From: Daniel Axtens <dja@axtens.net>
To: nayna@linux.ibm.com, cclaudio@linux.ibm.com,
linux-fsdevel@vger.kernel.org, greg@kroah.com,
linuxppc-dev@lists.ozlabs.org
Cc: Daniel Axtens <dja@axtens.net>
Subject: [WIP RFC PATCH 1/6] kernfs: add create() and unlink() hooks
Date: Mon, 20 May 2019 16:25:48 +1000 [thread overview]
Message-ID: <20190520062553.14947-2-dja@axtens.net> (raw)
In-Reply-To: <20190520062553.14947-1-dja@axtens.net>
I'm building a generic firmware variable filesystem on top of kernfs
and I'd like to be able to create and unlink files.
The hooks are fairly straightforward. create() returns a kernfs_node*,
which is safe with regards to cleanup on error paths, because there
is no way that things can fail after that point in the current
implementation. However, currently O_EXCL is not implemented and
that may create failure paths, in which case we may need to revisit
this later.
Signed-off-by: Daniel Axtens <dja@axtens.net>
---
fs/kernfs/dir.c | 55 ++++++++++++++++++++++++++++++++++++++++++
include/linux/kernfs.h | 3 +++
2 files changed, 58 insertions(+)
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 016ba88f7335..74fe51dbd027 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -1175,6 +1175,59 @@ static int kernfs_iop_rename(struct inode *old_dir, struct dentry *old_dentry,
return ret;
}
+static int kernfs_iop_create(struct inode *dir, struct dentry *dentry,
+ umode_t mode, bool excl)
+{
+ struct kernfs_node *parent = dir->i_private;
+ struct kernfs_node *kn;
+ struct kernfs_syscall_ops *scops = kernfs_root(parent)->syscall_ops;
+
+ if (!scops || !scops->create)
+ return -EPERM;
+
+ if (!kernfs_get_active(parent))
+ return -ENODEV;
+
+ // TODO: add some locking to ensure that scops->create
+ // is called only once, and possibly to handle the O_EXCL case
+ WARN_ONCE(excl, "excl unimplemented");
+
+ kn = scops->create(parent, dentry->d_name.name, mode);
+
+ if (!kn)
+ return -EPERM;
+
+ if (IS_ERR(kn))
+ return PTR_ERR(kn);
+
+ d_instantiate(dentry, kernfs_get_inode(dir->i_sb, kn));
+
+ return 0;
+}
+
+static int kernfs_iop_unlink(struct inode *dir, struct dentry *dentry)
+{
+ struct kernfs_node *parent = dir->i_private;
+ struct kernfs_node *kn = d_inode(dentry)->i_private;
+ struct kernfs_syscall_ops *scops = kernfs_root(parent)->syscall_ops;
+ int ret;
+
+
+ if (!scops || !scops->unlink)
+ return -EPERM;
+
+ if (!kernfs_get_active(parent))
+ return -ENODEV;
+
+ ret = scops->unlink(kn);
+ if (ret)
+ return ret;
+
+ drop_nlink(d_inode(dentry));
+ dput(dentry);
+ return 0;
+};
+
const struct inode_operations kernfs_dir_iops = {
.lookup = kernfs_iop_lookup,
.permission = kernfs_iop_permission,
@@ -1185,6 +1238,8 @@ const struct inode_operations kernfs_dir_iops = {
.mkdir = kernfs_iop_mkdir,
.rmdir = kernfs_iop_rmdir,
.rename = kernfs_iop_rename,
+ .create = kernfs_iop_create,
+ .unlink = kernfs_iop_unlink,
};
static struct kernfs_node *kernfs_leftmost_descendant(struct kernfs_node *pos)
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 2bf477f86eb1..282b96acbd7e 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -179,6 +179,9 @@ struct kernfs_syscall_ops {
const char *new_name);
int (*show_path)(struct seq_file *sf, struct kernfs_node *kn,
struct kernfs_root *root);
+ struct kernfs_node* (*create)(struct kernfs_node *parent,
+ const char *name, umode_t mode);
+ int (*unlink)(struct kernfs_node *kn);
};
struct kernfs_root {
--
2.19.1
next prev parent reply other threads:[~2019-05-20 6:26 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-20 6:25 [WIP RFC PATCH 0/6] Generic Firmware Variable Filesystem Daniel Axtens
2019-05-20 6:25 ` Daniel Axtens [this message]
2019-05-20 6:25 ` [WIP RFC PATCH 2/6] fwvarfs: a generic firmware variable filesystem Daniel Axtens
2019-05-20 6:25 ` [WIP RFC PATCH 3/6] fwvarfs: efi backend Daniel Axtens
2019-05-20 6:25 ` [WIP RFC PATCH 4/6] powerpc/powernv: Add support for OPAL secure variables Daniel Axtens
2019-05-20 6:25 ` [WIP RFC PATCH 5/6] powerpc/powernv: Remove EFI " Daniel Axtens
2019-05-20 6:25 ` [WIP RFC PATCH 6/6] fwvarfs: Add opal_secvar backend Daniel Axtens
2019-05-31 4:04 ` [WIP RFC PATCH 0/6] Generic Firmware Variable Filesystem Nayna
2019-06-03 6:04 ` Daniel Axtens
2019-06-03 7:29 ` Greg KH
2019-06-03 23:56 ` Daniel Axtens
2019-06-04 20:01 ` Nayna
2019-06-04 20:05 ` Matthew Garrett
2019-06-05 8:13 ` Greg KH
2019-06-04 20:33 ` Nayna
2019-06-05 6:14 ` Greg KH
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