Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 3 Jun 2002 20:38:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 3 Jun 2002 20:38:23 -0400 Received: from supreme.pcug.org.au ([203.10.76.34]:42650 "EHLO pcug.org.au") by vger.kernel.org with ESMTP id ; Mon, 3 Jun 2002 20:38:19 -0400 Date: Tue, 4 Jun 2002 10:37:52 +1000 From: Stephen Rothwell To: Marcelo Tosatti Cc: LKML , Matthew Wilcox , "Michael Kerrisk" Subject: [PATCH] Make file leases more stable Message-Id: <20020604103752.4e030763.sfr@canb.auug.org.au> X-Mailer: Sylpheed version 0.7.6 (GTK+ 1.2.10; i386-debian-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi Marcelo, If you deem it appropriate, please apply this patch. It makes the file leases much more stable and reliable in the presence of multiple shared leases. This patch cannot make things worse than they currently are. :-) There is a further problem with leases that I am working on, but that is harder and will require more testing. -- Cheers, Stephen Rothwell sfr@canb.auug.org.au http://www.canb.auug.org.au/~sfr/ diff -ruN 2.4.19-pre9/fs/locks.c 2.4.19-pre9-leases.1/fs/locks.c --- 2.4.19-pre9/fs/locks.c Wed Oct 24 16:12:29 2001 +++ 2.4.19-pre9-leases.1/fs/locks.c Wed May 29 10:38:57 2002 @@ -1051,6 +1051,30 @@ return -EINVAL; } +/* We already had a lease on this file; just change its type */ +static int lease_modify(struct file_lock **before, int arg) +{ + struct file_lock *fl = *before; + int error = assign_type(fl, arg); + if (error < 0) + goto out; + + locks_wake_up_blocks(fl, 0); + + if (arg == F_UNLCK) { + struct file *filp = fl->fl_file; + + filp->f_owner.pid = 0; + filp->f_owner.uid = 0; + filp->f_owner.euid = 0; + filp->f_owner.signum = 0; + locks_delete_lock(before, 0); + } + +out: + return error; +} + /** * __get_lease - revoke all outstanding leases on file * @inode: the inode of the file to return @@ -1068,10 +1092,15 @@ struct file_lock *fl; int alloc_err; - alloc_err = lease_alloc(NULL, 0, &new_fl); + alloc_err = lease_alloc(NULL, mode & FMODE_WRITE ? F_WRLCK : F_RDLCK, + &new_fl); lock_kernel(); + flock = inode->i_flock; + if ((flock->fl_flags & FL_LEASE) == 0) + goto out; + if (flock->fl_type & F_INPROGRESS) { if ((mode & O_NONBLOCK) || (flock->fl_owner == current->files)) { @@ -1111,11 +1140,10 @@ fl = flock; do { fl->fl_type = future; + kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG); fl = fl->fl_next; } while (fl != NULL && (fl->fl_flags & FL_LEASE)); - kill_fasync(&flock->fl_fasync, SIGIO, POLL_MSG); - if ((mode & O_NONBLOCK) || (flock->fl_owner == current->files)) { error = -EWOULDBLOCK; goto out; @@ -1128,13 +1156,30 @@ restart: error = locks_block_on_timeout(flock, new_fl, error); if (error == 0) { - /* We timed out. Unilaterally break the lease. */ - locks_delete_lock(&inode->i_flock, 0); - printk(KERN_WARNING "lease timed out\n"); + struct file_lock **fp; + /* We timed out. Unilaterally break any leases that + * are still in the process of being broken. + */ + fp = &inode->i_flock; + while (((fl = *fp) != NULL) && (fl->fl_flags & FL_LEASE)) { + if (!(fl->fl_type & F_INPROGRESS)) { + fp = &fl->fl_next; + continue; + } + printk(KERN_INFO "lease broken - owner pid = %d\n", + fl->fl_pid); + lease_modify(fp, fl->fl_type & ~F_INPROGRESS); + if (fl == *fp) + fp = &fl->fl_next; + } } else if (error > 0) { - flock = inode->i_flock; - if (flock && (flock->fl_flags & FL_LEASE)) - goto restart; + /* Wait for the next lease that has not been broken yet */ + for (flock = inode->i_flock; + flock && flock->fl_flags & FL_LEASE; + flock = flock->fl_next) { + if (flock->fl_type & F_INPROGRESS) + goto restart; + } error = 0; } @@ -1166,45 +1211,40 @@ * @filp: the file * * The value returned by this function will be one of + * (if no lease break is pending): * - * %F_RDLCK to indicate a read-only (type II) lease is held. + * %F_RDLCK to indicate a shared lease is held. * * %F_WRLCK to indicate an exclusive lease is held. * - * XXX: sfr & i disagree over whether F_INPROGRESS + * %F_UNLCK to indicate no lease is held. + * + * (if a lease break is pending): + * + * %F_RDLCK to indicate an exclusive lease needs to be + * changed to a shared lease (or removed). + * + * %F_UNLCK to indicate the lease needs to be removed. + * + * XXX: sfr & willy disagree over whether F_INPROGRESS * should be returned to userspace. */ int fcntl_getlease(struct file *filp) { struct file_lock *fl; - - fl = filp->f_dentry->d_inode->i_flock; - if ((fl == NULL) || ((fl->fl_flags & FL_LEASE) == 0)) - return F_UNLCK; - return fl->fl_type & ~F_INPROGRESS; -} + int type = F_UNLCK; -/* We already had a lease on this file; just change its type */ -static int lease_modify(struct file_lock **before, int arg, int fd, struct file *filp) -{ - struct file_lock *fl = *before; - int error = assign_type(fl, arg); - if (error < 0) - goto out; - - locks_wake_up_blocks(fl, 0); - - if (arg == F_UNLCK) { - filp->f_owner.pid = 0; - filp->f_owner.uid = 0; - filp->f_owner.euid = 0; - filp->f_owner.signum = 0; - locks_delete_lock(before, 0); - fasync_helper(fd, filp, 0, &fl->fl_fasync); + lock_kernel(); + for (fl = filp->f_dentry->d_inode->i_flock; + fl && (fl->fl_flags & FL_LEASE); + fl = fl->fl_next) { + if (fl->fl_file == filp) { + type = fl->fl_type & ~F_INPROGRESS; + break; + } } - -out: - return error; + unlock_kernel(); + return type; } /** @@ -1224,32 +1264,36 @@ struct inode *inode; int error, rdlease_count = 0, wrlease_count = 0; + lock_kernel(); + dentry = filp->f_dentry; inode = dentry->d_inode; + error = -EACCES; if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE)) - return -EACCES; + goto out_unlock; + error = -EINVAL; if (!S_ISREG(inode->i_mode)) - return -EINVAL; + goto out_unlock; /* * FIXME: What about F_RDLCK and files open for writing? */ + error = -EAGAIN; if ((arg == F_WRLCK) && ((atomic_read(&dentry->d_count) > 1) || (atomic_read(&inode->i_count) > 1))) - return -EAGAIN; + goto out_unlock; before = &inode->i_flock; - lock_kernel(); - while ((fl = *before) != NULL) { if (fl->fl_flags != FL_LEASE) break; if (fl->fl_file == filp) my_before = before; - else if (fl->fl_type & F_WRLCK) + else if ((fl->fl_type & F_WRLCK) + || (fl->fl_type == (F_INPROGRESS | F_UNLCK))) wrlease_count++; else rdlease_count++; @@ -1263,7 +1307,7 @@ } if (my_before != NULL) { - error = lease_modify(my_before, arg, fd, filp); + error = lease_modify(my_before, arg); goto out_unlock; } @@ -1710,10 +1754,15 @@ before = &inode->i_flock; while ((fl = *before) != NULL) { - if ((fl->fl_flags & (FL_FLOCK|FL_LEASE)) - && (fl->fl_file == filp)) { - locks_delete_lock(before, 0); - continue; + if (fl->fl_file == filp) { + if (fl->fl_flags & FL_FLOCK) { + locks_delete_lock(before, 0); + continue; + } + if (fl->fl_flags & FL_LEASE) { + lease_modify(before, F_UNLCK); + continue; + } } before = &fl->fl_next; } @@ -1769,7 +1818,13 @@ #endif out += sprintf(out, "FLOCK ADVISORY "); } else if (fl->fl_flags & FL_LEASE) { - out += sprintf(out, "LEASE MANDATORY "); + out += sprintf(out, "LEASE "); + if (fl->fl_type & F_INPROGRESS) + out += sprintf(out, "BREAKING "); + else if (fl->fl_file) + out += sprintf(out, "ACTIVE "); + else + out += sprintf(out, "BREAKER "); } else { out += sprintf(out, "UNKNOWN UNKNOWN "); } @@ -1782,7 +1837,9 @@ } else #endif out += sprintf(out, "%s ", - (fl->fl_type & F_WRLCK) ? "WRITE" : "READ "); + (fl->fl_type & F_INPROGRESS) + ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ " + : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ "); out += sprintf(out, "%d %s:%ld ", fl->fl_pid, inode ? kdevname(inode->i_dev) : "", - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/