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author | NeilBrown <neilb@suse.de> | 2014-07-14 01:28:20 (GMT) |
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committer | Trond Myklebust <trond.myklebust@primarydata.com> | 2014-08-03 21:14:11 (GMT) |
commit | d51ac1a8e9b86b2d17d349bb256869cab6522787 (patch) | |
tree | ddb2dc1a448c67d512465eaee7c73cfdbbe4bf23 /net/sunrpc/auth_generic.c | |
parent | 49317a7fdaa462b09b9bb4942b64c3a3316bd564 (diff) | |
download | linux-d51ac1a8e9b86b2d17d349bb256869cab6522787.tar.xz |
NFS: prepare for RCU-walk support but pushing tests later in code.
nfs_lookup_revalidate, nfs4_lookup_revalidate, and nfs_permission
all need to understand and handle RCU-walk for NFS to gain the
benefits of RCU-walk for cached information.
Currently these functions all immediately return -ECHILD
if the relevant flag (LOOKUP_RCU or MAY_NOT_BLOCK) is set.
This patch pushes those tests later in the code so that we only abort
immediately before we enter rcu-unsafe code. As subsequent patches
make that rcu-unsafe code rcu-safe, several of these new tests will
disappear.
With this patch there are several paths through the code which will no
longer return -ECHILD during an RCU-walk. However these are mostly
error paths or other uninteresting cases.
A noteworthy change in nfs_lookup_revalidate is that we don't take
(or put) the reference to ->d_parent when LOOKUP_RCU is set.
Rather we rcu_dereference ->d_parent, and check that ->d_inode
is not NULL. We also check that ->d_parent hasn't changed after
all the tests.
In nfs4_lookup_revalidate we simply avoid testing LOOKUP_RCU on the
path that only calls nfs_lookup_revalidate() as that function
already performs the required test.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Diffstat (limited to 'net/sunrpc/auth_generic.c')
0 files changed, 0 insertions, 0 deletions