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>

6 files changed, 161 insertions, 4 deletions

diff --git a/fs/squashfs/Makefile b/fs/squashfs/Makefile
index df8a19ef870d..c0da4a189cc4 100644
--- a/fs/squashfs/Makefile
+++ b/fs/squashfs/Makefile
@@ -5,3 +5,5 @@
 obj-$(CONFIG_SQUASHFS) += squashfs.o
 squashfs-y += block.o cache.o dir.o export.o file.o fragment.o id.o inode.o
 squashfs-y += namei.o super.o symlink.o zlib_wrapper.o decompressor.o
+squashfs-y += xattr_id.o
+
diff --git a/fs/squashfs/squashfs.h b/fs/squashfs/squashfs.h
index fe2587af5512..133befe2f8b8 100644
--- a/fs/squashfs/squashfs.h
+++ b/fs/squashfs/squashfs.h
@@ -73,6 +73,12 @@ extern struct inode *squashfs_iget(struct super_block *, long long,
                                 unsigned int);
 extern int squashfs_read_inode(struct inode *, long long);
 
+/* xattr_id.c */
+extern int squashfs_xattr_lookup(struct super_block *, unsigned int, int *,
+                                int *, long long *);
+extern __le64 *squashfs_read_xattr_id_table(struct super_block *, u64,
+                                u64 *, int *);
+
 /*
  * Inodes, files and decompressor operations
  */
diff --git a/fs/squashfs/squashfs_fs.h b/fs/squashfs/squashfs_fs.h
index 79024245ea00..c654e863d3c0 100644
--- a/fs/squashfs/squashfs_fs.h
+++ b/fs/squashfs/squashfs_fs.h
@@ -174,6 +174,24 @@
 
 #define SQUASHFS_ID_BLOCK_BYTES(A)      (SQUASHFS_ID_BLOCKS(A) *\
                                         sizeof(u64))
+/* xattr id lookup table defines */
+#define SQUASHFS_XATTR_BYTES(A)         ((A) * sizeof(struct squashfs_xattr_id))
+
+#define SQUASHFS_XATTR_BLOCK(A)         (SQUASHFS_XATTR_BYTES(A) / \
+                                        SQUASHFS_METADATA_SIZE)
+
+#define SQUASHFS_XATTR_BLOCK_OFFSET(A)  (SQUASHFS_XATTR_BYTES(A) % \
+                                        SQUASHFS_METADATA_SIZE)
+
+#define SQUASHFS_XATTR_BLOCKS(A)        ((SQUASHFS_XATTR_BYTES(A) + \
+                                        SQUASHFS_METADATA_SIZE - 1) / \
+                                        SQUASHFS_METADATA_SIZE)
+
+#define SQUASHFS_XATTR_BLOCK_BYTES(A)   (SQUASHFS_XATTR_BLOCKS(A) *\
+                                        sizeof(u64))
+#define SQUASHFS_XATTR_BLK(A)           ((unsigned int) ((A) >> 16))
+
+#define SQUASHFS_XATTR_OFFSET(A)        ((unsigned int) ((A) & 0xffff))
 
 /* cached data constants for filesystem */
 #define SQUASHFS_CACHED_BLKS            8
@@ -228,7 +246,7 @@ struct squashfs_super_block {
         __le64                  root_inode;
         __le64                  bytes_used;
         __le64                  id_table_start;
-        __le64                  xattr_table_start;
+        __le64                  xattr_id_table_start;
         __le64                  inode_table_start;
         __le64                  directory_table_start;
         __le64                  fragment_table_start;
@@ -377,4 +395,16 @@ struct squashfs_fragment_entry {
         unsigned int            unused;
 };
 
+struct squashfs_xattr_id {
+        __le64                  xattr;
+        __le32                  count;
+        __le32                  size;
+};
+
+struct squashfs_xattr_id_table {
+        __le64                  xattr_table_start;
+        __le32                  xattr_ids;
+        __le32                  unused;
+};
+
 #endif
diff --git a/fs/squashfs/squashfs_fs_sb.h b/fs/squashfs/squashfs_fs_sb.h
index 2e77dc547e25..d9037a5215f0 100644
--- a/fs/squashfs/squashfs_fs_sb.h
+++ b/fs/squashfs/squashfs_fs_sb.h
@@ -61,6 +61,7 @@ struct squashfs_sb_info {
         int                                     next_meta_index;
         __le64                                  *id_table;
         __le64                                  *fragment_index;
+        __le64                                  *xattr_id_table;
         struct mutex                            read_data_mutex;
         struct mutex                            meta_index_mutex;
         struct meta_index                       *meta_index;
@@ -68,9 +69,11 @@ struct squashfs_sb_info {
         __le64                                  *inode_lookup_table;
         u64                                     inode_table;
         u64                                     directory_table;
+        u64                                     xattr_table;
         unsigned int                            block_size;
         unsigned short                          block_log;
         long long                               bytes_used;
         unsigned int                            inodes;
+        int                                     xattr_ids;
 };
 #endif
diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c
index 48b6f4a385a6..c4dfc393fa52 100644
--- a/fs/squashfs/super.c
+++ b/fs/squashfs/super.c
@@ -36,6 +36,7 @@
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/magic.h>
+#include <linux/xattr.h>
 
 #include "squashfs_fs.h"
 #include "squashfs_fs_sb.h"
@@ -82,7 +83,7 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
         long long root_inode;
         unsigned short flags;
         unsigned int fragments;
-        u64 lookup_table_start;
+        u64 lookup_table_start, xattr_id_table_start;
         int err;
 
         TRACE("Entered squashfs_fill_superblock\n");
@@ -143,7 +144,7 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
          * Check if there's xattrs in the filesystem.  These are not
          * supported in this version, so warn that they will be ignored.
          */
-        if (le64_to_cpu(sblk->xattr_table_start) != SQUASHFS_INVALID_BLK)
+        if (le64_to_cpu(sblk->xattr_id_table_start) != SQUASHFS_INVALID_BLK)
                 ERROR("Xattrs in filesystem, these will be ignored\n");
 
         /* Check the filesystem does not extend beyond the end of the
@@ -253,7 +254,7 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
 allocate_lookup_table:
         lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
         if (lookup_table_start == SQUASHFS_INVALID_BLK)
-                goto allocate_root;
+                goto allocate_xattr_table;
 
         /* Allocate and read inode lookup table */
         msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
@@ -266,6 +267,19 @@ allocate_lookup_table:
 
         sb->s_export_op = &squashfs_export_ops;
 
+allocate_xattr_table:
+        xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);
+        if (xattr_id_table_start == SQUASHFS_INVALID_BLK)
+                goto allocate_root;
+
+        /* Allocate and read xattr id lookup table */
+        msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
+                xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids);
+        if (IS_ERR(msblk->xattr_id_table)) {
+                err = PTR_ERR(msblk->xattr_id_table);
+                msblk->xattr_id_table = NULL;
+                goto failed_mount;
+        }
 allocate_root:
         root = new_inode(sb);
         if (!root) {
@@ -301,6 +315,7 @@ failed_mount:
         kfree(msblk->inode_lookup_table);
         kfree(msblk->fragment_index);
         kfree(msblk->id_table);
+        kfree(msblk->xattr_id_table);
         kfree(sb->s_fs_info);
         sb->s_fs_info = NULL;
         kfree(sblk);
@@ -355,6 +370,7 @@ static void squashfs_put_super(struct super_block *sb)
                 kfree(sbi->fragment_index);
                 kfree(sbi->meta_index);
                 kfree(sbi->inode_lookup_table);
+                kfree(sbi->xattr_id_table);
                 kfree(sb->s_fs_info);
                 sb->s_fs_info = NULL;
         }
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;
+}