Squashfs: super block operations

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

1 files changed, 440 insertions, 0 deletions

diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c
new file mode 100644
index 000000000000..a0466d7467b2
--- /dev/null
+++ b/fs/squashfs/super.c
@@ -0,0 +1,440 @@
+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
+ * 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.
+ *
+ * super.c
+ */
+
+/*
+ * This file implements code to read the superblock, read and initialise
+ * in-memory structures at mount time, and all the VFS glue code to register
+ * the filesystem.
+ */
+
+#include <linux/fs.h>
+#include <linux/vfs.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/pagemap.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/zlib.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs_fs_i.h"
+#include "squashfs.h"
+
+static struct file_system_type squashfs_fs_type;
+static struct super_operations squashfs_super_ops;
+
+static int supported_squashfs_filesystem(short major, short minor, short comp)
+{
+        if (major < SQUASHFS_MAJOR) {
+                ERROR("Major/Minor mismatch, older Squashfs %d.%d "
+                        "filesystems are unsupported\n", major, minor);
+                return -EINVAL;
+        } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) {
+                ERROR("Major/Minor mismatch, trying to mount newer "
+                        "%d.%d filesystem\n", major, minor);
+                ERROR("Please update your kernel\n");
+                return -EINVAL;
+        }
+
+        if (comp != ZLIB_COMPRESSION)
+                return -EINVAL;
+
+        return 0;
+}
+
+
+static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
+{
+        struct squashfs_sb_info *msblk;
+        struct squashfs_super_block *sblk = NULL;
+        char b[BDEVNAME_SIZE];
+        struct inode *root;
+        long long root_inode;
+        unsigned short flags;
+        unsigned int fragments;
+        u64 lookup_table_start;
+        int err;
+
+        TRACE("Entered squashfs_fill_superblock\n");
+
+        sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
+        if (sb->s_fs_info == NULL) {
+                ERROR("Failed to allocate squashfs_sb_info\n");
+                return -ENOMEM;
+        }
+        msblk = sb->s_fs_info;
+
+        msblk->stream.workspace = kmalloc(zlib_inflate_workspacesize(),
+                GFP_KERNEL);
+        if (msblk->stream.workspace == NULL) {
+                ERROR("Failed to allocate zlib workspace\n");
+                goto failure;
+        }
+
+        sblk = kzalloc(sizeof(*sblk), GFP_KERNEL);
+        if (sblk == NULL) {
+                ERROR("Failed to allocate squashfs_super_block\n");
+                goto failure;
+        }
+
+        msblk->devblksize = sb_min_blocksize(sb, BLOCK_SIZE);
+        msblk->devblksize_log2 = ffz(~msblk->devblksize);
+
+        mutex_init(&msblk->read_data_mutex);
+        mutex_init(&msblk->meta_index_mutex);
+
+        /*
+         * msblk->bytes_used is checked in squashfs_read_table to ensure reads
+         * are not beyond filesystem end.  But as we're using
+         * squashfs_read_table here to read the superblock (including the value
+         * of bytes_used) we need to set it to an initial sensible dummy value
+         */
+        msblk->bytes_used = sizeof(*sblk);
+        err = squashfs_read_table(sb, sblk, SQUASHFS_START, sizeof(*sblk));
+
+        if (err < 0) {
+                ERROR("unable to read squashfs_super_block\n");
+                goto failed_mount;
+        }
+
+        /* Check it is a SQUASHFS superblock */
+        sb->s_magic = le32_to_cpu(sblk->s_magic);
+        if (sb->s_magic != SQUASHFS_MAGIC) {
+                if (!silent)
+                        ERROR("Can't find a SQUASHFS superblock on %s\n",
+                                                bdevname(sb->s_bdev, b));
+                err = -EINVAL;
+                goto failed_mount;
+        }
+
+        /* Check the MAJOR & MINOR versions and compression type */
+        err = supported_squashfs_filesystem(le16_to_cpu(sblk->s_major),
+                        le16_to_cpu(sblk->s_minor),
+                        le16_to_cpu(sblk->compression));
+        if (err < 0)
+                goto failed_mount;
+
+        err = -EINVAL;
+
+        /*
+         * 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)
+                ERROR("Xattrs in filesystem, these will be ignored\n");
+
+        /* Check the filesystem does not extend beyond the end of the
+           block device */
+        msblk->bytes_used = le64_to_cpu(sblk->bytes_used);
+        if (msblk->bytes_used < 0 || msblk->bytes_used >
+                        i_size_read(sb->s_bdev->bd_inode))
+                goto failed_mount;
+
+        /* Check block size for sanity */
+        msblk->block_size = le32_to_cpu(sblk->block_size);
+        if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE)
+                goto failed_mount;
+
+        msblk->block_log = le16_to_cpu(sblk->block_log);
+        if (msblk->block_log > SQUASHFS_FILE_MAX_LOG)
+                goto failed_mount;
+
+        /* Check the root inode for sanity */
+        root_inode = le64_to_cpu(sblk->root_inode);
+        if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE)
+                goto failed_mount;
+
+        msblk->inode_table = le64_to_cpu(sblk->inode_table_start);
+        msblk->directory_table = le64_to_cpu(sblk->directory_table_start);
+        msblk->inodes = le32_to_cpu(sblk->inodes);
+        flags = le16_to_cpu(sblk->flags);
+
+        TRACE("Found valid superblock on %s\n", bdevname(sb->s_bdev, b));
+        TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags)
+                                ? "un" : "");
+        TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags)
+                                ? "un" : "");
+        TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
+        TRACE("Block size %d\n", msblk->block_size);
+        TRACE("Number of inodes %d\n", msblk->inodes);
+        TRACE("Number of fragments %d\n", le32_to_cpu(sblk->fragments));
+        TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_ids));
+        TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
+        TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
+        TRACE("sblk->fragment_table_start %llx\n",
+                (u64) le64_to_cpu(sblk->fragment_table_start));
+        TRACE("sblk->id_table_start %llx\n",
+                (u64) le64_to_cpu(sblk->id_table_start));
+
+        sb->s_maxbytes = MAX_LFS_FILESIZE;
+        sb->s_flags |= MS_RDONLY;
+        sb->s_op = &squashfs_super_ops;
+
+        err = -ENOMEM;
+
+        msblk->block_cache = squashfs_cache_init("metadata",
+                        SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE);
+        if (msblk->block_cache == NULL)
+                goto failed_mount;
+
+        /* Allocate read_page block */
+        msblk->read_page = squashfs_cache_init("data", 1, msblk->block_size);
+        if (msblk->read_page == NULL) {
+                ERROR("Failed to allocate read_page block\n");
+                goto failed_mount;
+        }
+
+        /* Allocate and read id index table */
+        msblk->id_table = squashfs_read_id_index_table(sb,
+                le64_to_cpu(sblk->id_table_start), le16_to_cpu(sblk->no_ids));
+        if (IS_ERR(msblk->id_table)) {
+                err = PTR_ERR(msblk->id_table);
+                msblk->id_table = NULL;
+                goto failed_mount;
+        }
+
+        fragments = le32_to_cpu(sblk->fragments);
+        if (fragments == 0)
+                goto allocate_lookup_table;
+
+        msblk->fragment_cache = squashfs_cache_init("fragment",
+                SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
+        if (msblk->fragment_cache == NULL) {
+                err = -ENOMEM;
+                goto failed_mount;
+        }
+
+        /* Allocate and read fragment index table */
+        msblk->fragment_index = squashfs_read_fragment_index_table(sb,
+                le64_to_cpu(sblk->fragment_table_start), fragments);
+        if (IS_ERR(msblk->fragment_index)) {
+                err = PTR_ERR(msblk->fragment_index);
+                msblk->fragment_index = NULL;
+                goto failed_mount;
+        }
+
+allocate_lookup_table:
+        lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
+        if (lookup_table_start == SQUASHFS_INVALID_BLK)
+                goto allocate_root;
+
+        /* Allocate and read inode lookup table */
+        msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
+                lookup_table_start, msblk->inodes);
+        if (IS_ERR(msblk->inode_lookup_table)) {
+                err = PTR_ERR(msblk->inode_lookup_table);
+                msblk->inode_lookup_table = NULL;
+                goto failed_mount;
+        }
+
+        sb->s_export_op = &squashfs_export_ops;
+
+allocate_root:
+        root = new_inode(sb);
+        if (!root) {
+                err = -ENOMEM;
+                goto failed_mount;
+        }
+
+        err = squashfs_read_inode(root, root_inode);
+        if (err) {
+                iget_failed(root);
+                goto failed_mount;
+        }
+        insert_inode_hash(root);
+
+        sb->s_root = d_alloc_root(root);
+        if (sb->s_root == NULL) {
+                ERROR("Root inode create failed\n");
+                err = -ENOMEM;
+                iput(root);
+                goto failed_mount;
+        }
+
+        TRACE("Leaving squashfs_fill_super\n");
+        kfree(sblk);
+        return 0;
+
+failed_mount:
+        squashfs_cache_delete(msblk->block_cache);
+        squashfs_cache_delete(msblk->fragment_cache);
+        squashfs_cache_delete(msblk->read_page);
+        kfree(msblk->inode_lookup_table);
+        kfree(msblk->fragment_index);
+        kfree(msblk->id_table);
+        kfree(msblk->stream.workspace);
+        kfree(sb->s_fs_info);
+        sb->s_fs_info = NULL;
+        kfree(sblk);
+        return err;
+
+failure:
+        kfree(msblk->stream.workspace);
+        kfree(sb->s_fs_info);
+        sb->s_fs_info = NULL;
+        return -ENOMEM;
+}
+
+
+static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+        struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info;
+
+        TRACE("Entered squashfs_statfs\n");
+
+        buf->f_type = SQUASHFS_MAGIC;
+        buf->f_bsize = msblk->block_size;
+        buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1;
+        buf->f_bfree = buf->f_bavail = 0;
+        buf->f_files = msblk->inodes;
+        buf->f_ffree = 0;
+        buf->f_namelen = SQUASHFS_NAME_LEN;
+
+        return 0;
+}
+
+
+static int squashfs_remount(struct super_block *sb, int *flags, char *data)
+{
+        *flags |= MS_RDONLY;
+        return 0;
+}
+
+
+static void squashfs_put_super(struct super_block *sb)
+{
+        if (sb->s_fs_info) {
+                struct squashfs_sb_info *sbi = sb->s_fs_info;
+                squashfs_cache_delete(sbi->block_cache);
+                squashfs_cache_delete(sbi->fragment_cache);
+                squashfs_cache_delete(sbi->read_page);
+                kfree(sbi->id_table);
+                kfree(sbi->fragment_index);
+                kfree(sbi->meta_index);
+                kfree(sbi->stream.workspace);
+                kfree(sb->s_fs_info);
+                sb->s_fs_info = NULL;
+        }
+}
+
+
+static int squashfs_get_sb(struct file_system_type *fs_type, int flags,
+                                const char *dev_name, void *data,
+                                struct vfsmount *mnt)
+{
+        return get_sb_bdev(fs_type, flags, dev_name, data, squashfs_fill_super,
+                                mnt);
+}
+
+
+static struct kmem_cache *squashfs_inode_cachep;
+
+
+static void init_once(void *foo)
+{
+        struct squashfs_inode_info *ei = foo;
+
+        inode_init_once(&ei->vfs_inode);
+}
+
+
+static int __init init_inodecache(void)
+{
+        squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache",
+                sizeof(struct squashfs_inode_info), 0,
+                SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, init_once);
+
+        return squashfs_inode_cachep ? 0 : -ENOMEM;
+}
+
+
+static void destroy_inodecache(void)
+{
+        kmem_cache_destroy(squashfs_inode_cachep);
+}
+
+
+static int __init init_squashfs_fs(void)
+{
+        int err = init_inodecache();
+
+        if (err)
+                return err;
+
+        err = register_filesystem(&squashfs_fs_type);
+        if (err) {
+                destroy_inodecache();
+                return err;
+        }
+
+        printk(KERN_INFO "squashfs: version 4.0 (2009/01/03) "
+                "Phillip Lougher\n");
+
+        return 0;
+}
+
+
+static void __exit exit_squashfs_fs(void)
+{
+        unregister_filesystem(&squashfs_fs_type);
+        destroy_inodecache();
+}
+
+
+static struct inode *squashfs_alloc_inode(struct super_block *sb)
+{
+        struct squashfs_inode_info *ei =
+                kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL);
+
+        return ei ? &ei->vfs_inode : NULL;
+}
+
+
+static void squashfs_destroy_inode(struct inode *inode)
+{
+        kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
+}
+
+
+static struct file_system_type squashfs_fs_type = {
+        .owner = THIS_MODULE,
+        .name = "squashfs",
+        .get_sb = squashfs_get_sb,
+        .kill_sb = kill_block_super,
+        .fs_flags = FS_REQUIRES_DEV
+};
+
+static struct super_operations squashfs_super_ops = {
+        .alloc_inode = squashfs_alloc_inode,
+        .destroy_inode = squashfs_destroy_inode,
+        .statfs = squashfs_statfs,
+        .put_super = squashfs_put_super,
+        .remount_fs = squashfs_remount
+};
+
+module_init(init_squashfs_fs);
+module_exit(exit_squashfs_fs);
+MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem");
+MODULE_AUTHOR("Phillip Lougher <phillip@lougher.demon.co.uk>");
+MODULE_LICENSE("GPL");