X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=fs%2Flocks.c;fp=fs%2Flocks.c;h=af50ed20ded201fa0d8dde81266cf6e3c5cda0f6;hb=16c70f8c1b54b61c3b951b6fb220df250fe09b32;hp=7189834098a1b4ef1c1886de4d050e1f05ab7eef;hpb=4e76c8a9fa413ccc09d3f7f664183dcce3555d57;p=linux-2.6.git diff --git a/fs/locks.c b/fs/locks.c index 718983409..af50ed20d 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -715,7 +715,7 @@ EXPORT_SYMBOL(posix_test_lock); * 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; @@ -734,11 +734,13 @@ next_task: 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) { @@ -749,6 +751,8 @@ 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)) @@ -764,8 +768,11 @@ static int flock_lock_file(struct file *filp, struct file_lock *request) 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(); @@ -778,6 +785,7 @@ static int flock_lock_file(struct file *filp, struct file_lock *request) if (found) cond_resched(); +find_conflict: for_each_lock(inode, before) { struct file_lock *fl = *before; if (IS_POSIX(fl)) @@ -791,6 +799,8 @@ static int flock_lock_file(struct file *filp, struct file_lock *request) 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); @@ -808,7 +818,8 @@ static int __posix_lock_file_conf(struct inode *inode, struct file_lock *request 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; @@ -817,13 +828,19 @@ static int __posix_lock_file_conf(struct inode *inode, struct file_lock *request /* * 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) { @@ -852,14 +869,7 @@ static int __posix_lock_file_conf(struct inode *inode, struct file_lock *request 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. */ @@ -956,10 +966,28 @@ static int __posix_lock_file_conf(struct inode *inode, struct file_lock *request 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; @@ -1001,6 +1029,10 @@ static int __posix_lock_file_conf(struct inode *inode, struct file_lock *request * 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) { @@ -1909,19 +1941,18 @@ out: */ 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; @@ -1930,25 +1961,11 @@ void locks_remove_posix(struct file *filp, fl_owner_t 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); } @@ -2238,63 +2255,6 @@ int lock_may_write(struct inode *inode, loff_t start, unsigned long len) 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",