From c949d4eb40ce021b1abc3b63af23aa535662cb17 Mon Sep 17 00:00:00 2001 From: Jiri Kosina Date: Wed, 6 Dec 2006 20:39:38 -0800 Subject: [PATCH] autofs: fix error code path in autofs_fill_sb() When kernel is compiled with old version of autofs (CONFIG_AUTOFS_FS), and new (observed at least with 5.x.x) automount deamon is started, kernel correctly reports incompatible version of kernel and userland daemon, but then screws things up instead of correct handling of the error: autofs: kernel does not match daemon version ===================================== [ BUG: bad unlock balance detected! ] ------------------------------------- automount/4199 is trying to release lock (&type->s_umount_key) at: [] get_sb_nodev+0x76/0xa4 but there are no more locks to release! other info that might help us debug this: no locks held by automount/4199. stack backtrace: [] dump_trace+0x68/0x1b2 [] show_trace_log_lvl+0x18/0x2c [] show_trace+0xf/0x11 [] dump_stack+0x12/0x14 [] print_unlock_inbalance_bug+0xe7/0xf3 [] lock_release+0x8d/0x164 [] up_write+0x14/0x27 [] get_sb_nodev+0x76/0xa4 [] vfs_kern_mount+0x83/0xf6 [] do_kern_mount+0x2d/0x3e [] do_mount+0x607/0x67a [] sys_mount+0x72/0xa4 [] sysenter_past_esp+0x5f/0x99 DWARF2 unwinder stuck at sysenter_past_esp+0x5f/0x99 Leftover inexact backtrace: ======================= and then deadlock comes. The problem: autofs_fill_super() returns EINVAL to get_sb_nodev(), but before that, it calls kill_anon_super() to destroy the superblock which won't be needed. This is however way too soon to call kill_anon_super(), because get_sb_nodev() has to perform its own cleanup of the superblock first (deactivate_super(), etc.). The correct time to call kill_anon_super() is in the autofs_kill_sb() callback, which is called by deactivate_super() at proper time, when the superblock is ready to be killed. I can see the same faulty codepath also in autofs4. This patch solves issues in both filesystems in a same way - it postpones the kill_anon_super() until the proper time is signalized by deactivate_super() calling the kill_sb() callback. [raven@themaw.net: update comment] Signed-off-by: Jiri Kosina Acked-by: Ian Kent Cc: Signed-off-by: Ian Kent Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/autofs/inode.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'fs/autofs') diff --git a/fs/autofs/inode.c b/fs/autofs/inode.c index 38ede5c9d6f..f968d134280 100644 --- a/fs/autofs/inode.c +++ b/fs/autofs/inode.c @@ -28,10 +28,11 @@ void autofs_kill_sb(struct super_block *sb) /* * In the event of a failure in get_sb_nodev the superblock * info is not present so nothing else has been setup, so - * just exit when we are called from deactivate_super. + * just call kill_anon_super when we are called from + * deactivate_super. */ if (!sbi) - return; + goto out_kill_sb; if ( !sbi->catatonic ) autofs_catatonic_mode(sbi); /* Free wait queues, close pipe */ @@ -44,6 +45,7 @@ void autofs_kill_sb(struct super_block *sb) kfree(sb->s_fs_info); +out_kill_sb: DPRINTK(("autofs: shutting down\n")); kill_anon_super(sb); } @@ -209,7 +211,6 @@ fail_iput: fail_free: kfree(sbi); s->s_fs_info = NULL; - kill_anon_super(s); fail_unlock: return -EINVAL; } -- cgit v1.2.3-70-g09d2