autofs4: check kernel communication pipe is valid for write
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>
diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
index 1132cc2..dd2914d 100644
--- a/fs/autofs4/waitq.c
+++ b/fs/autofs4/waitq.c
@@ -99,6 +99,7 @@
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 @@
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,