kernfs: add kernfs_ops->open/release() callbacks
Add ->open/release() methods to kernfs_ops. ->open() is called when the file is opened and ->release() when the file is either released or severed. These callbacks can be used, for example, to manage persistent caching objects over multiple seq_file iterations. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: Acked-by: Zefan Li <lizefan@huawei.com>
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@ -468,7 +468,7 @@ static void kernfs_drain(struct kernfs_node *kn)
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rwsem_release(&kn->dep_map, 1, _RET_IP_);
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}
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kernfs_unmap_bin_file(kn);
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kernfs_drain_open_files(kn);
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mutex_lock(&kernfs_mutex);
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}
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@ -708,7 +708,8 @@ static int kernfs_fop_open(struct inode *inode, struct file *file)
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if (error)
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goto err_free;
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((struct seq_file *)file->private_data)->private = of;
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of->seq_file = file->private_data;
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of->seq_file->private = of;
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/* seq_file clears PWRITE unconditionally, restore it if WRITE */
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if (file->f_mode & FMODE_WRITE)
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@ -717,13 +718,22 @@ static int kernfs_fop_open(struct inode *inode, struct file *file)
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/* make sure we have open node struct */
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error = kernfs_get_open_node(kn, of);
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if (error)
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goto err_close;
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goto err_seq_release;
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if (ops->open) {
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/* nobody has access to @of yet, skip @of->mutex */
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error = ops->open(of);
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if (error)
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goto err_put_node;
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}
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/* open succeeded, put active references */
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kernfs_put_active(kn);
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return 0;
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err_close:
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err_put_node:
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kernfs_put_open_node(kn, of);
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err_seq_release:
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seq_release(inode, file);
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err_free:
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kfree(of->prealloc_buf);
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@ -733,11 +743,32 @@ err_out:
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return error;
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}
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/* used from release/drain to ensure that ->release() is called exactly once */
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static void kernfs_release_file(struct kernfs_node *kn,
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struct kernfs_open_file *of)
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{
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if (!(kn->flags & KERNFS_HAS_RELEASE))
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return;
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mutex_lock(&of->mutex);
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if (!of->released) {
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/*
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* A file is never detached without being released and we
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* need to be able to release files which are deactivated
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* and being drained. Don't use kernfs_ops().
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*/
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kn->attr.ops->release(of);
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of->released = true;
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}
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mutex_unlock(&of->mutex);
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}
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static int kernfs_fop_release(struct inode *inode, struct file *filp)
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{
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struct kernfs_node *kn = filp->f_path.dentry->d_fsdata;
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struct kernfs_open_file *of = kernfs_of(filp);
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kernfs_release_file(kn, of);
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kernfs_put_open_node(kn, of);
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seq_release(inode, filp);
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kfree(of->prealloc_buf);
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@ -746,12 +777,12 @@ static int kernfs_fop_release(struct inode *inode, struct file *filp)
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return 0;
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}
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void kernfs_unmap_bin_file(struct kernfs_node *kn)
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void kernfs_drain_open_files(struct kernfs_node *kn)
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{
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struct kernfs_open_node *on;
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struct kernfs_open_file *of;
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if (!(kn->flags & KERNFS_HAS_MMAP))
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if (!(kn->flags & (KERNFS_HAS_MMAP | KERNFS_HAS_RELEASE)))
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return;
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spin_lock_irq(&kernfs_open_node_lock);
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@ -763,10 +794,16 @@ void kernfs_unmap_bin_file(struct kernfs_node *kn)
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return;
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mutex_lock(&kernfs_open_file_mutex);
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list_for_each_entry(of, &on->files, list) {
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struct inode *inode = file_inode(of->file);
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unmap_mapping_range(inode->i_mapping, 0, 0, 1);
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if (kn->flags & KERNFS_HAS_MMAP)
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unmap_mapping_range(inode->i_mapping, 0, 0, 1);
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kernfs_release_file(kn, of);
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}
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mutex_unlock(&kernfs_open_file_mutex);
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kernfs_put_open_node(kn, NULL);
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@ -965,6 +1002,8 @@ struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
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kn->flags |= KERNFS_HAS_SEQ_SHOW;
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if (ops->mmap)
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kn->flags |= KERNFS_HAS_MMAP;
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if (ops->release)
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kn->flags |= KERNFS_HAS_RELEASE;
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rc = kernfs_add_one(kn);
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if (rc) {
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@ -104,7 +104,7 @@ struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
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*/
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extern const struct file_operations kernfs_file_fops;
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void kernfs_unmap_bin_file(struct kernfs_node *kn);
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void kernfs_drain_open_files(struct kernfs_node *kn);
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/*
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* symlink.c
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@ -46,6 +46,7 @@ enum kernfs_node_flag {
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KERNFS_SUICIDAL = 0x0400,
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KERNFS_SUICIDED = 0x0800,
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KERNFS_EMPTY_DIR = 0x1000,
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KERNFS_HAS_RELEASE = 0x2000,
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};
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/* @flags for kernfs_create_root() */
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@ -175,6 +176,7 @@ struct kernfs_open_file {
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/* published fields */
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struct kernfs_node *kn;
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struct file *file;
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struct seq_file *seq_file;
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void *priv;
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/* private fields, do not use outside kernfs proper */
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@ -186,10 +188,18 @@ struct kernfs_open_file {
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size_t atomic_write_len;
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bool mmapped:1;
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bool released:1;
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const struct vm_operations_struct *vm_ops;
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};
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struct kernfs_ops {
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/*
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* Optional open/release methods. Both are called with
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* @of->seq_file populated.
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*/
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int (*open)(struct kernfs_open_file *of);
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void (*release)(struct kernfs_open_file *of);
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/*
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* Read is handled by either seq_file or raw_read().
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*
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