fs/proc: calculate /proc/* and /proc/*/task/* nlink at init time

Runtime nlink calculation works but meh.  I don't know how to do it at
compile time, but I know how to do it at init time.

Shift "2+" part into init time as a bonus.

Link: http://lkml.kernel.org/r/20161122195549.GB29812@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 04a5fcad4c341aeefe9491b5bade96e24bb56581..9b99df4893a49489dd8975e3510cdb7045648e24 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -104,6 +104,9 @@
  *     in /proc for a task before it execs a suid executable.
  */
 
+static u8 nlink_tid;
+static u8 nlink_tgid;
+
 struct pid_entry {
        const char *name;
        unsigned int len;
@@ -139,13 +142,13 @@ struct pid_entry {
  * Count the number of hardlinks for the pid_entry table, excluding the .
  * and .. links.
  */
-static unsigned int pid_entry_count_dirs(const struct pid_entry *entries,
+static unsigned int __init pid_entry_nlink(const struct pid_entry *entries,
        unsigned int n)
 {
        unsigned int i;
        unsigned int count;
 
-       count = 0;
+       count = 2;
        for (i = 0; i < n; ++i) {
                if (S_ISDIR(entries[i].mode))
                        ++count;
@@ -3068,8 +3071,7 @@ static int proc_pid_instantiate(struct inode *dir,
        inode->i_fop = &proc_tgid_base_operations;
        inode->i_flags|=S_IMMUTABLE;
 
-       set_nlink(inode, 2 + pid_entry_count_dirs(tgid_base_stuff,
-                                                 ARRAY_SIZE(tgid_base_stuff)));
+       set_nlink(inode, nlink_tgid);
 
        d_set_d_op(dentry, &pid_dentry_operations);
 
@@ -3361,8 +3363,7 @@ static int proc_task_instantiate(struct inode *dir,
        inode->i_fop = &proc_tid_base_operations;
        inode->i_flags|=S_IMMUTABLE;
 
-       set_nlink(inode, 2 + pid_entry_count_dirs(tid_base_stuff,
-                                                 ARRAY_SIZE(tid_base_stuff)));
+       set_nlink(inode, nlink_tid);
 
        d_set_d_op(dentry, &pid_dentry_operations);
 
@@ -3552,3 +3553,9 @@ static const struct file_operations proc_task_operations = {
        .iterate_shared = proc_task_readdir,
        .llseek         = generic_file_llseek,
 };
+
+void __init set_proc_pid_nlink(void)
+{
+       nlink_tid = pid_entry_nlink(tid_base_stuff, ARRAY_SIZE(tid_base_stuff));
+       nlink_tgid = pid_entry_nlink(tgid_base_stuff, ARRAY_SIZE(tgid_base_stuff));
+}

diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index 153db5f85b479ccd00c6e1af2985eccd4a18c53c..bbba5d22aada1027c92bf459f9bf3d6c608072d7 100644 (file)
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -211,6 +211,7 @@ extern const struct inode_operations proc_link_inode_operations;
 extern const struct inode_operations proc_pid_link_inode_operations;
 
 extern void proc_init_inodecache(void);
+void set_proc_pid_nlink(void);
 extern struct inode *proc_get_inode(struct super_block *, struct proc_dir_entry *);
 extern int proc_fill_super(struct super_block *, void *data, int flags);
 extern void proc_entry_rundown(struct proc_dir_entry *);

diff --git a/fs/proc/root.c b/fs/proc/root.c
index 8d3e484055a6b3529982135289d693decc4dcb3c..4bd0373576b5362a51051ec581a454095b76e140 100644 (file)
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -122,6 +122,7 @@ void __init proc_root_init(void)
        int err;
 
        proc_init_inodecache();
+       set_proc_pid_nlink();
        err = register_filesystem(&proc_fs_type);
        if (err)
                return;