Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752345Ab3EEUv4 (ORCPT ); Sun, 5 May 2013 16:51:56 -0400 Received: from mail.ispras.ru ([83.149.199.45]:55784 "EHLO mail.ispras.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752065Ab3EEUvz (ORCPT ); Sun, 5 May 2013 16:51:55 -0400 From: Alexey Khoroshilov To: "Theodore Ts'o" Cc: Alexey Khoroshilov , Andreas Dilger , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, spruce-project@linuxtesting.org Subject: [PATCH] ext4: implement error handling of ext4_mb_new_preallocation() Date: Mon, 6 May 2013 00:51:15 +0400 Message-Id: <1367787075-11626-1-git-send-email-khoroshilov@ispras.ru> X-Mailer: git-send-email 1.7.9.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2491 Lines: 63 If memory allocation in ext4_mb_new_group_pa() is failed, it returns error code, ext4_mb_new_preallocation() propages it, but ext4_mb_new_blocks() ignores it. An observed result was: - allocation fail means ext4_mb_new_group_pa() does not update ext4_allocation_context; - ext4_mb_new_blocks() sets ext4_allocation_request->len (ar->len = ac->ac_b_ex.fe_len;) to number of blocks preallocated (512) instead of number of blocks requested (1); - that activates update cycle in ext4_splice_branch(): for (i = 1; i < blks; i++) <-- blks is 512 instead of 1 here *(where->p + i) = cpu_to_le32(current_block++); - it iterates 511 times and corrupts a chunk of memory including inode structure; - page fault happens at EXT4_SB(inode->i_sb) in ext4_mark_inode_dirty(); - system hangs with 'scheduling while atomic' BUG. The patch implements a check for ext4_mb_new_preallocation() error code and handles its failure as if ext4_mb_regular_allocator() fails. Found by Linux File System Verification project (linuxtesting.org). Signed-off-by: Alexey Khoroshilov --- fs/ext4/mballoc.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index b1ed9e0..95c6b0d 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4401,17 +4401,18 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle, repeat: /* allocate space in core */ *errp = ext4_mb_regular_allocator(ac); + if (!*errp) { + /* as we've just preallocated more space than + * user requested orinally, we store allocated + * space in a special descriptor */ + if (ac->ac_status == AC_STATUS_FOUND && + ac->ac_o_ex.fe_len < ac->ac_b_ex.fe_len) + *errp = ext4_mb_new_preallocation(ac); + } if (*errp) { ext4_discard_allocated_blocks(ac); goto errout; } - - /* as we've just preallocated more space than - * user requested orinally, we store allocated - * space in a special descriptor */ - if (ac->ac_status == AC_STATUS_FOUND && - ac->ac_o_ex.fe_len < ac->ac_b_ex.fe_len) - ext4_mb_new_preallocation(ac); } if (likely(ac->ac_status == AC_STATUS_FOUND)) { *errp = ext4_mb_mark_diskspace_used(ac, handle, reserv_clstrs); -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/