Commit 9a56c213 authored by Oleg Drokin's avatar Oleg Drokin Committed by Linus Torvalds
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[PATCH] Add lookup_instantiate_filp usage warning 



I think it would be nice to put an usage warning in header of
lookup_instantiate_filp() to indicate it is unsafe to use it on anything
but regular files (even that is potentially unsafe, but there your ->open()
is usually in your hands anyway), so that others won't fall into the same
trap I did.

Signed-off-by: default avatarOleg Drokin <green@linuxhacker.ru>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent b500531e

fs/open.c

+4 −0
Original line number Diff line number Diff line
@@ -890,6 +890,10 @@ EXPORT_SYMBOL(filp_open); 
 * a fully instantiated struct file to the caller.

 * This function is meant to be called from within a filesystem's

 * lookup method.

 * Beware of calling it for non-regular files! Those ->open methods might block

 * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo,

 * leading to a deadlock, as nobody can open that fifo anymore, because

 * another process to open fifo will block on locked parent when doing lookup).

 * Note that in case of error, nd->intent.open.file is destroyed, but the

 * path information remains valid.

 * If the open callback is set to NULL, then the standard f_op->open()