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Date: Tue, 12 Dec 2006 15:36:26 -0500
From: Peter Staubach <staubach@...hat.com>
To: Jeff Layton <jlayton@...hat.com>
CC: linux@...izon.com, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] ensure unique i_ino in filesystems without permanent
Jeff Layton wrote:
> linux@...izon.com wrote:
> >> 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?
> >
> > include/linux/types.h:36:typedef _Bool bool;
> >
> > It's already in there. And <linux/stddef.h> has false and true.
> >
> > Sorry; I write more user-level code.
> >
> > The'd be built-in, except that C99 didn't want to add a kewords that
> > might conflict with existing code.
>
> Ok, that makes sense. Though I just found a bug that I missed. I
> forgot to change the
> EXPORT_SYMBOL in libfs.c. This should fix it:
>
> Signed-off-by: Jeff Layton <jlayton@...hat.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;
> }
>
If iunique_register() fails, does not this create a memory leak
because root will need to get iput()'d?
> -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;
Does this not create a memory leak as well?
Thanx...
ps
> 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;
> @@ -618,7 +628,7 @@ EXPORT_SYMBOL(simple_dir_inode_operation
> EXPORT_SYMBOL(simple_dir_operations);
> EXPORT_SYMBOL(simple_empty);
> EXPORT_SYMBOL(d_alloc_name);
> -EXPORT_SYMBOL(simple_fill_super);
> +EXPORT_SYMBOL(__simple_fill_super);
> EXPORT_SYMBOL(simple_getattr);
> EXPORT_SYMBOL(simple_link);
> EXPORT_SYMBOL(simple_lookup);
> --- 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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