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Commit f9b5570d authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Al Viro
Browse files

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: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 9ea7df53

fs/direct-io.c

+5 −2
Original line number Original line Diff line number Diff line
@@ -1200,6 +1200,10 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, 
		}

		}

	}

	}





	/* watch out for a 0 len io from a tricksy fs */

	if (rw == READ && end == offset)

		return 0;



	dio = kmalloc(sizeof(*dio), GFP_KERNEL);

	dio = kmalloc(sizeof(*dio), GFP_KERNEL);

	retval = -ENOMEM;

	retval = -ENOMEM;

	if (!dio)

	if (!dio)
@@ -1213,8 +1217,7 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, 




	dio->flags = flags;

	dio->flags = flags;

	if (dio->flags & DIO_LOCKING) {

	if (dio->flags & DIO_LOCKING) {

		/* watch out for a 0 len io from a tricksy fs */

		if (rw == READ) {

		if (rw == READ && end > offset) {

			struct address_space *mapping =

			struct address_space *mapping =

					iocb->ki_filp->f_mapping;

					iocb->ki_filp->f_mapping;