* from a broken NFS client. But broken NFS clients have a lot more to
* worry about than proper deadlock detection anyway... --okir
*/
-int posix_locks_deadlock(struct file_lock *caller_fl,
+static int posix_locks_deadlock(struct file_lock *caller_fl,
struct file_lock *block_fl)
{
struct list_head *tmp;
return 0;
}
-EXPORT_SYMBOL(posix_locks_deadlock);
-
/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
* at the head of the list, but that's secret knowledge known only to
* flock_lock_file and posix_lock_file.
+ *
+ * Note that if called with an FL_EXISTS argument, the caller may determine
+ * whether or not a lock was successfully freed by testing the return
+ * value for -ENOENT.
*/
static int flock_lock_file(struct file *filp, struct file_lock *request)
{
int found = 0;
lock_kernel();
+ if (request->fl_flags & FL_ACCESS)
+ goto find_conflict;
for_each_lock(inode, before) {
struct file_lock *fl = *before;
if (IS_POSIX(fl))
break;
}
- if (request->fl_type == F_UNLCK)
+ if (request->fl_type == F_UNLCK) {
+ if ((request->fl_flags & FL_EXISTS) && !found)
+ error = -ENOENT;
goto out;
+ }
error = -ENOMEM;
new_fl = locks_alloc_lock();
if (found)
cond_resched();
+find_conflict:
for_each_lock(inode, before) {
struct file_lock *fl = *before;
if (IS_POSIX(fl))
locks_insert_block(fl, request);
goto out;
}
+ if (request->fl_flags & FL_ACCESS)
+ goto out;
locks_copy_lock(new_fl, request);
vx_locks_inc(new_fl);
locks_insert_lock(&inode->i_flock, new_fl);
struct file_lock *conflock, xid_t xid)
{
struct file_lock *fl;
- struct file_lock *new_fl, *new_fl2;
+ struct file_lock *new_fl = NULL;
+ struct file_lock *new_fl2 = NULL;
struct file_lock *left = NULL;
struct file_lock *right = NULL;
struct file_lock **before;
/*
* We may need two file_lock structures for this operation,
* so we get them in advance to avoid races.
+ *
+ * In some cases we can be sure, that no new locks will be needed
*/
- new_fl = locks_alloc_lock();
- new_fl->fl_xid = xid;
- vx_locks_inc(new_fl);
- new_fl2 = locks_alloc_lock();
- new_fl2->fl_xid = xid;
- vx_locks_inc(new_fl2);
+ if (!(request->fl_flags & FL_ACCESS) &&
+ (request->fl_type != F_UNLCK ||
+ request->fl_start != 0 || request->fl_end != OFFSET_MAX)) {
+ new_fl = locks_alloc_lock();
+ new_fl->fl_xid = xid;
+ vx_locks_inc(new_fl);
+ new_fl2 = locks_alloc_lock();
+ new_fl2->fl_xid = xid;
+ vx_locks_inc(new_fl2);
+ }
lock_kernel();
if (request->fl_type != F_UNLCK) {
if (request->fl_flags & FL_ACCESS)
goto out;
- error = -ENOLCK; /* "no luck" */
- if (!(new_fl && new_fl2))
- goto out;
-
/*
- * We've allocated the new locks in advance, so there are no
- * errors possible (and no blocking operations) from here on.
- *
* Find the first old lock with the same owner as the new lock.
*/
before = &fl->fl_next;
}
+ /*
+ * The above code only modifies existing locks in case of
+ * merging or replacing. If new lock(s) need to be inserted
+ * all modifications are done bellow this, so it's safe yet to
+ * bail out.
+ */
+ error = -ENOLCK; /* "no luck" */
+ if (right && left == right && !new_fl2)
+ goto out;
+
error = 0;
if (!added) {
- if (request->fl_type == F_UNLCK)
+ if (request->fl_type == F_UNLCK) {
+ if (request->fl_flags & FL_EXISTS)
+ error = -ENOENT;
goto out;
+ }
+
+ if (!new_fl) {
+ error = -ENOLCK;
+ goto out;
+ }
locks_copy_lock(new_fl, request);
locks_insert_lock(before, new_fl);
new_fl = NULL;
* Add a POSIX style lock to a file.
* We merge adjacent & overlapping locks whenever possible.
* POSIX locks are sorted by owner task, then by starting address
+ *
+ * Note that if called with an FL_EXISTS argument, the caller may determine
+ * whether or not a lock was successfully freed by testing the return
+ * value for -ENOENT.
*/
int posix_lock_file(struct file *filp, struct file_lock *fl)
{
*/
void locks_remove_posix(struct file *filp, fl_owner_t owner)
{
- struct file_lock lock, **before;
+ struct file_lock lock;
/*
* If there are no locks held on this file, we don't need to call
* posix_lock_file(). Another process could be setting a lock on this
* file at the same time, but we wouldn't remove that lock anyway.
*/
- before = &filp->f_dentry->d_inode->i_flock;
- if (*before == NULL)
+ if (!filp->f_dentry->d_inode->i_flock)
return;
lock.fl_type = F_UNLCK;
- lock.fl_flags = FL_POSIX;
+ lock.fl_flags = FL_POSIX | FL_CLOSE;
lock.fl_start = 0;
lock.fl_end = OFFSET_MAX;
lock.fl_owner = owner;
lock.fl_ops = NULL;
lock.fl_lmops = NULL;
- if (filp->f_op && filp->f_op->lock != NULL) {
+ if (filp->f_op && filp->f_op->lock != NULL)
filp->f_op->lock(filp, F_SETLK, &lock);
- goto out;
- }
+ else
+ posix_lock_file(filp, &lock);
- /* Can't use posix_lock_file here; we need to remove it no matter
- * which pid we have.
- */
- lock_kernel();
- while (*before != NULL) {
- struct file_lock *fl = *before;
- if (IS_POSIX(fl) && posix_same_owner(fl, &lock)) {
- locks_delete_lock(before);
- continue;
- }
- before = &fl->fl_next;
- }
- unlock_kernel();
-out:
if (lock.fl_ops && lock.fl_ops->fl_release_private)
lock.fl_ops->fl_release_private(&lock);
}
EXPORT_SYMBOL(lock_may_write);
-static inline void __steal_locks(struct file *file, fl_owner_t from)
-{
- struct inode *inode = file->f_dentry->d_inode;
- struct file_lock *fl = inode->i_flock;
-
- while (fl) {
- if (fl->fl_file == file && fl->fl_owner == from)
- fl->fl_owner = current->files;
- fl = fl->fl_next;
- }
-}
-
-/* When getting ready for executing a binary, we make sure that current
- * has a files_struct on its own. Before dropping the old files_struct,
- * we take over ownership of all locks for all file descriptors we own.
- * Note that we may accidentally steal a lock for a file that a sibling
- * has created since the unshare_files() call.
- */
-void steal_locks(fl_owner_t from)
-{
- struct files_struct *files = current->files;
- int i, j;
- struct fdtable *fdt;
-
- if (from == files)
- return;
-
- lock_kernel();
- j = 0;
-
- /*
- * We are not taking a ref to the file structures, so
- * we need to acquire ->file_lock.
- */
- spin_lock(&files->file_lock);
- fdt = files_fdtable(files);
- for (;;) {
- unsigned long set;
- i = j * __NFDBITS;
- if (i >= fdt->max_fdset || i >= fdt->max_fds)
- break;
- set = fdt->open_fds->fds_bits[j++];
- while (set) {
- if (set & 1) {
- struct file *file = fdt->fd[i];
- if (file)
- __steal_locks(file, from);
- }
- i++;
- set >>= 1;
- }
- }
- spin_unlock(&files->file_lock);
- unlock_kernel();
-}
-EXPORT_SYMBOL(steal_locks);
-
static int __init filelock_init(void)
{
filelock_cache = kmem_cache_create("file_lock_cache",
git://git.onelab.eu / linux-2.6.git / blobdiff