From: Eryu Guan Subject: [PATCH v2 1/2] direct-io: cleanup get_more_blocks() Date: Sun, 8 May 2016 02:31:49 +0800 Message-ID: <1462645910-23290-1-git-send-email-guaneryu@gmail.com> Cc: linux-ext4@vger.kernel.org, jmoyer@redhat.com, Eryu Guan To: linux-fsdevel@vger.kernel.org Return-path: Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org Save one level of indention by returning error early. Introduce some local variables to make the code easier to read a bit, and do preparation for next patch. Signed-off-by: Eryu Guan --- v2: split the cleanup code into a seperate patch to make the review easier fs/direct-io.c | 69 ++++++++++++++++++++++++++++++---------------------------- 1 file changed, 36 insertions(+), 33 deletions(-) diff --git a/fs/direct-io.c b/fs/direct-io.c index 4720377..9d5aff9 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -607,52 +607,55 @@ static int get_more_blocks(struct dio *dio, struct dio_submit *sdio, int ret; sector_t fs_startblk; /* Into file, in filesystem-sized blocks */ sector_t fs_endblk; /* Into file, in filesystem-sized blocks */ + sector_t block_in_file = sdio->block_in_file; unsigned long fs_count; /* Number of filesystem-sized blocks */ int create; - unsigned int i_blkbits = sdio->blkbits + sdio->blkfactor; + unsigned int blkbits = sdio->blkbits; + unsigned int blkfactor = sdio->blkfactor; + unsigned int i_blkbits = blkbits + blkfactor; + struct inode *inode = dio->inode; /* * If there was a memory error and we've overwritten all the * mapped blocks then we can now return that memory error */ ret = dio->page_errors; - if (ret == 0) { - BUG_ON(sdio->block_in_file >= sdio->final_block_in_request); - fs_startblk = sdio->block_in_file >> sdio->blkfactor; - fs_endblk = (sdio->final_block_in_request - 1) >> - sdio->blkfactor; - fs_count = fs_endblk - fs_startblk + 1; + if (ret) + return ret; - map_bh->b_state = 0; - map_bh->b_size = fs_count << i_blkbits; + BUG_ON(block_in_file >= sdio->final_block_in_request); + fs_startblk = block_in_file >> blkfactor; + fs_endblk = (sdio->final_block_in_request - 1) >> blkfactor; + fs_count = fs_endblk - fs_startblk + 1; - /* - * For writes inside i_size on a DIO_SKIP_HOLES filesystem we - * forbid block creations: only overwrites are permitted. - * We will return early to the caller once we see an - * unmapped buffer head returned, and the caller will fall - * back to buffered I/O. - * - * Otherwise the decision is left to the get_blocks method, - * which may decide to handle it or also return an unmapped - * buffer head. - */ - create = dio->rw & WRITE; - if (dio->flags & DIO_SKIP_HOLES) { - if (sdio->block_in_file < (i_size_read(dio->inode) >> - sdio->blkbits)) - create = 0; - } + map_bh->b_state = 0; + map_bh->b_size = fs_count << i_blkbits; + + /* + * For writes inside i_size on a DIO_SKIP_HOLES filesystem we + * forbid block creations: only overwrites are permitted. + * We will return early to the caller once we see an + * unmapped buffer head returned, and the caller will fall + * back to buffered I/O. + * + * Otherwise the decision is left to the get_blocks method, + * which may decide to handle it or also return an unmapped + * buffer head. + */ + create = dio->rw & WRITE; + if (dio->flags & DIO_SKIP_HOLES) { + if (block_in_file < (i_size_read(inode) >> blkbits)) + create = 0; + } - ret = (*sdio->get_block)(dio->inode, fs_startblk, - map_bh, create); + ret = (*sdio->get_block)(inode, fs_startblk, map_bh, create); - /* Store for completion */ - dio->private = map_bh->b_private; + /* Store for completion */ + dio->private = map_bh->b_private; + + if (ret == 0 && buffer_defer_completion(map_bh)) + ret = dio_set_defer_completion(dio); - if (ret == 0 && buffer_defer_completion(map_bh)) - ret = dio_set_defer_completion(dio); - } return ret; } -- 2.5.5