From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e28smtp02.in.ibm.com ([122.248.162.2]:54418 "EHLO e28smtp02.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756151AbbI3KTK (ORCPT ); Wed, 30 Sep 2015 06:19:10 -0400 Received: from /spool/local by e28smtp02.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 30 Sep 2015 15:49:08 +0530 Received: from d28relay04.in.ibm.com (d28relay04.in.ibm.com [9.184.220.61]) by d28dlp02.in.ibm.com (Postfix) with ESMTP id 65504394005E for ; Wed, 30 Sep 2015 15:49:06 +0530 (IST) Received: from d28av04.in.ibm.com (d28av04.in.ibm.com [9.184.220.66]) by d28relay04.in.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t8UAIpbR20054048 for ; Wed, 30 Sep 2015 15:48:52 +0530 Received: from d28av04.in.ibm.com (localhost [127.0.0.1]) by d28av04.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t8UAImsR012005 for ; Wed, 30 Sep 2015 15:48:50 +0530 From: Chandan Rajendra To: linux-btrfs@vger.kernel.org Cc: Chandan Rajendra , jbacik@fb.com, clm@fb.com, bo.li.liu@oracle.com, dsterba@suse.cz, quwenruo@cn.fujitsu.com, chandan@mykolab.com Subject: [RFC PATCH V4 08/13] Btrfs: btrfs_submit_direct_hook: Handle map_length < bio vector length Date: Wed, 30 Sep 2015 15:48:24 +0530 Message-Id: <1443608309-30154-9-git-send-email-chandan@linux.vnet.ibm.com> In-Reply-To: <1443608309-30154-1-git-send-email-chandan@linux.vnet.ibm.com> References: <1443608309-30154-1-git-send-email-chandan@linux.vnet.ibm.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: In subpagesize-blocksize scenario, map_length can be less than the length of a bio vector. Such a condition may cause btrfs_submit_direct_hook() to submit a zero length bio. Fix this by comparing map_length against block size rather than with bv_len. Signed-off-by: Chandan Rajendra --- fs/btrfs/inode.c | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 4fbe9de..b1ceba4 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -8148,9 +8148,11 @@ static int btrfs_submit_direct_hook(int rw, struct btrfs_dio_private *dip, u64 file_offset = dip->logical_offset; u64 submit_len = 0; u64 map_length; - int nr_pages = 0; - int ret; + u32 blocksize = root->sectorsize; int async_submit = 0; + int nr_sectors; + int ret; + int i; map_length = orig_bio->bi_iter.bi_size; ret = btrfs_map_block(root->fs_info, rw, start_sector << 9, @@ -8180,9 +8182,12 @@ static int btrfs_submit_direct_hook(int rw, struct btrfs_dio_private *dip, atomic_inc(&dip->pending_bios); while (bvec <= (orig_bio->bi_io_vec + orig_bio->bi_vcnt - 1)) { - if (map_length < submit_len + bvec->bv_len || - bio_add_page(bio, bvec->bv_page, bvec->bv_len, - bvec->bv_offset) < bvec->bv_len) { + nr_sectors = bvec->bv_len >> inode->i_blkbits; + i = 0; +next_block: + if (unlikely(map_length < submit_len + blocksize || + bio_add_page(bio, bvec->bv_page, blocksize, + bvec->bv_offset + (i * blocksize)) < blocksize)) { /* * inc the count before we submit the bio so * we know the end IO handler won't happen before @@ -8203,7 +8208,6 @@ static int btrfs_submit_direct_hook(int rw, struct btrfs_dio_private *dip, file_offset += submit_len; submit_len = 0; - nr_pages = 0; bio = btrfs_dio_bio_alloc(orig_bio->bi_bdev, start_sector, GFP_NOFS); @@ -8221,9 +8225,14 @@ static int btrfs_submit_direct_hook(int rw, struct btrfs_dio_private *dip, bio_put(bio); goto out_err; } + + goto next_block; } else { - submit_len += bvec->bv_len; - nr_pages++; + submit_len += blocksize; + if (--nr_sectors) { + i++; + goto next_block; + } bvec++; } } -- 2.1.0