Return-Path: linux-nfs-owner@vger.kernel.org Received: from fieldses.org ([174.143.236.118]:43940 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759449Ab2IEUzg (ORCPT ); Wed, 5 Sep 2012 16:55:36 -0400 From: "J. Bruce Fields" To: Al Viro Cc: linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, "J. Bruce Fields" , David Howells , Tyler Hicks , Dustin Kirkland Subject: [RFC PATCH 09/13] locks: break delegations on unlink Date: Wed, 5 Sep 2012 16:55:19 -0400 Message-Id: <1346878524-10585-10-git-send-email-bfields@redhat.com> In-Reply-To: <1346878524-10585-1-git-send-email-bfields@redhat.com> References: <1346878524-10585-1-git-send-email-bfields@redhat.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: From: "J. Bruce Fields" We need to break delegations on any operation that changes the set of links pointing to an inode. Start with unlink. Such operations also hold the i_mutex on a parent directory. Breaking a delegation may require waiting for a timeout (by default 90 seconds) in the case of a unresponsive NFS client. To avoid blocking all directory operations, we therefore drop locks before waiting for the delegation. The logic then looks like: acquire locks ... test for delegation; if found: take reference on inode release locks wait for delegation break drop reference on inode retry It is possible this could never terminate. (Even if we take precautions to prevent another delegation being acquired on the same inode, we could get a different inode on each retry.) But this seems very unlikely. The initial test for a delegation happens after the lock on the target inode is acquired, but the directory inode may have been acquired further up the call stack. We therefore add a "struct inode **" argument to any intervening functions, which we use to pass the inode back up to the caller in the case it needs a delegation synchronously broken. Cc: David Howells Cc: Tyler Hicks Cc: Dustin Kirkland Signed-off-by: J. Bruce Fields --- drivers/base/devtmpfs.c | 2 +- fs/cachefiles/namei.c | 2 +- fs/ecryptfs/inode.c | 2 +- fs/namei.c | 23 ++++++++++++++++++++--- fs/nfsd/vfs.c | 2 +- include/linux/fs.h | 2 +- ipc/mqueue.c | 2 +- 7 files changed, 26 insertions(+), 9 deletions(-) diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c index deb4a45..24162ec 100644 --- a/drivers/base/devtmpfs.c +++ b/drivers/base/devtmpfs.c @@ -317,7 +317,7 @@ static int handle_remove(const char *nodename, struct device *dev) mutex_lock(&dentry->d_inode->i_mutex); notify_change(dentry, &newattrs); mutex_unlock(&dentry->d_inode->i_mutex); - err = vfs_unlink(parent.dentry->d_inode, dentry); + err = vfs_unlink(parent.dentry->d_inode, dentry, NULL); if (!err || err == -ENOENT) deleted = 1; } diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c index b0b5f7c..10cf5c6 100644 --- a/fs/cachefiles/namei.c +++ b/fs/cachefiles/namei.c @@ -295,7 +295,7 @@ static int cachefiles_bury_object(struct cachefiles_cache *cache, if (ret < 0) { cachefiles_io_error(cache, "Unlink security error"); } else { - ret = vfs_unlink(dir->d_inode, rep); + ret = vfs_unlink(dir->d_inode, rep, NULL); if (preemptive) cachefiles_mark_object_buried(cache, rep); diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c index 534b129..17b917f 100644 --- a/fs/ecryptfs/inode.c +++ b/fs/ecryptfs/inode.c @@ -153,7 +153,7 @@ static int ecryptfs_do_unlink(struct inode *dir, struct dentry *dentry, dget(lower_dentry); lower_dir_dentry = lock_parent(lower_dentry); - rc = vfs_unlink(lower_dir_inode, lower_dentry); + rc = vfs_unlink(lower_dir_inode, lower_dentry, NULL); if (rc) { printk(KERN_ERR "Error in vfs_unlink; rc = [%d]\n", rc); goto out_unlock; diff --git a/fs/namei.c b/fs/namei.c index 10d6622..bdf1dca 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -3305,7 +3305,7 @@ SYSCALL_DEFINE1(rmdir, const char __user *, pathname) return do_rmdir(AT_FDCWD, pathname); } -int vfs_unlink(struct inode *dir, struct dentry *dentry) +int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) { struct inode *target = dentry->d_inode; int error = may_delete(dir, dentry, 0); @@ -3322,11 +3322,20 @@ int vfs_unlink(struct inode *dir, struct dentry *dentry) else { error = security_inode_unlink(dir, dentry); if (!error) { + error = break_deleg(target, O_WRONLY|O_NONBLOCK); + if (error) { + if (error == -EWOULDBLOCK && delegated_inode) { + *delegated_inode = target; + ihold(target); + } + goto out; + } error = dir->i_op->unlink(dir, dentry); if (!error) dont_mount(dentry); } } +out: mutex_unlock(&target->i_mutex); /* We don't d_delete() NFS sillyrenamed files--they still exist. */ @@ -3351,6 +3360,7 @@ static long do_unlinkat(int dfd, const char __user *pathname) struct dentry *dentry; struct nameidata nd; struct inode *inode = NULL; + struct inode *delegated_inode = NULL; error = user_path_parent(dfd, pathname, &nd, &name); if (error) @@ -3364,7 +3374,7 @@ static long do_unlinkat(int dfd, const char __user *pathname) error = mnt_want_write(nd.path.mnt); if (error) goto exit1; - +retry_deleg: mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); dentry = lookup_hash(&nd); error = PTR_ERR(dentry); @@ -3379,13 +3389,20 @@ static long do_unlinkat(int dfd, const char __user *pathname) error = security_path_unlink(&nd.path, dentry); if (error) goto exit2; - error = vfs_unlink(nd.path.dentry->d_inode, dentry); + error = vfs_unlink(nd.path.dentry->d_inode, dentry, &delegated_inode); exit2: dput(dentry); } mutex_unlock(&nd.path.dentry->d_inode->i_mutex); if (inode) iput(inode); /* truncate the inode here */ + if (delegated_inode) { + error = break_deleg(delegated_inode, O_WRONLY); + iput(delegated_inode); + delegated_inode = NULL; + if (!error) + goto retry_deleg; + } mnt_drop_write(nd.path.mnt); exit1: path_put(&nd.path); diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index a9269f1..9c39d26 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -1893,7 +1893,7 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, if (host_err) goto out_put; if (type != S_IFDIR) - host_err = vfs_unlink(dirp, rdentry); + host_err = vfs_unlink(dirp, rdentry, NULL); else host_err = vfs_rmdir(dirp, rdentry); if (!host_err) diff --git a/include/linux/fs.h b/include/linux/fs.h index 73157f7..6eb70a7 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1723,7 +1723,7 @@ extern int vfs_mknod(struct inode *, struct dentry *, umode_t, dev_t); extern int vfs_symlink(struct inode *, struct dentry *, const char *); extern int vfs_link(struct dentry *, struct inode *, struct dentry *); extern int vfs_rmdir(struct inode *, struct dentry *); -extern int vfs_unlink(struct inode *, struct dentry *); +extern int vfs_unlink(struct inode *, struct dentry *, struct inode **); extern int vfs_rename(struct inode *, struct dentry *, struct inode *, struct dentry *); /* diff --git a/ipc/mqueue.c b/ipc/mqueue.c index f8e54f5..910b5ea 100644 --- a/ipc/mqueue.c +++ b/ipc/mqueue.c @@ -881,7 +881,7 @@ SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name) err = mnt_want_write(ipc_ns->mq_mnt); if (err) goto out_err; - err = vfs_unlink(dentry->d_parent->d_inode, dentry); + err = vfs_unlink(dentry->d_parent->d_inode, dentry, NULL); mnt_drop_write(ipc_ns->mq_mnt); out_err: dput(dentry); -- 1.7.9.5