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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 | sbi->pipe = NULL; |
45 | autofs_hash_dputall(&sbi->dirhash); /* Remove all dentry pointers */ |
46 | } |
47 | |
48 | static int autofs_write(struct file *file, const void *addr, int bytes) |
49 | { |
50 | unsigned long sigpipe, flags; |
51 | mm_segment_t fs; |
52 | const char *data = (const char *)addr; |
53 | ssize_t wr = 0; |
54 | |
55 | /** WARNING: this is not safe for writing more than PIPE_BUF bytes! **/ |
56 | |
57 | sigpipe = sigismember(¤t->pending.signal, SIGPIPE); |
58 | |
59 | /* Save pointer to user space and point back to kernel space */ |
60 | fs = get_fs(); |
61 | set_fs(KERNEL_DS); |
62 | |
63 | while (bytes && |
64 | (wr = file->f_op->write(file,data,bytes,&file->f_pos)) > 0) { |
65 | data += wr; |
66 | bytes -= wr; |
67 | } |
68 | |
69 | set_fs(fs); |
70 | |
71 | /* Keep the currently executing process from receiving a |
72 | SIGPIPE unless it was already supposed to get one */ |
73 | if (wr == -EPIPE && !sigpipe) { |
74 | spin_lock_irqsave(¤t->sighand->siglock, flags); |
75 | sigdelset(¤t->pending.signal, SIGPIPE); |
76 | recalc_sigpending(); |
77 | spin_unlock_irqrestore(¤t->sighand->siglock, flags); |
78 | } |
79 | |
80 | return (bytes > 0); |
81 | } |
82 | |
83 | static void autofs_notify_daemon(struct autofs_sb_info *sbi, struct autofs_wait_queue *wq) |
84 | { |
85 | struct autofs_packet_missing pkt; |
86 | |
87 | DPRINTK(("autofs_wait: wait id = 0x%08lx, name = ", wq->wait_queue_token)); |
88 | autofs_say(wq->name,wq->len); |
89 | |
90 | memset(&pkt,0,sizeof pkt); /* For security reasons */ |
91 | |
92 | pkt.hdr.proto_version = AUTOFS_PROTO_VERSION; |
93 | pkt.hdr.type = autofs_ptype_missing; |
94 | pkt.wait_queue_token = wq->wait_queue_token; |
95 | pkt.len = wq->len; |
96 | memcpy(pkt.name, wq->name, pkt.len); |
97 | pkt.name[pkt.len] = '\0'; |
98 | |
99 | if ( autofs_write(sbi->pipe,&pkt,sizeof(struct autofs_packet_missing)) ) |
100 | autofs_catatonic_mode(sbi); |
101 | } |
102 | |
103 | int autofs_wait(struct autofs_sb_info *sbi, struct qstr *name) |
104 | { |
105 | struct autofs_wait_queue *wq; |
106 | int status; |
107 | |
108 | /* In catatonic mode, we don't wait for nobody */ |
109 | if ( sbi->catatonic ) |
110 | return -ENOENT; |
111 | |
112 | /* We shouldn't be able to get here, but just in case */ |
113 | if ( name->len > NAME_MAX ) |
114 | return -ENOENT; |
115 | |
116 | for ( wq = sbi->queues ; wq ; wq = wq->next ) { |
117 | if ( wq->hash == name->hash && |
118 | wq->len == name->len && |
119 | wq->name && !memcmp(wq->name,name->name,name->len) ) |
120 | break; |
121 | } |
122 | |
123 | if ( !wq ) { |
124 | /* Create a new wait queue */ |
125 | wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL); |
126 | if ( !wq ) |
127 | return -ENOMEM; |
128 | |
129 | wq->name = kmalloc(name->len,GFP_KERNEL); |
130 | if ( !wq->name ) { |
131 | kfree(wq); |
132 | return -ENOMEM; |
133 | } |
134 | wq->wait_queue_token = autofs_next_wait_queue++; |
135 | init_waitqueue_head(&wq->queue); |
136 | wq->hash = name->hash; |
137 | wq->len = name->len; |
138 | wq->status = -EINTR; /* Status return if interrupted */ |
139 | memcpy(wq->name, name->name, name->len); |
140 | wq->next = sbi->queues; |
141 | sbi->queues = wq; |
142 | |
143 | /* autofs_notify_daemon() may block */ |
144 | wq->wait_ctr = 2; |
145 | autofs_notify_daemon(sbi,wq); |
146 | } else |
147 | wq->wait_ctr++; |
148 | |
149 | /* wq->name is NULL if and only if the lock is already released */ |
150 | |
151 | if ( sbi->catatonic ) { |
152 | /* We might have slept, so check again for catatonic mode */ |
153 | wq->status = -ENOENT; |
154 | kfree(wq->name); |
155 | wq->name = NULL; |
156 | } |
157 | |
158 | if ( wq->name ) { |
159 | /* Block all but "shutdown" signals while waiting */ |
160 | sigset_t sigmask; |
161 | |
162 | siginitsetinv(&sigmask, SHUTDOWN_SIGS); |
163 | sigprocmask(SIG_BLOCK, &sigmask, &sigmask); |
164 | |
165 | interruptible_sleep_on(&wq->queue); |
166 | |
167 | sigprocmask(SIG_SETMASK, &sigmask, NULL); |
168 | } else { |
169 | DPRINTK(("autofs_wait: skipped sleeping\n")); |
170 | } |
171 | |
172 | status = wq->status; |
173 | |
174 | if ( ! --wq->wait_ctr ) /* Are we the last process to need status? */ |
175 | kfree(wq); |
176 | |
177 | return status; |
178 | } |
179 | |
180 | |
181 | int autofs_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status) |
182 | { |
183 | struct autofs_wait_queue *wq, **wql; |
184 | |
185 | for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) { |
186 | if ( wq->wait_queue_token == wait_queue_token ) |
187 | break; |
188 | } |
189 | if ( !wq ) |
190 | return -EINVAL; |
191 | |
192 | *wql = wq->next; /* Unlink from chain */ |
193 | kfree(wq->name); |
194 | wq->name = NULL; /* Do not wait on this queue */ |
195 | |
196 | wq->status = status; |
197 | |
198 | if ( ! --wq->wait_ctr ) /* Is anyone still waiting for this guy? */ |
199 | kfree(wq); |
200 | else |
201 | wake_up(&wq->queue); |
202 | |
203 | return 0; |
204 | } |
205 | |
206 |
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