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Subject[PATCH RESEND 1/2] fs/anon_inode: Introduce a new lib function anon_inode_getfile_private()

Introduce a new lib function anon_inode_getfile_private(), it creates a new file
instance by hooking it up to an anonymous inode, and a dentry that describe the
"class" of the file, similar to anon_inode_getfile(), but each file holds a
single inode. Furthermore, anyone who wants to create a private anon file will
benefit from this change.

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
---
fs/anon_inodes.c | 66 +++++++++++++++++++++++++++++++++++++++++++
include/linux/anon_inodes.h | 3 ++
2 files changed, 69 insertions(+), 0 deletions(-)

diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c
index 47a65df..85c9618 100644
--- a/fs/anon_inodes.c
+++ b/fs/anon_inodes.c
@@ -109,6 +109,72 @@ static struct file_system_type anon_inode_fs_type = {
};

/**
+ * anon_inode_getfile_private - creates a new file instance by hooking it up to an
+ * anonymous inode, and a dentry that describe the "class"
+ * of the file
+ *
+ * @name: [in] name of the "class" of the new file
+ * @fops: [in] file operations for the new file
+ * @priv: [in] private data for the new file (will be file's private_data)
+ * @flags: [in] flags
+ *
+ *
+ * Similar to anon_inode_getfile, but each file holds a single inode.
+ *
+ */
+struct file *anon_inode_getfile_private(const char *name,
+ const struct file_operations *fops,
+ void *priv, int flags)
+{
+ struct qstr this;
+ struct path path;
+ struct file *file;
+ struct inode *inode;
+
+ if (fops->owner && !try_module_get(fops->owner))
+ return ERR_PTR(-ENOENT);
+
+ inode = anon_inode_mkinode(anon_inode_mnt->mnt_sb);
+ if (IS_ERR(inode)) {
+ file = ERR_PTR(-ENOMEM);
+ goto err_module;
+ }
+
+ /*
+ * Link the inode to a directory entry by creating a unique name
+ * using the inode sequence number.
+ */
+ file = ERR_PTR(-ENOMEM);
+ this.name = name;
+ this.len = strlen(name);
+ this.hash = 0;
+ path.dentry = d_alloc_pseudo(anon_inode_mnt->mnt_sb, &this);
+ if (!path.dentry)
+ goto err_module;
+
+ path.mnt = mntget(anon_inode_mnt);
+
+ d_instantiate(path.dentry, inode);
+
+ file = alloc_file(&path, OPEN_FMODE(flags), fops);
+ if (IS_ERR(file))
+ goto err_dput;
+
+ file->f_mapping = inode->i_mapping;
+ file->f_flags = flags & (O_ACCMODE | O_NONBLOCK);
+ file->private_data = priv;
+
+ return file;
+
+err_dput:
+ path_put(&path);
+err_module:
+ module_put(fops->owner);
+ return file;
+}
+EXPORT_SYMBOL_GPL(anon_inode_getfile_private);
+
+/**
* anon_inode_getfile - creates a new file instance by hooking it up to an
* anonymous inode, and a dentry that describe the "class"
* of the file
diff --git a/include/linux/anon_inodes.h b/include/linux/anon_inodes.h
index 8013a45..cf573c2 100644
--- a/include/linux/anon_inodes.h
+++ b/include/linux/anon_inodes.h
@@ -13,6 +13,9 @@ struct file_operations;
struct file *anon_inode_getfile(const char *name,
const struct file_operations *fops,
void *priv, int flags);
+struct file *anon_inode_getfile_private(const char *name,
+ const struct file_operations *fops,
+ void *priv, int flags);
int anon_inode_getfd(const char *name, const struct file_operations *fops,
void *priv, int flags);

--
1.7.7


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