squashfs: add xattr id support

This patch adds support for mapping xattr ids (stored in inodes)
into the on-disk location of the xattrs themselves.

Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>

1 files changed, 100 insertions, 0 deletions

diff --git a/fs/squashfs/xattr_id.c b/fs/squashfs/xattr_id.c
new file mode 100644
index 000000000000..a74101244a98
--- /dev/null
+++ b/fs/squashfs/xattr_id.c
@@ -0,0 +1,100 @@
+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2010
+ * Phillip Lougher <phillip@lougher.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.
+ *
+ * xattr_id.c
+ */
+
+/*
+ * This file implements code to map the 32-bit xattr id stored in the inode
+ * into the on disk location of the xattr data.
+ */
+
+#include <linux/fs.h>
+#include <linux/vfs.h>
+#include <linux/slab.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs_fs_i.h"
+#include "squashfs.h"
+
+/*
+ * Map xattr id using the xattr id look up table
+ */
+int squashfs_xattr_lookup(struct super_block *sb, unsigned int index,
+                int *count, int *size, long long *xattr)
+{
+        struct squashfs_sb_info *msblk = sb->s_fs_info;
+        int block = SQUASHFS_XATTR_BLOCK(index);
+        int offset = SQUASHFS_XATTR_BLOCK_OFFSET(index);
+        u64 start_block = le64_to_cpu(msblk->xattr_id_table[block]);
+        struct squashfs_xattr_id id;
+        int err;
+
+        err = squashfs_read_metadata(sb, &id, &start_block, &offset,
+                                                        sizeof(id));
+        if (err < 0)
+                return err;
+
+        *xattr = le64_to_cpu(id.xattr);
+        *size = le32_to_cpu(id.size);
+        *count = le32_to_cpu(id.count);
+        return 0;
+}
+
+
+/*
+ * Read uncompressed xattr id lookup table indexes from disk into memory
+ */
+__le64 *squashfs_read_xattr_id_table(struct super_block *sb, u64 start,
+                u64 *xattr_table_start, int *xattr_ids)
+{
+        unsigned int len;
+        __le64 *xid_table;
+        struct squashfs_xattr_id_table id_table;
+        int err;
+
+        err = squashfs_read_table(sb, &id_table, start, sizeof(id_table));
+        if (err < 0) {
+                ERROR("unable to read xattr id table\n");
+                return ERR_PTR(err);
+        }
+        *xattr_table_start = le64_to_cpu(id_table.xattr_table_start);
+        *xattr_ids = le32_to_cpu(id_table.xattr_ids);
+        len = SQUASHFS_XATTR_BLOCK_BYTES(*xattr_ids);
+
+        TRACE("In read_xattr_index_table, length %d\n", len);
+
+        /* Allocate xattr id lookup table indexes */
+        xid_table = kmalloc(len, GFP_KERNEL);
+        if (xid_table == NULL) {
+                ERROR("Failed to allocate xattr id index table\n");
+                return ERR_PTR(-ENOMEM);
+        }
+
+        err = squashfs_read_table(sb, xid_table, start + sizeof(id_table), len);
+        if (err < 0) {
+                ERROR("unable to read xattr id index table\n");
+                kfree(xid_table);
+                return ERR_PTR(err);
+        }
+
+        return xid_table;
+}