Initial import

1 files changed, 401 insertions, 0 deletions

diff --git a/fs/afs/volume.c b/fs/afs/volume.c
new file mode 100644
index 000000000..d142a2449
--- /dev/null
+++ b/fs/afs/volume.c
@@ -0,0 +1,401 @@
+/* AFS volume management
+ *
+ * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/sched.h>
+#include "internal.h"
+
+static const char *afs_voltypes[] = { "R/W", "R/O", "BAK" };
+
+/*
+ * lookup a volume by name
+ * - this 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_volume_lookup(struct afs_mount_params *params)
+{
+	struct afs_vlocation *vlocation = NULL;
+	struct afs_volume *volume = NULL;
+	struct afs_server *server = NULL;
+	char srvtmask;
+	int ret, loop;
+
+	_enter("{%*.*s,%d}",
+	       params->volnamesz, params->volnamesz, params->volname, params->rwpath);
+
+	/* lookup the volume location record */
+	vlocation = afs_vlocation_lookup(params->cell, params->key,
+					 params->volname, params->volnamesz);
+	if (IS_ERR(vlocation)) {
+		ret = PTR_ERR(vlocation);
+		vlocation = NULL;
+		goto error;
+	}
+
+	/* make the final decision on the type we want */
+	ret = -ENOMEDIUM;
+	if (params->force && !(vlocation->vldb.vidmask & (1 << params->type)))
+		goto error;
+
+	srvtmask = 0;
+	for (loop = 0; loop < vlocation->vldb.nservers; loop++)
+		srvtmask |= vlocation->vldb.srvtmask[loop];
+
+	if (params->force) {
+		if (!(srvtmask & (1 << params->type)))
+			goto error;
+	} else if (srvtmask & AFS_VOL_VTM_RO) {
+		params->type = AFSVL_ROVOL;
+	} else if (srvtmask & AFS_VOL_VTM_RW) {
+		params->type = AFSVL_RWVOL;
+	} else {
+		goto error;
+	}
+
+	down_write(&params->cell->vl_sem);
+
+	/* is the volume already active? */
+	if (vlocation->vols[params->type]) {
+		/* yes - re-use it */
+		volume = vlocation->vols[params->type];
+		afs_get_volume(volume);
+		goto success;
+	}
+
+	/* create a new volume record */
+	_debug("creating new volume record");
+
+	ret = -ENOMEM;
+	volume = kzalloc(sizeof(struct afs_volume), GFP_KERNEL);
+	if (!volume)
+		goto error_up;
+
+	atomic_set(&volume->usage, 1);
+	volume->type		= params->type;
+	volume->type_force	= params->force;
+	volume->cell		= params->cell;
+	volume->vid		= vlocation->vldb.vid[params->type];
+
+	ret = bdi_setup_and_register(&volume->bdi, "afs");
+	if (ret)
+		goto error_bdi;
+
+	init_rwsem(&volume->server_sem);
+
+	/* look up all the applicable server records */
+	for (loop = 0; loop < 8; loop++) {
+		if (vlocation->vldb.srvtmask[loop] & (1 << volume->type)) {
+			server = afs_lookup_server(
+			       volume->cell, &vlocation->vldb.servers[loop]);
+			if (IS_ERR(server)) {
+				ret = PTR_ERR(server);
+				goto error_discard;
+			}
+
+			volume->servers[volume->nservers] = server;
+			volume->nservers++;
+		}
+	}
+
+	/* attach the cache and volume location */
+#ifdef CONFIG_AFS_FSCACHE
+	volume->cache = fscache_acquire_cookie(vlocation->cache,
+					       &afs_volume_cache_index_def,
+					       volume, true);
+#endif
+	afs_get_vlocation(vlocation);
+	volume->vlocation = vlocation;
+
+	vlocation->vols[volume->type] = volume;
+
+success:
+	_debug("kAFS selected %s volume %08x",
+	       afs_voltypes[volume->type], volume->vid);
+	up_write(&params->cell->vl_sem);
+	afs_put_vlocation(vlocation);
+	_leave(" = %p", volume);
+	return volume;
+
+	/* clean up */
+error_up:
+	up_write(&params->cell->vl_sem);
+error:
+	afs_put_vlocation(vlocation);
+	_leave(" = %d", ret);
+	return ERR_PTR(ret);
+
+error_discard:
+	bdi_destroy(&volume->bdi);
+error_bdi:
+	up_write(&params->cell->vl_sem);
+
+	for (loop = volume->nservers - 1; loop >= 0; loop--)
+		afs_put_server(volume->servers[loop]);
+
+	kfree(volume);
+	goto error;
+}
+
+/*
+ * destroy a volume record
+ */
+void afs_put_volume(struct afs_volume *volume)
+{
+	struct afs_vlocation *vlocation;
+	int loop;
+
+	if (!volume)
+		return;
+
+	_enter("%p", volume);
+
+	ASSERTCMP(atomic_read(&volume->usage), >, 0);
+
+	vlocation = volume->vlocation;
+
+	/* to prevent a race, the decrement and the dequeue must be effectively
+	 * atomic */
+	down_write(&vlocation->cell->vl_sem);
+
+	if (likely(!atomic_dec_and_test(&volume->usage))) {
+		up_write(&vlocation->cell->vl_sem);
+		_leave("");
+		return;
+	}
+
+	vlocation->vols[volume->type] = NULL;
+
+	up_write(&vlocation->cell->vl_sem);
+
+	/* finish cleaning up the volume */
+#ifdef CONFIG_AFS_FSCACHE
+	fscache_relinquish_cookie(volume->cache, 0);
+#endif
+	afs_put_vlocation(vlocation);
+
+	for (loop = volume->nservers - 1; loop >= 0; loop--)
+		afs_put_server(volume->servers[loop]);
+
+	bdi_destroy(&volume->bdi);
+	kfree(volume);
+
+	_leave(" [destroyed]");
+}
+
+/*
+ * pick a server to use to try accessing this volume
+ * - returns with an elevated usage count on the server chosen
+ */
+struct afs_server *afs_volume_pick_fileserver(struct afs_vnode *vnode)
+{
+	struct afs_volume *volume = vnode->volume;
+	struct afs_server *server;
+	int ret, state, loop;
+
+	_enter("%s", volume->vlocation->vldb.name);
+
+	/* stick with the server we're already using if we can */
+	if (vnode->server && vnode->server->fs_state == 0) {
+		afs_get_server(vnode->server);
+		_leave(" = %p [current]", vnode->server);
+		return vnode->server;
+	}
+
+	down_read(&volume->server_sem);
+
+	/* handle the no-server case */
+	if (volume->nservers == 0) {
+		ret = volume->rjservers ? -ENOMEDIUM : -ESTALE;
+		up_read(&volume->server_sem);
+		_leave(" = %d [no servers]", ret);
+		return ERR_PTR(ret);
+	}
+
+	/* basically, just search the list for the first live server and use
+	 * that */
+	ret = 0;
+	for (loop = 0; loop < volume->nservers; loop++) {
+		server = volume->servers[loop];
+		state = server->fs_state;
+
+		_debug("consider %d [%d]", loop, state);
+
+		switch (state) {
+			/* found an apparently healthy server */
+		case 0:
+			afs_get_server(server);
+			up_read(&volume->server_sem);
+			_leave(" = %p (picked %08x)",
+			       server, ntohl(server->addr.s_addr));
+			return server;
+
+		case -ENETUNREACH:
+			if (ret == 0)
+				ret = state;
+			break;
+
+		case -EHOSTUNREACH:
+			if (ret == 0 ||
+			    ret == -ENETUNREACH)
+				ret = state;
+			break;
+
+		case -ECONNREFUSED:
+			if (ret == 0 ||
+			    ret == -ENETUNREACH ||
+			    ret == -EHOSTUNREACH)
+				ret = state;
+			break;
+
+		default:
+		case -EREMOTEIO:
+			if (ret == 0 ||
+			    ret == -ENETUNREACH ||
+			    ret == -EHOSTUNREACH ||
+			    ret == -ECONNREFUSED)
+				ret = state;
+			break;
+		}
+	}
+
+	/* no available servers
+	 * - TODO: handle the no active servers case better
+	 */
+	up_read(&volume->server_sem);
+	_leave(" = %d", ret);
+	return ERR_PTR(ret);
+}
+
+/*
+ * release a server after use
+ * - releases the ref on the server struct that was acquired by picking
+ * - records result of using a particular server to access a volume
+ * - return 0 to try again, 1 if okay or to issue error
+ * - the caller must release the server struct if result was 0
+ */
+int afs_volume_release_fileserver(struct afs_vnode *vnode,
+				  struct afs_server *server,
+				  int result)
+{
+	struct afs_volume *volume = vnode->volume;
+	unsigned loop;
+
+	_enter("%s,%08x,%d",
+	       volume->vlocation->vldb.name, ntohl(server->addr.s_addr),
+	       result);
+
+	switch (result) {
+		/* success */
+	case 0:
+		server->fs_act_jif = jiffies;
+		server->fs_state = 0;
+		_leave("");
+		return 1;
+
+		/* the fileserver denied all knowledge of the volume */
+	case -ENOMEDIUM:
+		server->fs_act_jif = jiffies;
+		down_write(&volume->server_sem);
+
+		/* firstly, find where the server is in the active list (if it
+		 * is) */
+		for (loop = 0; loop < volume->nservers; loop++)
+			if (volume->servers[loop] == server)
+				goto present;
+
+		/* no longer there - may have been discarded by another op */
+		goto try_next_server_upw;
+
+	present:
+		volume->nservers--;
+		memmove(&volume->servers[loop],
+			&volume->servers[loop + 1],
+			sizeof(volume->servers[loop]) *
+			(volume->nservers - loop));
+		volume->servers[volume->nservers] = NULL;
+		afs_put_server(server);
+		volume->rjservers++;
+
+		if (volume->nservers > 0)
+			/* another server might acknowledge its existence */
+			goto try_next_server_upw;
+
+		/* handle the case where all the fileservers have rejected the
+		 * volume
+		 * - TODO: try asking the fileservers for volume information
+		 * - TODO: contact the VL server again to see if the volume is
+		 *         no longer registered
+		 */
+		up_write(&volume->server_sem);
+		afs_put_server(server);
+		_leave(" [completely rejected]");
+		return 1;
+
+		/* problem reaching the server */
+	case -ENETUNREACH:
+	case -EHOSTUNREACH:
+	case -ECONNREFUSED:
+	case -ETIME:
+	case -ETIMEDOUT:
+	case -EREMOTEIO:
+		/* mark the server as dead
+		 * TODO: vary dead timeout depending on error
+		 */
+		spin_lock(&server->fs_lock);
+		if (!server->fs_state) {
+			server->fs_dead_jif = jiffies + HZ * 10;
+			server->fs_state = result;
+			printk("kAFS: SERVER DEAD state=%d\n", result);
+		}
+		spin_unlock(&server->fs_lock);
+		goto try_next_server;
+
+		/* miscellaneous error */
+	default:
+		server->fs_act_jif = jiffies;
+	case -ENOMEM:
+	case -ENONET:
+		/* tell the caller to accept the result */
+		afs_put_server(server);
+		_leave(" [local failure]");
+		return 1;
+	}
+
+	/* tell the caller to loop around and try the next server */
+try_next_server_upw:
+	up_write(&volume->server_sem);
+try_next_server:
+	afs_put_server(server);
+	_leave(" [try next server]");
+	return 0;
+}