Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752209Ab0HTByY (ORCPT ); Thu, 19 Aug 2010 21:54:24 -0400 Received: from e23smtp07.au.ibm.com ([202.81.31.140]:49342 "EHLO e23smtp07.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751690Ab0HTBv5 (ORCPT ); Thu, 19 Aug 2010 21:51:57 -0400 From: "Aneesh Kumar K.V" To: hch@infradead.org, viro@zeniv.linux.org.uk, adilger@sun.com, corbet@lwn.net, neilb@suse.de, npiggin@suse.de, hooanon05@yahoo.co.jp, bfields@fieldses.org, miklos@szeredi.hu Cc: linux-fsdevel@vger.kernel.org, sfrench@us.ibm.com, philippe.deniel@CEA.FR, linux-kernel@vger.kernel.org, "Aneesh Kumar K.V" Subject: [PATCH -V18 02/13] vfs: Add name to file handle conversion support Date: Fri, 20 Aug 2010 07:21:26 +0530 Message-Id: <1282269097-26166-3-git-send-email-aneesh.kumar@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.0.4 In-Reply-To: <1282269097-26166-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> References: <1282269097-26166-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6096 Lines: 218 The syscall also return mount id which can be used to lookup file system specific information such as uuid in /proc//mountinfo Signed-off-by: Aneesh Kumar K.V --- fs/open.c | 129 ++++++++++++++++++++++++++++++++++++++++++++++ include/linux/exportfs.h | 3 + include/linux/fs.h | 8 +++ include/linux/syscalls.h | 5 ++- 4 files changed, 144 insertions(+), 1 deletions(-) diff --git a/fs/open.c b/fs/open.c index 630715f..efb1806 100644 --- a/fs/open.c +++ b/fs/open.c @@ -30,6 +30,7 @@ #include #include #include +#include #include "internal.h" @@ -1042,3 +1043,131 @@ int nonseekable_open(struct inode *inode, struct file *filp) } EXPORT_SYMBOL(nonseekable_open); + +#ifdef CONFIG_EXPORTFS +static long do_sys_name_to_handle(struct path *path, + struct file_handle __user *ufh, + int __user *mnt_id) +{ + long retval; + int handle_size; + struct file_handle f_handle; + struct file_handle *handle = NULL; + + 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; + } + + /* convert handle size to multiple of sizeof(u32) */ + handle_size = f_handle.handle_size >> 2; + + /* 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) { + /* + * set the handle_size to zero so we copy only + * non variable part of the file_handle + */ + handle_size = 0; + retval = -EOVERFLOW; + } else + retval = 0; + /* copy the mount id */ + if (copy_to_user(mnt_id, &path->mnt->mnt_id, sizeof(*mnt_id))) { + retval = -EFAULT; + goto err_free_out; + } + if (copy_to_user(ufh, handle, + sizeof(struct file_handle) + handle_size)) + retval = -EFAULT; +err_free_out: + kfree(handle); +err_out: + return retval; +} + +/** + * sys_name_to_handle_at: convert name to handle + * @dfd: directory relative to which name is interpreted if not absolute + * @name: name that should be converted to handle. + * @handle: resulting file handle + * @mnt_id: mount id of the file system containing the file + * @flag: flag value to indicate whether to follow symlink or not + * + * @handle->handle_size indicate the space available to store the + * variable part of the file handle in bytes. If there is not + * enough space, the field is updated to return the minimum + * value required. + */ +SYSCALL_DEFINE5(name_to_handle_at, int, dfd, const char __user *, name, + struct file_handle __user *, handle, int __user*, mnt_id, + int, flag) +{ + + int follow; + int fput_needed; + long ret = -EINVAL; + struct path path, *pp; + struct file *file = NULL; + + if ((flag & ~AT_SYMLINK_FOLLOW) != 0) + goto err_out; + + if (name == NULL && dfd != AT_FDCWD) { + file = fget_light(dfd, &fput_needed); + if (file) { + pp = &file->f_path; + ret = 0; + } else + ret = -EBADF; + } else { + follow = (flag & AT_SYMLINK_FOLLOW) ? LOOKUP_FOLLOW : 0; + ret = user_path_at(dfd, name, follow, &path); + pp = &path; + } + if (ret) + goto err_out; + /* + * We need t make sure wether the file system + * support decoding of the file handle + */ + if (!pp->mnt->mnt_sb->s_export_op || + !pp->mnt->mnt_sb->s_export_op->fh_to_dentry) { + ret = -EOPNOTSUPP; + goto out_path; + } + ret = do_sys_name_to_handle(pp, handle, mnt_id); + +out_path: + if (file) + fput_light(file, fput_needed); + else + path_put(&path); +err_out: + return ret; +} +#else +SYSCALL_DEFINE5(name_to_handle_at, int, dfd, const char __user *, name, + struct file_handle __user *, handle, int __user *, mnt_id, + int, flag) +{ + return -ENOSYS; +} +#endif diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h index acd0b2d..1a6d72f 100644 --- a/include/linux/exportfs.h +++ b/include/linux/exportfs.h @@ -8,6 +8,9 @@ struct inode; struct super_block; struct vfsmount; +/* limit the handle size to some value */ +#define MAX_HANDLE_SZ 4096 + /* * The fileid_type identifies how the file within the filesystem is encoded. * In theory this is freely set and parsed by the filesystem, but we try to diff --git a/include/linux/fs.h b/include/linux/fs.h index 9a96b4d..f2f7ad3 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -953,6 +953,14 @@ struct file { unsigned long f_mnt_write_state; #endif }; + +struct file_handle { + int handle_size; + int handle_type; + /* file identifier */ + unsigned char f_handle[0]; +}; + extern spinlock_t files_lock; #define file_list_lock() spin_lock(&files_lock); #define file_list_unlock() spin_unlock(&files_lock); diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index 6e5d197..f7aba76 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -62,6 +62,7 @@ struct robust_list_head; struct getcpu_cache; struct old_linux_dirent; struct perf_event_attr; +struct file_handle; #include #include @@ -831,5 +832,7 @@ asmlinkage long sys_mmap_pgoff(unsigned long addr, unsigned long len, unsigned long prot, unsigned long flags, unsigned long fd, unsigned long pgoff); asmlinkage long sys_old_mmap(struct mmap_arg_struct __user *arg); - +asmlinkage long sys_name_to_handle_at(int dfd, const char __user *name, + struct file_handle __user *handle, + int __user *mnt_id, int flag); #endif -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/