[Devel] [RFC V1] Replace pid_t in autofs4 with struct pid reference.
Daniel Lezcano
daniel.lezcano at free.fr
Tue Oct 5 10:28:16 PDT 2010
I resurect and refreshed this old patch from
https://lists.linux-foundation.org/pipermail/containers/2007-February/003726.html
This patch makes automount to work within a container.
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:
V1:
- fixed pgrp option in parse_options
- used get_task_pid(current, PIDTYPE_PGID) instead of task_pgrp
- fixed how is passed the 'pgrp' argument autofs4_fill_super
- fixed bad pid conversion, was pid_vnr not pid_nr in autofs4_wait
V0:
- Refreshed against linux-next (added dev-ioctl.c)
- 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>
Signed-off-by: Daniel Lezcano <daniel.lezcano at free.fr>
Cc: Ian Kent <raven at themaw.net>
Cc: Cedric Le Goater <clg at fr.ibm.com>
Cc: Dave Hansen <haveblue at us.ibm.com>
Cc: Serge E. Hallyn <serge.hallyn at canonical.com>
Cc: Eric Biederman <ebiederm at xmission.com>
Cc: Helmut Lichtenberg <heli at tzv.fal.de>
---
fs/autofs4/autofs_i.h | 31 +++++++++++++++++--------------
fs/autofs4/dev-ioctl.c | 32 +++++++++++++++++++-------------
fs/autofs4/inode.c | 35 +++++++++++++++++++++++++----------
fs/autofs4/root.c | 3 ++-
fs/autofs4/waitq.c | 4 ++--
5 files changed, 65 insertions(+), 40 deletions(-)
diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
index 3d283ab..bf2f9b1 100644
--- a/fs/autofs4/autofs_i.h
+++ b/fs/autofs4/autofs_i.h
@@ -39,25 +39,25 @@
/* #define DEBUG */
#ifdef DEBUG
-#define DPRINTK(fmt, args...) \
-do { \
- printk(KERN_DEBUG "pid %d: %s: " fmt "\n", \
- current->pid, __func__, ##args); \
+#define DPRINTK(fmt, args...) \
+do { \
+ printk(KERN_DEBUG "pid %d: %s: " fmt "\n", \
+ pid_nr(task_pid(current)), __func__, ##args); \
} while (0)
#else
#define DPRINTK(fmt, args...) do {} while (0)
#endif
-#define AUTOFS_WARN(fmt, args...) \
-do { \
- printk(KERN_WARNING "pid %d: %s: " fmt "\n", \
- current->pid, __func__, ##args); \
+#define AUTOFS_WARN(fmt, args...) \
+do { \
+ printk(KERN_WARNING "pid %d: %s: " fmt "\n", \
+ pid_nr(task_pid(current)), __func__, ##args); \
} while (0)
-#define AUTOFS_ERROR(fmt, args...) \
-do { \
- printk(KERN_ERR "pid %d: %s: " fmt "\n", \
- current->pid, __func__, ##args); \
+#define AUTOFS_ERROR(fmt, args...) \
+do { \
+ printk(KERN_ERR "pid %d: %s: " fmt "\n", \
+ pid_nr(task_pid(current)), __func__, ##args); \
} while (0)
/* Unified info structure. This is pointed to by both the dentry and
@@ -122,7 +122,7 @@ 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;
@@ -156,7 +156,10 @@ static inline struct autofs_info *autofs4_dentry_ino(struct dentry *dentry)
filesystem without "magic".) */
static inline int autofs4_oz_mode(struct autofs_sb_info *sbi) {
- return sbi->catatonic || task_pgrp_nr(current) == sbi->oz_pgrp;
+ struct pid *pgrp = get_task_pid(current, PIDTYPE_PGID);
+ bool oz_mode = sbi->catatonic || sbi->oz_pgrp == pgrp;
+ put_pid(pgrp);
+ return oz_mode;
}
/* Does a dentry have some pending activity? */
diff --git a/fs/autofs4/dev-ioctl.c b/fs/autofs4/dev-ioctl.c
index eff9a41..7db3b73 100644
--- a/fs/autofs4/dev-ioctl.c
+++ b/fs/autofs4/dev-ioctl.c
@@ -360,6 +360,7 @@ static int autofs_dev_ioctl_setpipefd(struct file *fp,
{
int pipefd;
int err = 0;
+ struct file *pipe;
if (param->setpipefd.pipefd == -1)
return -EINVAL;
@@ -368,22 +369,27 @@ static int autofs_dev_ioctl_setpipefd(struct file *fp,
mutex_lock(&sbi->wq_mutex);
if (!sbi->catatonic) {
- mutex_unlock(&sbi->wq_mutex);
- return -EBUSY;
- } else {
- struct file *pipe = fget(pipefd);
- if (!pipe->f_op || !pipe->f_op->write) {
- err = -EPIPE;
- fput(pipe);
- goto out;
- }
- sbi->oz_pgrp = task_pgrp_nr(current);
- sbi->pipefd = pipefd;
- sbi->pipe = pipe;
- sbi->catatonic = 0;
+ err = -EBUSY;
+ goto out;
+ }
+
+ pipe = fget(pipefd);
+ if (!pipe->f_op || !pipe->f_op->write) {
+ err = -EPIPE;
+ fput(pipe);
+ goto out;
}
+
+ sbi->pipefd = pipefd;
+ sbi->pipe = pipe;
+ sbi->catatonic = 0;
out:
mutex_unlock(&sbi->wq_mutex);
+ if (!err) {
+ put_pid(sbi->oz_pgrp);
+ sbi->oz_pgrp = get_task_pid(current, PIDTYPE_PGID);
+ }
+
return err;
}
diff --git a/fs/autofs4/inode.c b/fs/autofs4/inode.c
index 821b2b9..01d1515 100644
--- a/fs/autofs4/inode.c
+++ b/fs/autofs4/inode.c
@@ -112,6 +112,7 @@ void autofs4_kill_sb(struct super_block *sb)
/* Free wait queues, close pipe */
autofs4_catatonic_mode(sbi);
+ put_pid(sbi->oz_pgrp);
sb->s_fs_info = NULL;
kfree(sbi);
@@ -133,7 +134,7 @@ static int autofs4_show_options(struct seq_file *m, struct vfsmount *mnt)
seq_printf(m, ",uid=%u", root_inode->i_uid);
if (root_inode->i_gid != 0)
seq_printf(m, ",gid=%u", root_inode->i_gid);
- seq_printf(m, ",pgrp=%d", sbi->oz_pgrp);
+ seq_printf(m, ",pgrp=%d", pid_vnr(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);
@@ -170,15 +171,16 @@ static const match_table_t tokens = {
};
static int parse_options(char *options, int *pipefd, uid_t *uid, gid_t *gid,
- pid_t *pgrp, unsigned int *type, int *minproto, int *maxproto)
+ struct pid **oz_pgrp, unsigned int *type,
+ int *minproto, int *maxproto)
{
char *p;
substring_t args[MAX_OPT_ARGS];
+ struct pid *pgrp;
int option;
*uid = current_uid();
*gid = current_gid();
- *pgrp = task_pgrp_nr(current);
*minproto = AUTOFS_MIN_PROTO_VERSION;
*maxproto = AUTOFS_MAX_PROTO_VERSION;
@@ -212,7 +214,17 @@ static int parse_options(char *options, int *pipefd, uid_t *uid, gid_t *gid,
case Opt_pgrp:
if (match_int(args, &option))
return 1;
- *pgrp = option;
+
+ rcu_read_lock();
+ pgrp = find_vpid(option);
+ if (pgrp) {
+ put_pid(*oz_pgrp);
+ *oz_pgrp = get_pid(pgrp);
+ }
+ rcu_read_unlock();
+
+ if (!pgrp)
+ return 1;
break;
case Opt_minproto:
if (match_int(args, &option))
@@ -275,7 +287,7 @@ int autofs4_fill_super(struct super_block *s, void *data, int silent)
sbi->pipe = NULL;
sbi->catatonic = 1;
sbi->exp_timeout = 0;
- sbi->oz_pgrp = task_pgrp_nr(current);
+ sbi->oz_pgrp = get_task_pid(current, PIDTYPE_PGID);
sbi->sb = s;
sbi->version = 0;
sbi->sub_version = 0;
@@ -299,7 +311,8 @@ int autofs4_fill_super(struct super_block *s, void *data, int silent)
*/
ino = autofs4_mkroot(sbi);
if (!ino)
- goto fail_free;
+ goto fail_put_pid;
+
root_inode = autofs4_get_inode(s, ino);
if (!root_inode)
goto fail_ino;
@@ -342,9 +355,9 @@ int autofs4_fill_super(struct super_block *s, void *data, int silent)
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, pid_nr(sbi->oz_pgrp));
+
pipe = fget(pipefd);
-
if (!pipe) {
printk("autofs: could not open pipe file descriptor\n");
goto fail_dput;
@@ -370,13 +383,15 @@ fail_fput:
/* fall through */
fail_dput:
dput(root);
- goto fail_free;
+ goto fail_put_pid;
fail_iput:
printk("autofs: get root dentry failed\n");
iput(root_inode);
fail_ino:
kfree(ino);
-fail_free:
+fail_put_pid:
+ put_pid(sbi->oz_pgrp);
+
kfree(sbi);
s->s_fs_info = NULL;
fail_unlock:
diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index d5c1401..45c6bc2 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -541,7 +541,8 @@ static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, s
oz_mode = autofs4_oz_mode(sbi);
DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
- current->pid, task_pgrp_nr(current), sbi->catatonic, oz_mode);
+ pid_nr(task_pid(current)), task_pgrp_nr(current),
+ sbi->catatonic, oz_mode);
active = autofs4_lookup_active(dentry);
if (active) {
diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
index 2341375..e3ce7fe 100644
--- a/fs/autofs4/waitq.c
+++ b/fs/autofs4/waitq.c
@@ -387,8 +387,8 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
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_vnr(task_pid(current));
+ wq->tgid = pid_vnr(task_tgid(current));
wq->status = -EINTR; /* Status return if interrupted */
wq->wait_ctr = 2;
mutex_unlock(&sbi->wq_mutex);
--
1.7.0.4
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