Prev: [PATCH 0/4] Squashfs: add xattr file system support
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From: Phillip Lougher on 17 May 2010 15:30

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(a)lougher.demon.co.uk>
---
fs/squashfs/Makefile | 2 +
fs/squashfs/squashfs.h | 6 +++
fs/squashfs/squashfs_fs.h | 32 +++++++++++++-
fs/squashfs/squashfs_fs_sb.h | 3 +
fs/squashfs/super.c | 22 ++++++++-
fs/squashfs/xattr_id.c | 100 ++++++++++++++++++++++++++++++++++++++++++
6 files changed, 161 insertions(+), 4 deletions(-)
create mode 100644 fs/squashfs/xattr_id.c

diff --git a/fs/squashfs/Makefile b/fs/squashfs/Makefile
index df8a19e..c0da4a1 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 fe2587a..133befe 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 7902424..c654e86 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 2e77dc5..d9037a5 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 48b6f4a..c4dfc39 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 0000000..a741012
--- /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(a)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;
+}
--
1.6.3.3

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Prev: [PATCH 0/4] Squashfs: add xattr file system support
Next: perf: fix Makefile check for libdward