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Subject[PATCH 2/2] Replace pid_t in autofs with struct pid reference

From: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Subject: [PATCH 2/2] 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>

---
fs/autofs/autofs_i.h | 4 ++--
fs/autofs/inode.c | 20 ++++++++++++++++----
fs/autofs/root.c | 6 ++++--
3 files changed, 22 insertions(+), 8 deletions(-)
Index: lx26-21-rc3-mm2/fs/autofs/autofs_i.h
===================================================================
--- lx26-21-rc3-mm2.orig/fs/autofs/autofs_i.h 2007-03-12 17:12:05.000000000 -0700
+++ lx26-21-rc3-mm2/fs/autofs/autofs_i.h 2007-03-12 17:18:55.000000000 -0700
@@ -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 *aut
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 */
Index: lx26-21-rc3-mm2/fs/autofs/inode.c
===================================================================
--- lx26-21-rc3-mm2.orig/fs/autofs/inode.c 2007-03-12 17:18:48.000000000 -0700
+++ lx26-21-rc3-mm2/fs/autofs/inode.c 2007-03-12 17:18:55.000000000 -0700
@@ -37,6 +37,8 @@ void autofs_kill_sb(struct super_block *
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
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
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

/* 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
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
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;
Index: lx26-21-rc3-mm2/fs/autofs/root.c
===================================================================
--- lx26-21-rc3-mm2.orig/fs/autofs/root.c 2007-03-12 17:18:48.000000000 -0700
+++ lx26-21-rc3-mm2/fs/autofs/root.c 2007-03-12 17:18:55.000000000 -0700
@@ -213,8 +213,10 @@ static struct dentry *autofs_root_lookup
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
-
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