staging/lustre: Get rid of cl_env hash table

cl_env hash table is under heavy contention when there are lots of
processes doing IO at the same time;
reduce lock contention by replacing cl_env cache with percpu array;
remove cl_env_nested_get() and cl_env_nested_put();
remove cl_env_reenter() and cl_env_reexit();

Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-on: http://review.whamcloud.com/20254
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4257
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 25 insertions, 34 deletions

diff --git a/drivers/staging/lustre/lustre/llite/llite_mmap.c b/drivers/staging/lustre/lustre/llite/llite_mmap.c
index 436691814a5e3..ad2a699ea2f53 100644
--- a/drivers/staging/lustre/lustre/llite/llite_mmap.c
+++ b/drivers/staging/lustre/lustre/llite/llite_mmap.c
@@ -80,43 +80,24 @@ struct vm_area_struct *our_vma(struct mm_struct *mm, unsigned long addr,
  * API independent part for page fault initialization.
  * \param vma - virtual memory area addressed to page fault
  * \param env - corespondent lu_env to processing
- * \param nest - nested level
  * \param index - page index corespondent to fault.
  * \parm ra_flags - vma readahead flags.
  *
- * \return allocated and initialized env for fault operation.
- * \retval EINVAL if env can't allocated
- * \return other error codes from cl_io_init.
+ * \return error codes from cl_io_init.
  */
 static struct cl_io *
-ll_fault_io_init(struct vm_area_struct *vma, struct lu_env **env_ret,
-		 struct cl_env_nest *nest, pgoff_t index,
-		 unsigned long *ra_flags)
+ll_fault_io_init(struct lu_env *env, struct vm_area_struct *vma,
+		 pgoff_t index, unsigned long *ra_flags)
 {
 	struct file	       *file = vma->vm_file;
 	struct inode	       *inode = file_inode(file);
 	struct cl_io	       *io;
 	struct cl_fault_io     *fio;
-	struct lu_env	       *env;
 	int			rc;
 
-	*env_ret = NULL;
 	if (ll_file_nolock(file))
 		return ERR_PTR(-EOPNOTSUPP);
 
-	/*
-	 * page fault can be called when lustre IO is
-	 * already active for the current thread, e.g., when doing read/write
-	 * against user level buffer mapped from Lustre buffer. To avoid
-	 * stomping on existing context, optionally force an allocation of a new
-	 * one.
-	 */
-	env = cl_env_nested_get(nest);
-	if (IS_ERR(env))
-		return ERR_PTR(-EINVAL);
-
-	*env_ret = env;
-
 restart:
 	io = vvp_env_thread_io(env);
 	io->ci_obj = ll_i2info(inode)->lli_clob;
@@ -155,7 +136,6 @@ restart:
 		if (io->ci_need_restart)
 			goto restart;
 
-		cl_env_nested_put(nest, env);
 		io = ERR_PTR(rc);
 	}
 
@@ -169,13 +149,17 @@ static int ll_page_mkwrite0(struct vm_area_struct *vma, struct page *vmpage,
 	struct lu_env	   *env;
 	struct cl_io	    *io;
 	struct vvp_io	   *vio;
-	struct cl_env_nest       nest;
 	int		      result;
+	int refcheck;
 	sigset_t	     set;
 	struct inode	     *inode;
 	struct ll_inode_info     *lli;
 
-	io = ll_fault_io_init(vma, &env,  &nest, vmpage->index, NULL);
+	env = cl_env_get(&refcheck);
+	if (IS_ERR(env))
+		return PTR_ERR(env);
+
+	io = ll_fault_io_init(env, vma, vmpage->index, NULL);
 	if (IS_ERR(io)) {
 		result = PTR_ERR(io);
 		goto out;
@@ -240,8 +224,8 @@ static int ll_page_mkwrite0(struct vm_area_struct *vma, struct page *vmpage,
 
 out_io:
 	cl_io_fini(env, io);
-	cl_env_nested_put(&nest, env);
 out:
+	cl_env_put(env, &refcheck);
 	CDEBUG(D_MMAP, "%s mkwrite with %d\n", current->comm, result);
 	LASSERT(ergo(result == 0, PageLocked(vmpage)));
 
@@ -285,13 +269,19 @@ static int ll_fault0(struct vm_area_struct *vma, struct vm_fault *vmf)
 	struct vvp_io	   *vio = NULL;
 	struct page	     *vmpage;
 	unsigned long	    ra_flags;
-	struct cl_env_nest       nest;
-	int		      result;
+	int		      result = 0;
 	int		      fault_ret = 0;
+	int refcheck;
 
-	io = ll_fault_io_init(vma, &env,  &nest, vmf->pgoff, &ra_flags);
-	if (IS_ERR(io))
-		return to_fault_error(PTR_ERR(io));
+	env = cl_env_get(&refcheck);
+	if (IS_ERR(env))
+		return PTR_ERR(env);
+
+	io = ll_fault_io_init(env, vma, vmf->pgoff, &ra_flags);
+	if (IS_ERR(io)) {
+		result = to_fault_error(PTR_ERR(io));
+		goto out;
+	}
 
 	result = io->ci_result;
 	if (result == 0) {
@@ -322,14 +312,15 @@ static int ll_fault0(struct vm_area_struct *vma, struct vm_fault *vmf)
 		}
 	}
 	cl_io_fini(env, io);
-	cl_env_nested_put(&nest, env);
 
 	vma->vm_flags |= ra_flags;
+
+out:
+	cl_env_put(env, &refcheck);
 	if (result != 0 && !(fault_ret & VM_FAULT_RETRY))
 		fault_ret |= to_fault_error(result);
 
-	CDEBUG(D_MMAP, "%s fault %d/%d\n",
-	       current->comm, fault_ret, result);
+	CDEBUG(D_MMAP, "%s fault %d/%d\n", current->comm, fault_ret, result);
 	return fault_ret;
 }