![wanglei](/assets/img/avatar_default.png)
Implement the ability for the root directory of a mounted AFS filesystem to accept lookups of arbitrary directory names, to interpet the names as the names of cells, to look the cell names up in the DNS for AFSDB records and to mount the root.cell volume of the nominated cell on the pseudo-directory created by lookup. This facility is requested by passing: -o autocell to the mountpoint for which this is desired, usually the /afs mount. To use this facility, a DNS upcall program is required for AFSDB records. This can be obtained from: http://people.redhat.com/~dhowells/afs/dns.afsdb.c It should be compiled with -lresolv and -lkeyutils and installed as, say: /usr/sbin/dns.afsdb Then the following line needs to be added to /sbin/request-key.conf: create dns_resolver afsdb:* * /usr/sbin/dns.afsdb %k This can be tested by mounting AFS, say: insmod dns_resolver.ko insmod af-rxrpc.ko insmod kafs.ko rootcell=grand.central.org mount -t afs "#grand.central.org:root.cell." /afs -o autocell and doing: ls /afs/grand.central.org/ which should show: archive/ cvs/ doc/ local/ project/ service/ software/ user/ www/ if it works. Signed-off-by: Wang Lei <wang840925@gmail.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Steve French <sfrench@us.ibm.com>
560 lines
12 KiB
C
560 lines
12 KiB
C
/* AFS superblock handling
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*
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* Copyright (c) 2002, 2007 Red Hat, Inc. All rights reserved.
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*
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* This software may be freely redistributed under the terms of the
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* GNU General Public License.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* Authors: David Howells <dhowells@redhat.com>
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* David Woodhouse <dwmw2@infradead.org>
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*
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/mount.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/smp_lock.h>
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#include <linux/fs.h>
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#include <linux/pagemap.h>
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#include <linux/parser.h>
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#include <linux/statfs.h>
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#include <linux/sched.h>
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#include "internal.h"
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#define AFS_FS_MAGIC 0x6B414653 /* 'kAFS' */
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static void afs_i_init_once(void *foo);
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static int afs_get_sb(struct file_system_type *fs_type,
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int flags, const char *dev_name,
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void *data, struct vfsmount *mnt);
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static struct inode *afs_alloc_inode(struct super_block *sb);
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static void afs_put_super(struct super_block *sb);
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static void afs_destroy_inode(struct inode *inode);
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static int afs_statfs(struct dentry *dentry, struct kstatfs *buf);
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struct file_system_type afs_fs_type = {
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.owner = THIS_MODULE,
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.name = "afs",
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.get_sb = afs_get_sb,
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.kill_sb = kill_anon_super,
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.fs_flags = 0,
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};
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static const struct super_operations afs_super_ops = {
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.statfs = afs_statfs,
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.alloc_inode = afs_alloc_inode,
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.drop_inode = afs_drop_inode,
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.destroy_inode = afs_destroy_inode,
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.evict_inode = afs_evict_inode,
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.put_super = afs_put_super,
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.show_options = generic_show_options,
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};
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static struct kmem_cache *afs_inode_cachep;
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static atomic_t afs_count_active_inodes;
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enum {
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afs_no_opt,
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afs_opt_cell,
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afs_opt_rwpath,
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afs_opt_vol,
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afs_opt_autocell,
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};
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static const match_table_t afs_options_list = {
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{ afs_opt_cell, "cell=%s" },
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{ afs_opt_rwpath, "rwpath" },
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{ afs_opt_vol, "vol=%s" },
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{ afs_opt_autocell, "autocell" },
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{ afs_no_opt, NULL },
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};
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/*
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* initialise the filesystem
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*/
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int __init afs_fs_init(void)
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{
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int ret;
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_enter("");
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/* create ourselves an inode cache */
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atomic_set(&afs_count_active_inodes, 0);
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ret = -ENOMEM;
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afs_inode_cachep = kmem_cache_create("afs_inode_cache",
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sizeof(struct afs_vnode),
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0,
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SLAB_HWCACHE_ALIGN,
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afs_i_init_once);
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if (!afs_inode_cachep) {
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printk(KERN_NOTICE "kAFS: Failed to allocate inode cache\n");
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return ret;
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}
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/* now export our filesystem to lesser mortals */
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ret = register_filesystem(&afs_fs_type);
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if (ret < 0) {
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kmem_cache_destroy(afs_inode_cachep);
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_leave(" = %d", ret);
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return ret;
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}
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_leave(" = 0");
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return 0;
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}
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/*
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* clean up the filesystem
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*/
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void __exit afs_fs_exit(void)
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{
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_enter("");
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afs_mntpt_kill_timer();
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unregister_filesystem(&afs_fs_type);
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if (atomic_read(&afs_count_active_inodes) != 0) {
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printk("kAFS: %d active inode objects still present\n",
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atomic_read(&afs_count_active_inodes));
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BUG();
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}
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kmem_cache_destroy(afs_inode_cachep);
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_leave("");
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}
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/*
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* parse the mount options
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* - this function has been shamelessly adapted from the ext3 fs which
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* shamelessly adapted it from the msdos fs
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*/
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static int afs_parse_options(struct afs_mount_params *params,
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char *options, const char **devname)
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{
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struct afs_cell *cell;
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substring_t args[MAX_OPT_ARGS];
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char *p;
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int token;
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_enter("%s", options);
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options[PAGE_SIZE - 1] = 0;
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while ((p = strsep(&options, ","))) {
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if (!*p)
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continue;
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token = match_token(p, afs_options_list, args);
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switch (token) {
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case afs_opt_cell:
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cell = afs_cell_lookup(args[0].from,
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args[0].to - args[0].from,
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false);
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if (IS_ERR(cell))
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return PTR_ERR(cell);
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afs_put_cell(params->cell);
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params->cell = cell;
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break;
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case afs_opt_rwpath:
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params->rwpath = 1;
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break;
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case afs_opt_vol:
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*devname = args[0].from;
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break;
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case afs_opt_autocell:
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params->autocell = 1;
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break;
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default:
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printk(KERN_ERR "kAFS:"
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" Unknown or invalid mount option: '%s'\n", p);
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return -EINVAL;
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}
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}
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_leave(" = 0");
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return 0;
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}
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/*
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* parse a device name to get cell name, volume name, volume type and R/W
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* selector
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* - this can be one of the following:
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* "%[cell:]volume[.]" R/W volume
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* "#[cell:]volume[.]" R/O or R/W volume (rwpath=0),
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* or R/W (rwpath=1) volume
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* "%[cell:]volume.readonly" R/O volume
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* "#[cell:]volume.readonly" R/O volume
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* "%[cell:]volume.backup" Backup volume
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* "#[cell:]volume.backup" Backup volume
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*/
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static int afs_parse_device_name(struct afs_mount_params *params,
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const char *name)
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{
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struct afs_cell *cell;
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const char *cellname, *suffix;
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int cellnamesz;
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_enter(",%s", name);
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if (!name) {
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printk(KERN_ERR "kAFS: no volume name specified\n");
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return -EINVAL;
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}
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if ((name[0] != '%' && name[0] != '#') || !name[1]) {
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printk(KERN_ERR "kAFS: unparsable volume name\n");
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return -EINVAL;
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}
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/* determine the type of volume we're looking for */
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params->type = AFSVL_ROVOL;
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params->force = false;
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if (params->rwpath || name[0] == '%') {
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params->type = AFSVL_RWVOL;
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params->force = true;
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}
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name++;
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/* split the cell name out if there is one */
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params->volname = strchr(name, ':');
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if (params->volname) {
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cellname = name;
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cellnamesz = params->volname - name;
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params->volname++;
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} else {
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params->volname = name;
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cellname = NULL;
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cellnamesz = 0;
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}
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/* the volume type is further affected by a possible suffix */
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suffix = strrchr(params->volname, '.');
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if (suffix) {
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if (strcmp(suffix, ".readonly") == 0) {
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params->type = AFSVL_ROVOL;
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params->force = true;
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} else if (strcmp(suffix, ".backup") == 0) {
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params->type = AFSVL_BACKVOL;
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params->force = true;
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} else if (suffix[1] == 0) {
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} else {
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suffix = NULL;
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}
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}
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params->volnamesz = suffix ?
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suffix - params->volname : strlen(params->volname);
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_debug("cell %*.*s [%p]",
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cellnamesz, cellnamesz, cellname ?: "", params->cell);
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/* lookup the cell record */
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if (cellname || !params->cell) {
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cell = afs_cell_lookup(cellname, cellnamesz, true);
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if (IS_ERR(cell)) {
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printk(KERN_ERR "kAFS: unable to lookup cell '%*.*s'\n",
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cellnamesz, cellnamesz, cellname ?: "");
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return PTR_ERR(cell);
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}
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afs_put_cell(params->cell);
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params->cell = cell;
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}
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_debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
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params->cell->name, params->cell,
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params->volnamesz, params->volnamesz, params->volname,
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suffix ?: "-", params->type, params->force ? " FORCE" : "");
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return 0;
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}
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/*
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* check a superblock to see if it's the one we're looking for
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*/
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static int afs_test_super(struct super_block *sb, void *data)
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{
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struct afs_mount_params *params = data;
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struct afs_super_info *as = sb->s_fs_info;
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return as->volume == params->volume;
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}
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/*
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* fill in the superblock
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*/
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static int afs_fill_super(struct super_block *sb, void *data)
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{
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struct afs_mount_params *params = data;
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struct afs_super_info *as = NULL;
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struct afs_fid fid;
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struct dentry *root = NULL;
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struct inode *inode = NULL;
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int ret;
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_enter("");
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/* allocate a superblock info record */
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as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
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if (!as) {
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_leave(" = -ENOMEM");
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return -ENOMEM;
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}
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afs_get_volume(params->volume);
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as->volume = params->volume;
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/* fill in the superblock */
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sb->s_blocksize = PAGE_CACHE_SIZE;
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sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
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sb->s_magic = AFS_FS_MAGIC;
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sb->s_op = &afs_super_ops;
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sb->s_fs_info = as;
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sb->s_bdi = &as->volume->bdi;
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/* allocate the root inode and dentry */
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fid.vid = as->volume->vid;
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fid.vnode = 1;
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fid.unique = 1;
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inode = afs_iget(sb, params->key, &fid, NULL, NULL);
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if (IS_ERR(inode))
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goto error_inode;
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if (params->autocell)
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set_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(inode)->flags);
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ret = -ENOMEM;
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root = d_alloc_root(inode);
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if (!root)
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goto error;
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sb->s_root = root;
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_leave(" = 0");
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return 0;
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error_inode:
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ret = PTR_ERR(inode);
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inode = NULL;
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error:
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iput(inode);
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afs_put_volume(as->volume);
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kfree(as);
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sb->s_fs_info = NULL;
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_leave(" = %d", ret);
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return ret;
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}
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/*
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* get an AFS superblock
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*/
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static int afs_get_sb(struct file_system_type *fs_type,
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int flags,
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const char *dev_name,
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void *options,
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struct vfsmount *mnt)
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{
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struct afs_mount_params params;
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struct super_block *sb;
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struct afs_volume *vol;
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struct key *key;
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char *new_opts = kstrdup(options, GFP_KERNEL);
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int ret;
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_enter(",,%s,%p", dev_name, options);
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memset(¶ms, 0, sizeof(params));
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/* parse the options and device name */
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if (options) {
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ret = afs_parse_options(¶ms, options, &dev_name);
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if (ret < 0)
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goto error;
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}
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ret = afs_parse_device_name(¶ms, dev_name);
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if (ret < 0)
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goto error;
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/* try and do the mount securely */
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key = afs_request_key(params.cell);
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if (IS_ERR(key)) {
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_leave(" = %ld [key]", PTR_ERR(key));
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ret = PTR_ERR(key);
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goto error;
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}
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params.key = key;
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/* parse the device name */
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vol = afs_volume_lookup(¶ms);
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if (IS_ERR(vol)) {
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ret = PTR_ERR(vol);
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goto error;
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}
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params.volume = vol;
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/* allocate a deviceless superblock */
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sb = sget(fs_type, afs_test_super, set_anon_super, ¶ms);
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if (IS_ERR(sb)) {
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ret = PTR_ERR(sb);
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goto error;
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}
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if (!sb->s_root) {
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/* initial superblock/root creation */
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_debug("create");
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sb->s_flags = flags;
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ret = afs_fill_super(sb, ¶ms);
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if (ret < 0) {
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deactivate_locked_super(sb);
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goto error;
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}
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save_mount_options(sb, new_opts);
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sb->s_flags |= MS_ACTIVE;
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} else {
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_debug("reuse");
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ASSERTCMP(sb->s_flags, &, MS_ACTIVE);
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}
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simple_set_mnt(mnt, sb);
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afs_put_volume(params.volume);
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afs_put_cell(params.cell);
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kfree(new_opts);
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_leave(" = 0 [%p]", sb);
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return 0;
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error:
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afs_put_volume(params.volume);
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afs_put_cell(params.cell);
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key_put(params.key);
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kfree(new_opts);
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_leave(" = %d", ret);
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return ret;
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}
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/*
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* finish the unmounting process on the superblock
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*/
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static void afs_put_super(struct super_block *sb)
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{
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struct afs_super_info *as = sb->s_fs_info;
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_enter("");
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lock_kernel();
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afs_put_volume(as->volume);
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unlock_kernel();
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_leave("");
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}
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/*
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* initialise an inode cache slab element prior to any use
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*/
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static void afs_i_init_once(void *_vnode)
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{
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struct afs_vnode *vnode = _vnode;
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memset(vnode, 0, sizeof(*vnode));
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inode_init_once(&vnode->vfs_inode);
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init_waitqueue_head(&vnode->update_waitq);
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mutex_init(&vnode->permits_lock);
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mutex_init(&vnode->validate_lock);
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spin_lock_init(&vnode->writeback_lock);
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spin_lock_init(&vnode->lock);
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INIT_LIST_HEAD(&vnode->writebacks);
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INIT_LIST_HEAD(&vnode->pending_locks);
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INIT_LIST_HEAD(&vnode->granted_locks);
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INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);
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INIT_WORK(&vnode->cb_broken_work, afs_broken_callback_work);
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}
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/*
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* allocate an AFS inode struct from our slab cache
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*/
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static struct inode *afs_alloc_inode(struct super_block *sb)
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{
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struct afs_vnode *vnode;
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vnode = kmem_cache_alloc(afs_inode_cachep, GFP_KERNEL);
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if (!vnode)
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return NULL;
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atomic_inc(&afs_count_active_inodes);
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memset(&vnode->fid, 0, sizeof(vnode->fid));
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memset(&vnode->status, 0, sizeof(vnode->status));
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vnode->volume = NULL;
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vnode->update_cnt = 0;
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vnode->flags = 1 << AFS_VNODE_UNSET;
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vnode->cb_promised = false;
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_leave(" = %p", &vnode->vfs_inode);
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return &vnode->vfs_inode;
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}
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/*
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* destroy an AFS inode struct
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*/
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static void afs_destroy_inode(struct inode *inode)
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{
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struct afs_vnode *vnode = AFS_FS_I(inode);
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_enter("%p{%x:%u}", inode, vnode->fid.vid, vnode->fid.vnode);
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|
|
_debug("DESTROY INODE %p", inode);
|
|
|
|
ASSERTCMP(vnode->server, ==, NULL);
|
|
|
|
kmem_cache_free(afs_inode_cachep, vnode);
|
|
atomic_dec(&afs_count_active_inodes);
|
|
}
|
|
|
|
/*
|
|
* return information about an AFS volume
|
|
*/
|
|
static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
|
|
{
|
|
struct afs_volume_status vs;
|
|
struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
|
|
struct key *key;
|
|
int ret;
|
|
|
|
key = afs_request_key(vnode->volume->cell);
|
|
if (IS_ERR(key))
|
|
return PTR_ERR(key);
|
|
|
|
ret = afs_vnode_get_volume_status(vnode, key, &vs);
|
|
key_put(key);
|
|
if (ret < 0) {
|
|
_leave(" = %d", ret);
|
|
return ret;
|
|
}
|
|
|
|
buf->f_type = dentry->d_sb->s_magic;
|
|
buf->f_bsize = AFS_BLOCK_SIZE;
|
|
buf->f_namelen = AFSNAMEMAX - 1;
|
|
|
|
if (vs.max_quota == 0)
|
|
buf->f_blocks = vs.part_max_blocks;
|
|
else
|
|
buf->f_blocks = vs.max_quota;
|
|
buf->f_bavail = buf->f_bfree = buf->f_blocks - vs.blocks_in_use;
|
|
return 0;
|
|
}
|