From b4629fe2f094b719847f31be1ee5ab38300038b2 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Mon, 20 Mar 2006 13:44:12 -0500 Subject: VFS: New /proc file /proc/self/mountstats Create a new file under /proc/self, called mountstats, where mounted file systems can export information (configuration options, performance counters, and so on). Use a mechanism similar to /proc/mounts and s_ops->show_options. This mechanism does not violate namespace security, and is safe to use while other processes are unmounting file systems. Thanks to Mike Waychison for his review and comments. Test-plan: Test concurrent mount/unmount operations while cat'ing /proc/self/mountstats. Signed-off-by: Chuck Lever Signed-off-by: Trond Myklebust --- fs/proc/base.c | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) (limited to 'fs/proc') diff --git a/fs/proc/base.c b/fs/proc/base.c index 20feb7568de..8f1f49ceebe 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -104,6 +104,7 @@ enum pid_directory_inos { PROC_TGID_MAPS, PROC_TGID_NUMA_MAPS, PROC_TGID_MOUNTS, + PROC_TGID_MOUNTSTATS, PROC_TGID_WCHAN, #ifdef CONFIG_MMU PROC_TGID_SMAPS, @@ -144,6 +145,7 @@ enum pid_directory_inos { PROC_TID_MAPS, PROC_TID_NUMA_MAPS, PROC_TID_MOUNTS, + PROC_TID_MOUNTSTATS, PROC_TID_WCHAN, #ifdef CONFIG_MMU PROC_TID_SMAPS, @@ -201,6 +203,7 @@ static struct pid_entry tgid_base_stuff[] = { E(PROC_TGID_ROOT, "root", S_IFLNK|S_IRWXUGO), E(PROC_TGID_EXE, "exe", S_IFLNK|S_IRWXUGO), E(PROC_TGID_MOUNTS, "mounts", S_IFREG|S_IRUGO), + E(PROC_TGID_MOUNTSTATS, "mountstats", S_IFREG|S_IRUSR), #ifdef CONFIG_MMU E(PROC_TGID_SMAPS, "smaps", S_IFREG|S_IRUGO), #endif @@ -732,6 +735,38 @@ static struct file_operations proc_mounts_operations = { .poll = mounts_poll, }; +extern struct seq_operations mountstats_op; +static int mountstats_open(struct inode *inode, struct file *file) +{ + struct task_struct *task = proc_task(inode); + int ret = seq_open(file, &mountstats_op); + + if (!ret) { + struct seq_file *m = file->private_data; + struct namespace *namespace; + task_lock(task); + namespace = task->namespace; + if (namespace) + get_namespace(namespace); + task_unlock(task); + + if (namespace) + m->private = namespace; + else { + seq_release(inode, file); + ret = -EINVAL; + } + } + return ret; +} + +static struct file_operations proc_mountstats_operations = { + .open = mountstats_open, + .read = seq_read, + .llseek = seq_lseek, + .release = mounts_release, +}; + #define PROC_BLOCK_SIZE (3*1024) /* 4K page size but our output routines use some slack for overruns */ static ssize_t proc_info_read(struct file * file, char __user * buf, @@ -1730,6 +1765,10 @@ static struct dentry *proc_pident_lookup(struct inode *dir, inode->i_fop = &proc_smaps_operations; break; #endif + case PROC_TID_MOUNTSTATS: + case PROC_TGID_MOUNTSTATS: + inode->i_fop = &proc_mountstats_operations; + break; #ifdef CONFIG_SECURITY case PROC_TID_ATTR: inode->i_nlink = 2; -- cgit v1.2.3-70-g09d2