Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758120Ab0FORNZ (ORCPT ); Tue, 15 Jun 2010 13:13:25 -0400 Received: from e23smtp04.au.ibm.com ([202.81.31.146]:45900 "EHLO e23smtp04.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757671Ab0FORNX (ORCPT ); Tue, 15 Jun 2010 13:13:23 -0400 From: "Aneesh Kumar K.V" To: hch@infradead.org, viro@zeniv.linux.org.uk, adilger@sun.com, corbet@lwn.net, serue@us.ibm.com, neilb@suse.de, hooanon05@yahoo.co.jp, bfields@fieldses.org 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 -V14 02/11] vfs: Add name to file handle conversion support Date: Tue, 15 Jun 2010 22:42:52 +0530 Message-Id: <1276621981-2774-3-git-send-email-aneesh.kumar@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.1.331.ga5080 In-Reply-To: <1276621981-2774-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> References: <1276621981-2774-1-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: 5800 Lines: 212 This patch add a new superblock field unsigned char s_uuid[16] to store UUID mapping for the file system. The s_uuid[16] is used to identify the file system apart of file_handle Acked-by: Serge Hallyn Signed-off-by: Aneesh Kumar K.V --- fs/open.c | 128 ++++++++++++++++++++++++++++++++++++++++++++++ include/linux/fs.h | 11 ++++ include/linux/syscalls.h | 3 + 3 files changed, 142 insertions(+), 0 deletions(-) diff --git a/fs/open.c b/fs/open.c index 5463266..43ac798 100644 --- a/fs/open.c +++ b/fs/open.c @@ -29,6 +29,7 @@ #include #include #include +#include #include "internal.h" @@ -1040,3 +1041,130 @@ int nonseekable_open(struct inode *inode, struct file *filp) } EXPORT_SYMBOL(nonseekable_open); + +#ifdef CONFIG_EXPORTFS +/* 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) +{ + long retval; + int handle_size; + struct super_block *sb; + 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) { + /* get the uuid */ + sb = path->mnt->mnt_sb; + memcpy(handle->fs_uuid, + sb->s_uuid, + sizeof(handle->fs_uuid)); + retval = 0; + } 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; + + 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 + * @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_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, *pp; + struct file *file = NULL; + + if ((flag & ~AT_SYMLINK_FOLLOW) != 0) + goto err_out; + + if (name == NULL && dfd != AT_FDCWD) { + file = fget(dfd); + 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); + +out_path: + if (file) + fput(file); + else + path_put(&path); +err_out: + return ret; +} +#else +SYSCALL_DEFINE4(name_to_handle_at, int, dfd, const char __user *, name, + struct file_handle __user *, handle, int, flag) +{ + return -ENOSYS; +} +#endif diff --git a/include/linux/fs.h b/include/linux/fs.h index 471e1ff..ebc0f98 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -949,6 +949,16 @@ struct file { unsigned long f_mnt_write_state; #endif }; + +struct file_handle { + int handle_size; + int handle_type; + /* File system UUID identifier */ + u8 fs_uuid[16]; + /* 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); @@ -1357,6 +1367,7 @@ struct super_block { wait_queue_head_t s_wait_unfrozen; char s_id[32]; /* Informational name */ + u8 s_uuid[16]; /* UUID */ void *s_fs_info; /* Filesystem private info */ fmode_t s_mode; diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index 7f614ce..4d4e922 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -61,6 +61,7 @@ struct robust_list_head; struct getcpu_cache; struct old_linux_dirent; struct perf_event_attr; +struct file_handle; #include #include @@ -823,5 +824,7 @@ 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 flag); #endif -- 1.7.1.331.ga5080 -- 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/