Reject zero sized reads as soon as we know our I/O length, and don't
borther with locks or allocations that might have to be cleaned up
otherwise.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Index: linux-2.6/fs/direct-io.c
===================================================================
--- linux-2.6.orig/fs/direct-io.c 2011-06-11 12:10:10.205165161 +0200
+++ linux-2.6/fs/direct-io.c 2011-06-11 12:12:49.161823781 +0200
@@ -1200,6 +1200,10 @@ __blockdev_direct_IO(int rw, struct kioc
}
}
+ /* watch out for a 0 len io from a tricksy fs */
+ if (rw == READ && end == offset)
+ return 0;
+
dio = kmalloc(sizeof(*dio), GFP_KERNEL);
retval = -ENOMEM;
if (!dio)
@@ -1213,8 +1217,7 @@ __blockdev_direct_IO(int rw, struct kioc
dio->flags = flags;
if (dio->flags & DIO_LOCKING) {
- /* watch out for a 0 len io from a tricksy fs */
- if (rw == READ && end > offset) {
+ if (rw == READ) {
struct address_space *mapping =
iocb->ki_filp->f_mapping;
--
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