From: Ian Kent <raven@themaw.net>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Nick Piggin <npiggin@gmail.com>,
David Howells <dhowells@redhat.com>,
Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH 1/4] vfs - check non-mountpoint dentry might block in __follow_mount_rcu()
Date: Tue, 01 Mar 2011 12:56:57 +0800 [thread overview]
Message-ID: <20110301045657.4615.79048.stgit@localhost6.localdomain6> (raw)
In-Reply-To: <20110301044457.4615.40333.stgit@localhost6.localdomain6>
When following a mount in rcu-walk mode we must check if the incoming dentry
is telling us it may need to block, even if it isn't actually a mountpoint.
Signed-off-by: Ian Kent <raven@themaw.net>
---
fs/namei.c | 24 ++++++++++++++++++++----
1 files changed, 20 insertions(+), 4 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index 0087cf9..a0f2179 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1022,6 +1022,14 @@ int follow_down_one(struct path *path)
return 0;
}
+static bool managed_dentry_might_block(struct dentry *dentry)
+{
+ if (dentry->d_flags & DCACHE_MANAGE_TRANSIT &&
+ dentry->d_op->d_manage(dentry, false, true) < 0)
+ return true;
+ return false;
+}
+
/*
* Skip to top of mountpoint pile in rcuwalk mode. We abort the rcu-walk if we
* meet a managed dentry and we're not walking to "..". True is returned to
@@ -1030,12 +1038,17 @@ int follow_down_one(struct path *path)
static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
struct inode **inode, bool reverse_transit)
{
+ /*
+ * Don't forgat we might have a non-mountpoint managed dentry
+ * that wants to block transit.
+ */
+ *inode = path->dentry->d_inode;
+ if (!reverse_transit &&
+ unlikely(managed_dentry_might_block(path->dentry)))
+ return false;
+
while (d_mountpoint(path->dentry)) {
struct vfsmount *mounted;
- if (unlikely(path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) &&
- !reverse_transit &&
- path->dentry->d_op->d_manage(path->dentry, false, true) < 0)
- return false;
mounted = __lookup_mnt(path->mnt, path->dentry, 1);
if (!mounted)
break;
@@ -1043,6 +1056,9 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
path->dentry = mounted->mnt_root;
nd->seq = read_seqcount_begin(&path->dentry->d_seq);
*inode = path->dentry->d_inode;
+ if (!reverse_transit &&
+ unlikely(managed_dentry_might_block(path->dentry)))
+ return false;
}
if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT))
next prev parent reply other threads:[~2011-03-01 5:07 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-01 4:56 [PATCH 0/4] more on vfs-scale and vfs-automount Ian Kent
2011-03-01 4:56 ` Ian Kent [this message]
2011-03-01 4:57 ` [PATCH 2/4] autofs4 - fix rootless multi-mount race Ian Kent
2011-03-01 4:57 ` [PATCH 3/4] autofs4 - fix dentry leak in autofs4_expire_direct() Ian Kent
2011-03-01 4:57 ` [PATCH 4/4] autofs4 - fix autofs4_expire_indirect() traversal Ian Kent
2011-03-01 5:14 ` [PATCH 0/4] more on vfs-scale and vfs-automount Ian Kent
2011-03-01 12:49 ` Ian Kent
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