Patch "nfsd: hold reference to delegation when updating it for cb_getattr" has been added to the 6.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    nfsd: hold reference to delegation when updating it for cb_getattr

to the 6.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     nfsd-hold-reference-to-delegation-when-updating-it-f.patch
and it can be found in the queue-6.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit d5cef521ff861c969186dc5752519d49576691f1
Author: Jeff Layton <jlayton@xxxxxxxxxx>
Date:   Fri Aug 23 18:27:38 2024 -0400

    nfsd: hold reference to delegation when updating it for cb_getattr
    
    [ Upstream commit da05ba23d4c8d3e8a45846b952e53dd76c4b5e36 ]
    
    Once we've dropped the flc_lock, there is nothing that ensures that the
    delegation that was found will still be around later. Take a reference
    to it while holding the lock and then drop it when we've finished with
    the delegation.
    
    Fixes: c5967721e106 ("NFSD: handle GETATTR conflict with write delegation")
    Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
    Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index dafff707e23a4..19d39872be325 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -8837,7 +8837,6 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct inode *inode,
 	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
 	struct file_lock_context *ctx;
 	struct file_lease *fl;
-	struct nfs4_delegation *dp;
 	struct iattr attrs;
 	struct nfs4_cb_fattr *ncf;
 
@@ -8862,7 +8861,8 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct inode *inode,
 			goto break_lease;
 		}
 		if (type == F_WRLCK) {
-			dp = fl->c.flc_owner;
+			struct nfs4_delegation *dp = fl->c.flc_owner;
+
 			if (dp->dl_recall.cb_clp == *(rqstp->rq_lease_breaker)) {
 				spin_unlock(&ctx->flc_lock);
 				return 0;
@@ -8870,6 +8870,7 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct inode *inode,
 break_lease:
 			nfsd_stats_wdeleg_getattr_inc(nn);
 			dp = fl->c.flc_owner;
+			refcount_inc(&dp->dl_stid.sc_count);
 			ncf = &dp->dl_cb_fattr;
 			nfs4_cb_getattr(&dp->dl_cb_fattr);
 			spin_unlock(&ctx->flc_lock);
@@ -8879,8 +8880,10 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct inode *inode,
 				/* Recall delegation only if client didn't respond */
 				status = nfserrno(nfsd_open_break_lease(inode, NFSD_MAY_READ));
 				if (status != nfserr_jukebox ||
-						!nfsd_wait_for_delegreturn(rqstp, inode))
+						!nfsd_wait_for_delegreturn(rqstp, inode)) {
+					nfs4_put_stid(&dp->dl_stid);
 					return status;
+				}
 			}
 			if (!ncf->ncf_file_modified &&
 					(ncf->ncf_initial_cinfo != ncf->ncf_cb_change ||
@@ -8900,6 +8903,7 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct inode *inode,
 				*size = ncf->ncf_cur_fsize;
 				*modified = true;
 			}
+			nfs4_put_stid(&dp->dl_stid);
 			return 0;
 		}
 		break;