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    SubjectRe: [PATCH 2/3] ensure unique i_ino in filesystems without permanent
    linux@horizon.com wrote:
    >> Good catch on the inlining. I had meant to do that and missed it.
    >
    > Er... if you want it to *be* inlined, you have to put it into the .h
    > file so the compiler knows about it at the call site. "static inline"
    > tells gcc not avoid emitting a callable version.
    >
    > Something like this the following. (You'll also need to add
    > a "#include <stdbool.h>", unless you expand the "bool", "false" and
    > "true" macros to their values "_Bool", "0" and "1" by hand.)
    >

    Doh! Thanks for explaining that. Here's a respun patch with your suggestion
    incorporated. Seems to build correctly without stdbool.h. In fact, I don't see
    a stdbool.h in Linus' tree as of this morning. Are you sure that it's needed?

    Signed-off-by: Jeff Layton <jlayton@redhat.com>

    --- linux-2.6/fs/debugfs/inode.c.super
    +++ linux-2.6/fs/debugfs/inode.c
    @@ -107,7 +107,7 @@ static int debug_fill_super(struct super
    {
    static struct tree_descr debug_files[] = {{""}};

    - return simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
    + return registered_fill_super(sb, DEBUGFS_MAGIC, debug_files);
    }

    static int debug_get_sb(struct file_system_type *fs_type,
    --- linux-2.6/fs/fuse/control.c.super
    +++ linux-2.6/fs/fuse/control.c
    @@ -163,7 +163,7 @@ static int fuse_ctl_fill_super(struct su
    struct fuse_conn *fc;
    int err;

    - err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr);
    + err = registered_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr);
    if (err)
    return err;

    --- linux-2.6/fs/libfs.c.super
    +++ linux-2.6/fs/libfs.c
    @@ -215,7 +215,7 @@ int get_sb_pseudo(struct file_system_typ
    s->s_op = ops ? ops : &default_ops;
    s->s_time_gran = 1;
    root = new_inode(s);
    - if (!root)
    + if (!root || iunique_register(root, 0))
    goto Enomem;
    root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
    root->i_uid = root->i_gid = 0;
    @@ -356,7 +356,8 @@ int simple_commit_write(struct file *fil
    return 0;
    }

    -int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files)
    +int __simple_fill_super(struct super_block *s, int magic,
    + struct tree_descr *files, bool registered)
    {
    static struct super_operations s_ops = {.statfs = simple_statfs};
    struct inode *inode;
    @@ -380,6 +381,12 @@ int simple_fill_super(struct super_block
    inode->i_op = &simple_dir_inode_operations;
    inode->i_fop = &simple_dir_operations;
    inode->i_nlink = 2;
    + /*
    + * set this as high as a 32 bit val as possible to avoid collisions.
    + * This is also well above the highest value that iunique_register
    + * will assign to an inode
    + */
    + inode->i_ino = 0xffffffff;
    root = d_alloc_root(inode);
    if (!root) {
    iput(inode);
    @@ -394,12 +401,15 @@ int simple_fill_super(struct super_block
    inode = new_inode(s);
    if (!inode)
    goto out;
    + if (!registered)
    + inode->i_ino = i;
    + else if (iunique_register(inode, 0))
    + goto out;
    inode->i_mode = S_IFREG | files->mode;
    inode->i_uid = inode->i_gid = 0;
    inode->i_blocks = 0;
    inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
    inode->i_fop = files->ops;
    - inode->i_ino = i;
    d_add(dentry, inode);
    }
    s->s_root = root;
    --- linux-2.6/include/linux/fs.h.super
    +++ linux-2.6/include/linux/fs.h
    @@ -1879,10 +1879,35 @@ extern const struct file_operations simp
    extern struct inode_operations simple_dir_inode_operations;
    struct tree_descr { char *name; const struct file_operations *ops; int mode; };
    struct dentry *d_alloc_name(struct dentry *, const char *);
    -extern int simple_fill_super(struct super_block *, int, struct tree_descr *);
    +extern int __simple_fill_super(struct super_block *s, int magic,
    + struct tree_descr *files, bool registered);
    extern int simple_pin_fs(struct file_system_type *, struct vfsmount **mount, int *count);
    extern void simple_release_fs(struct vfsmount **mount, int *count);

    +/*
    + * Fill a superblock with a standard set of fields, and add the entries in the
    + * "files" struct. Assign i_ino values to the files sequentially. This function
    + * is appropriate for filesystems that need a particular i_ino value assigned
    + * to a particular "files" entry.
    + */
    +static inline int simple_fill_super(struct super_block *s, int magic,
    + struct tree_descr *files)
    +{
    + return __simple_fill_super(s, magic, files, false);
    +}
    +
    +/*
    + * Just like simple_fill_super, but does an iunique_register on the inodes
    + * created for "files" entries. This function is appropriate when you don't
    + * need a particular i_ino value assigned to each files entry, and when the
    + * filesystem will have other registered inodes.
    + */
    +static inline int registered_fill_super(struct super_block *s, int magic,
    + struct tree_descr *files)
    +{
    + return __simple_fill_super(s, magic, files, true);
    +}
    +
    extern ssize_t simple_read_from_buffer(void __user *, size_t, loff_t *, const void *, size_t);

    #ifdef CONFIG_MIGRATION
    --- linux-2.6/security/inode.c.super
    +++ linux-2.6/security/inode.c
    @@ -130,7 +130,7 @@ static int fill_super(struct super_block
    {
    static struct tree_descr files[] = {{""}};

    - return simple_fill_super(sb, SECURITYFS_MAGIC, files);
    + return registered_fill_super(sb, SECURITYFS_MAGIC, files);
    }

    static int get_sb(struct file_system_type *fs_type,
    -
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