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-rw-r--r--fs/dcache.c102
1 files changed, 102 insertions, 0 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index f2584d22cb45..101663d15e9f 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1220,6 +1220,107 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
return new;
}
+/**
+ * d_add_ci - lookup or allocate new dentry with case-exact name
+ * @inode: the inode case-insensitive lookup has found
+ * @dentry: the negative dentry that was passed to the parent's lookup func
+ * @name: the case-exact name to be associated with the returned dentry
+ *
+ * This is to avoid filling the dcache with case-insensitive names to the
+ * same inode, only the actual correct case is stored in the dcache for
+ * case-insensitive filesystems.
+ *
+ * For a case-insensitive lookup match and if the the case-exact dentry
+ * already exists in in the dcache, use it and return it.
+ *
+ * If no entry exists with the exact case name, allocate new dentry with
+ * the exact case, and return the spliced entry.
+ */
+struct dentry *d_add_ci(struct inode *inode, struct dentry *dentry,
+ struct qstr *name)
+{
+ int error;
+ struct dentry *found;
+ struct dentry *new;
+
+ /* Does a dentry matching the name exist already? */
+ found = d_hash_and_lookup(dentry->d_parent, name);
+ /* If not, create it now and return */
+ if (!found) {
+ new = d_alloc(dentry->d_parent, name);
+ if (!new) {
+ error = -ENOMEM;
+ goto err_out;
+ }
+ found = d_splice_alias(inode, new);
+ if (found) {
+ dput(new);
+ return found;
+ }
+ return new;
+ }
+ /* Matching dentry exists, check if it is negative. */
+ if (found->d_inode) {
+ if (unlikely(found->d_inode != inode)) {
+ /* This can't happen because bad inodes are unhashed. */
+ BUG_ON(!is_bad_inode(inode));
+ BUG_ON(!is_bad_inode(found->d_inode));
+ }
+ /*
+ * Already have the inode and the dentry attached, decrement
+ * the reference count to balance the iget() done
+ * earlier on. We found the dentry using d_lookup() so it
+ * cannot be disconnected and thus we do not need to worry
+ * about any NFS/disconnectedness issues here.
+ */
+ iput(inode);
+ return found;
+ }
+ /*
+ * Negative dentry: instantiate it unless the inode is a directory and
+ * has a 'disconnected' dentry (i.e. IS_ROOT and DCACHE_DISCONNECTED),
+ * in which case d_move() that in place of the found dentry.
+ */
+ if (!S_ISDIR(inode->i_mode)) {
+ /* Not a directory; everything is easy. */
+ d_instantiate(found, inode);
+ return found;
+ }
+ spin_lock(&dcache_lock);
+ if (list_empty(&inode->i_dentry)) {
+ /*
+ * Directory without a 'disconnected' dentry; we need to do
+ * d_instantiate() by hand because it takes dcache_lock which
+ * we already hold.
+ */
+ list_add(&found->d_alias, &inode->i_dentry);
+ found->d_inode = inode;
+ spin_unlock(&dcache_lock);
+ security_d_instantiate(found, inode);
+ return found;
+ }
+ /*
+ * Directory with a 'disconnected' dentry; get a reference to the
+ * 'disconnected' dentry.
+ */
+ new = list_entry(inode->i_dentry.next, struct dentry, d_alias);
+ dget_locked(new);
+ spin_unlock(&dcache_lock);
+ /* Do security vodoo. */
+ security_d_instantiate(found, inode);
+ /* Move new in place of found. */
+ d_move(new, found);
+ /* Balance the iget() we did above. */
+ iput(inode);
+ /* Throw away found. */
+ dput(found);
+ /* Use new as the actual dentry. */
+ return new;
+
+err_out:
+ iput(inode);
+ return ERR_PTR(error);
+}
/**
* d_lookup - search for a dentry
@@ -2254,6 +2355,7 @@ EXPORT_SYMBOL(d_path);
EXPORT_SYMBOL(d_prune_aliases);
EXPORT_SYMBOL(d_rehash);
EXPORT_SYMBOL(d_splice_alias);
+EXPORT_SYMBOL(d_add_ci);
EXPORT_SYMBOL(d_validate);
EXPORT_SYMBOL(dget_locked);
EXPORT_SYMBOL(dput);