int locks_mandatory_area(int read_write, struct inode *inode, struct file *filp, unsigned int offset, unsigned int count) { struct file_lock *fl; struct file_lock tfl; memset(&tfl, 0, sizeof(tfl)); tfl.fl_file = filp; tfl.fl_flags = FL_POSIX | FL_ACCESS; tfl.fl_owner = current; tfl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK; tfl.fl_start = offset; tfl.fl_end = offset + count - 1; repeat: /* If there are no FL_POSIX locks then go ahead. */ if (!(fl = inode->i_flock) || !(fl->fl_flags & FL_POSIX)) return (0); /* Search the lock list for this inode for locks that conflict with * the proposed read/write. */ while (fl != NULL) { /* Block for writes against a "read" lock, * and both reads and writes against a "write" lock. */ if (posix_locks_conflict(fl, &tfl)) { 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 (-EDEADLK); locks_insert_block(fl, &tfl); interruptible_sleep_on(&tfl.fl_wait); locks_delete_block(fl, &tfl); 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; } fl = fl->fl_next; } return (0); }
struct file_lock * posix_test_lock(struct file *filp, struct file_lock *fl) { struct file_lock *cfl; for (cfl = filp->f_dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) { if (!(cfl->fl_flags & FL_POSIX)) continue; if (posix_locks_conflict(cfl, fl)) break; } return (cfl); }
/* 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); }
static int posix_lock_file(struct file *filp, struct file_lock *caller, unsigned int wait) { struct file_lock *fl; struct file_lock *new_fl, *new_fl2; struct file_lock *left = NULL; struct file_lock *right = NULL; struct file_lock **before; int error; int added = 0; /* * We may need two file_lock structures for this operation, * so we get them in advance to avoid races. */ new_fl = locks_empty_lock(); new_fl2 = locks_empty_lock(); error = -ENOLCK; /* "no luck" */ if (!(new_fl && new_fl2)) goto out; if (caller->fl_type != F_UNLCK) { repeat: error = -EBUSY; if ((fl = filp->f_inode->i_flock) && (fl->fl_flags & FL_FLOCK)) goto out; while (fl != NULL) { if (!posix_locks_conflict(caller, fl)) { fl = fl->fl_next; continue; } error = -EAGAIN; if (!wait) goto out; error = -EDEADLK; if (posix_locks_deadlock(caller->fl_owner, fl->fl_owner)) goto out; error = -ERESTARTSYS; if (current->signal & ~current->blocked) goto out; locks_insert_block(fl, caller); interruptible_sleep_on(&caller->fl_wait); locks_delete_block(fl, caller); goto repeat; } } /* * 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 = &filp->f_inode->i_flock; error = -EBUSY; if ((*before != NULL) && ((*before)->fl_flags & FL_FLOCK)) goto out; /* First skip 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. */ locks_wake_up_blocks(fl, 0); 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; } error = 0; if (!added) { if (caller->fl_type == F_UNLCK) goto out; locks_init_lock(new_fl, caller); locks_insert_lock(before, new_fl); new_fl = NULL; } if (right) { if (left == right) { /* The new lock breaks the old one in two pieces, * so we have to use the second new lock (in this * case, even F_UNLCK may fail!). */ left = locks_init_lock(new_fl2, right); locks_insert_lock(before, left); new_fl2 = NULL; } right->fl_start = caller->fl_end + 1; locks_wake_up_blocks(right, 0); } if (left) { left->fl_end = caller->fl_start - 1; locks_wake_up_blocks(left, 0); } out: /* * Free any unused locks. (They haven't * ever been used, so we use kfree().) */ if (new_fl) kfree(new_fl); if (new_fl2) kfree(new_fl2); return error; }
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 (-EDEADLK); 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); }