From patchwork Tue Apr 9 00:06:12 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Qu Wenruo X-Patchwork-Id: 13621672 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 04E1A370; Tue, 9 Apr 2024 00:06:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.135.223.131 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712621181; cv=none; b=Dqd//k9UKJRcJZMGKrxey765oHAb/2MG6DUJRZQc+Fup2hQe9QY87NGhw8SjA5freYHTsWBjziRh78VBI7Zvpscw9YUTeds89PUcyHzwUz/fxMTWi0MjyjrxkFksnt61ylJleLa/JF8Sx7Yn2cvU83j7eVUGRM+gj7gN1UQYfX8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712621181; c=relaxed/simple; bh=y27PhrCaVviptffe0v4Ndes0B1MlEF2u32PvBAqdJwA=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=PQWmwQjnxgOPXVfSPP+nCFvGOxPRl6+ykGLajg46YRu2jsTgtP8rnkQ13lQpwUPSJub/h7iEo/40HR4u8IRW3p/5zINesMGuLNI/5qSC8eNXTxlicSkZUcbgDNDq0ASN+oPPdgQc3jbuWMW1VG33f87I64/DfNOViwHA98URBKw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b=WNV5wAyG; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b=WNV5wAyG; arc=none smtp.client-ip=195.135.223.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="WNV5wAyG"; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="WNV5wAyG" Received: from imap2.dmz-prg2.suse.org (imap2.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:98]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id F31AE20666; Tue, 9 Apr 2024 00:06:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1712621177; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=DGpvuEssG0+e8y0f5Ti0Sl29gMmDI+6BYc8lFPvzKJ0=; b=WNV5wAyGQcd/Pv4L8Ti0olwsPqpZbB3OAiKwe5Nu5VzKPbSg3tPULzOqxRH6/6HPnwWeg9 SjpiCXf2VbE65N02YEwphlQtoPfPa+Mn+JP59ikWnXrlh5gP5z8iH0EeRxF99w93SKqDJ5 j8WAa3usqxPvc2mqGlpkTLmOn3ALfto= Authentication-Results: smtp-out2.suse.de; dkim=pass header.d=suse.com header.s=susede1 header.b=WNV5wAyG DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1712621177; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=DGpvuEssG0+e8y0f5Ti0Sl29gMmDI+6BYc8lFPvzKJ0=; b=WNV5wAyGQcd/Pv4L8Ti0olwsPqpZbB3OAiKwe5Nu5VzKPbSg3tPULzOqxRH6/6HPnwWeg9 SjpiCXf2VbE65N02YEwphlQtoPfPa+Mn+JP59ikWnXrlh5gP5z8iH0EeRxF99w93SKqDJ5 j8WAa3usqxPvc2mqGlpkTLmOn3ALfto= Received: from imap2.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap2.dmz-prg2.suse.org (Postfix) with ESMTPS id AE4141376F; Tue, 9 Apr 2024 00:06:15 +0000 (UTC) Received: from dovecot-director2.suse.de ([10.150.64.162]) by imap2.dmz-prg2.suse.org with ESMTPSA id LP7CFXeGFGZ8XQAAn2gu4w (envelope-from ); Tue, 09 Apr 2024 00:06:15 +0000 From: Qu Wenruo To: linux-btrfs@vger.kernel.org Cc: stable@vger.kernel.org Subject: [PATCH v2] btrfs: fix wrong block_start calculation for btrfs_drop_extent_map_range() Date: Tue, 9 Apr 2024 09:36:12 +0930 Message-ID: X-Mailer: git-send-email 2.44.0 Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Level: X-Spamd-Result: default: False [-3.01 / 50.00]; BAYES_HAM(-3.00)[100.00%]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_MISSING_CHARSET(0.50)[]; R_DKIM_ALLOW(-0.20)[suse.com:s=susede1]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:104:10:150:64:98:from]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; MIME_TRACE(0.00)[0:+]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.com:dkim,suse.com:email]; RCPT_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; DKIM_SIGNED(0.00)[suse.com:s=susede1]; RCVD_TLS_ALL(0.00)[]; TO_DN_NONE(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DKIM_TRACE(0.00)[suse.com:+] X-Rspamd-Action: no action X-Rspamd-Queue-Id: F31AE20666 X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Spam-Flag: NO X-Spam-Score: -3.01 [BUG] During my extent_map cleanup/refactor, with extra sanity checks, extent-map-tests::test_case_7() would not pass the checks. The problem is, after btrfs_drop_extent_map_range(), the resulted extent_map has a @block_start way too large. Meanwhile my btrfs_file_extent_item based members are returning a correct @disk_bytenr/@offset combination. The extent map layout looks like this: 0 16K 32K 48K | PINNED | | Regular | The regular em at [32K, 48K) also has 32K @block_start. Then drop range [0, 36K), which should shrink the regular one to be [36K, 48K). However the @block_start is incorrect, we expect 32K + 4K, but got 52K. [CAUSE] Inside btrfs_drop_extent_map_range() function, if we hit an extent_map that covers the target range but is still beyond it, we need to split that extent map into half: |<-- drop range -->| |<----- existing extent_map --->| And if the extent map is not compressed, we need to forward extent_map::block_start by the difference between the end of drop range and the extent map start. However in that particular case, the difference is calculated using (start + len - em->start). The problem is @start can be modified if the drop range covers any pinned extent. This leads to wrong calculation, and would be caught by my later extent_map sanity checks, which checks the em::block_start against btrfs_file_extent_item::disk_bytenr + btrfs_file_extent_item::offset. This is a regression caused by commit c962098ca4af ("btrfs: fix incorrect splitting in btrfs_drop_extent_map_range"), which removed the @len update for pinned extents. [FIX] Fix it by avoiding using @start completely, and use @end - em->start instead, which @end is exclusive bytenr number. And update the test case to verify the @block_start to prevent such problem from happening. Thankfully this is not going to lead to any data corruption, as IO path does not utilize btrfs_drop_extent_map_range() with @skip_pinned set. So this fix is only here for the sake of consistency/correctness. CC: stable@vger.kernel.org # 6.5+ Fixes: c962098ca4af ("btrfs: fix incorrect splitting in btrfs_drop_extent_map_range") Signed-off-by: Qu Wenruo Reviewed-by: Filipe Manana --- Changelog: v2: - Remove the mention of possible corruption Thankfully this bug does not affect IO path thus it's fine. - Explain why c962098ca4af is the cause --- fs/btrfs/extent_map.c | 2 +- fs/btrfs/tests/extent-map-tests.c | 6 +++++- 2 files changed, 6 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c index 471654cb65b0..955ce300e5a1 100644 --- a/fs/btrfs/extent_map.c +++ b/fs/btrfs/extent_map.c @@ -799,7 +799,7 @@ void btrfs_drop_extent_map_range(struct btrfs_inode *inode, u64 start, u64 end, split->block_len = em->block_len; split->orig_start = em->orig_start; } else { - const u64 diff = start + len - em->start; + const u64 diff = end - em->start; split->block_len = split->len; split->block_start += diff; diff --git a/fs/btrfs/tests/extent-map-tests.c b/fs/btrfs/tests/extent-map-tests.c index 253cce7ffecf..80e71c5cb7ab 100644 --- a/fs/btrfs/tests/extent-map-tests.c +++ b/fs/btrfs/tests/extent-map-tests.c @@ -818,7 +818,6 @@ static int test_case_7(struct btrfs_fs_info *fs_info) test_err("em->len is %llu, expected 16K", em->len); goto out; } - free_extent_map(em); read_lock(&em_tree->lock); @@ -847,6 +846,11 @@ static int test_case_7(struct btrfs_fs_info *fs_info) goto out; } + if (em->block_start != SZ_32K + SZ_4K) { + test_err("em->block_start is %llu, expected 36K", em->block_start); + goto out; + } + free_extent_map(em); read_lock(&em_tree->lock);