afs: Overhaul cell database management
Overhaul the way that the in-kernel AFS client keeps track of cells in the
following manner:
(1) Cells are now held in an rbtree to make walking them quicker and RCU
managed (though this is probably overkill).
(2) Cells now have a manager work item that:
(A) Looks after fetching and refreshing the VL server list.
(B) Manages cell record lifetime, including initialising and
destruction.
(B) Manages cell record caching whereby threads are kept around for a
certain time after last use and then destroyed.
(C) Manages the FS-Cache index cookie for a cell. It is not permitted
for a cookie to be in use twice, so we have to be careful to not
allow a new cell record to exist at the same time as an old record
of the same name.
(3) Each AFS network namespace is given a manager work item that manages
the cells within it, maintaining a single timer to prod cells into
updating their DNS records.
This uses the reduce_timer() facility to make the timer expire at the
soonest timed event that needs happening.
(4) When a module is being unloaded, cells and cell managers are now
counted out using dec_after_work() to make sure the module text is
pinned until after the data structures have been cleaned up.
(5) Each cell's VL server list is now protected by a seqlock rather than a
semaphore.
Signed-off-by: David Howells <dhowells@redhat.com>
This commit is contained in:
David Howells
parent
be080a6f43
commit
989782dcdc
6 changed files with 740 additions and 353 deletions
988
fs/afs/cell.c
988
fs/afs/cell.c
File diff suppressed because it is too large
Load diff
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@ -207,13 +207,14 @@ struct afs_net {
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atomic_t nr_superblocks;
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/* Cell database */
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struct list_head cells;
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struct rb_root cells;
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struct afs_cell *ws_cell;
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rwlock_t cells_lock;
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struct rw_semaphore cells_sem;
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wait_queue_head_t cells_freeable_wq;
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struct work_struct cells_manager;
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struct timer_list cells_timer;
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atomic_t cells_outstanding;
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seqlock_t cells_lock;
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struct rw_semaphore proc_cells_sem;
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spinlock_t proc_cells_lock;
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struct list_head proc_cells;
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/* Volume location database */
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@ -242,14 +243,26 @@ struct afs_net {
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extern struct afs_net __afs_net;// Dummy AFS network namespace; TODO: replace with real netns
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enum afs_cell_state {
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AFS_CELL_UNSET,
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AFS_CELL_ACTIVATING,
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AFS_CELL_ACTIVE,
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AFS_CELL_DEACTIVATING,
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AFS_CELL_INACTIVE,
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AFS_CELL_FAILED,
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};
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/*
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* AFS cell record
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*/
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struct afs_cell {
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atomic_t usage;
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struct list_head link; /* main cell list link */
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struct afs_net *net; /* The network namespace */
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union {
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struct rcu_head rcu;
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struct rb_node net_node; /* Node in net->cells */
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};
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struct afs_net *net;
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struct key *anonymous_key; /* anonymous user key for this cell */
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struct work_struct manager; /* Manager for init/deinit/dns */
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struct list_head proc_link; /* /proc cell list link */
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#ifdef CONFIG_AFS_FSCACHE
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struct fscache_cookie *cache; /* caching cookie */
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@ -262,12 +275,26 @@ struct afs_cell {
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/* volume location record management */
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struct rw_semaphore vl_sem; /* volume management serialisation semaphore */
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struct list_head vl_list; /* cell's active VL record list */
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time64_t dns_expiry; /* Time AFSDB/SRV record expires */
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time64_t last_inactive; /* Time of last drop of usage count */
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atomic_t usage;
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unsigned long flags;
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#define AFS_CELL_FL_NOT_READY 0 /* The cell record is not ready for use */
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#define AFS_CELL_FL_NO_GC 1 /* The cell was added manually, don't auto-gc */
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#define AFS_CELL_FL_NOT_FOUND 2 /* Permanent DNS error */
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#define AFS_CELL_FL_DNS_FAIL 3 /* Failed to access DNS */
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enum afs_cell_state state;
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short error;
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spinlock_t vl_lock; /* vl_list lock */
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/* VLDB server list. */
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seqlock_t vl_addrs_lock;
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unsigned short vl_naddrs; /* number of VL servers in addr list */
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unsigned short vl_curr_svix; /* current server index */
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struct sockaddr_rxrpc vl_addrs[AFS_CELL_MAX_ADDRS]; /* cell VL server addresses */
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char name[0]; /* cell name - must go last */
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u8 name_len; /* Length of name */
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char name[64 + 1]; /* Cell name, case-flattened and NUL-padded */
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};
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/*
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@ -494,17 +521,20 @@ static inline struct afs_cb_interest *afs_get_cb_interest(struct afs_cb_interest
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/*
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* cell.c
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*/
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static inline struct afs_cell *afs_get_cell(struct afs_cell *cell)
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static inline struct afs_cell *afs_get_cell(struct afs_cell *cell)
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{
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if (cell)
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atomic_inc(&cell->usage);
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return cell;
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}
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extern int afs_cell_init(struct afs_net *, char *);
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extern struct afs_cell *afs_cell_create(struct afs_net *, const char *, unsigned, char *, bool);
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extern struct afs_cell *afs_cell_lookup(struct afs_net *, const char *, unsigned, bool);
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extern struct afs_cell *afs_grab_cell(struct afs_cell *);
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extern int afs_cell_init(struct afs_net *, const char *);
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extern struct afs_cell *afs_lookup_cell_rcu(struct afs_net *, const char *, unsigned);
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extern struct afs_cell *afs_lookup_cell(struct afs_net *, const char *, unsigned,
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const char *, bool);
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extern void afs_put_cell(struct afs_net *, struct afs_cell *);
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extern void afs_manage_cells(struct work_struct *);
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extern void afs_cells_timer(struct timer_list *);
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extern void __net_exit afs_cell_purge(struct afs_net *);
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/*
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@ -46,12 +46,15 @@ static int __net_init afs_net_init(struct afs_net *net)
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INIT_WORK(&net->charge_preallocation_work, afs_charge_preallocation);
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mutex_init(&net->socket_mutex);
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INIT_LIST_HEAD(&net->cells);
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rwlock_init(&net->cells_lock);
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init_rwsem(&net->cells_sem);
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init_waitqueue_head(&net->cells_freeable_wq);
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init_rwsem(&net->proc_cells_sem);
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net->cells = RB_ROOT;
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seqlock_init(&net->cells_lock);
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INIT_WORK(&net->cells_manager, afs_manage_cells);
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timer_setup(&net->cells_timer, afs_cells_timer, 0);
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spin_lock_init(&net->proc_cells_lock);
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INIT_LIST_HEAD(&net->proc_cells);
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INIT_LIST_HEAD(&net->vl_updates);
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INIT_LIST_HEAD(&net->vl_graveyard);
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INIT_DELAYED_WORK(&net->vl_reaper, afs_vlocation_reaper);
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@ -83,11 +86,14 @@ static int __net_init afs_net_init(struct afs_net *net)
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return 0;
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error_open_socket:
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net->live = false;
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afs_vlocation_purge(net);
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afs_cell_purge(net);
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error_cell_init:
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net->live = false;
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afs_proc_cleanup(net);
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error_proc:
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net->live = false;
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return ret;
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}
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@ -186,7 +186,7 @@ static void *afs_proc_cells_start(struct seq_file *m, loff_t *_pos)
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{
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struct afs_net *net = afs_seq2net(m);
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down_read(&net->proc_cells_sem);
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rcu_read_lock();
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return seq_list_start_head(&net->proc_cells, *_pos);
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}
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@ -205,9 +205,7 @@ static void *afs_proc_cells_next(struct seq_file *m, void *v, loff_t *pos)
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*/
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static void afs_proc_cells_stop(struct seq_file *m, void *v)
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{
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struct afs_net *net = afs_seq2net(m);
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up_read(&net->proc_cells_sem);
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rcu_read_unlock();
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}
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/*
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@ -225,8 +223,7 @@ static int afs_proc_cells_show(struct seq_file *m, void *v)
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}
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/* display one cell per line on subsequent lines */
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seq_printf(m, "%3d %s\n",
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atomic_read(&cell->usage), cell->name);
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seq_printf(m, "%3u %s\n", atomic_read(&cell->usage), cell->name);
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return 0;
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}
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@ -279,13 +276,13 @@ static ssize_t afs_proc_cells_write(struct file *file, const char __user *buf,
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if (strcmp(kbuf, "add") == 0) {
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struct afs_cell *cell;
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cell = afs_cell_create(net, name, strlen(name), args, false);
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cell = afs_lookup_cell(net, name, strlen(name), args, true);
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if (IS_ERR(cell)) {
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ret = PTR_ERR(cell);
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goto done;
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}
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afs_put_cell(net, cell);
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set_bit(AFS_CELL_FL_NO_GC, &cell->flags);
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printk("kAFS: Added new cell '%s'\n", name);
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} else {
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goto inval;
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@ -354,7 +351,7 @@ int afs_proc_cell_setup(struct afs_net *net, struct afs_cell *cell)
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{
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struct proc_dir_entry *dir;
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_enter("%p{%s}", cell, cell->name);
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_enter("%p{%s},%p", cell, cell->name, net->proc_afs);
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dir = proc_mkdir(cell->name, net->proc_afs);
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if (!dir)
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@ -200,10 +200,11 @@ static int afs_parse_options(struct afs_mount_params *params,
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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(params->net,
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args[0].from,
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args[0].to - args[0].from,
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false);
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rcu_read_lock();
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cell = afs_lookup_cell_rcu(params->net,
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args[0].from,
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args[0].to - args[0].from);
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rcu_read_unlock();
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if (IS_ERR(cell))
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return PTR_ERR(cell);
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afs_put_cell(params->net, params->cell);
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@ -308,7 +309,8 @@ static int afs_parse_device_name(struct afs_mount_params *params,
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/* lookup the cell record */
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if (cellname || !params->cell) {
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cell = afs_cell_lookup(params->net, cellname, cellnamesz, true);
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cell = afs_lookup_cell(params->net, cellname, cellnamesz,
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NULL, false);
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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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@ -45,7 +45,7 @@ static int afs_xattr_get_cell(const struct xattr_handler *handler,
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struct afs_cell *cell = vnode->volume->cell;
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size_t namelen;
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namelen = strlen(cell->name);
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namelen = cell->name_len;
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if (size == 0)
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return namelen;
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if (namelen > size)
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