Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932160Ab2KVSsX (ORCPT ); Thu, 22 Nov 2012 13:48:23 -0500 Received: from userp1050.oracle.com ([156.151.31.82]:18885 "EHLO userp1050.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754022Ab2KVSsS (ORCPT ); Thu, 22 Nov 2012 13:48:18 -0500 From: Dave Kleikamp To: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Zach Brown , "Maxim V. Patlasov" , Dave Kleikamp Subject: [PATCH v4 09/31] dio: create a dio_aligned() helper function Date: Wed, 21 Nov 2012 16:40:49 -0600 Message-Id: <1353537671-26284-10-git-send-email-dave.kleikamp@oracle.com> X-Mailer: git-send-email 1.8.0 In-Reply-To: <1353537671-26284-1-git-send-email-dave.kleikamp@oracle.com> References: <1353537671-26284-1-git-send-email-dave.kleikamp@oracle.com> X-Source-IP: userp1040.oracle.com [156.151.31.81] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3645 Lines: 113 From: Zach Brown __blockdev_direct_IO() had two instances of the same code to determine if a given offset wasn't aligned first to the inode's blkbits and then to the underlying device's blkbits. This was confusing enough but we're about to add code that performs the same check on offsets in bvec arrays. Rather than add yet more copies of this code let's have everyone call a helper. Signed-off-by: Dave Kleikamp Cc: Zach Brown --- fs/direct-io.c | 59 ++++++++++++++++++++++++++++++++++++---------------------- 1 file changed, 37 insertions(+), 22 deletions(-) diff --git a/fs/direct-io.c b/fs/direct-io.c index f86c720..035c0a3 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -1020,6 +1020,39 @@ static inline int drop_refcount(struct dio *dio) } /* + * Returns true if the given offset is aligned to either the IO size + * specified by the given blkbits or by the logical block size of the + * given block device. + * + * If the given offset isn't aligned to the blkbits arguments as this is + * called then blkbits is set to the block size of the specified block + * device. The call can then return either true or false. + * + * This bizarre calling convention matches the code paths that + * duplicated the functionality that this helper was built from. We + * reproduce the behaviour to avoid introducing subtle bugs. + */ +static int dio_aligned(unsigned long offset, unsigned *blkbits, + struct block_device *bdev) +{ + unsigned mask = (1 << *blkbits) - 1; + + /* + * Avoid references to bdev if not absolutely needed to give + * the early prefetch in the caller enough time. + */ + + if (offset & mask) { + if (bdev) + *blkbits = blksize_bits(bdev_logical_block_size(bdev)); + mask = (1 << *blkbits) - 1; + return !(offset & mask); + } + + return 1; +} + +/* * This is a library function for use by filesystem drivers. * * The locking rules are governed by the flags parameter: @@ -1054,7 +1087,6 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, size_t size; unsigned long addr; unsigned blkbits = inode->i_blkbits; - unsigned blocksize_mask = (1 << blkbits) - 1; ssize_t retval = -EINVAL; loff_t end = offset; struct dio *dio; @@ -1067,33 +1099,16 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, if (rw & WRITE) rw = WRITE_ODIRECT; - /* - * Avoid references to bdev if not absolutely needed to give - * the early prefetch in the caller enough time. - */ - - if (offset & blocksize_mask) { - if (bdev) - blkbits = blksize_bits(bdev_logical_block_size(bdev)); - blocksize_mask = (1 << blkbits) - 1; - if (offset & blocksize_mask) - goto out; - } + if (!dio_aligned(offset, &blkbits, bdev)) + goto out; /* Check the memory alignment. Blocks cannot straddle pages */ for (seg = 0; seg < nr_segs; seg++) { addr = (unsigned long)iov[seg].iov_base; size = iov[seg].iov_len; end += size; - if (unlikely((addr & blocksize_mask) || - (size & blocksize_mask))) { - if (bdev) - blkbits = blksize_bits( - bdev_logical_block_size(bdev)); - blocksize_mask = (1 << blkbits) - 1; - if ((addr & blocksize_mask) || (size & blocksize_mask)) - goto out; - } + if (!dio_aligned(addr|size, &blkbits, bdev)) + goto out; } /* watch out for a 0 len io from a tricksy fs */ -- 1.8.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/