aboutsummaryrefslogtreecommitdiffstats
path: root/fs/squashfs/super.c
diff options
context:
space:
mode:
authorPhillip Lougher <phillip@lougher.demon.co.uk>2009-01-05 08:46:25 +0000
committerPhillip Lougher <phillip@lougher.demon.co.uk>2009-01-05 08:46:25 +0000
commit0aa666190509ffab81c202c5095a166be23961ac (patch)
treee2262dd203b3916e241f31755cff6751ddf516b6 /fs/squashfs/super.c
parent1dc4bba39dd29c6d6f77ca7bf63cd3adeb6fc162 (diff)
Squashfs: super block operations
Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>
Diffstat (limited to 'fs/squashfs/super.c')
-rw-r--r--fs/squashfs/super.c440
1 files changed, 440 insertions, 0 deletions
diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c
new file mode 100644
index 00000000000..a0466d7467b
--- /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");