[Devel] Re: [PATCH 2/2] Replace pid_t in autofs with struct pid reference

Cedric Le Goater clg at fr.ibm.com
Fri Mar 16 07:44:31 PDT 2007 

> How about you send over the autofs4 bit and I'll have a look (the autofs
> patch looked fine). That would save me a bit of time and if there are
> any changes needed I can send an updated patch for you guys to review. I
> don't think autofs4 uses pids differently, in principle, than autofs so
> it "should" be straight forward.

Here's the latest.

thanks,

C.

From: Sukadev Bhattiprolu <sukadev at us.ibm.com>

Subject: Replace pid_t in autofs4 with struct pid reference.

Make autofs4 container-friendly by caching struct pid reference rather
than pid_t and using pid_nr() to retreive a task's pid_t.

ChangeLog:
	- Fix Eric Biederman's comments - Use find_get_pid() to hold a
	  reference to oz_pgrp and release while unmounting; separate out
	  changes to autofs and autofs4.
	- Also rollback my earlier change to autofs_wait_queue (pid and tgid
	  in the wait queue are just used to write to a userspace daemon's
	  pipe).
        - Fix Cedric's comments: retain old prototype of parse_options()
          and move necessary change to its caller.

Signed-off-by: Sukadev Bhattiprolu <sukadev at us.ibm.com>
Cc: Cedric Le Goater <clg at fr.ibm.com>
Cc: Dave Hansen <haveblue at us.ibm.com>
Cc: Serge Hallyn <serue at us.ibm.com>
Cc: Eric Biederman <ebiederm at xmission.com>
Cc: containers at lists.osdl.org

---
 fs/autofs4/autofs_i.h |    6 +++---
 fs/autofs4/inode.c    |   21 ++++++++++++++++-----
 fs/autofs4/root.c     |    3 ++-
 fs/autofs4/waitq.c    |    4 ++--
 4 files changed, 23 insertions(+), 11 deletions(-)

Index: 2.6.20/fs/autofs4/autofs_i.h
===================================================================
--- 2.6.20.orig/fs/autofs4/autofs_i.h
+++ 2.6.20/fs/autofs4/autofs_i.h
@@ -35,7 +35,7 @@
 /* #define DEBUG */
 
 #ifdef DEBUG
-#define DPRINTK(fmt,args...) do { printk(KERN_DEBUG "pid %d: %s: " fmt "\n" , current->pid , __FUNCTION__ , ##args); } while(0)
+#define DPRINTK(fmt,args...) do { printk(KERN_DEBUG "pid %d: %s: " fmt "\n" , pid_nr(task_pid(current)), __FUNCTION__ , ##args); } while(0)
 #else
 #define DPRINTK(fmt,args...) do {} while(0)
 #endif
@@ -96,7 +96,7 @@ struct autofs_sb_info {
 	u32 magic;
 	int pipefd;
 	struct file *pipe;
-	pid_t oz_pgrp;
+	struct pid *oz_pgrp;
 	int catatonic;
 	int version;
 	int sub_version;
@@ -127,7 +127,7 @@ static inline struct autofs_info *autofs
    filesystem without "magic".) */
 
 static inline int autofs4_oz_mode(struct autofs_sb_info *sbi) {
-	return sbi->catatonic || process_group(current) == sbi->oz_pgrp;
+	return sbi->catatonic || task_pgrp(current) == sbi->oz_pgrp;
 }
 
 /* Does a dentry have some pending activity? */
Index: 2.6.20/fs/autofs4/inode.c
===================================================================
--- 2.6.20.orig/fs/autofs4/inode.c
+++ 2.6.20/fs/autofs4/inode.c
@@ -163,6 +163,8 @@ void autofs4_kill_sb(struct super_block 
 	if ( !sbi->catatonic )
 		autofs4_catatonic_mode(sbi); /* Free wait queues, close pipe */
 
+	put_pid(sbi->oz_pgrp);
+
 	/* Clean up and release dangling references */
 	autofs4_force_release(sbi);
 
@@ -181,7 +183,7 @@ static int autofs4_show_options(struct s
 		return 0;
 
 	seq_printf(m, ",fd=%d", sbi->pipefd);
-	seq_printf(m, ",pgrp=%d", sbi->oz_pgrp);
+	seq_printf(m, ",pgrp=%d", pid_nr(sbi->oz_pgrp));
 	seq_printf(m, ",timeout=%lu", sbi->exp_timeout/HZ);
 	seq_printf(m, ",minproto=%d", sbi->min_proto);
 	seq_printf(m, ",maxproto=%d", sbi->max_proto);
@@ -311,6 +313,7 @@ int autofs4_fill_super(struct super_bloc
 	int pipefd;
 	struct autofs_sb_info *sbi;
 	struct autofs_info *ino;
+	pid_t pgid;
 
 	sbi = kmalloc(sizeof(*sbi), GFP_KERNEL);
 	if (!sbi)
@@ -325,7 +328,6 @@ int autofs4_fill_super(struct super_bloc
 	sbi->pipe = NULL;
 	sbi->catatonic = 1;
 	sbi->exp_timeout = 0;
-	sbi->oz_pgrp = process_group(current);
 	sbi->sb = s;
 	sbi->version = 0;
 	sbi->sub_version = 0;
@@ -361,7 +363,7 @@ int autofs4_fill_super(struct super_bloc
 
 	/* Can this call block? */
 	if (parse_options(data, &pipefd, &root_inode->i_uid, &root_inode->i_gid,
-				&sbi->oz_pgrp, &sbi->type, &sbi->min_proto,
+				&pgid, &sbi->type, &sbi->min_proto,
 				&sbi->max_proto)) {
 		printk("autofs: called with bogus options\n");
 		goto fail_dput;
@@ -389,12 +391,19 @@ int autofs4_fill_super(struct super_bloc
 		sbi->version = sbi->max_proto;
 	sbi->sub_version = AUTOFS_PROTO_SUBVERSION;
 
-	DPRINTK("pipe fd = %d, pgrp = %u", pipefd, sbi->oz_pgrp);
+	DPRINTK("pipe fd = %d, pgrp = %u", pipefd, pgid);
+
+	sbi->oz_pgrp = find_get_pid(pgid);
+	if (!sbi->oz_pgrp) {
+		printk("autofs: could not find process group %d\n", pgid);
+		goto fail_dput;
+	}
+
 	pipe = fget(pipefd);
 	
 	if (!pipe) {
 		printk("autofs: could not open pipe file descriptor\n");
-		goto fail_dput;
+		goto fail_put_pid;
 	}
 	if (!pipe->f_op || !pipe->f_op->write)
 		goto fail_fput;
@@ -415,6 +424,8 @@ fail_fput:
 	printk("autofs: pipe file descriptor does not contain proper ops\n");
 	fput(pipe);
 	/* fall through */
+fail_put_pid:
+	put_pid(sbi->oz_pgrp);
 fail_dput:
 	dput(root);
 	goto fail_free;
Index: 2.6.20/fs/autofs4/root.c
===================================================================
--- 2.6.20.orig/fs/autofs4/root.c
+++ 2.6.20/fs/autofs4/root.c
@@ -495,7 +495,8 @@ static struct dentry *autofs4_lookup(str
 	oz_mode = autofs4_oz_mode(sbi);
 
 	DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
-		 current->pid, process_group(current), sbi->catatonic, oz_mode);
+		 pid_nr(task_pid(current)), process_group(current),
+		 sbi->catatonic, oz_mode);
 
 	/*
 	 * Mark the dentry incomplete, but add it. This is needed so
Index: 2.6.20/fs/autofs4/waitq.c
===================================================================
--- 2.6.20.orig/fs/autofs4/waitq.c
+++ 2.6.20/fs/autofs4/waitq.c
@@ -292,8 +292,8 @@ int autofs4_wait(struct autofs_sb_info *
 		wq->ino = autofs4_get_ino(sbi);
 		wq->uid = current->uid;
 		wq->gid = current->gid;
-		wq->pid = current->pid;
-		wq->tgid = current->tgid;
+		wq->pid = pid_nr(task_pid(current));
+		wq->tgid = pid_nr(task_tgid(current));
 		wq->status = -EINTR; /* Status return if interrupted */
 		atomic_set(&wq->wait_ctr, 2);
 		mutex_unlock(&sbi->wq_mutex);
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