1 files changed, 413 insertions, 0 deletions

diff --git a/fs/afs/volume.c b/fs/afs/volume.c
new file mode 100644
index 000000000..f84194b79
--- /dev/null
+++ b/fs/afs/volume.c
@@ -0,0 +1,413 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* AFS volume management
+ *
+ * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include "internal.h"
+
+unsigned __read_mostly afs_volume_gc_delay = 10;
+unsigned __read_mostly afs_volume_record_life = 60 * 60;
+
+/*
+ * Insert a volume into a cell.  If there's an existing volume record, that is
+ * returned instead with a ref held.
+ */
+static struct afs_volume *afs_insert_volume_into_cell(struct afs_cell *cell,
+						      struct afs_volume *volume)
+{
+	struct afs_volume *p;
+	struct rb_node *parent = NULL, **pp;
+
+	write_seqlock(&cell->volume_lock);
+
+	pp = &cell->volumes.rb_node;
+	while (*pp) {
+		parent = *pp;
+		p = rb_entry(parent, struct afs_volume, cell_node);
+		if (p->vid < volume->vid) {
+			pp = &(*pp)->rb_left;
+		} else if (p->vid > volume->vid) {
+			pp = &(*pp)->rb_right;
+		} else {
+			volume = afs_get_volume(p, afs_volume_trace_get_cell_insert);
+			goto found;
+		}
+	}
+
+	rb_link_node_rcu(&volume->cell_node, parent, pp);
+	rb_insert_color(&volume->cell_node, &cell->volumes);
+	hlist_add_head_rcu(&volume->proc_link, &cell->proc_volumes);
+
+found:
+	write_sequnlock(&cell->volume_lock);
+	return volume;
+
+}
+
+static void afs_remove_volume_from_cell(struct afs_volume *volume)
+{
+	struct afs_cell *cell = volume->cell;
+
+	if (!hlist_unhashed(&volume->proc_link)) {
+		trace_afs_volume(volume->vid, atomic_read(&volume->usage),
+				 afs_volume_trace_remove);
+		write_seqlock(&cell->volume_lock);
+		hlist_del_rcu(&volume->proc_link);
+		rb_erase(&volume->cell_node, &cell->volumes);
+		write_sequnlock(&cell->volume_lock);
+	}
+}
+
+/*
+ * Allocate a volume record and load it up from a vldb record.
+ */
+static struct afs_volume *afs_alloc_volume(struct afs_fs_context *params,
+					   struct afs_vldb_entry *vldb,
+					   unsigned long type_mask)
+{
+	struct afs_server_list *slist;
+	struct afs_volume *volume;
+	int ret = -ENOMEM, nr_servers = 0, i;
+
+	for (i = 0; i < vldb->nr_servers; i++)
+		if (vldb->fs_mask[i] & type_mask)
+			nr_servers++;
+
+	volume = kzalloc(sizeof(struct afs_volume), GFP_KERNEL);
+	if (!volume)
+		goto error_0;
+
+	volume->vid		= vldb->vid[params->type];
+	volume->update_at	= ktime_get_real_seconds() + afs_volume_record_life;
+	volume->cell		= afs_get_cell(params->cell, afs_cell_trace_get_vol);
+	volume->type		= params->type;
+	volume->type_force	= params->force;
+	volume->name_len	= vldb->name_len;
+
+	atomic_set(&volume->usage, 1);
+	INIT_HLIST_NODE(&volume->proc_link);
+	rwlock_init(&volume->servers_lock);
+	rwlock_init(&volume->cb_v_break_lock);
+	memcpy(volume->name, vldb->name, vldb->name_len + 1);
+
+	slist = afs_alloc_server_list(params->cell, params->key, vldb, type_mask);
+	if (IS_ERR(slist)) {
+		ret = PTR_ERR(slist);
+		goto error_1;
+	}
+
+	refcount_set(&slist->usage, 1);
+	rcu_assign_pointer(volume->servers, slist);
+	trace_afs_volume(volume->vid, 1, afs_volume_trace_alloc);
+	return volume;
+
+error_1:
+	afs_put_cell(volume->cell, afs_cell_trace_put_vol);
+	kfree(volume);
+error_0:
+	return ERR_PTR(ret);
+}
+
+/*
+ * Look up or allocate a volume record.
+ */
+static struct afs_volume *afs_lookup_volume(struct afs_fs_context *params,
+					    struct afs_vldb_entry *vldb,
+					    unsigned long type_mask)
+{
+	struct afs_volume *candidate, *volume;
+
+	candidate = afs_alloc_volume(params, vldb, type_mask);
+	if (IS_ERR(candidate))
+		return candidate;
+
+	volume = afs_insert_volume_into_cell(params->cell, candidate);
+	if (volume != candidate)
+		afs_put_volume(params->net, candidate, afs_volume_trace_put_cell_dup);
+	return volume;
+}
+
+/*
+ * Look up a VLDB record for a volume.
+ */
+static struct afs_vldb_entry *afs_vl_lookup_vldb(struct afs_cell *cell,
+						 struct key *key,
+						 const char *volname,
+						 size_t volnamesz)
+{
+	struct afs_vldb_entry *vldb = ERR_PTR(-EDESTADDRREQ);
+	struct afs_vl_cursor vc;
+	int ret;
+
+	if (!afs_begin_vlserver_operation(&vc, cell, key))
+		return ERR_PTR(-ERESTARTSYS);
+
+	while (afs_select_vlserver(&vc)) {
+		vldb = afs_vl_get_entry_by_name_u(&vc, volname, volnamesz);
+	}
+
+	ret = afs_end_vlserver_operation(&vc);
+	return ret < 0 ? ERR_PTR(ret) : vldb;
+}
+
+/*
+ * Look up a volume in the VL server and create a candidate volume record for
+ * it.
+ *
+ * The volume name can be one of the following:
+ *	"%[cell:]volume[.]"		R/W volume
+ *	"#[cell:]volume[.]"		R/O or R/W volume (rwparent=0),
+ *					 or R/W (rwparent=1) volume
+ *	"%[cell:]volume.readonly"	R/O volume
+ *	"#[cell:]volume.readonly"	R/O volume
+ *	"%[cell:]volume.backup"		Backup volume
+ *	"#[cell:]volume.backup"		Backup volume
+ *
+ * The cell name is optional, and defaults to the current cell.
+ *
+ * See "The Rules of Mount Point Traversal" in Chapter 5 of the AFS SysAdmin
+ * Guide
+ * - Rule 1: Explicit type suffix forces access of that type or nothing
+ *           (no suffix, then use Rule 2 & 3)
+ * - Rule 2: If parent volume is R/O, then mount R/O volume by preference, R/W
+ *           if not available
+ * - Rule 3: If parent volume is R/W, then only mount R/W volume unless
+ *           explicitly told otherwise
+ */
+struct afs_volume *afs_create_volume(struct afs_fs_context *params)
+{
+	struct afs_vldb_entry *vldb;
+	struct afs_volume *volume;
+	unsigned long type_mask = 1UL << params->type;
+
+	vldb = afs_vl_lookup_vldb(params->cell, params->key,
+				  params->volname, params->volnamesz);
+	if (IS_ERR(vldb))
+		return ERR_CAST(vldb);
+
+	if (test_bit(AFS_VLDB_QUERY_ERROR, &vldb->flags)) {
+		volume = ERR_PTR(vldb->error);
+		goto error;
+	}
+
+	/* Make the final decision on the type we want */
+	volume = ERR_PTR(-ENOMEDIUM);
+	if (params->force) {
+		if (!(vldb->flags & type_mask))
+			goto error;
+	} else if (test_bit(AFS_VLDB_HAS_RO, &vldb->flags)) {
+		params->type = AFSVL_ROVOL;
+	} else if (test_bit(AFS_VLDB_HAS_RW, &vldb->flags)) {
+		params->type = AFSVL_RWVOL;
+	} else {
+		goto error;
+	}
+
+	type_mask = 1UL << params->type;
+	volume = afs_lookup_volume(params, vldb, type_mask);
+
+error:
+	kfree(vldb);
+	return volume;
+}
+
+/*
+ * Destroy a volume record
+ */
+static void afs_destroy_volume(struct afs_net *net, struct afs_volume *volume)
+{
+	_enter("%p", volume);
+
+#ifdef CONFIG_AFS_FSCACHE
+	ASSERTCMP(volume->cache, ==, NULL);
+#endif
+
+	afs_remove_volume_from_cell(volume);
+	afs_put_serverlist(net, rcu_access_pointer(volume->servers));
+	afs_put_cell(volume->cell, afs_cell_trace_put_vol);
+	trace_afs_volume(volume->vid, atomic_read(&volume->usage),
+			 afs_volume_trace_free);
+	kfree_rcu(volume, rcu);
+
+	_leave(" [destroyed]");
+}
+
+/*
+ * Get a reference on a volume record.
+ */
+struct afs_volume *afs_get_volume(struct afs_volume *volume,
+				  enum afs_volume_trace reason)
+{
+	if (volume) {
+		int u = atomic_inc_return(&volume->usage);
+		trace_afs_volume(volume->vid, u, reason);
+	}
+	return volume;
+}
+
+
+/*
+ * Drop a reference on a volume record.
+ */
+void afs_put_volume(struct afs_net *net, struct afs_volume *volume,
+		    enum afs_volume_trace reason)
+{
+	if (volume) {
+		afs_volid_t vid = volume->vid;
+		int u = atomic_dec_return(&volume->usage);
+		trace_afs_volume(vid, u, reason);
+		if (u == 0)
+			afs_destroy_volume(net, volume);
+	}
+}
+
+/*
+ * Activate a volume.
+ */
+void afs_activate_volume(struct afs_volume *volume)
+{
+#ifdef CONFIG_AFS_FSCACHE
+	volume->cache = fscache_acquire_cookie(volume->cell->cache,
+					       &afs_volume_cache_index_def,
+					       &volume->vid, sizeof(volume->vid),
+					       NULL, 0,
+					       volume, 0, true);
+#endif
+}
+
+/*
+ * Deactivate a volume.
+ */
+void afs_deactivate_volume(struct afs_volume *volume)
+{
+	_enter("%s", volume->name);
+
+#ifdef CONFIG_AFS_FSCACHE
+	fscache_relinquish_cookie(volume->cache, NULL,
+				  test_bit(AFS_VOLUME_DELETED, &volume->flags));
+	volume->cache = NULL;
+#endif
+
+	_leave("");
+}
+
+/*
+ * Query the VL service to update the volume status.
+ */
+static int afs_update_volume_status(struct afs_volume *volume, struct key *key)
+{
+	struct afs_server_list *new, *old, *discard;
+	struct afs_vldb_entry *vldb;
+	char idbuf[16];
+	int ret, idsz;
+
+	_enter("");
+
+	/* We look up an ID by passing it as a decimal string in the
+	 * operation's name parameter.
+	 */
+	idsz = sprintf(idbuf, "%llu", volume->vid);
+
+	vldb = afs_vl_lookup_vldb(volume->cell, key, idbuf, idsz);
+	if (IS_ERR(vldb)) {
+		ret = PTR_ERR(vldb);
+		goto error;
+	}
+
+	/* See if the volume got renamed. */
+	if (vldb->name_len != volume->name_len ||
+	    memcmp(vldb->name, volume->name, vldb->name_len) != 0) {
+		/* TODO: Use RCU'd string. */
+		memcpy(volume->name, vldb->name, AFS_MAXVOLNAME);
+		volume->name_len = vldb->name_len;
+	}
+
+	/* See if the volume's server list got updated. */
+	new = afs_alloc_server_list(volume->cell, key,
+				    vldb, (1 << volume->type));
+	if (IS_ERR(new)) {
+		ret = PTR_ERR(new);
+		goto error_vldb;
+	}
+
+	write_lock(&volume->servers_lock);
+
+	discard = new;
+	old = rcu_dereference_protected(volume->servers,
+					lockdep_is_held(&volume->servers_lock));
+	if (afs_annotate_server_list(new, old)) {
+		new->seq = volume->servers_seq + 1;
+		rcu_assign_pointer(volume->servers, new);
+		smp_wmb();
+		volume->servers_seq++;
+		discard = old;
+	}
+
+	volume->update_at = ktime_get_real_seconds() + afs_volume_record_life;
+	write_unlock(&volume->servers_lock);
+	ret = 0;
+
+	afs_put_serverlist(volume->cell->net, discard);
+error_vldb:
+	kfree(vldb);
+error:
+	_leave(" = %d", ret);
+	return ret;
+}
+
+/*
+ * Make sure the volume record is up to date.
+ */
+int afs_check_volume_status(struct afs_volume *volume, struct afs_operation *op)
+{
+	int ret, retries = 0;
+
+	_enter("");
+
+retry:
+	if (test_bit(AFS_VOLUME_WAIT, &volume->flags))
+		goto wait;
+	if (volume->update_at <= ktime_get_real_seconds() ||
+	    test_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags))
+		goto update;
+	_leave(" = 0");
+	return 0;
+
+update:
+	if (!test_and_set_bit_lock(AFS_VOLUME_UPDATING, &volume->flags)) {
+		clear_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags);
+		ret = afs_update_volume_status(volume, op->key);
+		if (ret < 0)
+			set_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags);
+		clear_bit_unlock(AFS_VOLUME_WAIT, &volume->flags);
+		clear_bit_unlock(AFS_VOLUME_UPDATING, &volume->flags);
+		wake_up_bit(&volume->flags, AFS_VOLUME_WAIT);
+		_leave(" = %d", ret);
+		return ret;
+	}
+
+wait:
+	if (!test_bit(AFS_VOLUME_WAIT, &volume->flags)) {
+		_leave(" = 0 [no wait]");
+		return 0;
+	}
+
+	ret = wait_on_bit(&volume->flags, AFS_VOLUME_WAIT,
+			  (op->flags & AFS_OPERATION_UNINTR) ?
+			  TASK_UNINTERRUPTIBLE : TASK_INTERRUPTIBLE);
+	if (ret == -ERESTARTSYS) {
+		_leave(" = %d", ret);
+		return ret;
+	}
+
+	retries++;
+	if (retries == 4) {
+		_leave(" = -ESTALE");
+		return -ESTALE;
+	}
+	goto retry;
+}