vfs: introduce FMODE_UNSIGNED_OFFSET for allowing negative f_pos
authorKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Fri, 1 Oct 2010 21:20:22 +0000 (14:20 -0700)
committerAl Viro <viro@zeniv.linux.org.uk>
Tue, 26 Oct 2010 01:18:21 +0000 (21:18 -0400)
commit4a3956c790290efeb647bbb0c3a90476bb57800e
tree18abb41325273d23ae271e49627f01054c5baeb6
parentba10f486658c0ca1bc84c936f6a996e40d071453
vfs: introduce FMODE_UNSIGNED_OFFSET for allowing negative f_pos

Now, rw_verify_area() checsk f_pos is negative or not.  And if negative,
returns -EINVAL.

But, some special files as /dev/(k)mem and /proc/<pid>/mem etc..  has
negative offsets.  And we can't do any access via read/write to the
file(device).

So introduce FMODE_UNSIGNED_OFFSET to allow negative file offsets.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
drivers/char/mem.c
fs/proc/base.c
fs/read_write.c
include/linux/fs.h