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dc351252b3
Backport of ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.22-rc1/2.6.22-rc1-mm1/broken-out/gregkh-driver-sysfs-allocate-inode-number-using-ida.patch For regular files in sysfs, sysfs_readdir wants to traverse sysfs_dirent->s_dentry->d_inode->i_ino to get to the inode number. But, the dentry can be reclaimed under memory pressure, and there is no synchronization with readdir. This patch follows Tejun's scheme of allocating and storing an inode number in the new s_ino member of a sysfs_dirent, when dirents are created, and retrieving it from there for readdir, so that the pointer chain doesn't have to be traversed. Tejun's upstream patch uses a new-ish "ida" allocator which brings along some extra complexity; this -stable patch has a brain-dead incrementing counter which does not guarantee uniqueness, but because sysfs doesn't hash inodes as iunique expects, uniqueness wasn't guaranteed today anyway. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
132 lines
3.6 KiB
C
132 lines
3.6 KiB
C
struct sysfs_dirent {
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atomic_t s_count;
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struct list_head s_sibling;
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struct list_head s_children;
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void * s_element;
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int s_type;
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umode_t s_mode;
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ino_t s_ino;
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struct dentry * s_dentry;
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struct iattr * s_iattr;
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atomic_t s_event;
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};
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extern struct vfsmount * sysfs_mount;
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extern struct kmem_cache *sysfs_dir_cachep;
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extern void sysfs_delete_inode(struct inode *inode);
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extern struct inode * sysfs_new_inode(mode_t mode, struct sysfs_dirent *);
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extern int sysfs_create(struct dentry *, int mode, int (*init)(struct inode *));
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extern int sysfs_dirent_exist(struct sysfs_dirent *, const unsigned char *);
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extern int sysfs_make_dirent(struct sysfs_dirent *, struct dentry *, void *,
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umode_t, int);
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extern int sysfs_add_file(struct dentry *, const struct attribute *, int);
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extern int sysfs_hash_and_remove(struct dentry * dir, const char * name);
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extern struct sysfs_dirent *sysfs_find(struct sysfs_dirent *dir, const char * name);
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extern int sysfs_create_subdir(struct kobject *, const char *, struct dentry **);
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extern void sysfs_remove_subdir(struct dentry *);
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extern const unsigned char * sysfs_get_name(struct sysfs_dirent *sd);
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extern void sysfs_drop_dentry(struct sysfs_dirent *sd, struct dentry *parent);
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extern int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
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extern struct rw_semaphore sysfs_rename_sem;
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extern struct super_block * sysfs_sb;
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extern const struct file_operations sysfs_dir_operations;
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extern const struct file_operations sysfs_file_operations;
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extern const struct file_operations bin_fops;
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extern const struct inode_operations sysfs_dir_inode_operations;
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extern const struct inode_operations sysfs_symlink_inode_operations;
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struct sysfs_symlink {
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char * link_name;
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struct kobject * target_kobj;
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};
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struct sysfs_buffer {
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struct list_head associates;
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size_t count;
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loff_t pos;
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char * page;
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struct sysfs_ops * ops;
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struct semaphore sem;
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int orphaned;
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int needs_read_fill;
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int event;
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};
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struct sysfs_buffer_collection {
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struct list_head associates;
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};
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static inline struct kobject * to_kobj(struct dentry * dentry)
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{
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struct sysfs_dirent * sd = dentry->d_fsdata;
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return ((struct kobject *) sd->s_element);
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}
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static inline struct attribute * to_attr(struct dentry * dentry)
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{
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struct sysfs_dirent * sd = dentry->d_fsdata;
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return ((struct attribute *) sd->s_element);
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}
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static inline struct bin_attribute * to_bin_attr(struct dentry * dentry)
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{
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struct sysfs_dirent * sd = dentry->d_fsdata;
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return ((struct bin_attribute *) sd->s_element);
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}
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static inline struct kobject *sysfs_get_kobject(struct dentry *dentry)
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{
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struct kobject * kobj = NULL;
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spin_lock(&dcache_lock);
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if (!d_unhashed(dentry)) {
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struct sysfs_dirent * sd = dentry->d_fsdata;
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if (sd->s_type & SYSFS_KOBJ_LINK) {
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struct sysfs_symlink * sl = sd->s_element;
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kobj = kobject_get(sl->target_kobj);
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} else
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kobj = kobject_get(sd->s_element);
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}
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spin_unlock(&dcache_lock);
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return kobj;
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}
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static inline void release_sysfs_dirent(struct sysfs_dirent * sd)
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{
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if (sd->s_type & SYSFS_KOBJ_LINK) {
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struct sysfs_symlink * sl = sd->s_element;
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kfree(sl->link_name);
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kobject_put(sl->target_kobj);
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kfree(sl);
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}
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kfree(sd->s_iattr);
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kmem_cache_free(sysfs_dir_cachep, sd);
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}
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static inline struct sysfs_dirent * sysfs_get(struct sysfs_dirent * sd)
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{
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if (sd) {
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WARN_ON(!atomic_read(&sd->s_count));
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atomic_inc(&sd->s_count);
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}
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return sd;
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}
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static inline void sysfs_put(struct sysfs_dirent * sd)
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{
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if (atomic_dec_and_test(&sd->s_count))
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release_sysfs_dirent(sd);
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}
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static inline int sysfs_is_shadowed_inode(struct inode *inode)
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{
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return S_ISDIR(inode->i_mode) && inode->i_op->follow_link;
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}
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