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>
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@ -630,6 +630,58 @@ static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
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return 0;
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}
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/*
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* Version 4 of autofs provides a pseudo direct mount implementation
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* that relies on directories at the leaves of a directory tree under
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* an indirect mount to trigger mounts. To allow for this we need to
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* set the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags on the leaves
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* of the directory tree. There is no need to clear the automount flag
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* following a mount or restore it after an expire because these mounts
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* are always covered. However, it is neccessary to ensure that these
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* flags are clear on non-empty directories to avoid unnecessary calls
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* during path walks.
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*/
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static void autofs_set_leaf_automount_flags(struct dentry *dentry)
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{
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struct dentry *parent;
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/* root and dentrys in the root are already handled */
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if (IS_ROOT(dentry->d_parent))
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return;
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managed_dentry_set_managed(dentry);
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parent = dentry->d_parent;
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/* only consider parents below dentrys in the root */
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if (IS_ROOT(parent->d_parent))
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return;
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managed_dentry_clear_managed(parent);
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return;
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}
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static void autofs_clear_leaf_automount_flags(struct dentry *dentry)
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{
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struct list_head *d_child;
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struct dentry *parent;
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/* flags for dentrys in the root are handled elsewhere */
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if (IS_ROOT(dentry->d_parent))
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return;
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managed_dentry_clear_managed(dentry);
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parent = dentry->d_parent;
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/* only consider parents below dentrys in the root */
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if (IS_ROOT(parent->d_parent))
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return;
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d_child = &dentry->d_u.d_child;
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/* Set parent managed if it's becoming empty */
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if (d_child->next == &parent->d_subdirs &&
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d_child->prev == &parent->d_subdirs)
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managed_dentry_set_managed(parent);
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return;
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}
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static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
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{
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struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
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@ -657,6 +709,9 @@ static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
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spin_unlock(&dentry->d_lock);
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spin_unlock(&autofs4_lock);
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if (sbi->version < 5)
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autofs_clear_leaf_automount_flags(dentry);
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if (atomic_dec_and_test(&ino->count)) {
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p_ino = autofs4_dentry_ino(dentry->d_parent);
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if (p_ino && dentry->d_parent != dentry)
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@ -699,6 +754,9 @@ static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
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}
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d_add(dentry, inode);
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if (sbi->version < 5)
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autofs_set_leaf_automount_flags(dentry);
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dentry->d_fsdata = ino;
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ino->dentry = dget(dentry);
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atomic_inc(&ino->count);
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