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Message-Id: <E1KqrTX-0001xo-4N@dylan>
Date: Fri, 17 Oct 2008 16:42:51 +0100
From: Phillip Lougher <phillip@...gher.demon.co.uk>
To: akpm@...ux-foundation.org, linux-embedded@...r.kernel.org,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
tim.bird@...sony.com
Subject: Subject: [PATCH 09/16] Squashfs: uid/gid lookup operations
Signed-off-by: Phillip Lougher <phillip@...gher.demon.co.uk>
---
fs/squashfs/id.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 84 insertions(+), 0 deletions(-)
diff --git a/fs/squashfs/id.c b/fs/squashfs/id.c
new file mode 100644
index 0000000..b4881d7
--- /dev/null
+++ b/fs/squashfs/id.c
@@ -0,0 +1,84 @@
+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
+ * Phillip Lougher <phillip@...gher.demon.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * id.c
+ */
+
+/*
+ * This file implements code to handle uids and gids.
+ *
+ * For space efficiency inodes store uid and gid indexes, which are
+ * converted to 32-bit uids/gids using an id look up table. This table is
+ * stored compressed into metadata blocks. A second index table is used to
+ * locate these. This second index table for speed of access (and because it
+ * is small) is read at mount time and cached in memory.
+ */
+
+#include <linux/fs.h>
+#include <linux/vfs.h>
+#include <linux/slab.h>
+#include <linux/zlib.h>
+#include <linux/squashfs_fs.h>
+#include <linux/squashfs_fs_sb.h>
+#include <linux/squashfs_fs_i.h>
+
+#include "squashfs.h"
+
+int squashfs_get_id(struct super_block *s, unsigned int index, unsigned int *id)
+{
+ struct squashfs_sb_info *msblk = s->s_fs_info;
+ int block = SQUASHFS_ID_BLOCK(index);
+ int offset = SQUASHFS_ID_BLOCK_OFFSET(index);
+ long long start_block = le64_to_cpu(msblk->id_table[block]);
+ __le32 disk_id;
+
+ if (!squashfs_read_metadata(s, &disk_id, start_block, offset,
+ sizeof(disk_id), &start_block, &offset))
+ return 0;
+
+ *id = le32_to_cpu(disk_id);
+ return 1;
+}
+
+
+__le64 *read_id_index_table(struct super_block *s, long long id_table_start,
+ unsigned short no_ids)
+{
+ unsigned int length = SQUASHFS_ID_BLOCK_BYTES(no_ids);
+ __le64 *id_table;
+
+ TRACE("In read_id_index_table, length %d\n", length);
+
+ /* Allocate id index table */
+ id_table = kmalloc(length, GFP_KERNEL);
+ if (id_table == NULL) {
+ ERROR("Failed to allocate id index table\n");
+ return NULL;
+ }
+
+ if (!squashfs_read_data(s, id_table, id_table_start, length |
+ SQUASHFS_COMPRESSED_BIT_BLOCK, NULL, length)) {
+ ERROR("unable to read id index table\n");
+ kfree(id_table);
+ return NULL;
+ }
+
+ return id_table;
+}
--
1.5.2.5
--
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