Changeset 1eaa3cf in mainline

Timestamp:

2013-09-13T15:52:21Z (11 years ago)

Author:

Maurizio Lombardi <m.lombardi85@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

eb40d86

Parents:

b5ba8f6

Message:

mfs: cache the number of free zones to speed up subsequent requests (do not scan the whole bitmap every time statfs() is invoked).

Location:

uspace/srv/fs/mfs

Files:

• mfs.h (modified) (2 diffs)
• mfs_balloc.c (modified) (2 diffs)
• mfs_ops.c (modified) (2 diffs)

uspace/srv/fs/mfs/mfs.h

@@ -44 +44 @@
 #include <errno.h>
 #include <assert.h>
+#include <stdbool.h>
 #include "../../vfs/vfs.h"
 
@@ -105 +106 @@
         unsigned isearch;
         unsigned zsearch;
+
+        bool nfree_zones_valid;
+        unsigned nfree_zones;
 };
 

uspace/srv/fs/mfs/mfs_balloc.c

@@ -88 +88 @@
 {
         int r = mfs_alloc_bit(inst, zone, BMAP_ZONE);
+        if (r != EOK)
+                return r;
+
+        /* Update the cached number of free zones */
+        struct mfs_sb_info *sbi = inst->sbi;
+        if (sbi->nfree_zones_valid)
+                sbi->nfree_zones--;
 
         *zone += inst->sbi->firstdatazone - 1;
@@ -103 +110 @@
 mfs_free_zone(struct mfs_instance *inst, uint32_t zone)
 {
+        int r;
+
         zone -= inst->sbi->firstdatazone - 1;
 
-        return mfs_free_bit(inst, zone, BMAP_ZONE);
+        r = mfs_free_bit(inst, zone, BMAP_ZONE);
+        if (r != EOK)
+                return r;
+
+        /* Update the cached number of free zones */
+        struct mfs_sb_info *sbi = inst->sbi;
+        if (sbi->nfree_zones_valid)
+                sbi->nfree_zones++;
+
+        return r;
 }
 

uspace/srv/fs/mfs/mfs_ops.c

@@ -216 +216 @@
         sbi->isearch = 0;
         sbi->zsearch = 0;
+        sbi->nfree_zones_valid = false;
+        sbi->nfree_zones = 0;
 
         if (version == MFS_VERSION_V3) {
@@ -1181 +1183 @@
                 return rc;
 
-        if (NULL == inst)
-                return ENOENT;
-
-        mfs_count_free_zones(inst, &block_free);
-        *count = block_free;
+        struct mfs_sb_info *sbi = inst->sbi;
+
+        if (!sbi->nfree_zones_valid) {
+                /* The cached number of free zones is not valid,
+                 * we need to scan the bitmap to retrieve the
+                 * current value.
+                 */
+
+                rc = mfs_count_free_zones(inst, &block_free);
+                if (rc != EOK)
+                        return rc;
+
+                sbi->nfree_zones = block_free;
+                sbi->nfree_zones_valid = true;
+        }
+
+        *count = sbi->nfree_zones;
 
         return EOK;