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authorTrond Myklebust <trond.myklebust@hammerspace.com>2018-09-02 15:57:01 -0400
committerTrond Myklebust <trond.myklebust@hammerspace.com>2018-09-30 15:35:17 -0400
commit0de43976fbe716379084f954b1e370c35aa87bf0 (patch)
tree64a6ea935fc8015c7369b9ece308771585cd3053 /fs/nfs/nfs4proc.c
parent6ba0c4e5bb08cc929662588aa2015e0ee7ee9376 (diff)
downloadlwn-0de43976fbe716379084f954b1e370c35aa87bf0.tar.gz
lwn-0de43976fbe716379084f954b1e370c35aa87bf0.zip
NFS: Convert lookups of the open context to RCU
Reduce contention on the inode->i_lock by ensuring that we use RCU when looking up the NFS open context. Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Diffstat (limited to 'fs/nfs/nfs4proc.c')
-rw-r--r--fs/nfs/nfs4proc.c30
1 files changed, 24 insertions, 6 deletions
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 8220a168282e..10c20a5b075d 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1933,23 +1933,41 @@ nfs4_opendata_to_nfs4_state(struct nfs4_opendata *data)
return ret;
}
-static struct nfs_open_context *nfs4_state_find_open_context(struct nfs4_state *state)
+static struct nfs_open_context *
+nfs4_state_find_open_context_mode(struct nfs4_state *state, fmode_t mode)
{
struct nfs_inode *nfsi = NFS_I(state->inode);
struct nfs_open_context *ctx;
- spin_lock(&state->inode->i_lock);
- list_for_each_entry(ctx, &nfsi->open_files, list) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(ctx, &nfsi->open_files, list) {
if (ctx->state != state)
continue;
- get_nfs_open_context(ctx);
- spin_unlock(&state->inode->i_lock);
+ if ((ctx->mode & mode) != mode)
+ continue;
+ if (!get_nfs_open_context(ctx))
+ continue;
+ rcu_read_unlock();
return ctx;
}
- spin_unlock(&state->inode->i_lock);
+ rcu_read_unlock();
return ERR_PTR(-ENOENT);
}
+static struct nfs_open_context *
+nfs4_state_find_open_context(struct nfs4_state *state)
+{
+ struct nfs_open_context *ctx;
+
+ ctx = nfs4_state_find_open_context_mode(state, FMODE_READ|FMODE_WRITE);
+ if (!IS_ERR(ctx))
+ return ctx;
+ ctx = nfs4_state_find_open_context_mode(state, FMODE_WRITE);
+ if (!IS_ERR(ctx))
+ return ctx;
+ return nfs4_state_find_open_context_mode(state, FMODE_READ);
+}
+
static struct nfs4_opendata *nfs4_open_recoverdata_alloc(struct nfs_open_context *ctx,
struct nfs4_state *state, enum open_claim_type4 claim)
{