leandrof/linux
1
0
Fork 0
forked from Minki/linux
Code Issues Pull Requests Packages Projects Releases Wiki Activity

kernfs: add kernfs_ops->open/release() callbacks

Browse Source 
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>
This commit is contained in:
Tejun Heo 2016-12-27 14:49:03 -05:00
parent a1d82aff5d
commit 0e67db2f9f
4 changed files with 57 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
fs/kernfs/dir.c
View File

@ -468,7 +468,7 @@ static void kernfs_drain(struct kernfs_node *kn)
rwsem_release(&kn->dep_map, 1, _RET_IP_);
}
kernfs_unmap_bin_file(kn);
kernfs_drain_open_files(kn);
mutex_lock(&kernfs_mutex);
}

51
fs/kernfs/file.c
View File

@ -708,7 +708,8 @@ static int kernfs_fop_open(struct inode *inode, struct file *file)
if (error)
goto err_free;
((struct seq_file *)file->private_data)->private = of;
of->seq_file = file->private_data;
of->seq_file->private = of;
/* seq_file clears PWRITE unconditionally, restore it if WRITE */
if (file->f_mode & FMODE_WRITE)
@ -717,13 +718,22 @@ static int kernfs_fop_open(struct inode *inode, struct file *file)
/* make sure we have open node struct */
error = kernfs_get_open_node(kn, of);
if (error)
goto err_close;
goto err_seq_release;
if (ops->open) {
/* nobody has access to @of yet, skip @of->mutex */
error = ops->open(of);
if (error)
goto err_put_node;
}
/* open succeeded, put active references */
kernfs_put_active(kn);
return 0;
err_close:
err_put_node:
kernfs_put_open_node(kn, of);
err_seq_release:
seq_release(inode, file);
err_free:
kfree(of->prealloc_buf);
@ -733,11 +743,32 @@ err_out:
return error;
}
/* used from release/drain to ensure that ->release() is called exactly once */
static void kernfs_release_file(struct kernfs_node *kn,
struct kernfs_open_file *of)
{
if (!(kn->flags & KERNFS_HAS_RELEASE))
return;
mutex_lock(&of->mutex);
if (!of->released) {
/*
* A file is never detached without being released and we
* need to be able to release files which are deactivated
* and being drained. Don't use kernfs_ops().
*/
kn->attr.ops->release(of);
of->released = true;
}
mutex_unlock(&of->mutex);
}
static int kernfs_fop_release(struct inode *inode, struct file *filp)
{
struct kernfs_node *kn = filp->f_path.dentry->d_fsdata;
struct kernfs_open_file *of = kernfs_of(filp);
kernfs_release_file(kn, of);
kernfs_put_open_node(kn, of);
seq_release(inode, filp);
kfree(of->prealloc_buf);
@ -746,12 +777,12 @@ static int kernfs_fop_release(struct inode *inode, struct file *filp)
return 0;
}
void kernfs_unmap_bin_file(struct kernfs_node *kn)
void kernfs_drain_open_files(struct kernfs_node *kn)
{
struct kernfs_open_node *on;
struct kernfs_open_file *of;
if (!(kn->flags & KERNFS_HAS_MMAP))
if (!(kn->flags & (KERNFS_HAS_MMAP | KERNFS_HAS_RELEASE)))
return;
spin_lock_irq(&kernfs_open_node_lock);
@ -763,10 +794,16 @@ void kernfs_unmap_bin_file(struct kernfs_node *kn)
return;
mutex_lock(&kernfs_open_file_mutex);
list_for_each_entry(of, &on->files, list) {
struct inode *inode = file_inode(of->file);
unmap_mapping_range(inode->i_mapping, 0, 0, 1);
if (kn->flags & KERNFS_HAS_MMAP)
unmap_mapping_range(inode->i_mapping, 0, 0, 1);
kernfs_release_file(kn, of);
}
mutex_unlock(&kernfs_open_file_mutex);
kernfs_put_open_node(kn, NULL);
@ -965,6 +1002,8 @@ struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
kn->flags |= KERNFS_HAS_SEQ_SHOW;
if (ops->mmap)
kn->flags |= KERNFS_HAS_MMAP;
if (ops->release)
kn->flags |= KERNFS_HAS_RELEASE;
rc = kernfs_add_one(kn);
if (rc) {

2
fs/kernfs/kernfs-internal.h
View File

@ -104,7 +104,7 @@ struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
*/
extern const struct file_operations kernfs_file_fops;
void kernfs_unmap_bin_file(struct kernfs_node *kn);
void kernfs_drain_open_files(struct kernfs_node *kn);
/*
* symlink.c

10
include/linux/kernfs.h
View File

@ -46,6 +46,7 @@ enum kernfs_node_flag {
KERNFS_SUICIDAL = 0x0400,
KERNFS_SUICIDED = 0x0800,
KERNFS_EMPTY_DIR = 0x1000,
KERNFS_HAS_RELEASE = 0x2000,
};
/* @flags for kernfs_create_root() */
@ -175,6 +176,7 @@ struct kernfs_open_file {
/* published fields */
struct kernfs_node *kn;
struct file *file;
struct seq_file *seq_file;
void *priv;
/* private fields, do not use outside kernfs proper */
@ -186,10 +188,18 @@ struct kernfs_open_file {
size_t atomic_write_len;
bool mmapped:1;
bool released:1;
const struct vm_operations_struct *vm_ops;
};
struct kernfs_ops {
/*
* Optional open/release methods. Both are called with
* @of->seq_file populated.
*/
int (*open)(struct kernfs_open_file *of);
void (*release)(struct kernfs_open_file *of);
/*
* Read is handled by either seq_file or raw_read().
*