From e656d8a6f7fdf7612d2f5771f0ddfca9487f59d9 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Sat, 10 Jul 2010 14:52:49 -0700 Subject: [PATCH] procfs: Use the proc generic infrastructure for proc/self. I had visions at one point of splitting proc into two filesystems. If that had happened proc/self being the the part of proc that actually deals with pids would have been a nice cleanup. As it is proc/self requires a lot of unnecessary infrastructure for a single file. The only user visible change is that a mounted /proc for a pid namespace that is dead now shows a broken proc symlink, instead of being completely invisible. I don't think anyone will notice or care. Signed-off-by: Eric W. Biederman --- fs/proc/Makefile | 1 + fs/proc/base.c | 154 +-------------------------------------------- fs/proc/internal.h | 1 + fs/proc/root.c | 1 + fs/proc/self.c | 59 +++++++++++++++++ 5 files changed, 64 insertions(+), 152 deletions(-) create mode 100644 fs/proc/self.c diff --git a/fs/proc/Makefile b/fs/proc/Makefile index 99349efbbc2b..981b05601931 100644 --- a/fs/proc/Makefile +++ b/fs/proc/Makefile @@ -21,6 +21,7 @@ proc-y += uptime.o proc-y += version.o proc-y += softirqs.o proc-y += namespaces.o +proc-y += self.o proc-$(CONFIG_PROC_SYSCTL) += proc_sysctl.o proc-$(CONFIG_NET) += proc_net.o proc-$(CONFIG_PROC_KCORE) += kcore.o diff --git a/fs/proc/base.c b/fs/proc/base.c index 144a96732dd7..cbe454e94af8 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2237,146 +2237,6 @@ static const struct file_operations proc_coredump_filter_operations = { }; #endif -/* - * /proc/self: - */ -static int proc_self_readlink(struct dentry *dentry, char __user *buffer, - int buflen) -{ - struct pid_namespace *ns = dentry->d_sb->s_fs_info; - pid_t tgid = task_tgid_nr_ns(current, ns); - char tmp[PROC_NUMBUF]; - if (!tgid) - return -ENOENT; - sprintf(tmp, "%d", tgid); - return vfs_readlink(dentry,buffer,buflen,tmp); -} - -static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd) -{ - struct pid_namespace *ns = dentry->d_sb->s_fs_info; - pid_t tgid = task_tgid_nr_ns(current, ns); - char *name = ERR_PTR(-ENOENT); - if (tgid) { - /* 11 for max length of signed int in decimal + NULL term */ - name = kmalloc(12, GFP_KERNEL); - if (!name) - name = ERR_PTR(-ENOMEM); - else - sprintf(name, "%d", tgid); - } - nd_set_link(nd, name); - return NULL; -} - -static void proc_self_put_link(struct dentry *dentry, struct nameidata *nd, - void *cookie) -{ - char *s = nd_get_link(nd); - if (!IS_ERR(s)) - kfree(s); -} - -static const struct inode_operations proc_self_inode_operations = { - .readlink = proc_self_readlink, - .follow_link = proc_self_follow_link, - .put_link = proc_self_put_link, -}; - -/* - * proc base - * - * These are the directory entries in the root directory of /proc - * that properly belong to the /proc filesystem, as they describe - * describe something that is process related. - */ -static const struct pid_entry proc_base_stuff[] = { - NOD("self", S_IFLNK|S_IRWXUGO, - &proc_self_inode_operations, NULL, {}), -}; - -static struct dentry *proc_base_instantiate(struct inode *dir, - struct dentry *dentry, struct task_struct *task, const void *ptr) -{ - const struct pid_entry *p = ptr; - struct inode *inode; - struct proc_inode *ei; - struct dentry *error; - - /* Allocate the inode */ - error = ERR_PTR(-ENOMEM); - inode = new_inode(dir->i_sb); - if (!inode) - goto out; - - /* Initialize the inode */ - ei = PROC_I(inode); - inode->i_ino = get_next_ino(); - inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; - - /* - * grab the reference to the task. - */ - ei->pid = get_task_pid(task, PIDTYPE_PID); - if (!ei->pid) - goto out_iput; - - inode->i_mode = p->mode; - if (S_ISDIR(inode->i_mode)) - set_nlink(inode, 2); - if (S_ISLNK(inode->i_mode)) - inode->i_size = 64; - if (p->iop) - inode->i_op = p->iop; - if (p->fop) - inode->i_fop = p->fop; - ei->op = p->op; - d_add(dentry, inode); - error = NULL; -out: - return error; -out_iput: - iput(inode); - goto out; -} - -static struct dentry *proc_base_lookup(struct inode *dir, struct dentry *dentry) -{ - struct dentry *error; - struct task_struct *task = get_proc_task(dir); - const struct pid_entry *p, *last; - - error = ERR_PTR(-ENOENT); - - if (!task) - goto out_no_task; - - /* Lookup the directory entry */ - last = &proc_base_stuff[ARRAY_SIZE(proc_base_stuff) - 1]; - for (p = proc_base_stuff; p <= last; p++) { - if (p->len != dentry->d_name.len) - continue; - if (!memcmp(dentry->d_name.name, p->name, p->len)) - break; - } - if (p > last) - goto out; - - error = proc_base_instantiate(dir, dentry, task, p); - -out: - put_task_struct(task); -out_no_task: - return error; -} - -static int proc_base_fill_cache(struct file *filp, void *dirent, - filldir_t filldir, struct task_struct *task, const struct pid_entry *p) -{ - return proc_fill_cache(filp, dirent, filldir, p->name, p->len, - proc_base_instantiate, task, p); -} - #ifdef CONFIG_TASK_IO_ACCOUNTING static int do_io_accounting(struct task_struct *task, char *buffer, int whole) { @@ -2767,15 +2627,11 @@ static struct dentry *proc_pid_instantiate(struct inode *dir, struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags) { - struct dentry *result; + struct dentry *result = NULL; struct task_struct *task; unsigned tgid; struct pid_namespace *ns; - result = proc_base_lookup(dir, dentry); - if (!IS_ERR(result) || PTR_ERR(result) != -ENOENT) - goto out; - tgid = name_to_int(dentry); if (tgid == ~0U) goto out; @@ -2838,7 +2694,7 @@ static struct tgid_iter next_tgid(struct pid_namespace *ns, struct tgid_iter ite return iter; } -#define TGID_OFFSET (FIRST_PROCESS_ENTRY + ARRAY_SIZE(proc_base_stuff)) +#define TGID_OFFSET (FIRST_PROCESS_ENTRY) static int proc_pid_fill_cache(struct file *filp, void *dirent, filldir_t filldir, struct tgid_iter iter) @@ -2872,12 +2728,6 @@ int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir) if (!reaper) goto out_no_task; - for (; nr < ARRAY_SIZE(proc_base_stuff); filp->f_pos++, nr++) { - const struct pid_entry *p = &proc_base_stuff[nr]; - if (proc_base_fill_cache(filp, dirent, filldir, reaper, p) < 0) - goto out; - } - ns = filp->f_dentry->d_sb->s_fs_info; iter.task = NULL; iter.tgid = filp->f_pos - TGID_OFFSET; diff --git a/fs/proc/internal.h b/fs/proc/internal.h index 43973b084abf..252544c05207 100644 --- a/fs/proc/internal.h +++ b/fs/proc/internal.h @@ -15,6 +15,7 @@ struct ctl_table_header; struct mempolicy; extern struct proc_dir_entry proc_root; +extern void proc_self_init(void); #ifdef CONFIG_PROC_SYSCTL extern int proc_sys_init(void); extern void sysctl_head_put(struct ctl_table_header *head); diff --git a/fs/proc/root.c b/fs/proc/root.c index 9889a92d2e01..5da984959edc 100644 --- a/fs/proc/root.c +++ b/fs/proc/root.c @@ -169,6 +169,7 @@ void __init proc_root_init(void) return; } + proc_self_init(); proc_symlink("mounts", NULL, "self/mounts"); proc_net_init(); diff --git a/fs/proc/self.c b/fs/proc/self.c new file mode 100644 index 000000000000..aa5cc3bff140 --- /dev/null +++ b/fs/proc/self.c @@ -0,0 +1,59 @@ +#include +#include +#include + +/* + * /proc/self: + */ +static int proc_self_readlink(struct dentry *dentry, char __user *buffer, + int buflen) +{ + struct pid_namespace *ns = dentry->d_sb->s_fs_info; + pid_t tgid = task_tgid_nr_ns(current, ns); + char tmp[PROC_NUMBUF]; + if (!tgid) + return -ENOENT; + sprintf(tmp, "%d", tgid); + return vfs_readlink(dentry,buffer,buflen,tmp); +} + +static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd) +{ + struct pid_namespace *ns = dentry->d_sb->s_fs_info; + pid_t tgid = task_tgid_nr_ns(current, ns); + char *name = ERR_PTR(-ENOENT); + if (tgid) { + /* 11 for max length of signed int in decimal + NULL term */ + name = kmalloc(12, GFP_KERNEL); + if (!name) + name = ERR_PTR(-ENOMEM); + else + sprintf(name, "%d", tgid); + } + nd_set_link(nd, name); + return NULL; +} + +static void proc_self_put_link(struct dentry *dentry, struct nameidata *nd, + void *cookie) +{ + char *s = nd_get_link(nd); + if (!IS_ERR(s)) + kfree(s); +} + +static const struct inode_operations proc_self_inode_operations = { + .readlink = proc_self_readlink, + .follow_link = proc_self_follow_link, + .put_link = proc_self_put_link, +}; + +void __init proc_self_init(void) +{ + struct proc_dir_entry *proc_self_symlink; + mode_t mode; + + mode = S_IFLNK | S_IRWXUGO; + proc_self_symlink = proc_create("self", mode, NULL, NULL ); + proc_self_symlink->proc_iops = &proc_self_inode_operations; +} -- 2.45.2