[PATCH AUTOSEL 4.19 30/36] NFSv4: Fix an Oops during delegation callbacks

Sasha Levin
2018-11-22T19:52:34Z

From: Trond Myklebust <trond.myklebust@hammerspace.com>

[ Upstream commit e39d8a186ed002854196668cb7562ffdfbc6d379 ]

If the server sends a CB_GETATTR or a CB_RECALL while the filesystem is
being unmounted, then we can Oops when releasing the inode in
nfs4_callback_getattr() and nfs4_callback_recall().

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/nfs/callback_proc.c | 4 ++--
fs/nfs/delegation.c | 11 +++++++++--
2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c
index fa515d5ea5ba..7b861bbc0b43 100644
--- a/fs/nfs/callback_proc.c
+++ b/fs/nfs/callback_proc.c
@@ -66,7 +66,7 @@ __be32 nfs4_callback_getattr(void *argp, void *resp,
out_iput:
rcu_read_unlock();
trace_nfs4_cb_getattr(cps->clp, &args->fh, inode, -ntohl(res->status));
- iput(inode);
+ nfs_iput_and_deactive(inode);
out:
dprintk("%s: exit with status = %d\n", __func__, ntohl(res->status));
return res->status;
@@ -108,7 +108,7 @@ __be32 nfs4_callback_recall(void *argp, void *resp,
}
trace_nfs4_cb_recall(cps->clp, &args->fh, inode,
&args->stateid, -ntohl(res));
- iput(inode);
+ nfs_iput_and_deactive(inode);
out:
dprintk("%s: exit with status = %d\n", __func__, ntohl(res));
return res;
diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index f033f3a69a3b..75fe92eaa681 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -849,16 +849,23 @@ nfs_delegation_find_inode_server(struct nfs_server *server,
const struct nfs_fh *fhandle)
{
struct nfs_delegation *delegation;
- struct inode *res = NULL;
+ struct inode *freeme, *res = NULL;

list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
spin_lock(&delegation->lock);
if (delegation->inode != NULL &&
nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
- res = igrab(delegation->inode);
+ freeme = igrab(delegation->inode);
+ if (freeme && nfs_sb_active(freeme->i_sb))
+ res = freeme;
spin_unlock(&delegation->lock);
if (res != NULL)
return res;
+ if (freeme) {
+ rcu_read_unlock();
+ iput(freeme);
+ rcu_read_lock();
+ }
return ERR_PTR(-EAGAIN);
}
spin_unlock(&delegation->lock);
--
2.17.1