return dentry_string_cmp(cs, ct, tcount);
}
+struct external_name {
+ union {
+ atomic_t count;
+ struct rcu_head head;
+ } u;
+ unsigned char name[];
+};
+
+static inline struct external_name *external_name(struct dentry *dentry)
+{
+ return container_of(dentry->d_name.name, struct external_name, name[0]);
+}
+
static void __d_free(struct rcu_head *head)
{
struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
WARN_ON(!hlist_unhashed(&dentry->d_alias));
- if (dname_external(dentry))
- kfree(dentry->d_name.name);
kmem_cache_free(dentry_cache, dentry);
}
+static void __d_free_external(struct rcu_head *head)
+{
+ struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
+ WARN_ON(!hlist_unhashed(&dentry->d_alias));
+ kfree(external_name(dentry));
+ kmem_cache_free(dentry_cache, dentry);
+}
+
+static inline int dname_external(const struct dentry *dentry)
+{
+ return dentry->d_name.name != dentry->d_iname;
+}
+
static void dentry_free(struct dentry *dentry)
{
+ if (unlikely(dname_external(dentry))) {
+ struct external_name *p = external_name(dentry);
+ if (likely(atomic_dec_and_test(&p->u.count))) {
+ call_rcu(&dentry->d_u.d_rcu, __d_free_external);
+ return;
+ }
+ }
/* if dentry was never visible to RCU, immediate free is OK */
if (!(dentry->d_flags & DCACHE_RCUACCESS))
__d_free(&dentry->d_u.d_rcu);
* inform the fs via d_prune that this dentry is about to be
* unhashed and destroyed.
*/
- if ((dentry->d_flags & DCACHE_OP_PRUNE) && !d_unhashed(dentry))
+ if (dentry->d_flags & DCACHE_OP_PRUNE)
dentry->d_op->d_prune(dentry);
if (dentry->d_flags & DCACHE_LRU_LIST) {
}
EXPORT_SYMBOL(dput);
-/**
- * d_invalidate - invalidate a dentry
- * @dentry: dentry to invalidate
- *
- * Try to invalidate the dentry if it turns out to be
- * possible. If there are other dentries that can be
- * reached through this one we can't delete it and we
- * return -EBUSY. On success we return 0.
- *
- * no dcache lock.
- */
-
-int d_invalidate(struct dentry * dentry)
-{
- /*
- * If it's already been dropped, return OK.
- */
- spin_lock(&dentry->d_lock);
- if (d_unhashed(dentry)) {
- spin_unlock(&dentry->d_lock);
- return 0;
- }
- /*
- * Check whether to do a partial shrink_dcache
- * to get rid of unused child entries.
- */
- if (!list_empty(&dentry->d_subdirs)) {
- spin_unlock(&dentry->d_lock);
- shrink_dcache_parent(dentry);
- spin_lock(&dentry->d_lock);
- }
-
- /*
- * Somebody else still using it?
- *
- * If it's a directory, we can't drop it
- * for fear of somebody re-populating it
- * with children (even though dropping it
- * would make it unreachable from the root,
- * we might still populate it if it was a
- * working directory or similar).
- * We also need to leave mountpoints alone,
- * directory or not.
- */
- if (dentry->d_lockref.count > 1 && dentry->d_inode) {
- if (S_ISDIR(dentry->d_inode->i_mode) || d_mountpoint(dentry)) {
- spin_unlock(&dentry->d_lock);
- return -EBUSY;
- }
- }
-
- __d_drop(dentry);
- spin_unlock(&dentry->d_lock);
- return 0;
-}
-EXPORT_SYMBOL(d_invalidate);
/* This must be called with d_lock held */
static inline void __dget_dlock(struct dentry *dentry)
* acquire the reference to alias and return it. Otherwise return NULL.
* Notice that if inode is a directory there can be only one alias and
* it can be unhashed only if it has no children, or if it is the root
- * of a filesystem.
+ * of a filesystem, or if the directory was renamed and d_revalidate
+ * was the first vfs operation to notice.
*
* If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer
* any other hashed alias over that one.
hlist_for_each_entry(dentry, &inode->i_dentry, d_alias) {
spin_lock(&dentry->d_lock);
if (!dentry->d_lockref.count) {
- /*
- * inform the fs via d_prune that this dentry
- * is about to be unhashed and destroyed.
- */
- if ((dentry->d_flags & DCACHE_OP_PRUNE) &&
- !d_unhashed(dentry))
- dentry->d_op->d_prune(dentry);
-
- __dget_dlock(dentry);
- __d_drop(dentry);
- spin_unlock(&dentry->d_lock);
- spin_unlock(&inode->i_lock);
- dput(dentry);
- goto restart;
+ struct dentry *parent = lock_parent(dentry);
+ if (likely(!dentry->d_lockref.count)) {
+ __dentry_kill(dentry);
+ goto restart;
+ }
+ if (parent)
+ spin_unlock(&parent->d_lock);
}
spin_unlock(&dentry->d_lock);
}
* reachable (e.g. NFS can unhash a directory dentry and then the complete
* subtree can become unreachable).
*
- * Only one of check_submounts_and_drop() and d_set_mounted() must succeed. For
+ * Only one of d_invalidate() and d_set_mounted() must succeed. For
* this reason take rename_lock and d_lock on dentry and ancestors.
*/
int d_set_mounted(struct dentry *dentry)
int ret = -ENOENT;
write_seqlock(&rename_lock);
for (p = dentry->d_parent; !IS_ROOT(p); p = p->d_parent) {
- /* Need exclusion wrt. check_submounts_and_drop() */
+ /* Need exclusion wrt. d_invalidate() */
spin_lock(&p->d_lock);
if (unlikely(d_unhashed(p))) {
spin_unlock(&p->d_lock);
}
}
-static enum d_walk_ret check_and_collect(void *_data, struct dentry *dentry)
+struct detach_data {
+ struct select_data select;
+ struct dentry *mountpoint;
+};
+static enum d_walk_ret detach_and_collect(void *_data, struct dentry *dentry)
{
- struct select_data *data = _data;
+ struct detach_data *data = _data;
if (d_mountpoint(dentry)) {
- data->found = -EBUSY;
+ __dget_dlock(dentry);
+ data->mountpoint = dentry;
return D_WALK_QUIT;
}
- return select_collect(_data, dentry);
+ return select_collect(&data->select, dentry);
}
static void check_and_drop(void *_data)
{
- struct select_data *data = _data;
+ struct detach_data *data = _data;
- if (d_mountpoint(data->start))
- data->found = -EBUSY;
- if (!data->found)
- __d_drop(data->start);
+ if (!data->mountpoint && !data->select.found)
+ __d_drop(data->select.start);
}
/**
- * check_submounts_and_drop - prune dcache, check for submounts and drop
+ * d_invalidate - detach submounts, prune dcache, and drop
+ * @dentry: dentry to invalidate (aka detach, prune and drop)
*
- * All done as a single atomic operation relative to has_unlinked_ancestor().
- * Returns 0 if successfully unhashed @parent. If there were submounts then
- * return -EBUSY.
+ * no dcache lock.
*
- * @dentry: dentry to prune and drop
+ * The final d_drop is done as an atomic operation relative to
+ * rename_lock ensuring there are no races with d_set_mounted. This
+ * ensures there are no unhashed dentries on the path to a mountpoint.
*/
-int check_submounts_and_drop(struct dentry *dentry)
+void d_invalidate(struct dentry *dentry)
{
- int ret = 0;
+ /*
+ * If it's already been dropped, return OK.
+ */
+ spin_lock(&dentry->d_lock);
+ if (d_unhashed(dentry)) {
+ spin_unlock(&dentry->d_lock);
+ return;
+ }
+ spin_unlock(&dentry->d_lock);
/* Negative dentries can be dropped without further checks */
if (!dentry->d_inode) {
d_drop(dentry);
- goto out;
+ return;
}
for (;;) {
- struct select_data data;
+ struct detach_data data;
- INIT_LIST_HEAD(&data.dispose);
- data.start = dentry;
- data.found = 0;
+ data.mountpoint = NULL;
+ INIT_LIST_HEAD(&data.select.dispose);
+ data.select.start = dentry;
+ data.select.found = 0;
+
+ d_walk(dentry, &data, detach_and_collect, check_and_drop);
- d_walk(dentry, &data, check_and_collect, check_and_drop);
- ret = data.found;
+ if (data.select.found)
+ shrink_dentry_list(&data.select.dispose);
- if (!list_empty(&data.dispose))
- shrink_dentry_list(&data.dispose);
+ if (data.mountpoint) {
+ detach_mounts(data.mountpoint);
+ dput(data.mountpoint);
+ }
- if (ret <= 0)
+ if (!data.mountpoint && !data.select.found)
break;
cond_resched();
}
-
-out:
- return ret;
}
-EXPORT_SYMBOL(check_submounts_and_drop);
+EXPORT_SYMBOL(d_invalidate);
/**
* __d_alloc - allocate a dcache entry
*/
dentry->d_iname[DNAME_INLINE_LEN-1] = 0;
if (name->len > DNAME_INLINE_LEN-1) {
- dname = kmalloc(name->len + 1, GFP_KERNEL);
- if (!dname) {
+ size_t size = offsetof(struct external_name, name[1]);
+ struct external_name *p = kmalloc(size + name->len, GFP_KERNEL);
+ if (!p) {
kmem_cache_free(dentry_cache, dentry);
return NULL;
}
+ atomic_set(&p->u.count, 1);
+ dname = p->name;
} else {
dname = dentry->d_iname;
}
struct dentry *dentry;
unsigned seq;
- do {
- seq = read_seqbegin(&rename_lock);
- dentry = __d_lookup(parent, name);
- if (dentry)
+ do {
+ seq = read_seqbegin(&rename_lock);
+ dentry = __d_lookup(parent, name);
+ if (dentry)
break;
} while (read_seqretry(&rename_lock, seq));
return dentry;
}
EXPORT_SYMBOL(dentry_update_name_case);
-static void switch_names(struct dentry *dentry, struct dentry *target,
- bool exchange)
+static void swap_names(struct dentry *dentry, struct dentry *target)
{
- if (dname_external(target)) {
- if (dname_external(dentry)) {
+ if (unlikely(dname_external(target))) {
+ if (unlikely(dname_external(dentry))) {
/*
* Both external: swap the pointers
*/
target->d_name.name = target->d_iname;
}
} else {
- if (dname_external(dentry)) {
+ if (unlikely(dname_external(dentry))) {
/*
* dentry:external, target:internal. Give dentry's
* storage to target and make dentry internal
*/
unsigned int i;
BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN, sizeof(long)));
- if (!exchange) {
- memcpy(dentry->d_iname, target->d_name.name,
- target->d_name.len + 1);
- dentry->d_name.hash_len = target->d_name.hash_len;
- return;
- }
for (i = 0; i < DNAME_INLINE_LEN / sizeof(long); i++) {
swap(((long *) &dentry->d_iname)[i],
((long *) &target->d_iname)[i]);
swap(dentry->d_name.hash_len, target->d_name.hash_len);
}
+static void copy_name(struct dentry *dentry, struct dentry *target)
+{
+ struct external_name *old_name = NULL;
+ if (unlikely(dname_external(dentry)))
+ old_name = external_name(dentry);
+ if (unlikely(dname_external(target))) {
+ atomic_inc(&external_name(target)->u.count);
+ dentry->d_name = target->d_name;
+ } else {
+ memcpy(dentry->d_iname, target->d_name.name,
+ target->d_name.len + 1);
+ dentry->d_name.name = dentry->d_iname;
+ dentry->d_name.hash_len = target->d_name.hash_len;
+ }
+ if (old_name && likely(atomic_dec_and_test(&old_name->u.count)))
+ kfree_rcu(old_name, u.head);
+}
+
static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target)
{
/*
}
/* Switch the names.. */
- switch_names(dentry, target, exchange);
+ if (exchange)
+ swap_names(dentry, target);
+ else
+ copy_name(dentry, target);
/* ... and switch them in the tree */
if (IS_ROOT(dentry)) {
goto out_err;
m2 = &alias->d_parent->d_inode->i_mutex;
out_unalias:
- if (likely(!d_mountpoint(alias))) {
- __d_move(alias, dentry, false);
- ret = alias;
- }
+ __d_move(alias, dentry, false);
+ ret = alias;
out_err:
spin_unlock(&inode->i_lock);
if (m2)
* the beginning of the name. The sequence number check at the caller will
* retry it again when a d_move() does happen. So any garbage in the buffer
* due to mismatched pointer and length will be discarded.
+ *
+ * Data dependency barrier is needed to make sure that we see that terminating
+ * NUL. Alpha strikes again, film at 11...
*/
static int prepend_name(char **buffer, int *buflen, struct qstr *name)
{
u32 dlen = ACCESS_ONCE(name->len);
char *p;
+ smp_read_barrier_depends();
+
*buflen -= dlen + 1;
if (*buflen < 0)
return -ENAMETOOLONG;
projects / cascardo / linux.git / blobdiff