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1 | /* -*- linux-c -*- --------------------------------------------------------- * |
2 | * | |
3 | * linux/fs/autofs/waitq.c | |
4 | * | |
5 | * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved | |
6 | * | |
7 | * This file is part of the Linux kernel and is made available under | |
8 | * the terms of the GNU General Public License, version 2, or at your | |
9 | * option, any later version, incorporated herein by reference. | |
10 | * | |
11 | * ------------------------------------------------------------------------- */ | |
12 | ||
13 | #include <linux/slab.h> | |
14 | #include <linux/time.h> | |
15 | #include <linux/signal.h> | |
16 | #include <linux/file.h> | |
17 | #include "autofs_i.h" | |
18 | ||
19 | /* We make this a static variable rather than a part of the superblock; it | |
20 | is better if we don't reassign numbers easily even across filesystems */ | |
21 | static autofs_wqt_t autofs_next_wait_queue = 1; | |
22 | ||
23 | /* These are the signals we allow interrupting a pending mount */ | |
24 | #define SHUTDOWN_SIGS (sigmask(SIGKILL) | sigmask(SIGINT) | sigmask(SIGQUIT)) | |
25 | ||
26 | void autofs_catatonic_mode(struct autofs_sb_info *sbi) | |
27 | { | |
28 | struct autofs_wait_queue *wq, *nwq; | |
29 | ||
30 | DPRINTK(("autofs: entering catatonic mode\n")); | |
31 | ||
32 | sbi->catatonic = 1; | |
33 | wq = sbi->queues; | |
34 | sbi->queues = NULL; /* Erase all wait queues */ | |
35 | while ( wq ) { | |
36 | nwq = wq->next; | |
37 | wq->status = -ENOENT; /* Magic is gone - report failure */ | |
38 | kfree(wq->name); | |
39 | wq->name = NULL; | |
40 | wake_up(&wq->queue); | |
41 | wq = nwq; | |
42 | } | |
43 | fput(sbi->pipe); /* Close the pipe */ | |
44 | autofs_hash_dputall(&sbi->dirhash); /* Remove all dentry pointers */ | |
45 | } | |
46 | ||
47 | static int autofs_write(struct file *file, const void *addr, int bytes) | |
48 | { | |
49 | unsigned long sigpipe, flags; | |
50 | mm_segment_t fs; | |
51 | const char *data = (const char *)addr; | |
52 | ssize_t wr = 0; | |
53 | ||
54 | /** WARNING: this is not safe for writing more than PIPE_BUF bytes! **/ | |
55 | ||
56 | sigpipe = sigismember(¤t->pending.signal, SIGPIPE); | |
57 | ||
58 | /* Save pointer to user space and point back to kernel space */ | |
59 | fs = get_fs(); | |
60 | set_fs(KERNEL_DS); | |
61 | ||
62 | while (bytes && | |
63 | (wr = file->f_op->write(file,data,bytes,&file->f_pos)) > 0) { | |
64 | data += wr; | |
65 | bytes -= wr; | |
66 | } | |
67 | ||
68 | set_fs(fs); | |
69 | ||
70 | /* Keep the currently executing process from receiving a | |
71 | SIGPIPE unless it was already supposed to get one */ | |
72 | if (wr == -EPIPE && !sigpipe) { | |
73 | spin_lock_irqsave(¤t->sighand->siglock, flags); | |
74 | sigdelset(¤t->pending.signal, SIGPIPE); | |
75 | recalc_sigpending(); | |
76 | spin_unlock_irqrestore(¤t->sighand->siglock, flags); | |
77 | } | |
78 | ||
79 | return (bytes > 0); | |
80 | } | |
81 | ||
82 | static void autofs_notify_daemon(struct autofs_sb_info *sbi, struct autofs_wait_queue *wq) | |
83 | { | |
84 | struct autofs_packet_missing pkt; | |
85 | ||
86 | DPRINTK(("autofs_wait: wait id = 0x%08lx, name = ", wq->wait_queue_token)); | |
87 | autofs_say(wq->name,wq->len); | |
88 | ||
89 | memset(&pkt,0,sizeof pkt); /* For security reasons */ | |
90 | ||
91 | pkt.hdr.proto_version = AUTOFS_PROTO_VERSION; | |
92 | pkt.hdr.type = autofs_ptype_missing; | |
93 | pkt.wait_queue_token = wq->wait_queue_token; | |
94 | pkt.len = wq->len; | |
95 | memcpy(pkt.name, wq->name, pkt.len); | |
96 | pkt.name[pkt.len] = '\0'; | |
97 | ||
98 | if ( autofs_write(sbi->pipe,&pkt,sizeof(struct autofs_packet_missing)) ) | |
99 | autofs_catatonic_mode(sbi); | |
100 | } | |
101 | ||
102 | int autofs_wait(struct autofs_sb_info *sbi, struct qstr *name) | |
103 | { | |
104 | struct autofs_wait_queue *wq; | |
105 | int status; | |
106 | ||
107 | /* In catatonic mode, we don't wait for nobody */ | |
108 | if ( sbi->catatonic ) | |
109 | return -ENOENT; | |
110 | ||
111 | /* We shouldn't be able to get here, but just in case */ | |
112 | if ( name->len > NAME_MAX ) | |
113 | return -ENOENT; | |
114 | ||
115 | for ( wq = sbi->queues ; wq ; wq = wq->next ) { | |
116 | if ( wq->hash == name->hash && | |
117 | wq->len == name->len && | |
118 | wq->name && !memcmp(wq->name,name->name,name->len) ) | |
119 | break; | |
120 | } | |
121 | ||
122 | if ( !wq ) { | |
123 | /* Create a new wait queue */ | |
124 | wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL); | |
125 | if ( !wq ) | |
126 | return -ENOMEM; | |
127 | ||
128 | wq->name = kmalloc(name->len,GFP_KERNEL); | |
129 | if ( !wq->name ) { | |
130 | kfree(wq); | |
131 | return -ENOMEM; | |
132 | } | |
133 | wq->wait_queue_token = autofs_next_wait_queue++; | |
134 | init_waitqueue_head(&wq->queue); | |
135 | wq->hash = name->hash; | |
136 | wq->len = name->len; | |
137 | wq->status = -EINTR; /* Status return if interrupted */ | |
138 | memcpy(wq->name, name->name, name->len); | |
139 | wq->next = sbi->queues; | |
140 | sbi->queues = wq; | |
141 | ||
142 | /* autofs_notify_daemon() may block */ | |
143 | wq->wait_ctr = 2; | |
144 | autofs_notify_daemon(sbi,wq); | |
145 | } else | |
146 | wq->wait_ctr++; | |
147 | ||
148 | /* wq->name is NULL if and only if the lock is already released */ | |
149 | ||
150 | if ( sbi->catatonic ) { | |
151 | /* We might have slept, so check again for catatonic mode */ | |
152 | wq->status = -ENOENT; | |
153 | if ( wq->name ) { | |
154 | kfree(wq->name); | |
155 | wq->name = NULL; | |
156 | } | |
157 | } | |
158 | ||
159 | if ( wq->name ) { | |
160 | /* Block all but "shutdown" signals while waiting */ | |
161 | sigset_t sigmask; | |
162 | ||
163 | siginitsetinv(&sigmask, SHUTDOWN_SIGS); | |
164 | sigprocmask(SIG_BLOCK, &sigmask, &sigmask); | |
165 | ||
166 | interruptible_sleep_on(&wq->queue); | |
167 | ||
168 | sigprocmask(SIG_SETMASK, &sigmask, NULL); | |
169 | } else { | |
170 | DPRINTK(("autofs_wait: skipped sleeping\n")); | |
171 | } | |
172 | ||
173 | status = wq->status; | |
174 | ||
175 | if ( ! --wq->wait_ctr ) /* Are we the last process to need status? */ | |
176 | kfree(wq); | |
177 | ||
178 | return status; | |
179 | } | |
180 | ||
181 | ||
182 | int autofs_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status) | |
183 | { | |
184 | struct autofs_wait_queue *wq, **wql; | |
185 | ||
186 | for ( wql = &sbi->queues ; (wq = *wql) != 0 ; wql = &wq->next ) { | |
187 | if ( wq->wait_queue_token == wait_queue_token ) | |
188 | break; | |
189 | } | |
190 | if ( !wq ) | |
191 | return -EINVAL; | |
192 | ||
193 | *wql = wq->next; /* Unlink from chain */ | |
194 | kfree(wq->name); | |
195 | wq->name = NULL; /* Do not wait on this queue */ | |
196 | ||
197 | wq->status = status; | |
198 | ||
199 | if ( ! --wq->wait_ctr ) /* Is anyone still waiting for this guy? */ | |
200 | kfree(wq); | |
201 | else | |
202 | wake_up(&wq->queue); | |
203 | ||
204 | return 0; | |
205 | } | |
206 |