X-Git-Url: http://git.vrable.net/?a=blobdiff_plain;f=bluesky%2Ffile.c;h=5fb19479149db76ed4100e90b6520554644edfef;hb=HEAD;hp=f10814ab40e40b9f7cf286437536a377e5231a6f;hpb=5d183280ac0033ad534af598fea85fd802e14ffe;p=bluesky.git

diff --git a/bluesky/file.c b/bluesky/file.c
index f10814a..5fb1947 100644
--- a/bluesky/file.c
+++ b/bluesky/file.c
@@ -3,7 +3,29 @@
  * Copyright (C) 2009  The Regents of the University of California
  * Written by Michael Vrable <mvrable@cs.ucsd.edu>
  *
- * TODO: Licensing
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
  */
 
 #include <stdint.h>
@@ -77,6 +99,15 @@ void bluesky_file_truncate(BlueSkyInode *inode, uint64_t size)
 
     uint64_t blocks = (size + BLUESKY_BLOCK_SIZE - 1) / BLUESKY_BLOCK_SIZE;
 
+    /* Calculate number of bytes in the last block of the file */
+    int lastblock_old, lastblock_new;
+    lastblock_old = inode->size % BLUESKY_BLOCK_SIZE;
+    if (lastblock_old == 0 && inode->size > 0)
+        lastblock_old = BLUESKY_BLOCK_SIZE;
+    lastblock_new = size % BLUESKY_BLOCK_SIZE;
+    if (lastblock_new == 0 && size > 0)
+        lastblock_new = BLUESKY_BLOCK_SIZE;
+
     if (blocks > inode->blocks->len) {
         /* Need to add new blocks to the end of a file.  New block structures
          * are automatically zeroed, which initializes them to be pointers to
@@ -88,10 +119,14 @@ void bluesky_file_truncate(BlueSkyInode *inode, uint64_t size)
                                              inode->blocks->len - 1);
 
             if (b->type != BLUESKY_BLOCK_ZERO
-                    && (b->type == BLUESKY_BLOCK_REF
-                        || b->dirty->len < BLUESKY_BLOCK_SIZE)) {
+                    && lastblock_old < BLUESKY_BLOCK_SIZE) {
                 bluesky_block_touch(inode, inode->blocks->len - 1, TRUE);
                 gsize old_size = b->dirty->len;
+                if (lastblock_old != old_size) {
+                    fprintf(stderr,
+                            "Warning: last block size = %zd, expected %d\n",
+                            old_size, lastblock_old);
+                }
                 bluesky_string_resize(b->dirty, BLUESKY_BLOCK_SIZE);
                 memset(&b->dirty->data[old_size], 0,
                        BLUESKY_BLOCK_SIZE - old_size);
@@ -117,7 +152,13 @@ void bluesky_file_truncate(BlueSkyInode *inode, uint64_t size)
         BlueSkyBlock *b = &g_array_index(inode->blocks, BlueSkyBlock,
                                          blocks - 1);
 
-        if (b->type != BLUESKY_BLOCK_ZERO) {
+        gboolean need_resize = TRUE;
+        if (b->type == BLUESKY_BLOCK_ZERO)
+            need_resize = FALSE;
+        else if (size < inode->size && lastblock_new == BLUESKY_BLOCK_SIZE)
+            need_resize = FALSE;
+
+        if (need_resize) {
             bluesky_block_touch(inode, blocks - 1, TRUE);
             gsize old_size = b->dirty->len;
             gsize new_size = size - (blocks - 1) * BLUESKY_BLOCK_SIZE;
@@ -144,16 +185,17 @@ void bluesky_file_write(BlueSkyInode *inode, uint64_t offset,
     if (len == 0)
         return;
 
-    // TODO: Optimization: If we are entirely overwriting a block we don't need
-    // to fetch it frm storage first.  We don't yet handle the case where the
-    // partial last block of a file is entirely overwritten.
     while (len > 0) {
         uint64_t block_num = offset / BLUESKY_BLOCK_SIZE;
         gint block_offset = offset % BLUESKY_BLOCK_SIZE;
         gint bytes = MIN(BLUESKY_BLOCK_SIZE - block_offset, len);
 
         gboolean preserve = TRUE;
-        if (block_offset == 0 && bytes == BLUESKY_BLOCK_SIZE) {
+        gsize block_size = BLUESKY_BLOCK_SIZE;
+        if (block_num == inode->blocks->len - 1) {
+            block_size = inode->size - block_num * BLUESKY_BLOCK_SIZE;
+        }
+        if (block_offset == 0 && bytes == block_size) {
             preserve = FALSE;
         }
         bluesky_block_touch(inode, block_num, preserve);