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Message-Id: <20250916044735.2316171-5-dolinux.peng@gmail.com>
Date: Tue, 16 Sep 2025 12:47:25 +0800
From: pengdonglin <dolinux.peng@...il.com>
To: tj@...nel.org,
tony.luck@...el.com,
jani.nikula@...ux.intel.com,
ap420073@...il.com,
jv@...sburgh.net,
freude@...ux.ibm.com,
bcrl@...ck.org,
trondmy@...nel.org,
longman@...hat.com,
kees@...nel.org
Cc: bigeasy@...utronix.de,
hdanton@...a.com,
paulmck@...nel.org,
linux-kernel@...r.kernel.org,
linux-rt-devel@...ts.linux.dev,
linux-nfs@...r.kernel.org,
linux-aio@...ck.org,
linux-fsdevel@...r.kernel.org,
linux-security-module@...r.kernel.org,
netdev@...r.kernel.org,
intel-gfx@...ts.freedesktop.org,
linux-wireless@...r.kernel.org,
linux-acpi@...r.kernel.org,
linux-s390@...r.kernel.org,
cgroups@...r.kernel.org,
pengdonglin <dolinux.peng@...il.com>,
Anna Schumaker <anna@...nel.org>,
pengdonglin <pengdonglin@...omi.com>
Subject: [PATCH v3 04/14] nfs: Remove redundant rcu_read_lock/unlock() in spin_lock
From: pengdonglin <pengdonglin@...omi.com>
Since commit a8bb74acd8efe ("rcu: Consolidate RCU-sched update-side function definitions")
there is no difference between rcu_read_lock(), rcu_read_lock_bh() and
rcu_read_lock_sched() in terms of RCU read section and the relevant grace
period. That means that spin_lock(), which implies rcu_read_lock_sched(),
also implies rcu_read_lock().
There is no need no explicitly start a RCU read section if one has already
been started implicitly by spin_lock().
Simplify the code and remove the inner rcu_read_lock() invocation.
Cc: Trond Myklebust <trondmy@...nel.org>
Cc: Anna Schumaker <anna@...nel.org>
Signed-off-by: pengdonglin <pengdonglin@...omi.com>
Signed-off-by: pengdonglin <dolinux.peng@...il.com>
---
fs/nfs/callback_proc.c | 2 --
fs/nfs/nfs4state.c | 2 --
fs/nfs/pnfs.c | 12 +-----------
fs/nfs/pnfs_dev.c | 4 ----
4 files changed, 1 insertion(+), 19 deletions(-)
diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c
index 8397c43358bd..16144db39335 100644
--- a/fs/nfs/callback_proc.c
+++ b/fs/nfs/callback_proc.c
@@ -721,7 +721,6 @@ __be32 nfs4_callback_offload(void *data, void *dummy,
return cpu_to_be32(NFS4ERR_DELAY);
spin_lock(&cps->clp->cl_lock);
- rcu_read_lock();
list_for_each_entry_rcu(server, &cps->clp->cl_superblocks,
client_link) {
list_for_each_entry(tmp_copy, &server->ss_copies, copies) {
@@ -736,7 +735,6 @@ __be32 nfs4_callback_offload(void *data, void *dummy,
}
}
out:
- rcu_read_unlock();
if (!found) {
memcpy(©->stateid, &args->coa_stateid, NFS4_STATEID_SIZE);
nfs4_copy_cb_args(copy, args);
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 7612e977e80b..598229fc07ed 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -241,13 +241,11 @@ const struct cred *nfs4_get_renew_cred(struct nfs_client *clp)
goto out;
spin_lock(&clp->cl_lock);
- rcu_read_lock();
list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
cred = nfs4_get_renew_cred_server_locked(server);
if (cred != NULL)
break;
}
- rcu_read_unlock();
spin_unlock(&clp->cl_lock);
out:
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index a3135b5af7ee..650f86fa144a 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -838,13 +838,12 @@ pnfs_layout_add_bulk_destroy_list(struct inode *inode,
return ret;
}
-/* Caller must hold rcu_read_lock and clp->cl_lock */
+/* Caller must hold clp->cl_lock (implies rcu_read_lock) */
static int
pnfs_layout_bulk_destroy_byserver_locked(struct nfs_client *clp,
struct nfs_server *server,
struct list_head *layout_list)
__must_hold(&clp->cl_lock)
- __must_hold(RCU)
{
struct pnfs_layout_hdr *lo, *next;
struct inode *inode;
@@ -862,16 +861,13 @@ pnfs_layout_bulk_destroy_byserver_locked(struct nfs_client *clp,
if (pnfs_layout_add_bulk_destroy_list(inode,
layout_list))
continue;
- rcu_read_unlock();
spin_unlock(&clp->cl_lock);
iput(inode);
} else {
- rcu_read_unlock();
spin_unlock(&clp->cl_lock);
}
nfs_sb_deactive(server->super);
spin_lock(&clp->cl_lock);
- rcu_read_lock();
return -EAGAIN;
}
return 0;
@@ -922,7 +918,6 @@ int pnfs_layout_destroy_byfsid(struct nfs_client *clp, struct nfs_fsid *fsid,
LIST_HEAD(layout_list);
spin_lock(&clp->cl_lock);
- rcu_read_lock();
restart:
list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
if (memcmp(&server->fsid, fsid, sizeof(*fsid)) != 0)
@@ -932,7 +927,6 @@ int pnfs_layout_destroy_byfsid(struct nfs_client *clp, struct nfs_fsid *fsid,
&layout_list) != 0)
goto restart;
}
- rcu_read_unlock();
spin_unlock(&clp->cl_lock);
return pnfs_layout_free_bulk_destroy_list(&layout_list, mode);
@@ -944,14 +938,12 @@ static void pnfs_layout_build_destroy_list_byclient(struct nfs_client *clp,
struct nfs_server *server;
spin_lock(&clp->cl_lock);
- rcu_read_lock();
restart:
list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
if (pnfs_layout_bulk_destroy_byserver_locked(clp, server,
list) != 0)
goto restart;
}
- rcu_read_unlock();
spin_unlock(&clp->cl_lock);
}
@@ -990,7 +982,6 @@ static void pnfs_layout_build_recover_list_byclient(struct nfs_client *clp,
struct nfs_server *server;
spin_lock(&clp->cl_lock);
- rcu_read_lock();
restart:
list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
if (!(server->caps & NFS_CAP_REBOOT_LAYOUTRETURN))
@@ -999,7 +990,6 @@ static void pnfs_layout_build_recover_list_byclient(struct nfs_client *clp,
list) != 0)
goto restart;
}
- rcu_read_unlock();
spin_unlock(&clp->cl_lock);
}
diff --git a/fs/nfs/pnfs_dev.c b/fs/nfs/pnfs_dev.c
index bf0f2d67e96c..d19752ec1a95 100644
--- a/fs/nfs/pnfs_dev.c
+++ b/fs/nfs/pnfs_dev.c
@@ -231,9 +231,7 @@ nfs4_delete_deviceid(const struct pnfs_layoutdriver_type *ld,
struct nfs4_deviceid_node *d;
spin_lock(&nfs4_deviceid_lock);
- rcu_read_lock();
d = _lookup_deviceid(ld, clp, id, nfs4_deviceid_hash(id));
- rcu_read_unlock();
if (!d) {
spin_unlock(&nfs4_deviceid_lock);
return;
@@ -331,14 +329,12 @@ _deviceid_purge_client(const struct nfs_client *clp, long hash)
HLIST_HEAD(tmp);
spin_lock(&nfs4_deviceid_lock);
- rcu_read_lock();
hlist_for_each_entry_rcu(d, &nfs4_deviceid_cache[hash], node)
if (d->nfs_client == clp && atomic_read(&d->ref)) {
hlist_del_init_rcu(&d->node);
hlist_add_head(&d->tmpnode, &tmp);
clear_bit(NFS_DEVICEID_NOCACHE, &d->flags);
}
- rcu_read_unlock();
spin_unlock(&nfs4_deviceid_lock);
if (hlist_empty(&tmp))
--
2.34.1
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