From patchwork Tue Jun 21 06:40:59 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Naohiro Aota X-Patchwork-Id: 12888716 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1FE69C433EF for ; Tue, 21 Jun 2022 06:44:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345976AbiFUGoH (ORCPT ); Tue, 21 Jun 2022 02:44:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56988 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345836AbiFUGoG (ORCPT ); Tue, 21 Jun 2022 02:44:06 -0400 Received: from esa3.hgst.iphmx.com (esa3.hgst.iphmx.com [216.71.153.141]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 145FC1B7B3 for ; Mon, 20 Jun 2022 23:44:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=wdc.com; i=@wdc.com; q=dns/txt; s=dkim.wdc.com; t=1655793843; x=1687329843; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=0ye5mulVRtQm8sh5Cog5V39eofpB8oOVMFQt6emy1IQ=; b=HHCZjpvtQJVnEbCdyqVFwvn9oHA/GZYtot6zA2hrJpiistW6jm02GByU y1Y4l36cGCLTDzSj2ryDNkqnjHjpXOpx9LJCBwS4TLNNGYfIMsP23csts DkApFm+l5JyxsWLBiLJaIUklf3kXEgmK4aBD2JGYcXJWaRiJGmwNGX3/s xkN2v+GJt5d0ev3JnMw95Alf/ufzlRz1YX/kgkwxp0Hxx3XVxCngnFpJn rTxzMrgbIho18r1beMr4T3Afv4OxHVZct6pBY4Imd2QlTVcsQ5AF4Ex61 /COHOd3Isgc7alPpGV2pqBNoCAeUzK7XUw7TKi7k7QX2PJ+EL/jAo4+rd w==; X-IronPort-AV: E=Sophos;i="5.92,209,1650902400"; d="scan'208";a="208550409" Received: from uls-op-cesaip02.wdc.com (HELO uls-op-cesaep02.wdc.com) ([199.255.45.15]) by ob1.hgst.iphmx.com with ESMTP; 21 Jun 2022 14:44:02 +0800 IronPort-SDR: T2y7C5o1whEkery/Crkjb8QSI6+kCdN+JLqDkj99XW8zm8HH6e5eYrvvQnRflZWOiWVJ5ItKI9 Y0oxCCfZ2q9CQC/T/cFMs7Zr60TCrFSpO+WIs5ENEznsJ8vVj5QxQgmyztpd8u2qmcam7iONzE eZj6lkR1L4HKfw8jeQ/ewRN8aagciulI+iw0S3eQSAOc6eWaz5cpKm4GsvvBgf7y7xtHL57A3G B78dBLAIFAOhTZyH3mwB7w6JtFOhHASgLhg9wHXfco1lj4+WUbyxK3lcjACUdmi9D5gjlviCNZ ocNMhuEETSJ2LFqR1bVcJn1/ Received: from uls-op-cesaip02.wdc.com ([10.248.3.37]) by uls-op-cesaep02.wdc.com with ESMTP/TLS/ECDHE-RSA-AES128-GCM-SHA256; 20 Jun 2022 23:02:11 -0700 IronPort-SDR: 40LYZqPjiQFWaSlqdUZnPKAgFZLJHDbrDcqu7/05YUwQyER/z+S66FY2Gn3C/DuXBi0U2s1CNv rwxVqG7LWcadpwtn60eiDLmZ3ok9Dz60q3sG8QnoDeNaBfMuEiYev5egss5C2Brfdq3VJKJ7n7 eiPtRmp/YlX7RJV099EyzZ2DuXb1ODla1Umz0q4V1P6anUo5okgmPjd7U03tuG4TpErT5poETC crUjmpVrojIUrB8UxMgaanrD/iFvVBjRAAQjHXIyx/WebgIDkfDEqs5AKOC/HXvOCeNE6VWPjR pb8= WDCIronportException: Internal Received: from dtjcyy2.ad.shared (HELO naota-xeon.wdc.com) ([10.225.48.142]) by uls-op-cesaip02.wdc.com with ESMTP; 20 Jun 2022 23:44:04 -0700 From: Naohiro Aota To: linux-btrfs@vger.kernel.org Cc: fdmanana@kernel.org, Naohiro Aota Subject: [PATCH v2 1/4] btrfs: ensure pages are unlocked on cow_file_range() failure Date: Tue, 21 Jun 2022 15:40:59 +0900 Message-Id: <3ae46fc143bf820a39e7cf425d675d6825af849d.1655791781.git.naohiro.aota@wdc.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org There is a hung_task report on zoned btrfs like below. https://github.com/naota/linux/issues/59 [ 726.328648] INFO: task rocksdb:high0:11085 blocked for more than 241 seconds. [ 726.329839] Not tainted 5.16.0-rc1+ #1 [ 726.330484] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 726.331603] task:rocksdb:high0 state:D stack: 0 pid:11085 ppid: 11082 flags:0x00000000 [ 726.331608] Call Trace: [ 726.331611] [ 726.331614] __schedule+0x2e5/0x9d0 [ 726.331622] schedule+0x58/0xd0 [ 726.331626] io_schedule+0x3f/0x70 [ 726.331629] __folio_lock+0x125/0x200 [ 726.331634] ? find_get_entries+0x1bc/0x240 [ 726.331638] ? filemap_invalidate_unlock_two+0x40/0x40 [ 726.331642] truncate_inode_pages_range+0x5b2/0x770 [ 726.331649] truncate_inode_pages_final+0x44/0x50 [ 726.331653] btrfs_evict_inode+0x67/0x480 [ 726.331658] evict+0xd0/0x180 [ 726.331661] iput+0x13f/0x200 [ 726.331664] do_unlinkat+0x1c0/0x2b0 [ 726.331668] __x64_sys_unlink+0x23/0x30 [ 726.331670] do_syscall_64+0x3b/0xc0 [ 726.331674] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 726.331677] RIP: 0033:0x7fb9490a171b [ 726.331681] RSP: 002b:00007fb943ffac68 EFLAGS: 00000246 ORIG_RAX: 0000000000000057 [ 726.331684] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fb9490a171b [ 726.331686] RDX: 00007fb943ffb040 RSI: 000055a6bbe6ec20 RDI: 00007fb94400d300 [ 726.331687] RBP: 00007fb943ffad00 R08: 0000000000000000 R09: 0000000000000000 [ 726.331688] R10: 0000000000000031 R11: 0000000000000246 R12: 00007fb943ffb000 [ 726.331690] R13: 00007fb943ffb040 R14: 0000000000000000 R15: 00007fb943ffd260 [ 726.331693] While we debug the issue, we found running fstests generic/551 on 5GB non-zoned null_blk device in the emulated zoned mode also had a similar hung issue. Also, we can reproduce the same symptom with an error injected cow_file_range() setup. The hang occurs when cow_file_range() fails in the middle of allocation. cow_file_range() called from do_allocation_zoned() can split the give region ([start, end]) for allocation depending on current block group usages. When btrfs can allocate bytes for one part of the split regions but fails for the other region (e.g. because of -ENOSPC), we return the error leaving the pages in the succeeded regions locked. Technically, this occurs only when @unlock == 0. Otherwise, we unlock the pages in an allocated region after creating an ordered extent. Considering the callers of cow_file_range(unlock=0) won't write out the pages, we can unlock the pages on error exit from cow_file_range(). So, we can ensure all the pages except @locked_page are unlocked on error case. In summary, cow_file_range now behaves like this: - page_started == 1 (return value) - All the pages are unlocked. IO is started. - unlock == 1 - All the pages except @locked_page are unlocked in any case - unlock == 0 - On success, all the pages are locked for writing out them - On failure, all the pages except @locked_page are unlocked Fixes: 42c011000963 ("btrfs: zoned: introduce dedicated data write path for zoned filesystems") CC: stable@vger.kernel.org # 5.12+ Signed-off-by: Naohiro Aota --- fs/btrfs/inode.c | 72 ++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 64 insertions(+), 8 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 6d5351454f11..4f453f6077fe 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -1133,6 +1133,28 @@ static u64 get_extent_allocation_hint(struct btrfs_inode *inode, u64 start, * *page_started is set to one if we unlock locked_page and do everything * required to start IO on it. It may be clean and already done with * IO when we return. + * + * When unlock == 1, we unlock the pages in successfully allocated regions. + * When unlock == 0, we leave them locked for writing them out. + * + * However, we unlock all the pages except @locked_page in case of failure. + * + * In summary, page locking state will be as follow: + * + * - page_started == 1 (return value) + * - All the pages are unlocked. IO is started. + * - Note that this can happen only on success + * - unlock == 1 + * - All the pages except @locked_page are unlocked in any case + * - unlock == 0 + * - On success, all the pages are locked for writing out them + * - On failure, all the pages except @locked_page are unlocked + * + * When a failure happens in the second or later iteration of the + * while-loop, the ordered extents created in previous iterations are kept + * intact. So, the caller must clean them up by calling + * btrfs_cleanup_ordered_extents(). See btrfs_run_delalloc_range() for + * example. */ static noinline int cow_file_range(struct btrfs_inode *inode, struct page *locked_page, @@ -1142,6 +1164,7 @@ static noinline int cow_file_range(struct btrfs_inode *inode, struct btrfs_root *root = inode->root; struct btrfs_fs_info *fs_info = root->fs_info; u64 alloc_hint = 0; + u64 orig_start = start; u64 num_bytes; unsigned long ram_size; u64 cur_alloc_size = 0; @@ -1329,18 +1352,44 @@ static noinline int cow_file_range(struct btrfs_inode *inode, btrfs_dec_block_group_reservations(fs_info, ins.objectid); btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset, 1); out_unlock: + /* + * Now, we have three regions to clean up, as shown below. + * + * |-------(1)----|---(2)---|-------------(3)----------| + * `- orig_start `- start `- start + cur_alloc_size `- end + * + * We process each region below. + */ + clear_bits = EXTENT_LOCKED | EXTENT_DELALLOC | EXTENT_DELALLOC_NEW | EXTENT_DEFRAG | EXTENT_CLEAR_META_RESV; page_ops = PAGE_UNLOCK | PAGE_START_WRITEBACK | PAGE_END_WRITEBACK; + /* - * If we reserved an extent for our delalloc range (or a subrange) and - * failed to create the respective ordered extent, then it means that - * when we reserved the extent we decremented the extent's size from - * the data space_info's bytes_may_use counter and incremented the - * space_info's bytes_reserved counter by the same amount. We must make - * sure extent_clear_unlock_delalloc() does not try to decrement again - * the data space_info's bytes_may_use counter, therefore we do not pass - * it the flag EXTENT_CLEAR_DATA_RESV. + * For the range (1). We have already instantiated the ordered extents + * for this region. They are cleaned up by + * btrfs_cleanup_ordered_extents() in e.g, + * btrfs_run_delalloc_range(). EXTENT_LOCKED | EXTENT_DELALLOC are + * already cleared in the above loop. And, EXTENT_DELALLOC_NEW | + * EXTENT_DEFRAG | EXTENT_CLEAR_META_RESV are handled by the cleanup + * function. + * + * However, in case of unlock == 0, we still need to unlock the pages + * (except @locked_page) to ensure all the pages are unlocked. + */ + if (!unlock && orig_start < start) + extent_clear_unlock_delalloc(inode, orig_start, start - 1, + locked_page, 0, page_ops); + + /* + * For the range (2). If we reserved an extent for our delalloc range + * (or a subrange) and failed to create the respective ordered extent, + * then it means that when we reserved the extent we decremented the + * extent's size from the data space_info's bytes_may_use counter and + * incremented the space_info's bytes_reserved counter by the same + * amount. We must make sure extent_clear_unlock_delalloc() does not try + * to decrement again the data space_info's bytes_may_use counter, + * therefore we do not pass it the flag EXTENT_CLEAR_DATA_RESV. */ if (extent_reserved) { extent_clear_unlock_delalloc(inode, start, @@ -1352,6 +1401,13 @@ static noinline int cow_file_range(struct btrfs_inode *inode, if (start >= end) goto out; } + + /* + * For the range (3). We never touched the region. In addition to the + * clear_bits above, we add EXTENT_CLEAR_DATA_RESV to release the data + * space_info's bytes_may_use counter, reserved in + * btrfs_check_data_free_space(). + */ extent_clear_unlock_delalloc(inode, start, end, locked_page, clear_bits | EXTENT_CLEAR_DATA_RESV, page_ops);