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Commit d863b50a authored by Boaz Harrosh's avatar Boaz Harrosh Committed by Linus Torvalds
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vfs: call rcu_barrier after ->kill_sb() 

In commit fa0d7e3d ("fs: icache RCU free inodes"), we use rcu free
inode instead of freeing the inode directly.  It causes a crash when we
rmmod immediately after we umount the volume[1].

So we need to call rcu_barrier after we kill_sb so that the inode is
freed before we do rmmod.  The idea is inspired by Aneesh Kumar.
rcu_barrier will wait for all callbacks to end before preceding.  The
original patch was done by Tao Ma, but synchronize_rcu() is not enough
here.

1. http://marc.info/?l=linux-fsdevel&m=129680863330185&w=2



Tested-by: default avatarTao Ma <boyu.mt@taobao.com>
Signed-off-by: default avatarBoaz Harrosh <bharrosh@panasas.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Chris Mason <chris.mason@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2dab5974

fs/super.c

+5 −0
Original line number Original line Diff line number Diff line
@@ -177,6 +177,11 @@ void deactivate_locked_super(struct super_block *s) 
	struct file_system_type *fs = s->s_type;

	struct file_system_type *fs = s->s_type;

	if (atomic_dec_and_test(&s->s_active)) {

	if (atomic_dec_and_test(&s->s_active)) {

		fs->kill_sb(s);

		fs->kill_sb(s);

		/*

		 * We need to call rcu_barrier so all the delayed rcu free

		 * inodes are flushed before we release the fs module.

		 */

		rcu_barrier();

		put_filesystem(fs);

		put_filesystem(fs);

		put_super(s);

		put_super(s);

	} else {

	} else {