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Violators will be prosecuted; Wed, 30 Sep 2015 20:29:46 +1000 X-Helo: d23dlp03.au.ibm.com X-MailFrom: chandan@linux.vnet.ibm.com X-RcptTo: linux-btrfs@vger.kernel.org Received: from d23relay08.au.ibm.com (d23relay08.au.ibm.com [9.185.71.33]) by d23dlp03.au.ibm.com (Postfix) with ESMTP id 7076C357804F for ; Wed, 30 Sep 2015 20:29:46 +1000 (EST) Received: from d23av02.au.ibm.com (d23av02.au.ibm.com [9.190.235.138]) by d23relay08.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t8UATRBv32768146 for ; Wed, 30 Sep 2015 20:29:35 +1000 Received: from d23av02.au.ibm.com (localhost [127.0.0.1]) by d23av02.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t8UATDhE023607 for ; Wed, 30 Sep 2015 20:29:14 +1000 Received: from localhost.in.ibm.com ([9.124.35.170]) by d23av02.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVin) with ESMTP id t8UAStB1022921; Wed, 30 Sep 2015 20:29:10 +1000 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: [PATCH V5 05/13] Btrfs: btrfs_page_mkwrite: Reserve space in sectorsized units Date: Wed, 30 Sep 2015 15:58:24 +0530 Message-Id: <1443608912-31667-6-git-send-email-chandan@linux.vnet.ibm.com> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1443608912-31667-1-git-send-email-chandan@linux.vnet.ibm.com> References: <1443608912-31667-1-git-send-email-chandan@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15093010-0029-0000-0000-0000023D95AA Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP In subpagesize-blocksize scenario, if i_size occurs in a block which is not the last block in the page, then the space to be reserved should be calculated appropriately. Reviewed-by: Liu Bo Signed-off-by: Chandan Rajendra --- fs/btrfs/inode.c | 36 +++++++++++++++++++++++++++++++----- 1 file changed, 31 insertions(+), 5 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 5301d4e..5e6052d 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -8659,11 +8659,24 @@ int btrfs_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) loff_t size; int ret; int reserved = 0; + u64 reserved_space; u64 page_start; u64 page_end; + u64 end; + + reserved_space = PAGE_CACHE_SIZE; sb_start_pagefault(inode->i_sb); - ret = btrfs_delalloc_reserve_space(inode, PAGE_CACHE_SIZE); + + /* + Reserving delalloc space after obtaining the page lock can lead to + deadlock. For example, if a dirty page is locked by this function + and the call to btrfs_delalloc_reserve_space() ends up triggering + dirty page write out, then the btrfs_writepage() function could + end up waiting indefinitely to get a lock on the page currently + being processed by btrfs_page_mkwrite() function. + */ + ret = btrfs_delalloc_reserve_space(inode, reserved_space); if (!ret) { ret = file_update_time(vma->vm_file); reserved = 1; @@ -8684,6 +8697,7 @@ again: size = i_size_read(inode); page_start = page_offset(page); page_end = page_start + PAGE_CACHE_SIZE - 1; + end = page_end; if ((page->mapping != inode->i_mapping) || (page_start >= size)) { @@ -8699,7 +8713,7 @@ again: * we can't set the delalloc bits if there are pending ordered * extents. Drop our locks and wait for them to finish */ - ordered = btrfs_lookup_ordered_extent(inode, page_start); + ordered = btrfs_lookup_ordered_range(inode, page_start, page_end); if (ordered) { unlock_extent_cached(io_tree, page_start, page_end, &cached_state, GFP_NOFS); @@ -8709,6 +8723,18 @@ again: goto again; } + if (page->index == ((size - 1) >> PAGE_CACHE_SHIFT)) { + reserved_space = round_up(size - page_start, root->sectorsize); + if (reserved_space < PAGE_CACHE_SIZE) { + end = page_start + reserved_space - 1; + spin_lock(&BTRFS_I(inode)->lock); + BTRFS_I(inode)->outstanding_extents++; + spin_unlock(&BTRFS_I(inode)->lock); + btrfs_delalloc_release_space(inode, + PAGE_CACHE_SIZE - reserved_space); + } + } + /* * XXX - page_mkwrite gets called every time the page is dirtied, even * if it was already dirty, so for space accounting reasons we need to @@ -8716,12 +8742,12 @@ again: * is probably a better way to do this, but for now keep consistent with * prepare_pages in the normal write path. */ - clear_extent_bit(&BTRFS_I(inode)->io_tree, page_start, page_end, + clear_extent_bit(&BTRFS_I(inode)->io_tree, page_start, end, EXTENT_DIRTY | EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG, 0, 0, &cached_state, GFP_NOFS); - ret = btrfs_set_extent_delalloc(inode, page_start, page_end, + ret = btrfs_set_extent_delalloc(inode, page_start, end, &cached_state); if (ret) { unlock_extent_cached(io_tree, page_start, page_end, @@ -8760,7 +8786,7 @@ out_unlock: } unlock_page(page); out: - btrfs_delalloc_release_space(inode, PAGE_CACHE_SIZE); + btrfs_delalloc_release_space(inode, reserved_space); out_noreserve: sb_end_pagefault(inode->i_sb); return ret;