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 <zhouzhouyi@xxxxxxxxx>
---
fs/nfs/dir.c | 9 +--------
1 files changed, 1 insertions(+), 8 deletions(-)
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 193d6fb..37b0c10 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -2732,14 +2732,7 @@ int nfs_permission(struct inode *inode, int mask)
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);
--
1.7.1
