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authorIan Kent <raven@themaw.net>2011-03-25 01:51:02 +0800
committerAl Viro <viro@zeniv.linux.org.uk>2011-03-24 14:24:32 -0400
commit62a7375e5d77d654695297c4b39d5d740d901184 (patch)
treeb479c60a43f22e3bb99d9ebf1af89de2a7020673 /fs
parentb81a618dcd3ea99de292dbe624f41ca68f464376 (diff)
vfs - check non-mountpoint dentry might block in __follow_mount_rcu()
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> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs')
-rw-r--r--fs/namei.c23
1 files changed, 18 insertions, 5 deletions
diff --git a/fs/namei.c b/fs/namei.c
index d0066e17d45d..3cb616d38d9c 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -992,6 +992,12 @@ int follow_down_one(struct path *path)
return 0;
}
+static inline bool managed_dentry_might_block(struct dentry *dentry)
+{
+ return (dentry->d_flags & DCACHE_MANAGE_TRANSIT &&
+ dentry->d_op->d_manage(dentry, true) < 0);
+}
+
/*
* 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
@@ -1000,19 +1006,26 @@ int follow_down_one(struct path *path)
static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
struct inode **inode, bool reverse_transit)
{
- while (d_mountpoint(path->dentry)) {
+ for (;;) {
struct vfsmount *mounted;
- if (unlikely(path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) &&
- !reverse_transit &&
- path->dentry->d_op->d_manage(path->dentry, true) < 0)
+ /*
+ * Don't forget 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;
+
+ if (!d_mountpoint(path->dentry))
+ break;
+
mounted = __lookup_mnt(path->mnt, path->dentry, 1);
if (!mounted)
break;
path->mnt = mounted;
path->dentry = mounted->mnt_root;
nd->seq = read_seqcount_begin(&path->dentry->d_seq);
- *inode = path->dentry->d_inode;
}
if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT))