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Message-ID: <4FD4656B.1070303@gmail.com>
Date: Sun, 10 Jun 2012 11:14:19 +0200
From: Marco Stornelli <marco.stornelli@...il.com>
To: Linux FS Devel <linux-fsdevel@...r.kernel.org>
CC: Linux Kernel <linux-kernel@...r.kernel.org>
Subject: [PATCH 05/17] pramfs: block operations
From: Marco Stornelli <marco.stornelli@...il.com>
Block allocation operations.
Signed-off-by: Marco Stornelli <marco.stornelli@...il.com>
---
diff -Nurp linux-3.5-rc2-orig/fs/pramfs/balloc.c linux-3.5-rc2/fs/pramfs/balloc.c
--- linux-3.5-rc2-orig/fs/pramfs/balloc.c 1970-01-01 01:00:00.000000000 +0100
+++ linux-3.5-rc2/fs/pramfs/balloc.c 2012-06-10 10:08:28.000000000 +0200
@@ -0,0 +1,160 @@
+/*
+ * BRIEF DESCRIPTION
+ *
+ * The blocks allocation and deallocation routines.
+ *
+ * Copyright 2009-2011 Marco Stornelli <marco.stornelli@...il.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/bitops.h>
+#include "pram.h"
+
+void pram_bitmap_fill(unsigned long *dst, int nbits)
+{
+ size_t nlongs = BITS_TO_LONGS(nbits);
+ if (!small_const_nbits(nbits)) {
+ int len = (nlongs - 1) * sizeof(unsigned long);
+ memset(dst, 0xff, len);
+ }
+ if (BITS_PER_LONG == 64)
+ dst[nlongs - 1] = cpu_to_le64(BITMAP_LAST_WORD_MASK(nbits));
+ else
+ dst[nlongs - 1] = cpu_to_le32(BITMAP_LAST_WORD_MASK(nbits));
+}
+
+/*
+ * 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);
+ unsigned long *bitmap = pram_get_bitmap(sb);
+ int blocks = be32_to_cpu(ps->s_bitmap_blocks);
+
+ memset(bitmap, 0, blocks << sb->s_blocksize_bits);
+
+ pram_bitmap_fill(bitmap, blocks);
+}
+
+
+/* Free absolute blocknr */
+void pram_free_block(struct super_block *sb, unsigned long blocknr)
+{
+ struct pram_super_block *ps;
+ u64 bitmap_block;
+ unsigned long bitmap_bnr;
+ void *bitmap;
+ void *bp;
+
+ 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_memunlock_block(sb, bp);
+ pram_clear_bit(blocknr, bitmap); /* mark the block free */
+ pram_memlock_block(sb, bp);
+
+ ps = pram_get_super(sb);
+ pram_memunlock_super(sb, ps);
+
+ if (blocknr < be32_to_cpu(ps->s_free_blocknr_hint))
+ ps->s_free_blocknr_hint = cpu_to_be32(blocknr);
+ be32_add_cpu(&ps->s_free_blocks_count, 1);
+ pram_memlock_super(sb, ps);
+
+ 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, unsigned long *blocknr, int zero)
+{
+ struct pram_super_block *ps;
+ u64 bitmap_block;
+ unsigned long bnr, bitmap_bnr;
+ int errval;
+ void *bitmap;
+ void *bp;
+
+ 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 = pram_find_next_zero_bit(bitmap,
+ be32_to_cpu(ps->s_blocks_count),
+ be32_to_cpu(ps->s_free_blocknr_hint));
+
+ if (bnr < be32_to_cpu(ps->s_bitmap_blocks) ||
+ bnr >= be32_to_cpu(ps->s_blocks_count)) {
+ pram_dbg("no free blocks found!\n");
+ errval = -ENOSPC;
+ goto fail;
+ }
+
+ pram_memunlock_super(sb, ps);
+ be32_add_cpu(&ps->s_free_blocks_count, -1);
+ if (bnr < (be32_to_cpu(ps->s_blocks_count)-1))
+ ps->s_free_blocknr_hint = cpu_to_be32(bnr+1);
+ else
+ ps->s_free_blocknr_hint = 0;
+ pram_memlock_super(sb, ps);
+ } else {
+ pram_dbg("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_memunlock_block(sb, bp);
+ pram_set_bit(bnr, bitmap); /* mark the new block in use */
+ pram_memlock_block(sb, bp);
+
+ if (zero) {
+ bp = pram_get_block(sb, pram_get_block_off(sb, bnr));
+ pram_memunlock_block(sb, bp);
+ memset(bp, 0, sb->s_blocksize);
+ pram_memlock_block(sb, bp);
+ }
+
+ *blocknr = bnr;
+ pram_dbg("allocated blocknr %lu", 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 be32_to_cpu(ps->s_free_blocks_count);
+}
--
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