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authorIan Kent <raven@themaw.net>2011-01-14 18:46:35 +0000
committerAl Viro <viro@zeniv.linux.org.uk>2011-01-15 20:07:44 -0500
commitdd89f90d2deb9aa5bc8e1b15d726ff5c0bb2b623 (patch)
tree0f3d8c9c66be46215cc5b10d51ccb25cc8e68da1
parent9e3fea16ba386fa549a0b2de8a203e5d412997a0 (diff)
downloadlinux-dd89f90d2deb9aa5bc8e1b15d726ff5c0bb2b623.tar.bz2
autofs4: Add v4 pseudo direct mount support
Version 4 of autofs provides a pseudo direct mount implementation that relies on directories at the leaves of a directory tree under an indirect mount to trigger mounts. This patch adds support for that functionality. Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--fs/autofs4/root.c58
1 files changed, 58 insertions, 0 deletions
diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index 8315565ed7d4..9194e274f849 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -630,6 +630,58 @@ static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
return 0;
}
+/*
+ * Version 4 of autofs provides a pseudo direct mount implementation
+ * that relies on directories at the leaves of a directory tree under
+ * an indirect mount to trigger mounts. To allow for this we need to
+ * set the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags on the leaves
+ * of the directory tree. There is no need to clear the automount flag
+ * following a mount or restore it after an expire because these mounts
+ * are always covered. However, it is neccessary to ensure that these
+ * flags are clear on non-empty directories to avoid unnecessary calls
+ * during path walks.
+ */
+static void autofs_set_leaf_automount_flags(struct dentry *dentry)
+{
+ struct dentry *parent;
+
+ /* root and dentrys in the root are already handled */
+ if (IS_ROOT(dentry->d_parent))
+ return;
+
+ managed_dentry_set_managed(dentry);
+
+ parent = dentry->d_parent;
+ /* only consider parents below dentrys in the root */
+ if (IS_ROOT(parent->d_parent))
+ return;
+ managed_dentry_clear_managed(parent);
+ return;
+}
+
+static void autofs_clear_leaf_automount_flags(struct dentry *dentry)
+{
+ struct list_head *d_child;
+ struct dentry *parent;
+
+ /* flags for dentrys in the root are handled elsewhere */
+ if (IS_ROOT(dentry->d_parent))
+ return;
+
+ managed_dentry_clear_managed(dentry);
+
+ parent = dentry->d_parent;
+ /* only consider parents below dentrys in the root */
+ if (IS_ROOT(parent->d_parent))
+ return;
+ d_child = &dentry->d_u.d_child;
+ /* Set parent managed if it's becoming empty */
+ if (d_child->next == &parent->d_subdirs &&
+ d_child->prev == &parent->d_subdirs)
+ managed_dentry_set_managed(parent);
+ return;
+}
+
static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
{
struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
@@ -657,6 +709,9 @@ static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
spin_unlock(&dentry->d_lock);
spin_unlock(&autofs4_lock);
+ if (sbi->version < 5)
+ autofs_clear_leaf_automount_flags(dentry);
+
if (atomic_dec_and_test(&ino->count)) {
p_ino = autofs4_dentry_ino(dentry->d_parent);
if (p_ino && dentry->d_parent != dentry)
@@ -699,6 +754,9 @@ static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
}
d_add(dentry, inode);
+ if (sbi->version < 5)
+ autofs_set_leaf_automount_flags(dentry);
+
dentry->d_fsdata = ino;
ino->dentry = dget(dentry);
atomic_inc(&ino->count);