bool try_prep_async_create(struct inode *dir,
struct dentry *dentry,
unsigned long *pino)
{
struct ceph_inode_info *ci = ceph_inode(dir);
+ struct ceph_dentry_info *di = ceph_dentry(dentry);
bool ret = false;
unsigned long ino;
@@ -474,16 +475,19 @@ static bool try_prep_async_create(struct inode
*dir, struct dentry *dentry,
if (!ceph_file_layout_is_valid(&ci->i_cached_layout))
goto no_async;
- /* Use LOOKUP_RCU since we're under i_ceph_lock */
- if (!__ceph_dir_is_complete(ci) &&
- !dentry_lease_is_valid(dentry, LOOKUP_RCU))
- goto no_async;
-
if ((__ceph_caps_issued(ci, NULL) &
(CEPH_CAP_FILE_EXCL | CEPH_CAP_DIR_CREATE)) !=
(CEPH_CAP_FILE_EXCL | CEPH_CAP_DIR_CREATE))
goto no_async;
+ if (d_in_lookup(dentry)) {
+ if (!__ceph_dir_is_complete(ci))
+ goto no_async;
+ } else if (atomic_read(&ci->i_shared_gen) !=
+ READ_ONCE(di->lease_shared_gen)) {
+ goto no_async;
+ }
+
ino = ceph_get_deleg_ino(ci->i_auth_cap->session);
if (!ino)
goto no_async;
--
2.24.1
