From eb095c14030fbb07fcc61c64b6b39cc297a429c6 Mon Sep 17 00:00:00 2001 From: Zhouyi Zhou Date: Fri, 6 Mar 2020 03:45:26 +0000 Subject: NFS:remove redundant call to nfs_do_access In function nfs_permission: 1. the rcu_read_lock and rcu_read_unlock around nfs_do_access is unnecessary because the rcu critical data structure is already protected in subsidiary function nfs_access_get_cached_rcu. No other data structure needs rcu_read_lock in nfs_do_access. 2. call nfs_do_access once is enough, because: 2-1. when mask has MAY_NOT_BLOCK bit The second call to nfs_do_access will not happen. 2-2. when mask has no MAY_NOT_BLOCK bit The second call to nfs_do_access will happen if res == -ECHILD, which means the first nfs_do_access goes out after statement if (!may_block). The second call to nfs_do_access will go through this procedure once again except continue the work after if (!may_block). But above work can be performed by only one call to nfs_do_access without mangling the mask flag. Tested in x86_64 Signed-off-by: Zhouyi Zhou Signed-off-by: Trond Myklebust --- fs/nfs/dir.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-) (limited to 'fs/nfs') diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index f22366f350a9..b3a675da84a2 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -2759,14 +2759,7 @@ force_lookup: if (!NFS_PROTO(inode)->access) goto out_notsup; - /* Always try fast lookups first */ - rcu_read_lock(); - res = nfs_do_access(inode, cred, mask|MAY_NOT_BLOCK); - rcu_read_unlock(); - if (res == -ECHILD && !(mask & MAY_NOT_BLOCK)) { - /* Fast lookup failed, try the slow way */ - res = nfs_do_access(inode, cred, mask); - } + res = nfs_do_access(inode, cred, mask); out: if (!res && (mask & MAY_EXEC)) res = nfs_execute_ok(inode, mask); -- cgit v1.2.3