Replace pid_t in autofs with struct pid reference

Make autofs 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.
	- Fix Cedric's comments: retain old prototype of parse_options()
	  and move necessary change to its caller.

Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: containers@lists.osdl.org
Acked-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 22 insertions, 8 deletions

diff --git a/fs/autofs/autofs_i.h b/fs/autofs/autofs_i.h
index 4ef544434b51..8b4cca3c4705 100644
--- a/fs/autofs/autofs_i.h
+++ b/fs/autofs/autofs_i.h
@@ -101,7 +101,7 @@ struct autofs_symlink {
 struct autofs_sb_info {
         u32 magic;
         struct file *pipe;
-        pid_t oz_pgrp;
+        struct pid *oz_pgrp;
         int catatonic;
         struct super_block *sb;
         unsigned long exp_timeout;
@@ -122,7 +122,7 @@ static inline struct autofs_sb_info *autofs_sbi(struct super_block *sb)
    filesystem without "magic".) */
 
 static inline int autofs_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;
 }
 
 /* Hash operations */
diff --git a/fs/autofs/inode.c b/fs/autofs/inode.c
index d8315e61731e..e7204d71acc9 100644
--- a/fs/autofs/inode.c
+++ b/fs/autofs/inode.c
@@ -37,6 +37,8 @@ void autofs_kill_sb(struct super_block *sb)
         if (!sbi->catatonic)
                 autofs_catatonic_mode(sbi); /* Free wait queues, close pipe */
 
+        put_pid(sbi->oz_pgrp);
+
         autofs_hash_nuke(sbi);
         for (n = 0; n < AUTOFS_MAX_SYMLINKS; n++) {
                 if (test_bit(n, sbi->symlink_bitmap))
@@ -139,6 +141,7 @@ int autofs_fill_super(struct super_block *s, void *data, int silent)
         int pipefd;
         struct autofs_sb_info *sbi;
         int minproto, maxproto;
+        pid_t pgid;
 
         sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
         if (!sbi)
@@ -150,7 +153,6 @@ int autofs_fill_super(struct super_block *s, void *data, int silent)
         sbi->pipe = NULL;
         sbi->catatonic = 1;
         sbi->exp_timeout = 0;
-        sbi->oz_pgrp = process_group(current);
         autofs_initialize_hash(&sbi->dirhash);
         sbi->queues = NULL;
         memset(sbi->symlink_bitmap, 0, sizeof(long)*AUTOFS_SYMLINK_BITMAP_LEN);
@@ -171,7 +173,7 @@ int autofs_fill_super(struct super_block *s, void *data, int silent)
 
         /* Can this call block?  - WTF cares? s is locked. */
         if (parse_options(data, &pipefd, &root_inode->i_uid,
-                                &root_inode->i_gid, &sbi->oz_pgrp, &minproto,
+                                &root_inode->i_gid, &pgid, &minproto,
                                 &maxproto)) {
                 printk("autofs: called with bogus options\n");
                 goto fail_dput;
@@ -184,13 +186,21 @@ int autofs_fill_super(struct super_block *s, void *data, int silent)
                 goto fail_dput;
         }
 
-        DPRINTK(("autofs: pipe fd = %d, pgrp = %u\n", pipefd, sbi->oz_pgrp));
+        DPRINTK(("autofs: pipe fd = %d, pgrp = %u\n", 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;
         sbi->pipe = pipe;
@@ -205,6 +215,8 @@ int autofs_fill_super(struct super_block *s, void *data, int silent)
 fail_fput:
         printk("autofs: pipe file descriptor does not contain proper ops\n");
         fput(pipe);
+fail_put_pid:
+        put_pid(sbi->oz_pgrp);
 fail_dput:
         dput(root);
         goto fail_free;
diff --git a/fs/autofs/root.c b/fs/autofs/root.c
index 6fa04dd6d167..c1489533277a 100644
--- a/fs/autofs/root.c
+++ b/fs/autofs/root.c
@@ -213,8 +213,10 @@ static struct dentry *autofs_root_lookup(struct inode *dir, struct dentry *dentr
         sbi = autofs_sbi(dir->i_sb);
 
         oz_mode = autofs_oz_mode(sbi);
-        DPRINTK(("autofs_lookup: pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d\n",
-                 current->pid, process_group(current), sbi->catatonic, oz_mode));
+        DPRINTK(("autofs_lookup: pid = %u, pgrp = %u, catatonic = %d, "
+                                "oz_mode = %d\n", pid_nr(task_pid(current)),
+                                process_group(current), sbi->catatonic,
+                                oz_mode));
 
         /*
          * Mark the dentry incomplete, but add it. This is needed so