lkml.org 
[lkml]   [2010]   [May]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH -V7 3/9] vfs: Add name to file handle conversion support
Date
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
fs/open.c | 109 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 109 insertions(+), 0 deletions(-)

diff --git a/fs/open.c b/fs/open.c
index 74e5cd9..9a34b81 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -30,6 +30,8 @@
#include <linux/falloc.h>
#include <linux/fs_struct.h>
#include <linux/ima.h>
+#include <linux/exportfs.h>
+#include <linux/mnt_namespace.h>

#include "internal.h"

@@ -1206,3 +1208,110 @@ int nonseekable_open(struct inode *inode, struct file *filp)
}

EXPORT_SYMBOL(nonseekable_open);
+
+/* limit the handle size to some value */
+#define MAX_HANDLE_SZ 4096
+static long do_sys_name_to_handle(struct path *path,
+ struct file_handle __user *ufh)
+{
+ int retval;
+ int handle_size;
+ struct vfsmount *mnt;
+ struct super_block *sb;
+ struct uuid this_fs_id;
+ struct file_handle f_handle;
+ struct file_handle *handle = NULL;
+
+ sb = path->mnt->mnt_sb;
+ if (!sb->s_op->get_fsid) {
+ retval = -EOPNOTSUPP;
+ goto err_out;
+ }
+ if (copy_from_user(&f_handle, ufh, sizeof(struct file_handle))) {
+ retval = -EFAULT;
+ goto err_out;
+ }
+ if (f_handle.handle_size > MAX_HANDLE_SZ) {
+ retval = -EINVAL;
+ goto err_out;
+ }
+ handle = kmalloc(sizeof(struct file_handle) + f_handle.handle_size,
+ GFP_KERNEL);
+ if (!handle) {
+ retval = -ENOMEM;
+ goto err_out;
+ }
+ handle_size = f_handle.handle_size;
+
+ /* we ask for a non connected handle */
+ retval = exportfs_encode_fh(path->dentry,
+ (struct fid *)handle->f_handle,
+ &handle_size, 0);
+ /* convert handle size to bytes */
+ handle_size *= sizeof(u32);
+ handle->handle_type = retval;
+ handle->handle_size = handle_size;
+ if (handle_size <= f_handle.handle_size) {
+ /* get the uuid */
+ retval = sb->s_op->get_fsid(sb, &this_fs_id);
+ if (!retval) {
+ /*
+ * Now verify whether we get the same vfsmount
+ * if we lookup with uuid. In case we end up having
+ * same uuid for the multiple file systems. When doing
+ * uuid based lookup we would return the first one.So
+ * with name_to_handle if we don't find the same
+ * vfsmount with lookup return EOPNOTSUPP
+ */
+ mnt = fs_get_vfsmount(current, &this_fs_id);
+ if (mnt != path->mnt) {
+ retval = -EOPNOTSUPP;
+ mntput(mnt);
+ goto err_free_out;
+ }
+ mntput(mnt);
+ memcpy(handle->fsid.uuid,
+ this_fs_id.uuid,
+ sizeof(handle->fsid.uuid));
+ } else {
+ retval = -EOPNOTSUPP;
+ goto err_free_out;
+ }
+ } else {
+ /*
+ * set the handle_size to zero so we copy only
+ * non variable part of the file_handle
+ */
+ handle_size = 0;
+ retval = -EOVERFLOW;
+ }
+ if (copy_to_user(ufh, handle,
+ sizeof(struct file_handle) + handle_size))
+ retval = -EFAULT;
+err_free_out:
+ kfree(handle);
+err_out:
+ return retval;
+}
+
+SYSCALL_DEFINE4(name_to_handle_at, int, dfd, const char __user *, name,
+ struct file_handle __user *, handle, int, flag)
+{
+ int follow;
+ long ret = -EINVAL;
+ struct path path;
+
+ if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
+ goto err_out;
+
+ follow = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
+ ret = user_path_at(dfd, name, follow, &path);
+ if (ret)
+ goto err_out;
+ ret = do_sys_name_to_handle(&path, handle);
+ path_put(&path);
+err_out:
+ /* avoid REGPARM breakage on x86: */
+ asmlinkage_protect(4, ret, dfd, name, handle, flag);
+ return ret;
+}
--
1.7.1.78.g212f0


\
 
 \ /
  Last update: 2010-05-12 17:55    [W:0.164 / U:20.888 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site