From: Ian Kent <[email protected]> Subject: autofs: fix lockref lookup
autofs needs to be able to see private data dentry flags for its dentrys that are being created but not yet hashed and for its dentrys that have been rmdir()ed but not yet freed. It needs to do this so it can block processes in these states until a status has been returned to indicate the given operation is complete. It does this by keeping two lists, active and expring, of dentrys in this state and uses ->d_release() to keep them stable while it checks the reference count to determine if they should be used. But with the recent lockref changes dentrys being freed sometimes don't transition to a reference count of 0 before being freed so autofs can occassionally use a dentry that is invalid which can lead to a panic. Signed-off-by: Ian Kent <[email protected]> Cc: Al Viro <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> --- fs/autofs4/root.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff -puN fs/autofs4/root.c~autofs-fix-lockref-lookup fs/autofs4/root.c --- a/fs/autofs4/root.c~autofs-fix-lockref-lookup +++ a/fs/autofs4/root.c @@ -179,7 +179,7 @@ static struct dentry *autofs4_lookup_act spin_lock(&active->d_lock); /* Already gone? */ - if (!d_count(active)) + if ((int) d_count(active) <= 0) goto next; qstr = &active->d_name; @@ -230,7 +230,7 @@ static struct dentry *autofs4_lookup_exp spin_lock(&expiring->d_lock); - /* Bad luck, we've already been dentry_iput */ + /* We've already been dentry_iput or unlinked */ if (!expiring->d_inode) goto next; _ -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
