fs: simplify handling of zero sized reads in __blockdev_direct_IO
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@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/direct-io.c b/fs/direct-io.c
index ac5f164..98ce3ac 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -1200,6 +1200,10 @@
}
}
+ /* 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 @@
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;