Re: [PATCH RFC 06/24] vfs: break parent dir delegations in open(..., O_CREAT) codepath

From: Stefan Metzmacher
Date: Mon Mar 18 2024 - 04:25:59 EST


Hi Jeff,

In order to add directory delegation support, we need to break
delegations on the parent whenever there is going to be a change in the
directory.

Add a delegated_inode parameter to lookup_open and have it break the
delegation. Then, open_last_lookups can wait for the delegation break
and retry the call to lookup_open once it's done.

Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/namei.c | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index f00d8d708001..88598a62ec64 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3404,7 +3404,7 @@ static struct dentry *atomic_open(struct nameidata *nd, struct dentry *dentry,
*/
static struct dentry *lookup_open(struct nameidata *nd, struct file *file,
const struct open_flags *op,
- bool got_write)
+ bool got_write, struct inode **delegated_inode)

Does NFS has a concept of lease keys and parent lease keys?

In SMB it's possible that the client passes a lease key (16 client chosen bytes) to a directory open,
when asking for a directory lease.

Then operations on files within that directory, take that lease key from the directory as
'parent lease keys' in addition to a unique lease key for the file.

That way a client can avoid breaking its own directory leases when creating/move/delete... files
in the directory.

metze