libntfs: Cache opened inodes.

include/ntfs/inode.h

@@ -27,6 +27,7 @@
 /* Forward declaration */
 typedef struct _ntfs_inode ntfs_inode;
 
+#include "list.h"
 #include "types.h"
 #include "layout.h"
 #include "support.h"
@@ -132,7 +133,7 @@ struct _ntfs_inode {
 	/* Below fields are valid only for base inode. */
 
 	/*
-	 * This two fields are used to sync filename index and guaranteed to be
+	 * These two fields are used to sync filename index and guaranteed to be
 	 * correct, however value in index itself maybe wrong (windows itself
 	 * do not update them properly).
 	 */
@@ -144,12 +145,26 @@ struct _ntfs_inode {
 				   of the unnamed data attribute for sparse or
 				   compressed files.) */
 
+	/*
+	 * These four fields are copy of relevant fields from
+	 * STANDARD_INFORMATION attribute and used to sync it and FILE_NAME
+	 * attribute in the index.
+	 */
 	time_t creation_time;
 	time_t last_data_change_time;
 	time_t last_mft_change_time;
 	time_t last_access_time;
+
+	/* These 2 fields are used to keep track of opened inodes. */
+	struct list_head list_entry;	/* Keep pointers to the next/prev list
+					   entry. */
+	int nr_references;		/* How many times this inode was
+					   opened.  We really close inode only
+					   when this reaches zero. */
 };
 
+extern void __ntfs_inode_add_to_cache(ntfs_inode *ni);
+
 extern ntfs_inode *ntfs_inode_allocate(ntfs_volume *vol);
 
 extern ntfs_inode *ntfs_inode_open(ntfs_volume *vol, const MFT_REF mref);

include/ntfs/volume.h

@@ -44,6 +44,7 @@
 /* Forward declaration */
 typedef struct _ntfs_volume ntfs_volume;
 
+#include "list.h"
 #include "types.h"
 #include "support.h"
 #include "device.h"
@@ -131,6 +132,9 @@ typedef enum {
 
 #define NTFS_BUF_SIZE 8192
 
+#define NTFS_INODE_CACHE_SIZE 512 /* WARNING: This should be power of 2. */
+#define NTFS_INODE_CACHE_SIZE_BITS (NTFS_INODE_CACHE_SIZE - 1)
+
 /**
  * struct _ntfs_volume - structure describing an open volume in memory.
  */
@@ -211,6 +215,9 @@ struct _ntfs_volume {
 
 	long nr_free_clusters;	/* This two are self explaining. */
 	long nr_free_mft_records;
+
+	struct list_head inode_cache[NTFS_INODE_CACHE_SIZE]; /* List of opened
+								inodes. */
 };
 
 extern ntfs_volume *ntfs_volume_alloc(void);

libntfs/inode.c

@@ -99,6 +99,16 @@ static int __ntfs_inode_release(ntfs_inode *ni)
 	return 0;
 }
 
+/**
+ * __ntfs_inode_add_to_cache - do not use me! Only for internal library use.
+ */
+void __ntfs_inode_add_to_cache(ntfs_inode *ni)
+{
+	list_add_tail(&ni->list_entry, &ni->vol->inode_cache[
+			ni->mft_no & NTFS_INODE_CACHE_SIZE_BITS]);
+	ni->nr_references = 1;
+}
+
 /**
  * ntfs_inode_open - open an inode ready for access
  * @vol:	volume to get the inode from
@@ -129,12 +139,27 @@ ntfs_inode *ntfs_inode_open(ntfs_volume *vol, const MFT_REF mref)
 	ntfs_attr_search_ctx *ctx;
 	int err = 0;
 	STANDARD_INFORMATION *std_info;
+	struct list_head *pos;
 
 	ntfs_log_trace("Entering for inode 0x%llx.\n", MREF(mref));
 	if (!vol) {
 		errno = EINVAL;
 		return NULL;
 	}
+	/* Check cache, maybe this inode already opened? */
+	list_for_each(pos, &vol->inode_cache[MREF(mref) &
+			NTFS_INODE_CACHE_SIZE_BITS]) {
+		ntfs_inode *tmp_ni;
+
+		tmp_ni = list_entry(pos, ntfs_inode, list_entry);
+		if (tmp_ni->mft_no == MREF(mref)) {
+			ntfs_log_trace("Found this inode in cache, increment "
+					"reference count and return it.\n");
+			tmp_ni->nr_references++;
+			return tmp_ni;
+		}
+	}
+	/* Search failed. Properly open inode. */
 	ni = __ntfs_inode_allocate(vol);
 	if (!ni)
 		return NULL;
@@ -212,6 +237,7 @@ get_size:
 		}
 	}
 	ntfs_attr_put_search_ctx(ctx);
+	__ntfs_inode_add_to_cache(ni);
 	return ni;
 put_err_out:
 	if (!err)
@@ -254,6 +280,18 @@ int ntfs_inode_close(ntfs_inode *ni)
 
 	ntfs_log_trace("Entering for inode 0x%llx.\n", (long long) ni->mft_no);
 
+	/* Decrement number of users. If there are left then just return. */
+	if (ni->nr_extents != -1) {
+		ni->nr_references--;
+		if (ni->nr_references) {
+			ntfs_log_trace("There are %d more references left to "
+					"this inode.\n",
+					ni->nr_references);
+			return 0;
+		} else
+			ntfs_log_trace("There are no more references left to "
+					"this inode.\n");
+	}
 	/* If we have dirty metadata, write it out. */
 	if (NInoDirty(ni) || NInoAttrListDirty(ni)) {
 		if (ntfs_inode_sync(ni)) {
@@ -312,9 +350,12 @@ int ntfs_inode_close(ntfs_inode *ni)
 			break;
 		}
 		if (i != -1)
-			ntfs_log_debug("Extent inode was not attached to base inode! "
-					"Weird! Continuing regardless.\n");
+			ntfs_log_debug("Extent inode was not attached to base "
+					"inode! Continuing regardless.\n");
 	}
+	/* Remove inode from the list of opened inodes. */
+	if (ni->nr_extents != -1)
+		list_del(&ni->list_entry);
 	return __ntfs_inode_release(ni);
 }
 

libntfs/mft.c

@@ -1460,9 +1460,12 @@ mft_rec_already_initialized:
 	ni->creation_time = ni->last_data_change_time =
 			ni->last_mft_change_time =
 			ni->last_access_time = time(NULL);
-	/* Update the default mft allocation position if it was used. */
-	if (!base_ni)
+	if (!base_ni) {
+		/* Update the default mft allocation position if it was used. */
 		vol->mft_data_pos = bit + 1;
+		/* Add inode to cache. */
+		__ntfs_inode_add_to_cache(ni);
+	}
 	/* Return the opened, allocated inode of the allocated mft record. */
 	ntfs_log_debug("Returning opened, allocated %sinode 0x%llx.\n",
 			base_ni ? "extent " : "", (long long)bit);

libntfs/volume.c

@@ -76,7 +76,15 @@
  */
 ntfs_volume *ntfs_volume_alloc(void)
 {
-	return calloc(1, sizeof(ntfs_volume));
+	ntfs_volume *vol;
+	int i;
+
+	vol = calloc(1, sizeof(ntfs_volume));
+	if (vol) {
+		for (i = 0; i < NTFS_INODE_CACHE_SIZE; i++)
+			INIT_LIST_HEAD(&vol->inode_cache[i]);
+	}
+	return vol;
 }
 
 /**
@@ -162,6 +170,7 @@ static int ntfs_mft_load(ntfs_volume *vol)
 	}
 	vol->mft_ni->mft_no = 0;
 	vol->mft_ni->mrec = mb;
+	__ntfs_inode_add_to_cache(vol->mft_ni);
 	/* Can't use any of the higher level functions yet! */
 	l = ntfs_mst_pread(vol->dev, vol->mft_lcn << vol->cluster_size_bits, 1,
 			vol->mft_record_size, mb);