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vfs: Convert squashfs to use the new mount API
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Convert the squashfs filesystem to the new internal mount API as the old
one will be obsoleted and removed.  This allows greater flexibility in
communication of mount parameters between userspace, the VFS and the
filesystem.

See Documentation/filesystems/mount_api.txt for more information.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Phillip Lougher <phillip@squashfs.org.uk>
cc: squashfs-devel@lists.sourceforge.net
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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David Howells authored and Al Viro committed Sep 5, 2019
1 parent 6d56e41 commit 5a2be12
Showing 1 changed file with 55 additions and 45 deletions.
100 changes: 55 additions & 45 deletions fs/squashfs/super.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/fs.h>
#include <linux/fs_context.h>
#include <linux/vfs.h>
#include <linux/slab.h>
#include <linux/mutex.h>
Expand All @@ -36,34 +37,35 @@
static struct file_system_type squashfs_fs_type;
static const struct super_operations squashfs_super_ops;

static const struct squashfs_decompressor *supported_squashfs_filesystem(short
major, short minor, short id)
static const struct squashfs_decompressor *supported_squashfs_filesystem(
struct fs_context *fc,
short major, short minor, short id)
{
const struct squashfs_decompressor *decompressor;

if (major < SQUASHFS_MAJOR) {
ERROR("Major/Minor mismatch, older Squashfs %d.%d "
"filesystems are unsupported\n", major, minor);
errorf(fc, "Major/Minor mismatch, older Squashfs %d.%d "
"filesystems are unsupported", major, minor);
return NULL;
} 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");
errorf(fc, "Major/Minor mismatch, trying to mount newer "
"%d.%d filesystem", major, minor);
errorf(fc, "Please update your kernel");
return NULL;
}

decompressor = squashfs_lookup_decompressor(id);
if (!decompressor->supported) {
ERROR("Filesystem uses \"%s\" compression. This is not "
"supported\n", decompressor->name);
errorf(fc, "Filesystem uses \"%s\" compression. This is not supported",
decompressor->name);
return NULL;
}

return decompressor;
}


static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
{
struct squashfs_sb_info *msblk;
struct squashfs_super_block *sblk = NULL;
Expand Down Expand Up @@ -98,7 +100,7 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
sblk = squashfs_read_table(sb, SQUASHFS_START, sizeof(*sblk));

if (IS_ERR(sblk)) {
ERROR("unable to read squashfs_super_block\n");
errorf(fc, "unable to read squashfs_super_block");
err = PTR_ERR(sblk);
sblk = NULL;
goto failed_mount;
Expand All @@ -109,14 +111,15 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
/* 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 %pg\n",
sb->s_bdev);
if (!(fc->sb_flags & SB_SILENT))
errorf(fc, "Can't find a SQUASHFS superblock on %pg",
sb->s_bdev);
goto failed_mount;
}

/* Check the MAJOR & MINOR versions and lookup compression type */
msblk->decompressor = supported_squashfs_filesystem(
fc,
le16_to_cpu(sblk->s_major),
le16_to_cpu(sblk->s_minor),
le16_to_cpu(sblk->compression));
Expand All @@ -133,15 +136,15 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
/* 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;
goto insanity;

/*
* Check the system page size is not larger than the filesystem
* block size (by default 128K). This is currently not supported.
*/
if (PAGE_SIZE > msblk->block_size) {
ERROR("Page size > filesystem block size (%d). This is "
"currently not supported!\n", msblk->block_size);
errorf(fc, "Page size > filesystem block size (%d). This is "
"currently not supported!", msblk->block_size);
goto failed_mount;
}

Expand All @@ -152,12 +155,12 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)

/* Check that block_size and block_log match */
if (msblk->block_size != (1 << msblk->block_log))
goto failed_mount;
goto insanity;

/* 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;
goto insanity;

msblk->inode_table = le64_to_cpu(sblk->inode_table_start);
msblk->directory_table = le64_to_cpu(sblk->directory_table_start);
Expand Down Expand Up @@ -197,15 +200,15 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
msblk->read_page = squashfs_cache_init("data",
squashfs_max_decompressors(), msblk->block_size);
if (msblk->read_page == NULL) {
ERROR("Failed to allocate read_page block\n");
errorf(fc, "Failed to allocate read_page block");
goto failed_mount;
}

msblk->stream = squashfs_decompressor_setup(sb, flags);
if (IS_ERR(msblk->stream)) {
err = PTR_ERR(msblk->stream);
msblk->stream = NULL;
goto failed_mount;
goto insanity;
}

/* Handle xattrs */
Expand All @@ -220,7 +223,7 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
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)) {
ERROR("unable to read xattr id index table\n");
errorf(fc, "unable to read xattr id index table");
err = PTR_ERR(msblk->xattr_id_table);
msblk->xattr_id_table = NULL;
if (err != -ENOTSUPP)
Expand All @@ -234,7 +237,7 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
le64_to_cpu(sblk->id_table_start), next_table,
le16_to_cpu(sblk->no_ids));
if (IS_ERR(msblk->id_table)) {
ERROR("unable to read id index table\n");
errorf(fc, "unable to read id index table");
err = PTR_ERR(msblk->id_table);
msblk->id_table = NULL;
goto failed_mount;
Expand All @@ -250,7 +253,7 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
lookup_table_start, next_table, msblk->inodes);
if (IS_ERR(msblk->inode_lookup_table)) {
ERROR("unable to read inode lookup table\n");
errorf(fc, "unable to read inode lookup table");
err = PTR_ERR(msblk->inode_lookup_table);
msblk->inode_lookup_table = NULL;
goto failed_mount;
Expand All @@ -275,7 +278,7 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
msblk->fragment_index = squashfs_read_fragment_index_table(sb,
le64_to_cpu(sblk->fragment_table_start), next_table, fragments);
if (IS_ERR(msblk->fragment_index)) {
ERROR("unable to read fragment index table\n");
errorf(fc, "unable to read fragment index table");
err = PTR_ERR(msblk->fragment_index);
msblk->fragment_index = NULL;
goto failed_mount;
Expand All @@ -286,13 +289,13 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
/* Sanity check directory_table */
if (msblk->directory_table > next_table) {
err = -EINVAL;
goto failed_mount;
goto insanity;
}

/* Sanity check inode_table */
if (msblk->inode_table >= msblk->directory_table) {
err = -EINVAL;
goto failed_mount;
goto insanity;
}

/* allocate root */
Expand Down Expand Up @@ -321,6 +324,8 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
kfree(sblk);
return 0;

insanity:
errorf(fc, "squashfs image failed sanity check");
failed_mount:
squashfs_cache_delete(msblk->block_cache);
squashfs_cache_delete(msblk->fragment_cache);
Expand All @@ -336,6 +341,28 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
return err;
}

static int squashfs_get_tree(struct fs_context *fc)
{
return get_tree_bdev(fc, squashfs_fill_super);
}

static int squashfs_reconfigure(struct fs_context *fc)
{
sync_filesystem(fc->root->d_sb);
fc->sb_flags |= SB_RDONLY;
return 0;
}

static const struct fs_context_operations squashfs_context_ops = {
.get_tree = squashfs_get_tree,
.reconfigure = squashfs_reconfigure,
};

static int squashfs_init_fs_context(struct fs_context *fc)
{
fc->ops = &squashfs_context_ops;
return 0;
}

static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
Expand All @@ -358,14 +385,6 @@ static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
}


static int squashfs_remount(struct super_block *sb, int *flags, char *data)
{
sync_filesystem(sb);
*flags |= SB_RDONLY;
return 0;
}


static void squashfs_put_super(struct super_block *sb)
{
if (sb->s_fs_info) {
Expand All @@ -384,14 +403,6 @@ static void squashfs_put_super(struct super_block *sb)
}
}


static struct dentry *squashfs_mount(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
{
return mount_bdev(fs_type, flags, dev_name, data, squashfs_fill_super);
}


static struct kmem_cache *squashfs_inode_cachep;


Expand Down Expand Up @@ -468,7 +479,7 @@ static void squashfs_free_inode(struct inode *inode)
static struct file_system_type squashfs_fs_type = {
.owner = THIS_MODULE,
.name = "squashfs",
.mount = squashfs_mount,
.init_fs_context = squashfs_init_fs_context,
.kill_sb = kill_block_super,
.fs_flags = FS_REQUIRES_DEV
};
Expand All @@ -479,7 +490,6 @@ static const struct super_operations squashfs_super_ops = {
.free_inode = squashfs_free_inode,
.statfs = squashfs_statfs,
.put_super = squashfs_put_super,
.remount_fs = squashfs_remount
};

module_init(init_squashfs_fs);
Expand Down

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