From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754346Ab2HZO21 (ORCPT ); Sun, 26 Aug 2012 10:28:27 -0400 Received: from mail-lb0-f174.google.com ([209.85.217.174]:55439 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752727Ab2HZO2Y (ORCPT ); Sun, 26 Aug 2012 10:28:24 -0400 Date: Sun, 26 Aug 2012 18:28:20 +0400 From: Cyrill Gorcunov To: Al Viro Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Alexey Dobriyan , Andrew Morton , Pavel Emelyanov , James Bottomley , Matthew Helsley , aneesh.kumar@linux.vnet.ibm.com, bfields@fieldses.org Subject: Re: [patch 2/9] procfs: Convert /proc/pid/fdinfo/ handling routines to seq-file v2 Message-ID: <20120826142820.GA16038@moon> References: <20120823104323.040550004@openvz.org> <20120823104725.686586462@openvz.org> <20120826024653.GY23464@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120826024653.GY23464@ZenIV.linux.org.uk> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Aug 26, 2012 at 03:46:53AM +0100, Al Viro wrote: > > IMO doing that at open() time is just a headache for no good reason - > resolving descriptor to struct file * at read() time as we do now > is much saner. Better do that in your ->show(), since you are using > a single-shot iterator anyway... Al, the updated version is below. I suppose I can grab proc inode then and lookup for file position and flags at show method. (I remember what you've said about O_CLOEXEC bit, but I'll address this in another patch). --- From: Cyrill Gorcunov Subject: procfs: Convert /proc/pid/fdinfo/ handling routines to seq-file v3 This patch converts /proc/pid/fdinfo/ handling routines to seq-file which is needed to extend seq operations and plug in auxiliary fdinfo provides from subsystems like eventfd/eventpoll/fsnotify. Note the proc_fd_link no longer call for proc_fd_info, simply because proc_fd_info is converted to seq_fdinfo_open (which is seq-file open() prototype). v2 (by Al Viro): - Don't use helper function with optional arguments, thus proc_fd_info get deprecated - Use proc_fdinfo structure with seq_file embedded, thus we can use container_of helper - Use fput to free reference to the file we've grabbed v3 (by Al Viro): - Don't grab struct file at read(2) time since it breaks ABI, instead all manipulations should be done at ->show() call. Signed-off-by: Cyrill Gorcunov CC: Pavel Emelyanov CC: Al Viro CC: Alexey Dobriyan CC: Andrew Morton CC: James Bottomley CC: "Aneesh Kumar K.V" CC: Alexey Dobriyan CC: Matthew Helsley CC: "J. Bruce Fields" CC: "Aneesh Kumar K.V" --- fs/proc/fd.c | 142 +++++++++++++++++++++++++++++++++++++++-------------------- 1 file changed, 95 insertions(+), 47 deletions(-) Index: linux-2.6.git/fs/proc/fd.c =================================================================== --- linux-2.6.git.orig/fs/proc/fd.c +++ linux-2.6.git/fs/proc/fd.c @@ -6,61 +6,100 @@ #include #include #include +#include +#include #include #include "internal.h" #include "fd.h" -#define PROC_FDINFO_MAX 64 +struct proc_fdinfo { + struct seq_file m; + struct inode *inode; +}; -static int proc_fd_info(struct inode *inode, struct path *path, char *info) +static int seq_show(struct seq_file *m, void *v) { - struct task_struct *task = get_proc_task(inode); + struct proc_fdinfo *fdinfo = container_of(m, struct proc_fdinfo, m); struct files_struct *files = NULL; - int fd = proc_fd(inode); - struct file *file; + int f_flags = 0, ret = -ENOENT; + struct file *file = NULL; + struct task_struct *task; + + task = get_proc_task(fdinfo->inode); + if (!task) + return -ENOENT; + + files = get_files_struct(task); + put_task_struct(task); - if (task) { - files = get_files_struct(task); - put_task_struct(task); - } if (files) { - /* - * We are not taking a ref to the file structure, so we must - * hold ->file_lock. - */ + int fd = proc_fd(fdinfo->inode); + spin_lock(&files->file_lock); file = fcheck_files(files, fd); if (file) { - unsigned int f_flags; - struct fdtable *fdt; + struct fdtable *fdt = files_fdtable(files); - fdt = files_fdtable(files); f_flags = file->f_flags & ~O_CLOEXEC; if (close_on_exec(fd, fdt)) f_flags |= O_CLOEXEC; - if (path) { - *path = file->f_path; - path_get(&file->f_path); - } - if (info) - snprintf(info, PROC_FDINFO_MAX, - "pos:\t%lli\n" - "flags:\t0%o\n", - (long long) file->f_pos, - f_flags); - spin_unlock(&files->file_lock); - put_files_struct(files); - return 0; + get_file(file); + ret = 0; } spin_unlock(&files->file_lock); put_files_struct(files); } - return -ENOENT; + + if (!ret) { + seq_printf(m, "pos:\t%lli\nflags:\t0%o\n", + (long long)file->f_pos, f_flags); + fput(file); + } + + return ret; +} + +static int seq_fdinfo_open(struct inode *inode, struct file *file) +{ + struct proc_fdinfo *fdinfo; + int ret = 0; + + fdinfo = kmalloc(sizeof(*fdinfo), GFP_KERNEL); + if (!fdinfo) + return -ENOMEM; + + ihold(inode); + fdinfo->inode = inode; + + file->private_data = &fdinfo->m; + ret = single_open(file, seq_show, NULL); + if (ret) { + iput(inode); + kfree(fdinfo); + } + + return ret; +} + +static int seq_fdinfo_release(struct inode *inode, struct file *file) +{ + struct proc_fdinfo *fdinfo = + container_of((struct seq_file *)file->private_data, + struct proc_fdinfo, m); + iput(fdinfo->inode); + return single_release(inode, file); } +static const struct file_operations proc_fdinfo_file_operations = { + .open = seq_fdinfo_open, + .read = seq_read, + .llseek = seq_lseek, + .release = seq_fdinfo_release, +}; + static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags) { struct files_struct *files; @@ -130,7 +169,32 @@ static const struct dentry_operations ti static int proc_fd_link(struct dentry *dentry, struct path *path) { - return proc_fd_info(dentry->d_inode, path, NULL); + struct files_struct *files = NULL; + struct task_struct *task; + int ret = -ENOENT; + + task = get_proc_task(dentry->d_inode); + if (task) { + files = get_files_struct(task); + put_task_struct(task); + } + + if (files) { + int fd = proc_fd(dentry->d_inode); + struct file *fd_file; + + spin_lock(&files->file_lock); + fd_file = fcheck_files(files, fd); + if (fd_file) { + *path = fd_file->f_path; + path_get(&fd_file->f_path); + ret = 0; + } + spin_unlock(&files->file_lock); + put_files_struct(files); + } + + return ret; } static struct dentry * @@ -245,22 +309,6 @@ out_no_task: return retval; } -static ssize_t proc_fdinfo_read(struct file *file, char __user *buf, - size_t len, loff_t *ppos) -{ - char tmp[PROC_FDINFO_MAX]; - int err = proc_fd_info(file->f_path.dentry->d_inode, NULL, tmp); - if (!err) - err = simple_read_from_buffer(buf, len, ppos, tmp, strlen(tmp)); - return err; -} - -static const struct file_operations proc_fdinfo_file_operations = { - .open = nonseekable_open, - .read = proc_fdinfo_read, - .llseek = no_llseek, -}; - static int proc_readfd(struct file *filp, void *dirent, filldir_t filldir) { return proc_readfd_common(filp, dirent, filldir, proc_fd_instantiate);