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,
Linus Torvalds <torvalds@linux-foundation.org>,
"J. Bruce Fields" <bfields@redhat.com>,
David Howells <dhowells@redhat.com>,
Tyler Hicks <tyhicks@canonical.com>,
Dustin Kirkland <dustin.kirkland@gazzang.com>
Subject: [PATCH 08/12] locks: break delegations on unlink
Date: Tue, 16 Apr 2013 21:46:20 -0400 [thread overview]
Message-ID: <1366163185-10317-9-git-send-email-bfields@redhat.com> (raw)
In-Reply-To: <1366163185-10317-1-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 | 24 +++++++++++++++++++++---
fs/nfsd/vfs.c | 2 +-
include/linux/fs.h | 2 +-
ipc/mqueue.c | 2 +-
7 files changed, 27 insertions(+), 9 deletions(-)
diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
index 01fc5b0..288f64b 100644
--- a/drivers/base/devtmpfs.c
+++ b/drivers/base/devtmpfs.c
@@ -318,7 +318,7 @@ 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 8c01c5fc..d61d884 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -294,7 +294,7 @@ 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 5eab400..af42d88 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 0c2ee90..6b8698f 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3384,7 +3384,7 @@ 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);
@@ -3401,11 +3401,20 @@ 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. */
@@ -3430,6 +3439,7 @@ 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;
unsigned int lookup_flags = 0;
retry:
name = user_path_parent(dfd, pathname, &nd, lookup_flags);
@@ -3444,7 +3454,7 @@ retry:
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);
@@ -3459,13 +3469,21 @@ retry:
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 */
+ inode = NULL;
+ 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 2b2e239..b32c66b 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1884,7 +1884,7 @@ 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 8c78d0d..f2d0194 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1461,7 +1461,7 @@ 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 e4e47f6..384eb35 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -884,7 +884,7 @@ SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
err = -ENOENT;
} else {
ihold(inode);
- err = vfs_unlink(dentry->d_parent->d_inode, dentry);
+ err = vfs_unlink(dentry->d_parent->d_inode, dentry, NULL);
}
dput(dentry);
--
1.7.9.5
next prev parent reply other threads:[~2013-04-17 1:46 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-17 1:46 [PATCH 00/12] Implement NFSv4 delegations, take 7 J. Bruce Fields
2013-04-17 1:46 ` [PATCH 01/12] vfs: pull ext4's double-i_mutex-locking into common code J. Bruce Fields
2013-04-17 1:46 ` [PATCH 03/12] vfs: rename I_MUTEX_QUOTA now that it's not used for quotas J. Bruce Fields
[not found] ` <1366163185-10317-1-git-send-email-bfields-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2013-04-17 1:46 ` [PATCH 02/12] vfs: don't use PARENT/CHILD lock classes for non-directories J. Bruce Fields
2013-04-17 1:46 ` [PATCH 04/12] vfs: take i_mutex on renamed file J. Bruce Fields
2013-04-17 1:46 ` [PATCH 07/12] namei: minor vfs_unlink cleanup J. Bruce Fields
2013-04-17 1:46 ` [PATCH 10/12] locks: break delegations on rename J. Bruce Fields
2013-04-17 1:46 ` [PATCH 05/12] locks: introduce new FL_DELEG lock flag J. Bruce Fields
2013-04-17 1:46 ` [PATCH 06/12] locks: implement delegations J. Bruce Fields
2013-04-17 1:46 ` J. Bruce Fields [this message]
2013-04-17 1:46 ` [PATCH 09/12] locks: helper functions for delegation breaking J. Bruce Fields
2013-04-17 1:46 ` [PATCH 11/12] locks: break delegations on link J. Bruce Fields
2013-04-17 1:46 ` [PATCH 12/12] locks: break delegations on any attribute modification J. Bruce Fields
-- strict thread matches above, loose matches on Subject: below --
2013-09-05 16:30 [PATCH 00/12] Implement NFSv4 delegations, take 10 J. Bruce Fields
2013-09-05 16:30 ` [PATCH 08/12] locks: break delegations on unlink J. Bruce Fields
2013-07-03 20:12 [PATCH 00/12] Implement NFSv4 delegations, take 8 J. Bruce Fields
2013-07-03 20:12 ` [PATCH 08/12] locks: break delegations on unlink J. Bruce Fields
[not found] ` <1372882356-14168-9-git-send-email-bfields-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2013-07-09 13:05 ` Jeff Layton
[not found] ` <20130709090506.71c96841-9yPaYZwiELC+kQycOl6kW4xkIHaj4LzF@public.gmane.org>
2013-07-09 13:07 ` Jeff Layton
2013-07-09 15:58 ` J. Bruce Fields
2013-07-09 16:02 ` Jeff Layton
2013-07-09 19:29 ` J. Bruce Fields
2013-02-03 16:31 [PATCH 00/12] Implement NFSv4 delegations, take 6 J. Bruce Fields
2013-02-03 16:31 ` [PATCH 08/12] locks: break delegations on unlink J. Bruce Fields
2012-10-16 22:01 [PATCH 00/12] Implement NFSv4 delegations, take 5 J. Bruce Fields
[not found] ` <1350424897-26894-1-git-send-email-bfields-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2012-10-16 22:01 ` [PATCH 08/12] locks: break delegations on unlink J. Bruce Fields
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