From: "J. Bruce Fields" <bfields@redhat.com>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
"J. Bruce Fields" <bfields@redhat.com>,
David Howells <dhowells@redhat.com>,
Tyler Hicks <tyhicks@canonical.com>,
Dustin Kirkland <dustin.kirkland@gazzang.com>
Subject: [RFC PATCH 09/13] locks: break delegations on unlink
Date: Wed, 5 Sep 2012 16:55:19 -0400 [thread overview]
Message-ID: <1346878524-10585-10-git-send-email-bfields@redhat.com> (raw)
In-Reply-To: <1346878524-10585-1-git-send-email-bfields@redhat.com>
From: "J. Bruce Fields" <bfields@redhat.com>
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 <dhowells@redhat.com>
Cc: Tyler Hicks <tyhicks@canonical.com>
Cc: Dustin Kirkland <dustin.kirkland@gazzang.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
---
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
next prev parent reply other threads:[~2012-09-05 20:55 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-05 20:55 [RFC PATCH 00/13] Implement NFSv4 delegations, take 4 J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 01/13] gfs2: Get rid of I_MUTEX_QUOTA usage J. Bruce Fields
2012-09-05 20:59 ` J. Bruce Fields
2012-09-06 14:27 ` Steven Whitehouse
2012-09-06 17:08 ` J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 02/13] vfs: pull ext4's double-i_mutex-locking into common code J. Bruce Fields
2012-09-06 2:53 ` Guo Chao
2012-09-06 13:49 ` J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 03/13] vfs: don't use PARENT/CHILD lock classes for non-directories J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 04/13] vfs: rename I_MUTEX_QUOTA now that it's not used for quotas J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 05/13] vfs: take i_mutex on renamed file J. Bruce Fields
2012-09-06 3:05 ` Guo Chao
2012-09-06 17:51 ` J. Bruce Fields
2012-09-07 2:27 ` Guo Chao
2012-09-07 21:39 ` J. Bruce Fields
2012-09-10 2:40 ` Guo Chao
2012-09-10 5:10 ` Ram Pai
2012-09-10 6:37 ` Guo Chao
2012-09-10 7:27 ` Ram Pai
2013-02-14 2:01 ` Al Viro
2012-09-10 14:35 ` J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 06/13] locks: introduce new FL_DELEG lock flag J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 07/13] locks: implement delegations J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 08/13] namei: minor vfs_unlink cleanup J. Bruce Fields
2012-09-05 20:55 ` J. Bruce Fields [this message]
2012-09-05 20:55 ` [RFC PATCH 10/13] locks: helper functions for delegation breaking J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 11/13] locks: break delegations on rename J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 12/13] locks: break delegations on link J. Bruce Fields
2012-09-05 21:02 ` J. Bruce Fields
2012-09-06 11:01 ` Jeff Layton
2012-09-06 13:33 ` J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 13/13] locks: break delegations on any attribute modification J. Bruce Fields
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