From: Marco Stornelli <marco.storne...@gmail.com>
Block allocation and deallocation routines.
Signed-off-by: Marco Stornelli <marco.storne...@gmail.com>
---
diff -uprN linux-2.6.30-orig/fs/pramfs/balloc.c
linux-2.6.30/fs/pramfs/balloc.c
--- linux-2.6.30-orig/fs/pramfs/balloc.c 1970-01-01 01:00:00.000000000
+0100
+++ linux-2.6.30/fs/pramfs/balloc.c 2009-06-13 12:51:24.000000000 +0200
@@ -0,0 +1,157 @@
+/*
+ * FILE NAME fs/pramfs/balloc.c
+ *
+ * BRIEF MODULE DESCRIPTION
+ *
+ * The blocks allocation and deallocation routines.
+ *
+ * Copyright 2009 Marco Stornelli <marco.storne...@gmail.com>
+ * Copyright 2003 Sony Corporation
+ * Copyright 2003 Matsushita Electric Industrial Co., Ltd.
+ * 2003-2004 (c) MontaVista Software, Inc. , Steve Longerbeam
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/fs.h>
+#include <linux/quotaops.h>
+#include <linux/bitops.h>
+#include "pram_fs.h"
+
+/*
+ * This just marks in-use the blocks that make up the bitmap.
+ * The bitmap must be writeable before calling.
+ */
+void pram_init_bitmap(struct super_block *sb)
+{
+ struct pram_super_block *ps = pram_get_super(sb);
+ u32 *bitmap = pram_get_bitmap(sb);
+ int blocks = ps->s_bitmap_blocks;
+
+ memset(bitmap, 0, blocks<<sb->s_blocksize_bits);
+
+ while (blocks >= 32) {
+ *bitmap++ = 0xffffffff;
+ blocks -= 32;
+ }
+
+ if (blocks)
+ *bitmap = (1<<blocks) - 1;
+}
+
+
+/* Free absolute blocknr */
+void pram_free_block(struct super_block *sb, int blocknr)
+{
+ struct pram_super_block *ps;
+ off_t bitmap_block;
+ int bitmap_bnr;
+ void *bitmap;
+ void *bp;
+ unsigned long flags;
+
+ flags = 0;
+
+ lock_super(sb);
+
+ bitmap = pram_get_bitmap(sb);
+ /*
+ * find the block within the bitmap that contains the inuse bit
+ * for the block we need to free. We need to unlock this bitmap
+ * block to clear the inuse bit.
+ */
+ bitmap_bnr = blocknr >> (3 + sb->s_blocksize_bits);
+ bitmap_block = pram_get_block_off(sb, bitmap_bnr);
+ bp = pram_get_block(sb, bitmap_block);
+
+ pram_lock_block(sb, bp, flags);
+ clear_bit(blocknr, bitmap); /* mark the block free */
+ pram_unlock_block(sb, bp, flags);
+
+ ps = pram_get_super(sb);
+ pram_lock_super(ps, flags);
+ if (blocknr < ps->s_free_blocknr_hint)
+ ps->s_free_blocknr_hint = blocknr;
+ ps->s_free_blocks_count++;
+ pram_unlock_super(ps, flags);
+
+ unlock_super(sb);
+}
+
+
+/*
+ * allocate a block and return it's absolute blocknr. Zeroes out the
+ * block if zero set.
+ */
+int pram_new_block(struct super_block *sb, int *blocknr, int zero)
+{
+ struct pram_super_block *ps;
+ off_t bitmap_block;
+ int bnr, bitmap_bnr, errval;
+ void *bitmap;
+ void *bp;
+ unsigned long flags;
+
+ flags = 0;
+
+ lock_super(sb);
+ ps = pram_get_super(sb);
+ bitmap = pram_get_bitmap(sb);
+
+ if (ps->s_free_blocks_count) {
+ /* find the oldest unused block */
+ bnr = find_next_zero_bit(bitmap,
+ ps->s_blocks_count,
+ ps->s_free_blocknr_hint);
+
+ if (bnr < ps->s_bitmap_blocks || bnr >= ps->s_blocks_count) {
+ pram_err("no free blocks found!\n");
+ errval = -ENOSPC;
+ goto fail;
+ }
+
+ pram_dbg("allocating blocknr %d\n", bnr);
+ pram_lock_super(ps, flags);
+ ps->s_free_blocks_count--;
+ ps->s_free_blocknr_hint =
+ (bnr < ps->s_blocks_count-1) ? bnr+1 : 0;
+ pram_unlock_super(ps, flags);
+ } else {
+ pram_err("all blocks allocated\n");
+ errval = -ENOSPC;
+ goto fail;
+ }
+
+ /*
+ * find the block within the bitmap that contains the inuse bit
+ * for the unused block we just found. We need to unlock it to
+ * set the inuse bit.
+ */
+ bitmap_bnr = bnr >> (3 + sb->s_blocksize_bits);
+ bitmap_block = pram_get_block_off(sb, bitmap_bnr);
+ bp = pram_get_block(sb, bitmap_block);
+
+ pram_lock_block(sb, bp, flags);
+ set_bit(bnr, bitmap); /* mark the new block in use */
+ pram_unlock_block(sb, bp, flags);
+
+ if (zero) {
+ bp = pram_get_block(sb, pram_get_block_off(sb, bnr));
+ pram_lock_block(sb, bp, flags);
+ memset(bp, 0, sb->s_blocksize);
+ pram_unlock_block(sb, bp, flags);
+ }
+
+ *blocknr = bnr;
+ errval = 0;
+ fail:
+ unlock_super(sb);
+ return errval;
+}
+
+unsigned long pram_count_free_blocks(struct super_block *sb)
+{
+ struct pram_super_block *ps = pram_get_super(sb);
+ return ps->s_free_blocks_count;
+}
--
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