/*
* linux/fs/locks.c
*
* Provide support for fcntl()'s F_GETLK, F_SETLK, and F_SETLKW calls.
* Doug Evans (dje@spiff.uucp), August 07, 1992
*
* Deadlock detection added.
* FIXME: one thing isn't handled yet:
* - mandatory locks (requires lots of changes elsewhere)
* Kelly Carmichael (kelly@[142.24.8.65]), September 17, 1994.
*
* Miscellaneous edits, and a total rewrite of posix_lock_file() code.
* Kai Petzke (wpp@marie.physik.tu-berlin.de), 1994
*
* Converted file_lock_table to a linked list from an array, which eliminates
* the limits on how many active file locks are open.
* Chad Page (pageone@netcom.com), November 27, 1994
*
* Removed dependency on file descriptors. dup()'ed file descriptors now
* get the same locks as the original file descriptors, and a close() on
* any file descriptor removes ALL the locks on the file for the current
* process. Since locks still depend on the process id, locks are inherited
* after an exec() but not after a fork(). This agrees with POSIX, and both
* BSD and SVR4 practice.
* Andy Walker (andy@lysaker.kvaerner.no), February 14, 1995
*
* Scrapped free list which is redundant now that we allocate locks
* dynamically with kmalloc()/kfree().
* Andy Walker (andy@lysaker.kvaerner.no), February 21, 1995
*
* Implemented two lock personalities - F_FLOCK and F_POSIX.
*
* F_POSIX locks are created with calls to fcntl() and lockf() through the
* fcntl() system call. They have the semantics described above.
*
* F_FLOCK locks are created with calls to flock(), through the flock()
* system call, which is new. Old C libraries implement flock() via fcntl()
* and will continue to use the old, broken implementation.
*
* F_FLOCK locks follow the 4.4 BSD flock() semantics. They are associated
* with a file pointer (filp). As a result they can be shared by a parent
* process and its children after a fork(). They are removed when the last
* file descriptor referring to the file pointer is closed (unless explicitly
* unlocked).
*
* F_FLOCK locks never deadlock, an existing lock is always removed before
* upgrading from shared to exclusive (or vice versa). When this happens
* any processes blocked by the current lock are woken up and allowed to
* run before the new lock is applied.
* Andy Walker (andy@lysaker.kvaerner.no), June 09, 1995
*
* Removed some race conditions in flock_lock_file(), marked other possible
* races. Just grep for FIXME to see them.
* Dmitry Gorodchanin (begemot@bgm.rosprint.net), February 09, 1996.
*
* Addressed Dmitry's concerns. Deadlock checking no longer recursive.
* Lock allocation changed to GFP_ATOMIC as we can't afford to sleep
* once we've checked for blocking and deadlocking.
* Andy Walker (andy@lysaker.kvaerner.no), April 03, 1996.
*
* Initial implementation of mandatory locks. SunOS turned out to be
* a rotten model, so I implemented the "obvious" semantics.
* See 'linux/Documentation/mandatory.txt' for details.
* Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996.
*
* Don't allow mandatory locks on mmap()'ed files. Added simple functions to
* check if a file has mandatory locks, used by mmap(), open() and creat() to
* see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference
* Manual, Section 2.
* Andy Walker (andy@lysaker.kvaerner.no), April 09, 1996.
*
* Tidied up block list handling. Added '/proc/locks' interface.
* Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996.
*
* Fixed deadlock condition for pathological code that mixes calls to
* flock() and fcntl().
* Andy Walker (andy@lysaker.kvaerner.no), April 29, 1996.
*
* Allow only one type of locking scheme (F_POSIX or F_FLOCK) to be in use
* for a given file at a time. Changed the CONFIG_MANDATORY_OPTION scheme to
* guarantee sensible behaviour in the case where file system modules might
* be compiled with different options than the kernel itself.
* Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
*
* Added a couple of missing wake_up() calls.
* Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
*
* TODO: Do not honour mandatory locks on remote file systems. This matches
* the SVR4 semantics and neatly sidesteps a pile of awkward issues that
* would otherwise have to be addressed.
*/
#include <linux/config.h>
#include <linux/malloc.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/stat.h>
#include <linux/fcntl.h>
#include <asm/segment.h>
#define OFFSET_MAX ((off_t)0x7fffffff) /* FIXME: move elsewhere? */
static int flock_make_lock(struct file *filp, struct file_lock *fl,
unsigned int cmd);
static int posix_make_lock(struct file *filp, struct file_lock *fl,
struct flock *l);
static int flock_locks_conflict(struct file_lock *caller_fl,
struct file_lock *sys_fl);
static int posix_locks_conflict(struct file_lock *caller_fl,
struct file_lock *sys_fl);
static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl);
static int flock_lock_file(struct file *filp, struct file_lock *caller,
unsigned int wait);
static int posix_lock_file(struct file *filp, struct file_lock *caller,
unsigned int wait);
static int posix_locks_deadlock(struct task_struct *my_task,
struct task_struct *blocked_task);
static int locks_overlap(struct file_lock *fl1, struct file_lock *fl2);
static void posix_remove_locks(struct file_lock **before, struct task_struct *task);
static void flock_remove_locks(struct file_lock **before, struct file *filp);
static struct file_lock *locks_alloc_lock(struct file_lock *fl);
static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl);
static void locks_delete_lock(struct file_lock **fl, unsigned int wait);
static char *lock_get_status(struct file_lock *fl, char *p, int id, char *pfx);
static struct file_lock *file_lock_table = NULL;
/* Free lock not inserted in any queue */
static inline void locks_free_lock(struct file_lock *fl)
{
kfree(fl);
return;
}
/* Add lock fl to the blocked list pointed to by block.
* We search to the end of the existing list and insert the the new
* struct. This ensures processes will be woken up in the order they
* blocked.
* NOTE: nowhere does the documentation insist that processes be woken
* up in this order, but it seems like the reasonable thing to do.
* If the blocked list gets long then this search could get expensive,
* in which case we could consider waking the processes up in reverse
* order, or making the blocked list a doubly linked circular list.
*
* This functions are called only from one place (flock_lock_file)
* so they are inlined now. -- Dmitry Gorodchanin 02/09/96.
*/
static inline void locks_insert_block(struct file_lock *bfl,
struct file_lock *fl)
{
while (bfl->fl_block != NULL) {
bfl = bfl->fl_block;
}
bfl->fl_block = fl;
fl->fl_block = NULL;
return;
}
static inline void locks_delete_block(struct file_lock *bfl,
struct file_lock *fl)
{
struct file_lock *tfl;
while ((tfl = bfl->fl_block) != NULL) {
if (tfl == fl) {
bfl->fl_block = fl->fl_block;
fl->fl_block = NULL;
return;
}
bfl = tfl;
}
return;
}
/* flock() system call entry point. Apply a FLOCK style lock to
* an open file descriptor.
*/
asmlinkage int sys_flock(unsigned int fd, unsigned int cmd)
{
struct file_lock file_lock;
struct file *filp;
if ((fd >= NR_OPEN) || !(filp = current->files->fd[fd]))
return (-EBADF);
if (!flock_make_lock(filp, &file_lock, cmd))
return (-EINVAL);
if ((file_lock.fl_type != F_UNLCK) && !(filp->f_mode & 3))
return (-EBADF);
return (flock_lock_file(filp, &file_lock, cmd & LOCK_UN ? 0 : cmd & LOCK_NB ? 0 : 1));
}
/* Report the first existing lock that would conflict with l.
* This implements the F_GETLK command of fcntl().
*/
int fcntl_getlk(unsigned int fd, struct flock *l)
{
int error;
struct flock flock;
struct file *filp;
struct file_lock *fl,file_lock;
if ((fd >= NR_OPEN) || !(filp = current->files->fd[fd]))
return (-EBADF);
error = verify_area(VERIFY_WRITE, l, sizeof(*l));
if (error)
return (error);
memcpy_fromfs(&flock, l, sizeof(flock));
if ((flock.l_type == F_UNLCK) || (flock.l_type == F_EXLCK) ||
(flock.l_type == F_SHLCK))
return (-EINVAL);
if (!filp->f_inode || !posix_make_lock(filp, &file_lock, &flock))
return (-EINVAL);
if ((fl = filp->f_inode->i_flock) && (fl->fl_flags & F_POSIX)) {
while (fl != NULL) {
if (posix_locks_conflict(&file_lock, fl)) {
flock.l_pid = fl->fl_owner->pid;
flock.l_start = fl->fl_start;
flock.l_len = fl->fl_end == OFFSET_MAX ? 0 :
fl->fl_end - fl->fl_start + 1;
flock.l_whence = 0;
flock.l_type = fl->fl_type;
memcpy_tofs(l, &flock, sizeof(flock));
return (0);
}
fl = fl->fl_next;
}
}
flock.l_type = F_UNLCK; /* no conflict found */
memcpy_tofs(l, &flock, sizeof(flock));
return (0);
}
/* Apply the lock described by l to an open file descriptor.
* This implements both the F_SETLK and F_SETLKW commands of fcntl().
* It also emulates flock() in a pretty broken way for older C
* libraries.
*/
int fcntl_setlk(unsigned int fd, unsigned int cmd, struct flock *l)
{
int error;
struct file *filp;
struct file_lock file_lock;
struct flock flock;
struct inode *inode;
/*
* Get arguments and validate them ...
*/
if ((fd >= NR_OPEN) || !(filp = current->files->fd[fd]))
return (-EBADF);
error = verify_area(VERIFY_READ, l, sizeof(*l));
if (error)
return (error);
if (!(inode = filp->f_inode))
return (-EINVAL);
#ifdef CONFIG_LOCK_MANDATORY
/* Don't allow mandatory locks on files that may be memory mapped
* and shared.
*/
if ((inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID && inode->i_mmap) {
struct vm_area_struct *vma = inode->i_mmap;
do {
if (vma->vm_flags & VM_MAYSHARE)
return (-EAGAIN);
vma = vma->vm_next_share;
} while (vma != inode->i_mmap);
}
#endif
memcpy_fromfs(&flock, l, sizeof(flock));
if (!posix_make_lock(filp, &file_lock, &flock))
return (-EINVAL);
switch (flock.l_type) {
case F_RDLCK :
if (!(filp->f_mode & 1))
return (-EBADF);
break;
case F_WRLCK :
if (!(filp->f_mode & 2))
return (-EBADF);
break;
case F_SHLCK :
case F_EXLCK :
#if 1
/* warn a bit for now, but don't overdo it */
{
static int count = 0;
if (!count) {
count=1;
printk(KERN_WARNING
"fcntl_setlk() called by process %d (%s) with broken flock() emulation\n",
current->pid, current->comm);
}
}
#endif
if (!(filp->f_mode & 3))
return (-EBADF);
break;
case F_UNLCK :
break;
}
return (posix_lock_file(filp, &file_lock, cmd == F_SETLKW));
}
/* This function is called when the file is closed.
*/
void locks_remove_locks(struct task_struct *task, struct file *filp)
{
struct file_lock *fl;
/* For POSIX locks we free all locks on this file for the given task.
* For FLOCK we only free locks on this *open* file if it is the last
* close on that file.
*/
if ((fl = filp->f_inode->i_flock) != NULL) {
if (fl->fl_flags & F_POSIX)
posix_remove_locks(&filp->f_inode->i_flock, task);
else
flock_remove_locks(&filp->f_inode->i_flock, filp);
}
return;
}
static void posix_remove_locks(struct file_lock **before, struct task_struct *task)
{
struct file_lock *fl;
while ((fl = *before) != NULL) {
if (fl->fl_owner == task)
locks_delete_lock(before, 0);
else
before = &fl->fl_next;
}
return;
}
static void flock_remove_locks(struct file_lock **before, struct file *filp)
{
struct file_lock *fl;
while ((fl = *before) != NULL) {
if ((fl->fl_file == filp) && (filp->f_count == 1))
locks_delete_lock(before, 0);
else
before = &fl->fl_next;
}
return;
}
int locks_verify_locked(struct inode *inode)
{
#ifdef CONFIG_LOCK_MANDATORY
/* Candidates for mandatory locking have the setgid bit set
* but no group execute bit - an otherwise meaningless combination.
*/
if ((inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID)
return (locks_mandatory_locked(inode));
#endif
return (0);
}
int locks_verify_area(int read_write, struct inode *inode, struct file *filp,
unsigned int offset, unsigned int count)
{
#ifdef CONFIG_LOCK_MANDATORY
/* Candidates for mandatory locking have the setgid bit set
* but no group execute bit - an otherwise meaningless combination.
*/
if ((inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID)
return (locks_mandatory_area(read_write, inode, filp, offset,
count));
#endif
return (0);
}
int locks_mandatory_locked(struct inode *inode)
{
#ifdef CONFIG_LOCK_MANDATORY
struct file_lock *fl;
/* Search the lock list for this inode for any POSIX locks.
*/
if ((fl = inode->i_flock) && (fl->fl_flags & F_FLOCK))
return (0);
while (fl != NULL) {
if (fl->fl_owner != current)
return (-EAGAIN);
fl = fl->fl_next;
}
#endif
return (0);
}
int locks_mandatory_area(int read_write, struct inode *inode,
struct file *filp, unsigned int offset,
unsigned int count)
{
#ifdef CONFIG_LOCK_MANDATORY
struct file_lock *fl;
repeat:
/* Check that there are locks, and that they're not F_FLOCK locks.
*/
if ((fl = inode->i_flock) && (fl->fl_flags & F_FLOCK))
return (0);
/*
* Search the lock list for this inode for locks that conflict with
* the proposed read/write.
*/
while (fl != NULL) {
if (fl->fl_owner == current ||
fl->fl_end < offset || fl->fl_start >= offset + count)
goto next_lock;
/*
* Block for writes against a "read" lock,
* and both reads and writes against a "write" lock.
*/
if ((read_write == FLOCK_VERIFY_WRITE) ||
(fl->fl_type == F_WRLCK)) {
if (filp && (filp->f_flags & O_NONBLOCK))
return (-EAGAIN);
if (current->signal & ~current->blocked)
return (-ERESTARTSYS);
if (posix_locks_deadlock(current, fl->fl_owner))
return (-EDEADLOCK);
interruptible_sleep_on(&fl->fl_wait);
if (current->signal & ~current->blocked)
return (-ERESTARTSYS);
/*
* If we've been sleeping someone might have
* changed the permissions behind our back.
*/
if ((inode->i_mode & (S_ISGID | S_IXGRP)) != S_ISGID)
break;
goto repeat;
}
next_lock:
fl = fl->fl_next;
}
#endif
return (0);
}
/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
* style lock.
*/
static int posix_make_lock(struct file *filp, struct file_lock *fl,
struct flock *l)
{
off_t start;
fl->fl_flags = F_POSIX;
switch (l->l_type) {
case F_RDLCK :
case F_WRLCK :
case F_UNLCK :
fl->fl_type = l->l_type;
break;
case F_SHLCK :
fl->fl_type = F_RDLCK;
fl->fl_flags |= F_BROKEN;
break;
case F_EXLCK :
fl->fl_type = F_WRLCK;
fl->fl_flags |= F_BROKEN;
break;
default :
return (0);
}
switch (l->l_whence) {
case 0 : /*SEEK_SET*/
start = 0;
break;
case 1 : /*SEEK_CUR*/
start = filp->f_pos;
break;
case 2 : /*SEEK_END*/
start = filp->f_inode->i_size;
break;
default :
return (0);
}
if (((start += l->l_start) < 0) || (l->l_len < 0))
return (0);
fl->fl_start = start; /* we record the absolute position */
if ((l->l_len == 0) || ((fl->fl_end = start + l->l_len - 1) < 0))
fl->fl_end = OFFSET_MAX;
fl->fl_file = filp;
fl->fl_owner = current;
fl->fl_wait = NULL; /* just for cleanliness */
return (1);
}
/* Verify a call to flock() and fill in a file_lock structure with
* an appropriate FLOCK lock.
*/
static int flock_make_lock(struct file *filp, struct file_lock *fl,
unsigned int cmd)
{
if (!filp->f_inode) /* just in case */
return (0);
switch (cmd & ~LOCK_NB) {
case LOCK_SH :
fl->fl_type = F_RDLCK;
break;
case LOCK_EX :
fl->fl_type = F_WRLCK;
break;
case LOCK_UN :
fl->fl_type = F_UNLCK;
break;
default :
return (0);
}
fl->fl_flags = F_FLOCK;
fl->fl_start = 0;
fl->fl_end = OFFSET_MAX;
fl->fl_file = filp;
fl->fl_owner = NULL;
fl->fl_wait = NULL; /* just for cleanliness */
return (1);
}
/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
* checking before calling the locks_conflict().
*/
static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
{
/* POSIX locks owned by the same process do not conflict with
* each other.
*/
if (caller_fl->fl_owner == sys_fl->fl_owner)
return (0);
return (locks_conflict(caller_fl, sys_fl));
}
/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
* checking before calling the locks_conflict().
*/
static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
{
/* FLOCK locks referring to the same filp do not conflict with
* each other.
*/
if (caller_fl->fl_file == sys_fl->fl_file)
return (0);
return (locks_conflict(caller_fl, sys_fl));
}
/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
* checks for overlapping locks and shared/exclusive status.
*/
static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
{
if (!locks_overlap(caller_fl, sys_fl))
return (0);
switch (caller_fl->fl_type) {
case F_RDLCK :
return (sys_fl->fl_type == F_WRLCK);
case F_WRLCK :
return (1);
default:
printk("locks_conflict(): impossible lock type - %d\n",
caller_fl->fl_type);
break;
}
return (0); /* This should never happen */
}
/* Check if two locks overlap each other.
*/
static int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
{
return ((fl1->fl_end >= fl2->fl_start) &&
(fl2->fl_end >= fl1->fl_start));
}
/* This function tests for deadlock condition before putting a process to
* sleep. The detection scheme is no longer recursive. Recursive was neat,
* but dangerous - we risked stack corruption if the lock data was bad, or
* if the recursion was too deep for any other reason.
*
* We rely on the fact that a task can only be on one lock's wait queue
* at a time. When we find blocked_task on a wait queue we can re-search
* with blocked_task equal to that queue's owner, until either blocked_task
* isn't found, or blocked_task is found on a queue owned by my_task.
*/
static int posix_locks_deadlock(struct task_struct *my_task,
struct task_struct *blocked_task)
{
struct wait_queue *dlock_wait;
struct file_lock *fl;
next_task:
if (my_task == blocked_task)
return (1);
for (fl = file_lock_table; fl != NULL; fl = fl->fl_nextlink) {
if (fl->fl_owner == NULL || fl->fl_wait == NULL)
continue;
dlock_wait = fl->fl_wait;
do {
if (dlock_wait->task == blocked_task) {
if (fl->fl_owner == my_task) {
return (1);
}
blocked_task = fl->fl_owner;
goto next_task;
}
dlock_wait = dlock_wait->next;
} while (dlock_wait != fl->fl_wait);
}
return (0);
}
/* Try to create a FLOCK lock on filp. We always insert new locks at
* the head of the list.
*/
static int flock_lock_file(struct file *filp, struct file_lock *caller,
unsigned int wait)
{
struct file_lock *fl;
struct file_lock *new_fl;
struct file_lock **before;
int change = 0;
before = &filp->f_inode->i_flock;
if ((fl = *before) && (fl->fl_flags & F_POSIX))
return (-EBUSY);
while ((fl = *before) != NULL) {
if (caller->fl_file == fl->fl_file) {
if (caller->fl_type == fl->fl_type)
return (0);
change = 1;
break;
}
before = &fl->fl_next;
}
/* change means that we are changing the type of an existing lock, or
* or else unlocking it.
*/
if (change)
locks_delete_lock(before, caller->fl_type != F_UNLCK);
if (caller->fl_type == F_UNLCK)
return (0);
if ((new_fl = locks_alloc_lock(caller)) == NULL)
return (-ENOLCK);
repeat:
if ((fl = filp->f_inode->i_flock) && (fl->fl_flags & F_POSIX)) {
locks_free_lock(new_fl);
return (-EBUSY);
}
while (fl != NULL) {
if (flock_locks_conflict(new_fl, fl)) {
if (!wait) {
locks_free_lock(new_fl);
return (-EAGAIN);
}
if (current->signal & ~current->blocked) {
/* Note: new_fl is not in any queue at this
* point, so we must use locks_free_lock()
* instead of locks_delete_lock()
* Dmitry Gorodchanin 09/02/96.
*/
locks_free_lock(new_fl);
return (-ERESTARTSYS);
}
locks_insert_block(fl, new_fl);
interruptible_sleep_on(&new_fl->fl_wait);
wake_up(&new_fl->fl_wait);
if (current->signal & ~current->blocked) {
/* If we are here, than we were awakened
* by a signal, so new_fl is still in the
* block queue of fl. We need to remove
* new_fl and then free it.
* Dmitry Gorodchanin 09/02/96.
*/
locks_delete_block(fl, new_fl);
locks_free_lock(new_fl);
return (-ERESTARTSYS);
}
goto repeat;
}
fl = fl->fl_next;
}
locks_insert_lock(&filp->f_inode->i_flock, new_fl);
return (0);
}
/* Add a POSIX style lock to a file.
* We merge adjacent locks whenever possible. POSIX locks come after FLOCK
* locks in the list and are sorted by owner task, then by starting address
*
* Kai Petzke writes:
* To make freeing a lock much faster, we keep a pointer to the lock before the
* actual one. But the real gain of the new coding was, that lock_it() and
* unlock_it() became one function.
*
* To all purists: Yes, I use a few goto's. Just pass on to the next function.
*/
static int posix_lock_file(struct file *filp, struct file_lock *caller,
unsigned int wait)
{
struct file_lock *fl;
struct file_lock *new_fl;
struct file_lock *left = NULL;
struct file_lock *right = NULL;
struct file_lock **before;
int added = 0;
repeat:
if ((fl = filp->f_inode->i_flock) && (fl->fl_flags & F_FLOCK))
return (-EBUSY);
if (caller->fl_type != F_UNLCK) {
while (fl != NULL) {
if (posix_locks_conflict(caller, fl)) {
if (!wait)
return (-EAGAIN);
if (current->signal & ~current->blocked)
return (-ERESTARTSYS);
if (posix_locks_deadlock(caller->fl_owner, fl->fl_owner))
return (-EDEADLOCK);
interruptible_sleep_on(&fl->fl_wait);
if (current->signal & ~current->blocked)
return (-ERESTARTSYS);
goto repeat;
}
fl = fl->fl_next;
}
}
/*
* Find the first old lock with the same owner as the new lock.
*/
before = &filp->f_inode->i_flock;
/* First skip FLOCK locks and locks owned by other processes.
*/
while ((fl = *before) && (caller->fl_owner != fl->fl_owner)) {
before = &fl->fl_next;
}
/* Process locks with this owner.
*/
while ((fl = *before) && (caller->fl_owner == fl->fl_owner)) {
/* Detect adjacent or overlapping regions (if same lock type)
*/
if (caller->fl_type == fl->fl_type) {
if (fl->fl_end < caller->fl_start - 1)
goto next_lock;
/* If the next lock in the list has entirely bigger
* addresses than the new one, insert the lock here.
*/
if (fl->fl_start > caller->fl_end + 1)
break;
/* If we come here, the new and old lock are of the
* same type and adjacent or overlapping. Make one
* lock yielding from the lower start address of both
* locks to the higher end address.
*/
if (fl->fl_start > caller->fl_start)
fl->fl_start = caller->fl_start;
else
caller->fl_start = fl->fl_start;
if (fl->fl_end < caller->fl_end)
fl->fl_end = caller->fl_end;
else
caller->fl_end = fl->fl_end;
if (added) {
locks_delete_lock(before, 0);
continue;
}
caller = fl;
added = 1;
}
else {
/* Processing for different lock types is a bit
* more complex.
*/
if (fl->fl_end < caller->fl_start)
goto next_lock;
if (fl->fl_start > caller->fl_end)
break;
if (caller->fl_type == F_UNLCK)
added = 1;
if (fl->fl_start < caller->fl_start)
left = fl;
/* If the next lock in the list has a higher end
* address than the new one, insert the new one here.
*/
if (fl->fl_end > caller->fl_end) {
right = fl;
break;
}
if (fl->fl_start >= caller->fl_start) {
/* The new lock completely replaces an old
* one (This may happen several times).
*/
if (added) {
locks_delete_lock(before, 0);
continue;
}
/* Replace the old lock with the new one.
* Wake up anybody waiting for the old one,
* as the change in lock type might satisfy
* their needs.
*/
wake_up(&fl->fl_wait);
fl->fl_start = caller->fl_start;
fl->fl_end = caller->fl_end;
fl->fl_type = caller->fl_type;
caller = fl;
added = 1;
}
}
/* Go on to next lock.
*/
next_lock:
before = &fl->fl_next;
}
if (!added) {
if (caller->fl_type == F_UNLCK)
return (0);
if ((new_fl = locks_alloc_lock(caller)) == NULL)
return (-ENOLCK);
locks_insert_lock(before, new_fl);
}
if (right) {
if (left == right) {
/* The new lock breaks the old one in two pieces, so we
* have to allocate one more lock (in this case, even
* F_UNLCK may fail!).
*/
if ((left = locks_alloc_lock(right)) == NULL) {
if (!added)
locks_delete_lock(before, 0);
return (-ENOLCK);
}
locks_insert_lock(before, left);
}
right->fl_start = caller->fl_end + 1;
wake_up(&right->fl_wait);
}
if (left) {
left->fl_end = caller->fl_start - 1;
wake_up(&left->fl_wait);
}
return (0);
}
/* Allocate memory for a new lock and initialize its fields from
* fl. The lock is not inserted into any lists until locks_insert_lock()
* or locks_insert_block() are called.
*/
static struct file_lock *locks_alloc_lock(struct file_lock *fl)
{
struct file_lock *tmp;
/* Okay, let's make a new file_lock structure... */
if ((tmp = (struct file_lock *)kmalloc(sizeof(struct file_lock),
GFP_ATOMIC)) == NULL)
return (tmp);
tmp->fl_nextlink = NULL;
tmp->fl_prevlink = NULL;
tmp->fl_next = NULL;
tmp->fl_block = NULL;
tmp->fl_flags = fl->fl_flags;
tmp->fl_owner = fl->fl_owner;
tmp->fl_file = fl->fl_file;
tmp->fl_wait = NULL;
tmp->fl_type = fl->fl_type;
tmp->fl_start = fl->fl_start;
tmp->fl_end = fl->fl_end;
return (tmp);
}
/* Insert file lock fl into an inode's lock list at the position indicated
* by pos. At the same time add the lock to the global file lock list.
*/
static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl)
{
fl->fl_nextlink = file_lock_table;
fl->fl_prevlink = NULL;
if (file_lock_table != NULL)
file_lock_table->fl_prevlink = fl;
file_lock_table = fl;
fl->fl_next = *pos; /* insert into file's list */
*pos = fl;
return;
}
/* Delete a lock and free it.
* First remove our lock from the lock lists. Then remove all the blocked
* locks from our blocked list, waking up the processes that own them. If
* told to wait, then sleep on each of these lock's wait queues. Each
* blocked process will wake up and immediately wake up its own wait queue
* allowing us to be scheduled again. Lastly, wake up our own wait queue
* before freeing the file_lock structure.
*/
static void locks_delete_lock(struct file_lock **fl_p, unsigned int wait)
{
struct file_lock *fl;
struct file_lock *pfl;
struct file_lock *nfl;
fl = *fl_p;
*fl_p = fl->fl_next;
pfl = fl->fl_prevlink;
nfl = fl->fl_nextlink;
if (nfl != NULL)
nfl->fl_prevlink = pfl;
if (pfl != NULL)
pfl->fl_nextlink = nfl;
else
file_lock_table = nfl;
while ((nfl = fl->fl_block) != NULL) {
fl->fl_block = nfl->fl_block;
nfl->fl_block = NULL;
wake_up(&nfl->fl_wait);
if (wait)
sleep_on(&nfl->fl_wait);
}
wake_up(&fl->fl_wait);
kfree(fl);
return;
}
static char *lock_get_status(struct file_lock *fl, char *p, int id, char *pfx)
{
struct wait_queue *wt;
p += sprintf(p, "%d:%s ", id, pfx);
if (fl->fl_flags & F_POSIX) {
#ifdef CONFIG_LOCK_MANDATORY
p += sprintf(p, "%s %s ",
(fl->fl_flags & F_BROKEN) ? "BROKEN" : "POSIX ",
((fl->fl_file->f_inode->i_mode & (S_IXGRP | S_ISGID))
== S_ISGID) ? "MANDATORY" : "ADVISORY ");
#else
p += sprintf(p, "%s ADVISORY ",
(fl->fl_flags & F_BROKEN) ? "BROKEN" : "POSIX ");
#endif
}
else {
p += sprintf(p, "FLOCK ADVISORY ");
}
p += sprintf(p, "%s ", (fl->fl_type == F_RDLCK) ? "READ " : "WRITE");
p += sprintf(p, "%d %s:%ld %ld %ld ",
fl->fl_owner ? fl->fl_owner->pid : 0,
kdevname(fl->fl_file->f_inode->i_dev),
fl->fl_file->f_inode->i_ino, fl->fl_start,
fl->fl_end);
p += sprintf(p, "%08lx %08lx %08lx %08lx %08lx\n%d:%s",
(long)fl, (long)fl->fl_prevlink, (long)fl->fl_nextlink,
(long)fl->fl_next, (long)fl->fl_block, id, pfx);
if ((wt = fl->fl_wait) != NULL) {
do {
p += sprintf(p, " %d", wt->task->pid);
wt = wt->next;
} while (wt != fl->fl_wait);
}
p += sprintf(p, "\n");
return (p);
}
int get_locks_status(char *buf)
{
struct file_lock *fl;
struct file_lock *bfl;
char *p;
int i;
p = buf;
for (fl = file_lock_table, i = 1; fl != NULL; fl = fl->fl_nextlink, i++) {
p = lock_get_status(fl, p, i, "");
for (bfl = fl; bfl->fl_block != NULL; bfl = bfl->fl_block)
p = lock_get_status(bfl->fl_block, p, i, " ->");
}
return (p - buf);
}