[PATCH 10/23] proc: Fix the link count for /proc/<pid>/task

[Eric W. Biederman]

Use getattr to get an accurate link count when needed.  This is cheaper
and more accurate than trying to derive it by walking the thread list
of a process.

Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>


---

 fs/proc/base.c |   21 +++++++++++++++++++--
 1 files changed, 19 insertions(+), 2 deletions(-)

eec5c7327c53b862025a595985a72fa01509c5e4
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 81c2f2a..1a39258 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1466,6 +1466,7 @@ out:
 
 static int proc_task_readdir(struct file * filp, void * dirent, filldir_t filldir);
 static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd);
+static int proc_task_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat);
 
 static struct file_operations proc_fd_operations = {
 	.read		= generic_read_dir,
@@ -1486,6 +1487,7 @@ static struct inode_operations proc_fd_i
 
 static struct inode_operations proc_task_inode_operations = {
 	.lookup		= proc_task_lookup,
+	.getattr	= proc_task_getattr,
 };
 
 #ifdef CONFIG_SECURITY
@@ -1592,7 +1594,7 @@ static struct dentry *proc_pident_lookup
 	 */
 	switch(p->type) {
 		case PROC_TGID_TASK:
-			inode->i_nlink = 2 + get_tid_list(2, NULL, dir);
+			inode->i_nlink = 2;
 			inode->i_op = &proc_task_inode_operations;
 			inode->i_fop = &proc_task_operations;
 			break;
@@ -2189,7 +2191,6 @@ static int proc_task_readdir(struct file
 	}
 
 	nr_tids = get_tid_list(pos, tid_array, inode);
-	inode->i_nlink = pos + nr_tids;
 
 	for (i = 0; i < nr_tids; i++) {
 		unsigned long j = PROC_NUMBUF;
@@ -2209,3 +2210,19 @@ out:
 	filp->f_pos = pos;
 	return retval;
 }
+
+static int proc_task_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
+{
+	struct inode *inode = dentry->d_inode;
+	struct task_struct *p = proc_task(inode);
+	generic_fillattr(inode, stat);
+
+	if (pid_alive(p)) {
+		task_lock(p);
+		if (p->signal)
+			stat->nlink += atomic_read(&p->signal->count);
+		task_unlock(p);
+	}
+		
+	return 0;
+}
-- 
1.2.2.g709a

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