return new;
}
+/**
+ * enum d_walk_ret - action to talke during tree walk
+ * @D_WALK_CONTINUE: contrinue walk
+ * @D_WALK_QUIT: quit walk
+ * @D_WALK_NORETRY: quit when retry is needed
+ * @D_WALK_SKIP: skip this dentry and its children
+ */
+enum d_walk_ret {
+ D_WALK_CONTINUE,
+ D_WALK_QUIT,
+ D_WALK_NORETRY,
+ D_WALK_SKIP,
+};
-/*
- * Search for at least 1 mount point in the dentry's subdirs.
- * We descend to the next level whenever the d_subdirs
- * list is non-empty and continue searching.
- */
-
/**
- * have_submounts - check for mounts over a dentry
- * @parent: dentry to check.
+ * d_walk - walk the dentry tree
+ * @parent: start of walk
+ * @data: data passed to @enter() and @finish()
+ * @enter: callback when first entering the dentry
+ * @finish: callback when successfully finished the walk
*
- * Return true if the parent or its subdirectories contain
- * a mount point
+ * The @enter() and @finish() callbacks are called with d_lock held.
*/
-int have_submounts(struct dentry *parent)
+static void d_walk(struct dentry *parent, void *data,
+ enum d_walk_ret (*enter)(void *, struct dentry *),
+ void (*finish)(void *))
{
struct dentry *this_parent;
struct list_head *next;
unsigned seq;
int locked = 0;
+ enum d_walk_ret ret;
+ bool retry = true;
seq = read_seqbegin(&rename_lock);
again:
this_parent = parent;
-
- if (d_mountpoint(parent))
- goto positive;
spin_lock(&this_parent->d_lock);
+
+ ret = enter(data, this_parent);
+ switch (ret) {
+ case D_WALK_CONTINUE:
+ break;
+ case D_WALK_QUIT:
+ case D_WALK_SKIP:
+ goto out_unlock;
+ case D_WALK_NORETRY:
+ retry = false;
+ break;
+ }
repeat:
next = this_parent->d_subdirs.next;
resume:
next = tmp->next;
spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
- /* Have we found a mount point ? */
- if (d_mountpoint(dentry)) {
+
+ ret = enter(data, dentry);
+ switch (ret) {
+ case D_WALK_CONTINUE:
+ break;
+ case D_WALK_QUIT:
spin_unlock(&dentry->d_lock);
- spin_unlock(&this_parent->d_lock);
- goto positive;
+ goto out_unlock;
+ case D_WALK_NORETRY:
+ retry = false;
+ break;
+ case D_WALK_SKIP:
+ spin_unlock(&dentry->d_lock);
+ continue;
}
+
if (!list_empty(&dentry->d_subdirs)) {
spin_unlock(&this_parent->d_lock);
spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
next = child->d_u.d_child.next;
goto resume;
}
- spin_unlock(&this_parent->d_lock);
- if (!locked && read_seqretry(&rename_lock, seq))
- goto rename_retry;
- if (locked)
- write_sequnlock(&rename_lock);
- return 0; /* No mount points found in tree */
-positive:
- if (!locked && read_seqretry(&rename_lock, seq))
+ if (!locked && read_seqretry(&rename_lock, seq)) {
+ spin_unlock(&this_parent->d_lock);
goto rename_retry;
+ }
+ if (finish)
+ finish(data);
+
+out_unlock:
+ spin_unlock(&this_parent->d_lock);
if (locked)
write_sequnlock(&rename_lock);
- return 1;
+ return;
rename_retry:
+ if (!retry)
+ return;
if (locked)
goto again;
locked = 1;
write_seqlock(&rename_lock);
goto again;
}
+
+/*
+ * Search for at least 1 mount point in the dentry's subdirs.
+ * We descend to the next level whenever the d_subdirs
+ * list is non-empty and continue searching.
+ */
+
+/**
+ * have_submounts - check for mounts over a dentry
+ * @parent: dentry to check.
+ *
+ * Return true if the parent or its subdirectories contain
+ * a mount point
+ */
+
+static enum d_walk_ret check_mount(void *data, struct dentry *dentry)
+{
+ int *ret = data;
+ if (d_mountpoint(dentry)) {
+ *ret = 1;
+ return D_WALK_QUIT;
+ }
+ return D_WALK_CONTINUE;
+}
+
+int have_submounts(struct dentry *parent)
+{
+ int ret = 0;
+
+ d_walk(parent, &ret, check_mount, NULL);
+
+ return ret;
+}
EXPORT_SYMBOL(have_submounts);
+/*
+ * Called by mount code to set a mountpoint and check if the mountpoint is
+ * 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
+ * this reason take rename_lock and d_lock on dentry and ancestors.
+ */
+int d_set_mounted(struct dentry *dentry)
+{
+ struct dentry *p;
+ 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() */
+ spin_lock(&p->d_lock);
+ if (unlikely(d_unhashed(p))) {
+ spin_unlock(&p->d_lock);
+ goto out;
+ }
+ spin_unlock(&p->d_lock);
+ }
+ spin_lock(&dentry->d_lock);
+ if (!d_unlinked(dentry)) {
+ dentry->d_flags |= DCACHE_MOUNTED;
+ ret = 0;
+ }
+ spin_unlock(&dentry->d_lock);
+out:
+ write_sequnlock(&rename_lock);
+ return ret;
+}
+
/*
* Search the dentry child list of the specified parent,
* and move any unused dentries to the end of the unused
* drop the lock and return early due to latency
* constraints.
*/
-static int select_parent(struct dentry *parent, struct list_head *dispose)
-{
- struct dentry *this_parent;
- struct list_head *next;
- unsigned seq;
- int found = 0;
- int locked = 0;
- seq = read_seqbegin(&rename_lock);
-again:
- this_parent = parent;
- spin_lock(&this_parent->d_lock);
-repeat:
- next = this_parent->d_subdirs.next;
-resume:
- while (next != &this_parent->d_subdirs) {
- struct list_head *tmp = next;
- struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
- next = tmp->next;
-
- spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
+struct select_data {
+ struct dentry *start;
+ struct list_head dispose;
+ int found;
+};
- /*
- * move only zero ref count dentries to the dispose list.
- *
- * Those which are presently on the shrink list, being processed
- * by shrink_dentry_list(), shouldn't be moved. Otherwise the
- * loop in shrink_dcache_parent() might not make any progress
- * and loop forever.
- */
- if (dentry->d_lockref.count) {
- dentry_lru_del(dentry);
- } else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) {
- dentry_lru_move_list(dentry, dispose);
- dentry->d_flags |= DCACHE_SHRINK_LIST;
- found++;
- }
- /*
- * We can return to the caller if we have found some (this
- * ensures forward progress). We'll be coming back to find
- * the rest.
- */
- if (found && need_resched()) {
- spin_unlock(&dentry->d_lock);
- goto out;
- }
+static enum d_walk_ret select_collect(void *_data, struct dentry *dentry)
+{
+ struct select_data *data = _data;
+ enum d_walk_ret ret = D_WALK_CONTINUE;
- /*
- * Descend a level if the d_subdirs list is non-empty.
- */
- if (!list_empty(&dentry->d_subdirs)) {
- spin_unlock(&this_parent->d_lock);
- spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
- this_parent = dentry;
- spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
- goto repeat;
- }
+ if (data->start == dentry)
+ goto out;
- spin_unlock(&dentry->d_lock);
- }
/*
- * All done at this level ... ascend and resume the search.
+ * move only zero ref count dentries to the dispose list.
+ *
+ * Those which are presently on the shrink list, being processed
+ * by shrink_dentry_list(), shouldn't be moved. Otherwise the
+ * loop in shrink_dcache_parent() might not make any progress
+ * and loop forever.
*/
- if (this_parent != parent) {
- struct dentry *child = this_parent;
- this_parent = try_to_ascend(this_parent, locked, seq);
- if (!this_parent)
- goto rename_retry;
- next = child->d_u.d_child.next;
- goto resume;
+ if (dentry->d_lockref.count) {
+ dentry_lru_del(dentry);
+ } else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) {
+ dentry_lru_move_list(dentry, &data->dispose);
+ dentry->d_flags |= DCACHE_SHRINK_LIST;
+ data->found++;
+ ret = D_WALK_NORETRY;
}
+ /*
+ * We can return to the caller if we have found some (this
+ * ensures forward progress). We'll be coming back to find
+ * the rest.
+ */
+ if (data->found && need_resched())
+ ret = D_WALK_QUIT;
out:
- spin_unlock(&this_parent->d_lock);
- if (!locked && read_seqretry(&rename_lock, seq))
- goto rename_retry;
- if (locked)
- write_sequnlock(&rename_lock);
- return found;
-
-rename_retry:
- if (found)
- return found;
- if (locked)
- goto again;
- locked = 1;
- write_seqlock(&rename_lock);
- goto again;
+ return ret;
}
/**
*
* Prune the dcache to remove unused children of the parent dentry.
*/
-void shrink_dcache_parent(struct dentry * parent)
+void shrink_dcache_parent(struct dentry *parent)
{
- LIST_HEAD(dispose);
- int found;
+ for (;;) {
+ struct select_data data;
+
+ INIT_LIST_HEAD(&data.dispose);
+ data.start = parent;
+ data.found = 0;
- while ((found = select_parent(parent, &dispose)) != 0) {
- shrink_dentry_list(&dispose);
+ d_walk(parent, &data, select_collect, NULL);
+ if (!data.found)
+ break;
+
+ shrink_dentry_list(&data.dispose);
cond_resched();
}
}
EXPORT_SYMBOL(shrink_dcache_parent);
+static enum d_walk_ret check_and_collect(void *_data, struct dentry *dentry)
+{
+ struct select_data *data = _data;
+
+ if (d_mountpoint(dentry)) {
+ data->found = -EBUSY;
+ return D_WALK_QUIT;
+ }
+
+ return select_collect(_data, dentry);
+}
+
+static void check_and_drop(void *_data)
+{
+ struct select_data *data = _data;
+
+ if (d_mountpoint(data->start))
+ data->found = -EBUSY;
+ if (!data->found)
+ __d_drop(data->start);
+}
+
+/**
+ * check_submounts_and_drop - prune dcache, check for submounts 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.
+ *
+ * @dentry: dentry to prune and drop
+ */
+int check_submounts_and_drop(struct dentry *dentry)
+{
+ int ret = 0;
+
+ /* Negative dentries can be dropped without further checks */
+ if (!dentry->d_inode) {
+ d_drop(dentry);
+ goto out;
+ }
+
+ for (;;) {
+ struct select_data data;
+
+ INIT_LIST_HEAD(&data.dispose);
+ data.start = dentry;
+ data.found = 0;
+
+ d_walk(dentry, &data, check_and_collect, check_and_drop);
+ ret = data.found;
+
+ if (!list_empty(&data.dispose))
+ shrink_dentry_list(&data.dispose);
+
+ if (ret <= 0)
+ break;
+
+ cond_resched();
+ }
+
+out:
+ return ret;
+}
+EXPORT_SYMBOL(check_submounts_and_drop);
+
/**
* __d_alloc - allocate a dcache entry
* @sb: filesystem it will belong to
return result;
}
-void d_genocide(struct dentry *root)
+static enum d_walk_ret d_genocide_kill(void *data, struct dentry *dentry)
{
- struct dentry *this_parent;
- struct list_head *next;
- unsigned seq;
- int locked = 0;
+ struct dentry *root = data;
+ if (dentry != root) {
+ if (d_unhashed(dentry) || !dentry->d_inode)
+ return D_WALK_SKIP;
- seq = read_seqbegin(&rename_lock);
-again:
- this_parent = root;
- spin_lock(&this_parent->d_lock);
-repeat:
- next = this_parent->d_subdirs.next;
-resume:
- while (next != &this_parent->d_subdirs) {
- struct list_head *tmp = next;
- struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
- next = tmp->next;
-
- spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
- if (d_unhashed(dentry) || !dentry->d_inode) {
- spin_unlock(&dentry->d_lock);
- continue;
- }
- if (!list_empty(&dentry->d_subdirs)) {
- spin_unlock(&this_parent->d_lock);
- spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
- this_parent = dentry;
- spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
- goto repeat;
- }
if (!(dentry->d_flags & DCACHE_GENOCIDE)) {
dentry->d_flags |= DCACHE_GENOCIDE;
dentry->d_lockref.count--;
}
- spin_unlock(&dentry->d_lock);
- }
- if (this_parent != root) {
- struct dentry *child = this_parent;
- if (!(this_parent->d_flags & DCACHE_GENOCIDE)) {
- this_parent->d_flags |= DCACHE_GENOCIDE;
- this_parent->d_lockref.count--;
- }
- this_parent = try_to_ascend(this_parent, locked, seq);
- if (!this_parent)
- goto rename_retry;
- next = child->d_u.d_child.next;
- goto resume;
}
- spin_unlock(&this_parent->d_lock);
- if (!locked && read_seqretry(&rename_lock, seq))
- goto rename_retry;
- if (locked)
- write_sequnlock(&rename_lock);
- return;
+ return D_WALK_CONTINUE;
+}
-rename_retry:
- if (locked)
- goto again;
- locked = 1;
- write_seqlock(&rename_lock);
- goto again;
+void d_genocide(struct dentry *parent)
+{
+ d_walk(parent, parent, d_genocide_kill, NULL);
}
void d_tmpfile(struct dentry *dentry, struct inode *inode)
struct inode *inode;
struct dentry *parent;
struct fuse_conn *fc;
+ int ret;
inode = ACCESS_ONCE(entry->d_inode);
if (inode && is_bad_inode(inode))
- return 0;
+ goto invalid;
else if (fuse_dentry_time(entry) < get_jiffies_64()) {
int err;
struct fuse_entry_out outarg;
/* For negative dentries, always do a fresh lookup */
if (!inode)
- return 0;
+ goto invalid;
+ ret = -ECHILD;
if (flags & LOOKUP_RCU)
- return -ECHILD;
+ goto out;
fc = get_fuse_conn(inode);
req = fuse_get_req_nopages(fc);
+ ret = PTR_ERR(req);
if (IS_ERR(req))
- return 0;
+ goto out;
forget = fuse_alloc_forget();
if (!forget) {
fuse_put_request(fc, req);
- return 0;
+ ret = -ENOMEM;
+ goto out;
}
attr_version = fuse_get_attr_version(fc);
struct fuse_inode *fi = get_fuse_inode(inode);
if (outarg.nodeid != get_node_id(inode)) {
fuse_queue_forget(fc, forget, outarg.nodeid, 1);
- return 0;
+ goto invalid;
}
spin_lock(&fc->lock);
fi->nlookup++;
}
kfree(forget);
if (err || (outarg.attr.mode ^ inode->i_mode) & S_IFMT)
- return 0;
+ goto invalid;
fuse_change_attributes(inode, &outarg.attr,
entry_attr_timeout(&outarg),
dput(parent);
}
}
- return 1;
+ ret = 1;
+out:
+ return ret;
+
+invalid:
+ ret = 0;
+ if (check_submounts_and_drop(entry) != 0)
+ ret = 1;
+ goto out;
}
static int invalid_nodeid(u64 nodeid)
S_ISBLK(m) || S_ISFIFO(m) || S_ISSOCK(m);
}
-/*
- * Add a directory inode to a dentry, ensuring that no other dentry
- * refers to this inode. Called with fc->inst_mutex.
- */
-static struct dentry *fuse_d_add_directory(struct dentry *entry,
- struct inode *inode)
-{
- struct dentry *alias = d_find_alias(inode);
- if (alias && !(alias->d_flags & DCACHE_DISCONNECTED)) {
- /* This tries to shrink the subtree below alias */
- fuse_invalidate_entry(alias);
- dput(alias);
- if (!hlist_empty(&inode->i_dentry))
- return ERR_PTR(-EBUSY);
- } else {
- dput(alias);
- }
- return d_splice_alias(inode, entry);
-}
-
int fuse_lookup_name(struct super_block *sb, u64 nodeid, struct qstr *name,
struct fuse_entry_out *outarg, struct inode **inode)
{
return err;
}
+static struct dentry *fuse_materialise_dentry(struct dentry *dentry,
+ struct inode *inode)
+{
+ struct dentry *newent;
+
+ if (inode && S_ISDIR(inode->i_mode)) {
+ struct fuse_conn *fc = get_fuse_conn(inode);
+
+ mutex_lock(&fc->inst_mutex);
+ newent = d_materialise_unique(dentry, inode);
+ mutex_unlock(&fc->inst_mutex);
+ } else {
+ newent = d_materialise_unique(dentry, inode);
+ }
+
+ return newent;
+}
+
static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry,
unsigned int flags)
{
struct fuse_entry_out outarg;
struct inode *inode;
struct dentry *newent;
- struct fuse_conn *fc = get_fuse_conn(dir);
bool outarg_valid = true;
err = fuse_lookup_name(dir->i_sb, get_node_id(dir), &entry->d_name,
if (inode && get_node_id(inode) == FUSE_ROOT_ID)
goto out_iput;
- if (inode && S_ISDIR(inode->i_mode)) {
- mutex_lock(&fc->inst_mutex);
- newent = fuse_d_add_directory(entry, inode);
- mutex_unlock(&fc->inst_mutex);
- err = PTR_ERR(newent);
- if (IS_ERR(newent))
- goto out_iput;
- } else {
- newent = d_splice_alias(inode, entry);
- }
+ newent = fuse_materialise_dentry(entry, inode);
+ err = PTR_ERR(newent);
+ if (IS_ERR(newent))
+ goto out_err;
entry = newent ? newent : entry;
if (outarg_valid)
if (!inode)
goto out;
- if (S_ISDIR(inode->i_mode)) {
- mutex_lock(&fc->inst_mutex);
- alias = fuse_d_add_directory(dentry, inode);
- mutex_unlock(&fc->inst_mutex);
- err = PTR_ERR(alias);
- if (IS_ERR(alias)) {
- iput(inode);
- goto out;
- }
- } else {
- alias = d_splice_alias(inode, dentry);
- }
+ alias = fuse_materialise_dentry(dentry, inode);
+ err = PTR_ERR(alias);
+ if (IS_ERR(alias))
+ goto out;
if (alias) {
dput(dentry);
projects / linux-beck.git / commitdiff