r3056: added a id -> pointer data structure (a type of radix tree). This is

an extremely efficient way of mapping from an integer handle (such as
an open file handle) to a pointer (such as the structure containing
the open file information). The code is taken from lib/idr.c in the
2.6 Linux kernel, and is very fast and space efficient. By using
talloc it even has auto cleanup.

This commit converts the handling of open file handles and open
directory search handles to use the idtree routines. In combination
with talloc destructors, this simplifies the structure handling in the
pvfs backend a lot. For example, we no longer need to keep a linked
list of open directory searches at all, and we no longer need to do
linear scans of the list of open files on most operations.

The end result is that the pvfs code is now extremely scalable. You
can have 10s of thousands of open files and open searches and the code
still runs very fast.

I have also added a small optimisation into the file close path, to
avoid looking in the byte range locking database if we know that there
are no locks outstanding.
(This used to be commit 16835a0ef91a16fa01145b773aad8d43da215dbf)

1 files changed, 35 insertions, 58 deletions

diff --git a/source4/ntvfs/posix/pvfs_search.c b/source4/ntvfs/posix/pvfs_search.c
index 07f2a0f127..7b0da321d3 100644
--- a/source4/ntvfs/posix/pvfs_search.c
+++ b/source4/ntvfs/posix/pvfs_search.c
@@ -23,6 +23,17 @@
 #include "include/includes.h"
 #include "vfs_posix.h"
 
+
+/*
+  destroy an open search
+*/
+static int pvfs_search_destructor(void *ptr)
+{
+	struct pvfs_search_state *search = ptr;
+	idr_remove(search->pvfs->idtree_search, search->handle);
+	return 0;
+}
+
 /*
   fill in a single search result for a given info level
 */
@@ -224,32 +235,6 @@ static NTSTATUS pvfs_search_fill(struct pvfs_state *pvfs, TALLOC_CTX *mem_ctx,
 	return NT_STATUS_OK;
 }
 
-/*
-  return the next available search handle
-*/
-static NTSTATUS pvfs_next_search_handle(struct pvfs_state *pvfs, uint16_t *handle, 
-					uint_t max_handles)
-{
-	struct pvfs_search_state *search;
-
-	if (pvfs->search.num_active_searches >= max_handles) {
-		return NT_STATUS_INSUFFICIENT_RESOURCES;
-	}
-
-	(*handle) = (pvfs->search.next_search_handle) & (max_handles-1);
-again:
-	for (search=pvfs->search.open_searches;search;search=search->next) {
-		if (*handle == search->handle) {
-			*handle = ((*handle)+1) & (max_handles-1);
-			goto again;
-		} 
-	}
-	pvfs->search.next_search_handle = ((*handle)+1) & (max_handles-1);
-
-	return NT_STATUS_OK;
-}
-
-
 /* 
    list files in a directory matching a wildcard pattern - old SMBsearch interface
 */
@@ -266,6 +251,7 @@ static NTSTATUS pvfs_search_first_old(struct ntvfs_module_context *ntvfs,
 	const char *pattern;
 	NTSTATUS status;
 	struct pvfs_filename *name;
+	int id;
 
 	search_attrib = io->search_first.in.search_attrib;
 	pattern       = io->search_first.in.pattern;
@@ -301,15 +287,19 @@ static NTSTATUS pvfs_search_first_old(struct ntvfs_module_context *ntvfs,
 
 	/* we need to give a handle back to the client so it
 	   can continue a search */
-	status = pvfs_next_search_handle(pvfs, &search->handle, 0x100);
-	if (!NT_STATUS_IS_OK(status)) {
-		return status;
+	id = idr_get_new(pvfs->idtree_search, search, 0x100);
+	if (id == -1) {
+		return NT_STATUS_INSUFFICIENT_RESOURCES;
 	}
-	
+
+	search->pvfs = pvfs;
+	search->handle = id;
 	search->dir = dir;
 	search->current_index = 0;
 	search->search_attrib = search_attrib;
 
+	talloc_set_destructor(search, pvfs_search_destructor);
+
 	status = pvfs_search_fill(pvfs, req, io->search_first.in.max_count, search, io->generic.level,
 				  &reply_count, search_private, callback);
 	if (!NT_STATUS_IS_OK(status)) {
@@ -323,9 +313,7 @@ static NTSTATUS pvfs_search_first_old(struct ntvfs_module_context *ntvfs,
 		return STATUS_NO_MORE_FILES;
 	}
 
-	pvfs->search.num_active_searches++;
 	talloc_steal(pvfs, search);
-	DLIST_ADD(pvfs->search.open_searches, search);
 
 	return NT_STATUS_OK;
 }
@@ -346,11 +334,8 @@ static NTSTATUS pvfs_search_next_old(struct ntvfs_module_context *ntvfs,
 	handle    = io->search_next.in.id.handle;
 	max_count = io->search_next.in.max_count;
 
-	for (search=pvfs->search.open_searches; search; search = search->next) {
-		if (search->handle == handle) break;
-	}
-	
-	if (!search) {
+	search = idr_find(pvfs->idtree_search, handle);
+	if (search == NULL) {
 		/* we didn't find the search handle */
 		return NT_STATUS_INVALID_HANDLE;
 	}
@@ -369,7 +354,6 @@ static NTSTATUS pvfs_search_next_old(struct ntvfs_module_context *ntvfs,
 
 	/* not matching any entries means end of search */
 	if (reply_count == 0) {
-		DLIST_REMOVE(pvfs->search.open_searches, search);
 		talloc_free(search);
 	}
 
@@ -392,6 +376,7 @@ NTSTATUS pvfs_search_first(struct ntvfs_module_context *ntvfs,
 	const char *pattern;
 	NTSTATUS status;
 	struct pvfs_filename *name;
+	int id;
 
 	if (io->generic.level >= RAW_SEARCH_SEARCH) {
 		return pvfs_search_first_old(ntvfs, req, io, search_private, callback);
@@ -430,17 +415,19 @@ NTSTATUS pvfs_search_first(struct ntvfs_module_context *ntvfs,
 		return status;
 	}
 
-	/* we need to give a handle back to the client so it
-	   can continue a search */
-	status = pvfs_next_search_handle(pvfs, &search->handle, 0x10000);
-	if (!NT_STATUS_IS_OK(status)) {
-		return status;
+	id = idr_get_new(pvfs->idtree_search, search, 0x10000);
+	if (id == -1) {
+		return NT_STATUS_INSUFFICIENT_RESOURCES;
 	}
-	
+
+	search->pvfs = pvfs;
+	search->handle = id;
 	search->dir = dir;
 	search->current_index = 0;
 	search->search_attrib = search_attrib;
 
+	talloc_set_destructor(search, pvfs_search_destructor);
+
 	status = pvfs_search_fill(pvfs, req, max_count, search, io->generic.level,
 				  &reply_count, search_private, callback);
 	if (!NT_STATUS_IS_OK(status)) {
@@ -463,9 +450,7 @@ NTSTATUS pvfs_search_first(struct ntvfs_module_context *ntvfs,
 	     io->t2ffirst.out.end_of_search)) {
 		talloc_free(search);
 	} else {
-		pvfs->search.num_active_searches++;
 		talloc_steal(pvfs, search);
-		DLIST_ADD(pvfs->search.open_searches, search);
 	}
 
 	return NT_STATUS_OK;
@@ -491,11 +476,8 @@ NTSTATUS pvfs_search_next(struct ntvfs_module_context *ntvfs,
 
 	handle = io->t2fnext.in.handle;
 
-	for (search=pvfs->search.open_searches; search; search = search->next) {
-		if (search->handle == handle) break;
-	}
-	
-	if (!search) {
+	search = idr_find(pvfs->idtree_search, handle);
+	if (search == NULL) {
 		/* we didn't find the search handle */
 		return NT_STATUS_INVALID_HANDLE;
 	}
@@ -544,7 +526,6 @@ found:
 	if ((io->t2fnext.in.flags & FLAG_TRANS2_FIND_CLOSE) ||
 	    ((io->t2fnext.in.flags & FLAG_TRANS2_FIND_CLOSE_IF_END) && 
 	     io->t2fnext.out.end_of_search)) {
-		DLIST_REMOVE(pvfs->search.open_searches, search);
 		talloc_free(search);
 	}
 
@@ -565,16 +546,12 @@ NTSTATUS pvfs_search_close(struct ntvfs_module_context *ntvfs,
 		handle = io->findclose.in.handle;
 	}
 
-	for (search=pvfs->search.open_searches; search; search = search->next) {
-		if (search->handle == handle) break;
-	}
-	
-	if (!search) {
+	search = idr_find(pvfs->idtree_search, handle);
+	if (search == NULL) {
 		/* we didn't find the search handle */
 		return NT_STATUS_INVALID_HANDLE;
 	}
 
-	DLIST_REMOVE(pvfs->search.open_searches, search);
 	talloc_free(search);
 
 	return NT_STATUS_OK;