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autofs4: check kernel communication pipe is valid for write

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It is possible for an autofs mount to become catatonic (and for the daemon
communication pipe to become NULL) after a wait has been initiallized but
before the request has been sent to the daemon.  We need to check for this
before sending the request packet.

Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Ian Kent 2008-07-23 21:30:20 -07:00 committed by Linus Torvalds
parent f4c7da0261
commit e64be33cca
1 changed files with 14 additions and 2 deletions
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16
fs/autofs4/waitq.c
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@ -99,6 +99,7 @@ static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
union autofs_packet_union v4_pkt;
union autofs_v5_packet_union v5_pkt;
} pkt;
struct file *pipe = NULL;
size_t pktsz;
DPRINTK("wait id = 0x%08lx, name = %.*s, type=%d",
@ -164,8 +165,19 @@ static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
return;
}
if (autofs4_write(sbi->pipe, &pkt, pktsz))
autofs4_catatonic_mode(sbi);
/* Check if we have become catatonic */
mutex_lock(&sbi->wq_mutex);
if (!sbi->catatonic) {
pipe = sbi->pipe;
get_file(pipe);
}
mutex_unlock(&sbi->wq_mutex);
if (pipe) {
if (autofs4_write(pipe, &pkt, pktsz))
autofs4_catatonic_mode(sbi);
fput(pipe);
}
}
static int autofs4_getpath(struct autofs_sb_info *sbi,