kernel/acct.c - LeafOS-Devices/android_kernel_samsung_gta4xl - Gitiles

 /*
  *  linux/kernel/acct.c
  *
  *  BSD Process Accounting for Linux
  *
  *  Author: Marco van Wieringen <mvw@planets.elm.net>
  *
  *  Some code based on ideas and code from:
  *  Thomas K. Dyas <tdyas@eden.rutgers.edu>
  *
  *  This file implements BSD-style process accounting. Whenever any
  *  process exits, an accounting record of type "struct acct" is
  *  written to the file specified with the acct() system call. It is
  *  up to user-level programs to do useful things with the accounting
  *  log. The kernel just provides the raw accounting information.
  *
  * (C) Copyright 1995 - 1997 Marco van Wieringen - ELM Consultancy B.V.
  *
  *  Plugged two leaks. 1) It didn't return acct_file into the free_filps if
  *  the file happened to be read-only. 2) If the accounting was suspended
  *  due to the lack of space it happily allowed to reopen it and completely
  *  lost the old acct_file. 3/10/98, Al Viro.
  *
  *  Now we silently close acct_file on attempt to reopen. Cleaned sys_acct().
  *  XTerms and EMACS are manifestations of pure evil. 21/10/98, AV.
  *
  *  Fixed a nasty interaction with with sys_umount(). If the accointing
  *  was suspeneded we failed to stop it on umount(). Messy.
  *  Another one: remount to readonly didn't stop accounting.
  *	Question: what should we do if we have CAP_SYS_ADMIN but not
  *  CAP_SYS_PACCT? Current code does the following: umount returns -EBUSY
  *  unless we are messing with the root. In that case we are getting a
  *  real mess with do_remount_sb(). 9/11/98, AV.
  *
  *  Fixed a bunch of races (and pair of leaks). Probably not the best way,
  *  but this one obviously doesn't introduce deadlocks. Later. BTW, found
  *  one race (and leak) in BSD implementation.
  *  OK, that's better. ANOTHER race and leak in BSD variant. There always
  *  is one more bug... 10/11/98, AV.
  *
  *	Oh, fsck... Oopsable SMP race in do_process_acct() - we must hold
  * ->mmap_sem to walk the vma list of current->mm. Nasty, since it leaks
  * a struct file opened for write. Fixed. 2/6/2000, AV.
  */

 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/acct.h>
 #include <linux/capability.h>
 #include <linux/file.h>
 #include <linux/tty.h>
 #include <linux/security.h>
 #include <linux/vfs.h>
 #include <linux/jiffies.h>
 #include <linux/times.h>
 #include <linux/syscalls.h>
 #include <linux/mount.h>
 #include <linux/uaccess.h>
 #include <asm/div64.h>
 #include <linux/blkdev.h> /* sector_div */
 #include <linux/pid_namespace.h>

 /*
  * These constants control the amount of freespace that suspend and
  * resume the process accounting system, and the time delay between
  * each check.
  * Turned into sysctl-controllable parameters. AV, 12/11/98
  */

 int acct_parm[3] = {4, 2, 30};
 #define RESUME		(acct_parm[0])	/* >foo% free space - resume */
 #define SUSPEND		(acct_parm[1])	/* <foo% free space - suspend */
 #define ACCT_TIMEOUT	(acct_parm[2])	/* foo second timeout between checks */

 /*
  * External references and all of the globals.
  */
 static void do_acct_process(struct bsd_acct_struct *acct,
 		struct pid_namespace *ns, struct file *);

 /*
  * This structure is used so that all the data protected by lock
  * can be placed in the same cache line as the lock.  This primes
  * the cache line to have the data after getting the lock.
  */
 struct bsd_acct_struct {
 	int			active;
 	unsigned long		needcheck;
 	struct file		*file;
 	struct pid_namespace	*ns;
 	struct list_head	list;
 };

 static DEFINE_SPINLOCK(acct_lock);
 static LIST_HEAD(acct_list);

 /*
  * Check the amount of free space and suspend/resume accordingly.
  */
 static int check_free_space(struct bsd_acct_struct *acct, struct file *file)
 {
 	struct kstatfs sbuf;
 	int res;
 	int act;
 	u64 resume;
 	u64 suspend;

 	spin_lock(&acct_lock);
 	res = acct->active;
 	if (!file || time_is_before_jiffies(acct->needcheck))
 		goto out;
 	spin_unlock(&acct_lock);

 	/* May block */
 	if (vfs_statfs(&file->f_path, &sbuf))
 		return res;
 	suspend = sbuf.f_blocks * SUSPEND;
 	resume = sbuf.f_blocks * RESUME;

 	do_div(suspend, 100);
 	do_div(resume, 100);

 	if (sbuf.f_bavail <= suspend)
 		act = -1;
 	else if (sbuf.f_bavail >= resume)
 		act = 1;
 	else
 		act = 0;

 	/*
 	 * If some joker switched acct->file under us we'ld better be
 	 * silent and _not_ touch anything.
 	 */
 	spin_lock(&acct_lock);
 	if (file != acct->file) {
 		if (act)
 			res = act>0;
 		goto out;
 	}

 	if (acct->active) {
 		if (act < 0) {
 			acct->active = 0;
 			printk(KERN_INFO "Process accounting paused\n");
 		}
 	} else {
 		if (act > 0) {
 			acct->active = 1;
 			printk(KERN_INFO "Process accounting resumed\n");
 		}
 	}

 	acct->needcheck = jiffies + ACCT_TIMEOUT*HZ;
 	res = acct->active;
 out:
 	spin_unlock(&acct_lock);
 	return res;
 }

 /*
  * Close the old accounting file (if currently open) and then replace
  * it with file (if non-NULL).
  *
  * NOTE: acct_lock MUST be held on entry and exit.
  */
 static void acct_file_reopen(struct bsd_acct_struct *acct, struct file *file,
 		struct pid_namespace *ns)
 {
 	struct file *old_acct = NULL;
 	struct pid_namespace *old_ns = NULL;

 	if (acct->file) {
 		old_acct = acct->file;
 		old_ns = acct->ns;
 		acct->active = 0;
 		acct->file = NULL;
 		acct->ns = NULL;
 		list_del(&acct->list);
 	}
 	if (file) {
 		acct->file = file;
 		acct->ns = ns;
 		acct->needcheck = jiffies + ACCT_TIMEOUT*HZ;
 		acct->active = 1;
 		list_add(&acct->list, &acct_list);
 	}
 	if (old_acct) {
 		mnt_unpin(old_acct->f_path.mnt);
 		spin_unlock(&acct_lock);
 		do_acct_process(acct, old_ns, old_acct);
 		filp_close(old_acct, NULL);
 		spin_lock(&acct_lock);
 	}
 }

 static int acct_on(struct filename *pathname)
 {
 	struct file *file;
 	struct vfsmount *mnt;
 	struct pid_namespace *ns;
 	struct bsd_acct_struct *acct = NULL;

 	/* Difference from BSD - they don't do O_APPEND */
 	file = file_open_name(pathname, O_WRONLY|O_APPEND|O_LARGEFILE, 0);
 	if (IS_ERR(file))
 		return PTR_ERR(file);

 	if (!S_ISREG(file_inode(file)->i_mode)) {
 		filp_close(file, NULL);
 		return -EACCES;
 	}

 	if (!file->f_op->write) {
 		filp_close(file, NULL);
 		return -EIO;
 	}

 	ns = task_active_pid_ns(current);
 	if (ns->bacct == NULL) {
 		acct = kzalloc(sizeof(struct bsd_acct_struct), GFP_KERNEL);
 		if (acct == NULL) {
 			filp_close(file, NULL);
 			return -ENOMEM;
 		}
 	}

 	spin_lock(&acct_lock);
 	if (ns->bacct == NULL) {
 		ns->bacct = acct;
 		acct = NULL;
 	}

 	mnt = file->f_path.mnt;
 	mnt_pin(mnt);
 	acct_file_reopen(ns->bacct, file, ns);
 	spin_unlock(&acct_lock);

 	mntput(mnt); /* it's pinned, now give up active reference */
 	kfree(acct);

 	return 0;
 }

 /**
  * sys_acct - enable/disable process accounting
  * @name: file name for accounting records or NULL to shutdown accounting
  *
  * Returns 0 for success or negative errno values for failure.
  *
  * sys_acct() is the only system call needed to implement process
  * accounting. It takes the name of the file where accounting records
  * should be written. If the filename is NULL, accounting will be
  * shutdown.
  */
 SYSCALL_DEFINE1(acct, const char __user *, name)
 {
 	int error = 0;

 	if (!capable(CAP_SYS_PACCT))
 		return -EPERM;

 	if (name) {
 		struct filename *tmp = getname(name);
 		if (IS_ERR(tmp))
 			return (PTR_ERR(tmp));
 		error = acct_on(tmp);
 		putname(tmp);
 	} else {
 		struct bsd_acct_struct *acct;

 		acct = task_active_pid_ns(current)->bacct;
 		if (acct == NULL)
 			return 0;

 		spin_lock(&acct_lock);
 		acct_file_reopen(acct, NULL, NULL);
 		spin_unlock(&acct_lock);
 	}

 	return error;
 }

 /**
  * acct_auto_close - turn off a filesystem's accounting if it is on
  * @m: vfsmount being shut down
  *
  * If the accounting is turned on for a file in the subtree pointed to
  * to by m, turn accounting off.  Done when m is about to die.
  */
 void acct_auto_close_mnt(struct vfsmount *m)
 {
 	struct bsd_acct_struct *acct;

 	spin_lock(&acct_lock);
 restart:
 	list_for_each_entry(acct, &acct_list, list)
 		if (acct->file && acct->file->f_path.mnt == m) {
 			acct_file_reopen(acct, NULL, NULL);
 			goto restart;
 		}
 	spin_unlock(&acct_lock);
 }

 /**
  * acct_auto_close - turn off a filesystem's accounting if it is on
  * @sb: super block for the filesystem
  *
  * If the accounting is turned on for a file in the filesystem pointed
  * to by sb, turn accounting off.
  */
 void acct_auto_close(struct super_block *sb)
 {
 	struct bsd_acct_struct *acct;

 	spin_lock(&acct_lock);
 restart:
 	list_for_each_entry(acct, &acct_list, list)
 		if (acct->file && acct->file->f_path.dentry->d_sb == sb) {
 			acct_file_reopen(acct, NULL, NULL);
 			goto restart;
 		}
 	spin_unlock(&acct_lock);
 }

 void acct_exit_ns(struct pid_namespace *ns)
 {
 	struct bsd_acct_struct *acct = ns->bacct;

 	if (acct == NULL)
 		return;

 	spin_lock(&acct_lock);
 	if (acct->file != NULL)
 		acct_file_reopen(acct, NULL, NULL);
 	spin_unlock(&acct_lock);

 	kfree(acct);
 }

 /*
  *  encode an unsigned long into a comp_t
  *
  *  This routine has been adopted from the encode_comp_t() function in
  *  the kern_acct.c file of the FreeBSD operating system. The encoding
  *  is a 13-bit fraction with a 3-bit (base 8) exponent.
  */

 #define	MANTSIZE	13			/* 13 bit mantissa. */
 #define	EXPSIZE		3			/* Base 8 (3 bit) exponent. */
 #define	MAXFRACT	((1 << MANTSIZE) - 1)	/* Maximum fractional value. */

 static comp_t encode_comp_t(unsigned long value)
 {
 	int exp, rnd;

 	exp = rnd = 0;
 	while (value > MAXFRACT) {
 		rnd = value & (1 << (EXPSIZE - 1));	/* Round up? */
 		value >>= EXPSIZE;	/* Base 8 exponent == 3 bit shift. */
 		exp++;
 	}

 	/*
 	 * If we need to round up, do it (and handle overflow correctly).
 	 */
 	if (rnd && (++value > MAXFRACT)) {
 		value >>= EXPSIZE;
 		exp++;
 	}

 	/*
 	 * Clean it up and polish it off.
 	 */
 	exp <<= MANTSIZE;		/* Shift the exponent into place */
 	exp += value;			/* and add on the mantissa. */
 	return exp;
 }

 #if ACCT_VERSION==1 || ACCT_VERSION==2
 /*
  * encode an u64 into a comp2_t (24 bits)
  *
  * Format: 5 bit base 2 exponent, 20 bits mantissa.
  * The leading bit of the mantissa is not stored, but implied for
  * non-zero exponents.
  * Largest encodable value is 50 bits.
  */

 #define MANTSIZE2       20                      /* 20 bit mantissa. */
 #define EXPSIZE2        5                       /* 5 bit base 2 exponent. */
 #define MAXFRACT2       ((1ul << MANTSIZE2) - 1) /* Maximum fractional value. */
 #define MAXEXP2         ((1 <<EXPSIZE2) - 1)    /* Maximum exponent. */

 static comp2_t encode_comp2_t(u64 value)
 {
 	int exp, rnd;

 	exp = (value > (MAXFRACT2>>1));
 	rnd = 0;
 	while (value > MAXFRACT2) {
 		rnd = value & 1;
 		value >>= 1;
 		exp++;
 	}

 	/*
 	 * If we need to round up, do it (and handle overflow correctly).
 	 */
 	if (rnd && (++value > MAXFRACT2)) {
 		value >>= 1;
 		exp++;
 	}

 	if (exp > MAXEXP2) {
 		/* Overflow. Return largest representable number instead. */
 		return (1ul << (MANTSIZE2+EXPSIZE2-1)) - 1;
 	} else {
 		return (value & (MAXFRACT2>>1)) | (exp << (MANTSIZE2-1));
 	}
 }
 #endif

 #if ACCT_VERSION==3
 /*
  * encode an u64 into a 32 bit IEEE float
  */
 static u32 encode_float(u64 value)
 {
 	unsigned exp = 190;
 	unsigned u;

 	if (value==0) return 0;
 	while ((s64)value > 0){
 		value <<= 1;
 		exp--;
 	}
 	u = (u32)(value >> 40) & 0x7fffffu;
 	return u | (exp << 23);
 }
 #endif

 /*
  *  Write an accounting entry for an exiting process
  *
  *  The acct_process() call is the workhorse of the process
  *  accounting system. The struct acct is built here and then written
  *  into the accounting file. This function should only be called from
  *  do_exit() or when switching to a different output file.
  */

 /*
  *  do_acct_process does all actual work. Caller holds the reference to file.
  */
 static void do_acct_process(struct bsd_acct_struct *acct,
 		struct pid_namespace *ns, struct file *file)
 {
 	struct pacct_struct *pacct = &current->signal->pacct;
 	acct_t ac;
 	mm_segment_t fs;
 	unsigned long flim;
 	u64 elapsed;
 	u64 run_time;
 	struct timespec uptime;
 	struct tty_struct *tty;
 	const struct cred *orig_cred;

 	/* Perform file operations on behalf of whoever enabled accounting */
 	orig_cred = override_creds(file->f_cred);

 	/*
 	 * First check to see if there is enough free_space to continue
 	 * the process accounting system.
 	 */
 	if (!check_free_space(acct, file))
 		goto out;

 	/*
 	 * Fill the accounting struct with the needed info as recorded
 	 * by the different kernel functions.
 	 */
 	memset(&ac, 0, sizeof(acct_t));

 	ac.ac_version = ACCT_VERSION | ACCT_BYTEORDER;
 	strlcpy(ac.ac_comm, current->comm, sizeof(ac.ac_comm));

 	/* calculate run_time in nsec*/
 	do_posix_clock_monotonic_gettime(&uptime);
 	run_time = (u64)uptime.tv_sec*NSEC_PER_SEC + uptime.tv_nsec;
 	run_time -= (u64)current->group_leader->start_time.tv_sec * NSEC_PER_SEC
 		       + current->group_leader->start_time.tv_nsec;
 	/* convert nsec -> AHZ */
 	elapsed = nsec_to_AHZ(run_time);
 #if ACCT_VERSION==3
 	ac.ac_etime = encode_float(elapsed);
 #else
 	ac.ac_etime = encode_comp_t(elapsed < (unsigned long) -1l ?
 	                       (unsigned long) elapsed : (unsigned long) -1l);
 #endif
 #if ACCT_VERSION==1 || ACCT_VERSION==2
 	{
 		/* new enlarged etime field */
 		comp2_t etime = encode_comp2_t(elapsed);
 		ac.ac_etime_hi = etime >> 16;
 		ac.ac_etime_lo = (u16) etime;
 	}
 #endif
 	do_div(elapsed, AHZ);
 	ac.ac_btime = get_seconds() - elapsed;
 	/* we really need to bite the bullet and change layout */
 	ac.ac_uid = from_kuid_munged(file->f_cred->user_ns, orig_cred->uid);
 	ac.ac_gid = from_kgid_munged(file->f_cred->user_ns, orig_cred->gid);
 #if ACCT_VERSION==2
 	ac.ac_ahz = AHZ;
 #endif
 #if ACCT_VERSION==1 || ACCT_VERSION==2
 	/* backward-compatible 16 bit fields */
 	ac.ac_uid16 = ac.ac_uid;
 	ac.ac_gid16 = ac.ac_gid;
 #endif
 #if ACCT_VERSION==3
 	ac.ac_pid = task_tgid_nr_ns(current, ns);
 	rcu_read_lock();
 	ac.ac_ppid = task_tgid_nr_ns(rcu_dereference(current->real_parent), ns);
 	rcu_read_unlock();
 #endif

 	spin_lock_irq(&current->sighand->siglock);
 	tty = current->signal->tty;	/* Safe as we hold the siglock */
 	ac.ac_tty = tty ? old_encode_dev(tty_devnum(tty)) : 0;
 	ac.ac_utime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_utime)));
 	ac.ac_stime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_stime)));
 	ac.ac_flag = pacct->ac_flag;
 	ac.ac_mem = encode_comp_t(pacct->ac_mem);
 	ac.ac_minflt = encode_comp_t(pacct->ac_minflt);
 	ac.ac_majflt = encode_comp_t(pacct->ac_majflt);
 	ac.ac_exitcode = pacct->ac_exitcode;
 	spin_unlock_irq(&current->sighand->siglock);
 	ac.ac_io = encode_comp_t(0 /* current->io_usage */);	/* %% */
 	ac.ac_rw = encode_comp_t(ac.ac_io / 1024);
 	ac.ac_swaps = encode_comp_t(0);

 	/*
 	 * Get freeze protection. If the fs is frozen, just skip the write
 	 * as we could deadlock the system otherwise.
 	 */
 	if (!file_start_write_trylock(file))
 		goto out;
 	/*
 	 * Kernel segment override to datasegment and write it
 	 * to the accounting file.
 	 */
 	fs = get_fs();
 	set_fs(KERNEL_DS);
 	/*
 	 * Accounting records are not subject to resource limits.
 	 */
 	flim = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
 	current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
 	file->f_op->write(file, (char *)&ac,
 			       sizeof(acct_t), &file->f_pos);
 	current->signal->rlim[RLIMIT_FSIZE].rlim_cur = flim;
 	set_fs(fs);
 	file_end_write(file);
 out:
 	revert_creds(orig_cred);
 }

 /**
  * acct_collect - collect accounting information into pacct_struct
  * @exitcode: task exit code
  * @group_dead: not 0, if this thread is the last one in the process.
  */
 void acct_collect(long exitcode, int group_dead)
 {
 	struct pacct_struct *pacct = &current->signal->pacct;
 	cputime_t utime, stime;
 	unsigned long vsize = 0;

 	if (group_dead && current->mm) {
 		struct vm_area_struct *vma;
 		down_read(&current->mm->mmap_sem);
 		vma = current->mm->mmap;
 		while (vma) {
 			vsize += vma->vm_end - vma->vm_start;
 			vma = vma->vm_next;
 		}
 		up_read(&current->mm->mmap_sem);
 	}

 	spin_lock_irq(&current->sighand->siglock);
 	if (group_dead)
 		pacct->ac_mem = vsize / 1024;
 	if (thread_group_leader(current)) {
 		pacct->ac_exitcode = exitcode;
 		if (current->flags & PF_FORKNOEXEC)
 			pacct->ac_flag |= AFORK;
 	}
 	if (current->flags & PF_SUPERPRIV)
 		pacct->ac_flag |= ASU;
 	if (current->flags & PF_DUMPCORE)
 		pacct->ac_flag |= ACORE;
 	if (current->flags & PF_SIGNALED)
 		pacct->ac_flag |= AXSIG;
 	task_cputime(current, &utime, &stime);
 	pacct->ac_utime += utime;
 	pacct->ac_stime += stime;
 	pacct->ac_minflt += current->min_flt;
 	pacct->ac_majflt += current->maj_flt;
 	spin_unlock_irq(&current->sighand->siglock);
 }

 static void acct_process_in_ns(struct pid_namespace *ns)
 {
 	struct file *file = NULL;
 	struct bsd_acct_struct *acct;

 	acct = ns->bacct;
 	/*
 	 * accelerate the common fastpath:
 	 */
 	if (!acct || !acct->file)
 		return;

 	spin_lock(&acct_lock);
 	file = acct->file;
 	if (unlikely(!file)) {
 		spin_unlock(&acct_lock);
 		return;
 	}
 	get_file(file);
 	spin_unlock(&acct_lock);

 	do_acct_process(acct, ns, file);
 	fput(file);
 }

 /**
  * acct_process - now just a wrapper around acct_process_in_ns,
  * which in turn is a wrapper around do_acct_process.
  *
  * handles process accounting for an exiting task
  */
 void acct_process(void)
 {
 	struct pid_namespace *ns;

 	/*
 	 * This loop is safe lockless, since current is still
 	 * alive and holds its namespace, which in turn holds
 	 * its parent.
 	 */
 	for (ns = task_active_pid_ns(current); ns != NULL; ns = ns->parent)
 		acct_process_in_ns(ns);
 }
	/*
	* linux/kernel/acct.c
	*
	* BSD Process Accounting for Linux
	*
	* Author: Marco van Wieringen <mvw@planets.elm.net>
	*
	* Some code based on ideas and code from:
	* Thomas K. Dyas <tdyas@eden.rutgers.edu>
	*
	* This file implements BSD-style process accounting. Whenever any
	* process exits, an accounting record of type "struct acct" is
	* written to the file specified with the acct() system call. It is
	* up to user-level programs to do useful things with the accounting
	* log. The kernel just provides the raw accounting information.
	*
	* (C) Copyright 1995 - 1997 Marco van Wieringen - ELM Consultancy B.V.
	*
	* Plugged two leaks. 1) It didn't return acct_file into the free_filps if
	* the file happened to be read-only. 2) If the accounting was suspended
	* due to the lack of space it happily allowed to reopen it and completely
	* lost the old acct_file. 3/10/98, Al Viro.
	*
	* Now we silently close acct_file on attempt to reopen. Cleaned sys_acct().
	* XTerms and EMACS are manifestations of pure evil. 21/10/98, AV.
	*
	* Fixed a nasty interaction with with sys_umount(). If the accointing
	* was suspeneded we failed to stop it on umount(). Messy.
	* Another one: remount to readonly didn't stop accounting.
	* Question: what should we do if we have CAP_SYS_ADMIN but not
	* CAP_SYS_PACCT? Current code does the following: umount returns -EBUSY
	* unless we are messing with the root. In that case we are getting a
	* real mess with do_remount_sb(). 9/11/98, AV.
	*
	* Fixed a bunch of races (and pair of leaks). Probably not the best way,
	* but this one obviously doesn't introduce deadlocks. Later. BTW, found
	* one race (and leak) in BSD implementation.
	* OK, that's better. ANOTHER race and leak in BSD variant. There always
	* is one more bug... 10/11/98, AV.
	*
	* Oh, fsck... Oopsable SMP race in do_process_acct() - we must hold
	* ->mmap_sem to walk the vma list of current->mm. Nasty, since it leaks
	* a struct file opened for write. Fixed. 2/6/2000, AV.
	*/

	#include <linux/mm.h>
	#include <linux/slab.h>
	#include <linux/acct.h>
	#include <linux/capability.h>
	#include <linux/file.h>
	#include <linux/tty.h>
	#include <linux/security.h>
	#include <linux/vfs.h>
	#include <linux/jiffies.h>
	#include <linux/times.h>
	#include <linux/syscalls.h>
	#include <linux/mount.h>
	#include <linux/uaccess.h>
	#include <asm/div64.h>
	#include <linux/blkdev.h> /* sector_div */
	#include <linux/pid_namespace.h>

	/*
	* These constants control the amount of freespace that suspend and
	* resume the process accounting system, and the time delay between
	* each check.
	* Turned into sysctl-controllable parameters. AV, 12/11/98
	*/

	int acct_parm[3] = {4, 2, 30};
	#define RESUME (acct_parm[0]) /* >foo% free space - resume */
	#define SUSPEND (acct_parm[1]) /* <foo% free space - suspend */
	#define ACCT_TIMEOUT (acct_parm[2]) /* foo second timeout between checks */

	/*
	* External references and all of the globals.
	*/
	static void do_acct_process(struct bsd_acct_struct *acct,
	struct pid_namespace ns, struct file );

	/*
	* This structure is used so that all the data protected by lock
	* can be placed in the same cache line as the lock. This primes
	* the cache line to have the data after getting the lock.
	*/
	struct bsd_acct_struct {
	int active;
	unsigned long needcheck;
	struct file *file;
	struct pid_namespace *ns;
	struct list_head list;
	};

	static DEFINE_SPINLOCK(acct_lock);
	static LIST_HEAD(acct_list);

	/*
	* Check the amount of free space and suspend/resume accordingly.
	*/
	static int check_free_space(struct bsd_acct_struct acct, struct file file)
	{
	struct kstatfs sbuf;
	int res;
	int act;
	u64 resume;
	u64 suspend;

	spin_lock(&acct_lock);
	res = acct->active;
	if (!file \|\| time_is_before_jiffies(acct->needcheck))
	goto out;
	spin_unlock(&acct_lock);

	/* May block */
	if (vfs_statfs(&file->f_path, &sbuf))
	return res;
	suspend = sbuf.f_blocks * SUSPEND;
	resume = sbuf.f_blocks * RESUME;

	do_div(suspend, 100);
	do_div(resume, 100);

	if (sbuf.f_bavail <= suspend)
	act = -1;
	else if (sbuf.f_bavail >= resume)
	act = 1;
	else
	act = 0;

	/*
	* If some joker switched acct->file under us we'ld better be
	* silent and _not_ touch anything.
	*/
	spin_lock(&acct_lock);
	if (file != acct->file) {
	if (act)
	res = act>0;
	goto out;
	}

	if (acct->active) {
	if (act < 0) {
	acct->active = 0;
	printk(KERN_INFO "Process accounting paused\n");
	}
	} else {
	if (act > 0) {
	acct->active = 1;
	printk(KERN_INFO "Process accounting resumed\n");
	}
	}

	acct->needcheck = jiffies + ACCT_TIMEOUT*HZ;
	res = acct->active;
	out:
	spin_unlock(&acct_lock);
	return res;
	}

	/*
	* Close the old accounting file (if currently open) and then replace
	* it with file (if non-NULL).
	*
	* NOTE: acct_lock MUST be held on entry and exit.
	*/
	static void acct_file_reopen(struct bsd_acct_struct acct, struct file file,
	struct pid_namespace *ns)
	{
	struct file *old_acct = NULL;
	struct pid_namespace *old_ns = NULL;

	if (acct->file) {
	old_acct = acct->file;
	old_ns = acct->ns;
	acct->active = 0;
	acct->file = NULL;
	acct->ns = NULL;
	list_del(&acct->list);
	}
	if (file) {
	acct->file = file;
	acct->ns = ns;
	acct->needcheck = jiffies + ACCT_TIMEOUT*HZ;
	acct->active = 1;
	list_add(&acct->list, &acct_list);
	}
	if (old_acct) {
	mnt_unpin(old_acct->f_path.mnt);
	spin_unlock(&acct_lock);
	do_acct_process(acct, old_ns, old_acct);
	filp_close(old_acct, NULL);
	spin_lock(&acct_lock);
	}
	}

	static int acct_on(struct filename *pathname)
	{
	struct file *file;
	struct vfsmount *mnt;
	struct pid_namespace *ns;
	struct bsd_acct_struct *acct = NULL;

	/* Difference from BSD - they don't do O_APPEND */
	file = file_open_name(pathname, O_WRONLY\|O_APPEND\|O_LARGEFILE, 0);
	if (IS_ERR(file))
	return PTR_ERR(file);

	if (!S_ISREG(file_inode(file)->i_mode)) {
	filp_close(file, NULL);
	return -EACCES;
	}

	if (!file->f_op->write) {
	filp_close(file, NULL);
	return -EIO;
	}

	ns = task_active_pid_ns(current);
	if (ns->bacct == NULL) {
	acct = kzalloc(sizeof(struct bsd_acct_struct), GFP_KERNEL);
	if (acct == NULL) {
	filp_close(file, NULL);
	return -ENOMEM;
	}
	}

	spin_lock(&acct_lock);
	if (ns->bacct == NULL) {
	ns->bacct = acct;
	acct = NULL;
	}

	mnt = file->f_path.mnt;
	mnt_pin(mnt);
	acct_file_reopen(ns->bacct, file, ns);
	spin_unlock(&acct_lock);

	mntput(mnt); /* it's pinned, now give up active reference */
	kfree(acct);

	return 0;
	}

	/**
	* sys_acct - enable/disable process accounting
	* @name: file name for accounting records or NULL to shutdown accounting
	*
	* Returns 0 for success or negative errno values for failure.
	*
	* sys_acct() is the only system call needed to implement process
	* accounting. It takes the name of the file where accounting records
	* should be written. If the filename is NULL, accounting will be
	* shutdown.
	*/
	SYSCALL_DEFINE1(acct, const char __user *, name)
	{
	int error = 0;

	if (!capable(CAP_SYS_PACCT))
	return -EPERM;

	if (name) {
	struct filename *tmp = getname(name);
	if (IS_ERR(tmp))
	return (PTR_ERR(tmp));
	error = acct_on(tmp);
	putname(tmp);
	} else {
	struct bsd_acct_struct *acct;

	acct = task_active_pid_ns(current)->bacct;
	if (acct == NULL)
	return 0;

	spin_lock(&acct_lock);
	acct_file_reopen(acct, NULL, NULL);
	spin_unlock(&acct_lock);
	}

	return error;
	}

	/**
	* acct_auto_close - turn off a filesystem's accounting if it is on
	* @m: vfsmount being shut down
	*
	* If the accounting is turned on for a file in the subtree pointed to
	* to by m, turn accounting off. Done when m is about to die.
	*/
	void acct_auto_close_mnt(struct vfsmount *m)
	{
	struct bsd_acct_struct *acct;

	spin_lock(&acct_lock);
	restart:
	list_for_each_entry(acct, &acct_list, list)
	if (acct->file && acct->file->f_path.mnt == m) {
	acct_file_reopen(acct, NULL, NULL);
	goto restart;
	}
	spin_unlock(&acct_lock);
	}

	/**
	* acct_auto_close - turn off a filesystem's accounting if it is on
	* @sb: super block for the filesystem
	*
	* If the accounting is turned on for a file in the filesystem pointed
	* to by sb, turn accounting off.
	*/
	void acct_auto_close(struct super_block *sb)
	{
	struct bsd_acct_struct *acct;

	spin_lock(&acct_lock);
	restart:
	list_for_each_entry(acct, &acct_list, list)
	if (acct->file && acct->file->f_path.dentry->d_sb == sb) {
	acct_file_reopen(acct, NULL, NULL);
	goto restart;
	}
	spin_unlock(&acct_lock);
	}

	void acct_exit_ns(struct pid_namespace *ns)
	{
	struct bsd_acct_struct *acct = ns->bacct;

	if (acct == NULL)
	return;

	spin_lock(&acct_lock);
	if (acct->file != NULL)
	acct_file_reopen(acct, NULL, NULL);
	spin_unlock(&acct_lock);

	kfree(acct);
	}

	/*
	* encode an unsigned long into a comp_t
	*
	* This routine has been adopted from the encode_comp_t() function in
	* the kern_acct.c file of the FreeBSD operating system. The encoding
	* is a 13-bit fraction with a 3-bit (base 8) exponent.
	*/

	#define MANTSIZE 13 /* 13 bit mantissa. */
	#define EXPSIZE 3 /* Base 8 (3 bit) exponent. */
	#define MAXFRACT ((1 << MANTSIZE) - 1) /* Maximum fractional value. */

	static comp_t encode_comp_t(unsigned long value)
	{
	int exp, rnd;

	exp = rnd = 0;
	while (value > MAXFRACT) {
	rnd = value & (1 << (EXPSIZE - 1)); /* Round up? */
	value >>= EXPSIZE; /* Base 8 exponent == 3 bit shift. */
	exp++;
	}

	/*
	* If we need to round up, do it (and handle overflow correctly).
	*/
	if (rnd && (++value > MAXFRACT)) {
	value >>= EXPSIZE;
	exp++;
	}

	/*
	* Clean it up and polish it off.
	*/
	exp <<= MANTSIZE; /* Shift the exponent into place */
	exp += value; /* and add on the mantissa. */
	return exp;
	}

	#if ACCT_VERSION==1 \|\| ACCT_VERSION==2
	/*
	* encode an u64 into a comp2_t (24 bits)
	*
	* Format: 5 bit base 2 exponent, 20 bits mantissa.
	* The leading bit of the mantissa is not stored, but implied for
	* non-zero exponents.
	* Largest encodable value is 50 bits.
	*/

	#define MANTSIZE2 20 /* 20 bit mantissa. */
	#define EXPSIZE2 5 /* 5 bit base 2 exponent. */
	#define MAXFRACT2 ((1ul << MANTSIZE2) - 1) /* Maximum fractional value. */
	#define MAXEXP2 ((1 <<EXPSIZE2) - 1) /* Maximum exponent. */

	static comp2_t encode_comp2_t(u64 value)
	{
	int exp, rnd;

	exp = (value > (MAXFRACT2>>1));
	rnd = 0;
	while (value > MAXFRACT2) {
	rnd = value & 1;
	value >>= 1;
	exp++;
	}

	/*
	* If we need to round up, do it (and handle overflow correctly).
	*/
	if (rnd && (++value > MAXFRACT2)) {
	value >>= 1;
	exp++;
	}

	if (exp > MAXEXP2) {
	/* Overflow. Return largest representable number instead. */
	return (1ul << (MANTSIZE2+EXPSIZE2-1)) - 1;
	} else {
	return (value & (MAXFRACT2>>1)) \| (exp << (MANTSIZE2-1));
	}
	}
	#endif

	#if ACCT_VERSION==3
	/*
	* encode an u64 into a 32 bit IEEE float
	*/
	static u32 encode_float(u64 value)
	{
	unsigned exp = 190;
	unsigned u;

	if (value==0) return 0;
	while ((s64)value > 0){
	value <<= 1;
	exp--;
	}
	u = (u32)(value >> 40) & 0x7fffffu;
	return u \| (exp << 23);
	}
	#endif

	/*
	* Write an accounting entry for an exiting process
	*
	* The acct_process() call is the workhorse of the process
	* accounting system. The struct acct is built here and then written
	* into the accounting file. This function should only be called from
	* do_exit() or when switching to a different output file.
	*/

	/*
	* do_acct_process does all actual work. Caller holds the reference to file.
	*/
	static void do_acct_process(struct bsd_acct_struct *acct,
	struct pid_namespace ns, struct file file)
	{
	struct pacct_struct *pacct = &current->signal->pacct;
	acct_t ac;
	mm_segment_t fs;
	unsigned long flim;
	u64 elapsed;
	u64 run_time;
	struct timespec uptime;
	struct tty_struct *tty;
	const struct cred *orig_cred;

	/* Perform file operations on behalf of whoever enabled accounting */
	orig_cred = override_creds(file->f_cred);

	/*
	* First check to see if there is enough free_space to continue
	* the process accounting system.
	*/
	if (!check_free_space(acct, file))
	goto out;

	/*
	* Fill the accounting struct with the needed info as recorded
	* by the different kernel functions.
	*/
	memset(&ac, 0, sizeof(acct_t));

	ac.ac_version = ACCT_VERSION \| ACCT_BYTEORDER;
	strlcpy(ac.ac_comm, current->comm, sizeof(ac.ac_comm));

	/* calculate run_time in nsec*/
	do_posix_clock_monotonic_gettime(&uptime);
	run_time = (u64)uptime.tv_sec*NSEC_PER_SEC + uptime.tv_nsec;
	run_time -= (u64)current->group_leader->start_time.tv_sec * NSEC_PER_SEC
	+ current->group_leader->start_time.tv_nsec;
	/* convert nsec -> AHZ */
	elapsed = nsec_to_AHZ(run_time);
	#if ACCT_VERSION==3
	ac.ac_etime = encode_float(elapsed);
	#else
	ac.ac_etime = encode_comp_t(elapsed < (unsigned long) -1l ?
	(unsigned long) elapsed : (unsigned long) -1l);
	#endif
	#if ACCT_VERSION==1 \|\| ACCT_VERSION==2
	{
	/* new enlarged etime field */
	comp2_t etime = encode_comp2_t(elapsed);
	ac.ac_etime_hi = etime >> 16;
	ac.ac_etime_lo = (u16) etime;
	}
	#endif
	do_div(elapsed, AHZ);
	ac.ac_btime = get_seconds() - elapsed;
	/* we really need to bite the bullet and change layout */
	ac.ac_uid = from_kuid_munged(file->f_cred->user_ns, orig_cred->uid);
	ac.ac_gid = from_kgid_munged(file->f_cred->user_ns, orig_cred->gid);
	#if ACCT_VERSION==2
	ac.ac_ahz = AHZ;
	#endif
	#if ACCT_VERSION==1 \|\| ACCT_VERSION==2
	/* backward-compatible 16 bit fields */
	ac.ac_uid16 = ac.ac_uid;
	ac.ac_gid16 = ac.ac_gid;
	#endif
	#if ACCT_VERSION==3
	ac.ac_pid = task_tgid_nr_ns(current, ns);
	rcu_read_lock();
	ac.ac_ppid = task_tgid_nr_ns(rcu_dereference(current->real_parent), ns);
	rcu_read_unlock();
	#endif

	spin_lock_irq(&current->sighand->siglock);
	tty = current->signal->tty; /* Safe as we hold the siglock */
	ac.ac_tty = tty ? old_encode_dev(tty_devnum(tty)) : 0;
	ac.ac_utime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_utime)));
	ac.ac_stime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_stime)));
	ac.ac_flag = pacct->ac_flag;
	ac.ac_mem = encode_comp_t(pacct->ac_mem);
	ac.ac_minflt = encode_comp_t(pacct->ac_minflt);
	ac.ac_majflt = encode_comp_t(pacct->ac_majflt);
	ac.ac_exitcode = pacct->ac_exitcode;
	spin_unlock_irq(&current->sighand->siglock);
	ac.ac_io = encode_comp_t(0 /* current->io_usage /); / %% */
	ac.ac_rw = encode_comp_t(ac.ac_io / 1024);
	ac.ac_swaps = encode_comp_t(0);

	/*
	* Get freeze protection. If the fs is frozen, just skip the write
	* as we could deadlock the system otherwise.
	*/
	if (!file_start_write_trylock(file))
	goto out;
	/*
	* Kernel segment override to datasegment and write it
	* to the accounting file.
	*/
	fs = get_fs();
	set_fs(KERNEL_DS);
	/*
	* Accounting records are not subject to resource limits.
	*/
	flim = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
	current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
	file->f_op->write(file, (char *)&ac,
	sizeof(acct_t), &file->f_pos);
	current->signal->rlim[RLIMIT_FSIZE].rlim_cur = flim;
	set_fs(fs);
	file_end_write(file);
	out:
	revert_creds(orig_cred);
	}

	/**
	* acct_collect - collect accounting information into pacct_struct
	* @exitcode: task exit code
	* @group_dead: not 0, if this thread is the last one in the process.
	*/
	void acct_collect(long exitcode, int group_dead)
	{
	struct pacct_struct *pacct = &current->signal->pacct;
	cputime_t utime, stime;
	unsigned long vsize = 0;

	if (group_dead && current->mm) {
	struct vm_area_struct *vma;
	down_read(&current->mm->mmap_sem);
	vma = current->mm->mmap;
	while (vma) {
	vsize += vma->vm_end - vma->vm_start;
	vma = vma->vm_next;
	}
	up_read(&current->mm->mmap_sem);
	}

	spin_lock_irq(&current->sighand->siglock);
	if (group_dead)
	pacct->ac_mem = vsize / 1024;
	if (thread_group_leader(current)) {
	pacct->ac_exitcode = exitcode;
	if (current->flags & PF_FORKNOEXEC)
	pacct->ac_flag \|= AFORK;
	}
	if (current->flags & PF_SUPERPRIV)
	pacct->ac_flag \|= ASU;
	if (current->flags & PF_DUMPCORE)
	pacct->ac_flag \|= ACORE;
	if (current->flags & PF_SIGNALED)
	pacct->ac_flag \|= AXSIG;
	task_cputime(current, &utime, &stime);
	pacct->ac_utime += utime;
	pacct->ac_stime += stime;
	pacct->ac_minflt += current->min_flt;
	pacct->ac_majflt += current->maj_flt;
	spin_unlock_irq(&current->sighand->siglock);
	}

	static void acct_process_in_ns(struct pid_namespace *ns)
	{
	struct file *file = NULL;
	struct bsd_acct_struct *acct;

	acct = ns->bacct;
	/*
	* accelerate the common fastpath:
	*/
	if (!acct \|\| !acct->file)
	return;

	spin_lock(&acct_lock);
	file = acct->file;
	if (unlikely(!file)) {
	spin_unlock(&acct_lock);
	return;
	}
	get_file(file);
	spin_unlock(&acct_lock);

	do_acct_process(acct, ns, file);
	fput(file);
	}

	/**
	* acct_process - now just a wrapper around acct_process_in_ns,
	* which in turn is a wrapper around do_acct_process.
	*
	* handles process accounting for an exiting task
	*/
	void acct_process(void)
	{
	struct pid_namespace *ns;

	/*
	* This loop is safe lockless, since current is still
	* alive and holds its namespace, which in turn holds
	* its parent.
	*/
	for (ns = task_active_pid_ns(current); ns != NULL; ns = ns->parent)
	acct_process_in_ns(ns);
	}