Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754801AbaKKMIK (ORCPT ); Tue, 11 Nov 2014 07:08:10 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:57205 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753587AbaKKLJX (ORCPT ); Tue, 11 Nov 2014 06:09:23 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Eric Sandeen , "Theodore Ts'o" , Luis Henriques Subject: [PATCH 3.16.y-ckt 024/170] ext4: fix reservation overflow in ext4_da_write_begin Date: Tue, 11 Nov 2014 11:06:23 +0000 Message-Id: <1415704129-12709-25-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1415704129-12709-1-git-send-email-luis.henriques@canonical.com> References: <1415704129-12709-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.7-ckt1 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Sandeen commit 0ff8947fc5f700172b37cbca811a38eb9cb81e08 upstream. Delalloc write journal reservations only reserve 1 credit, to update the inode if necessary. However, it may happen once in a filesystem's lifetime that a file will cross the 2G threshold, and require the LARGE_FILE feature to be set in the superblock as well, if it was not set already. This overruns the transaction reservation, and can be demonstrated simply on any ext4 filesystem without the LARGE_FILE feature already set: dd if=/dev/zero of=testfile bs=1 seek=2147483646 count=1 \ conv=notrunc of=testfile sync dd if=/dev/zero of=testfile bs=1 seek=2147483647 count=1 \ conv=notrunc of=testfile leads to: EXT4-fs: ext4_do_update_inode:4296: aborting transaction: error 28 in __ext4_handle_dirty_super EXT4-fs error (device loop0) in ext4_do_update_inode:4301: error 28 EXT4-fs error (device loop0) in ext4_reserve_inode_write:4757: Readonly filesystem EXT4-fs error (device loop0) in ext4_dirty_inode:4876: error 28 EXT4-fs error (device loop0) in ext4_da_write_end:2685: error 28 Adjust the number of credits based on whether the flag is already set, and whether the current write may extend past the LARGE_FILE limit. Signed-off-by: Eric Sandeen Signed-off-by: Theodore Ts'o Reviewed-by: Andreas Dilger Signed-off-by: Luis Henriques --- fs/ext4/inode.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 2b06bac72c94..05b441641a33 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -2631,6 +2631,20 @@ static int ext4_nonda_switch(struct super_block *sb) return 0; } +/* We always reserve for an inode update; the superblock could be there too */ +static int ext4_da_write_credits(struct inode *inode, loff_t pos, unsigned len) +{ + if (likely(EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb, + EXT4_FEATURE_RO_COMPAT_LARGE_FILE))) + return 1; + + if (pos + len <= 0x7fffffffULL) + return 1; + + /* We might need to update the superblock to set LARGE_FILE */ + return 2; +} + static int ext4_da_write_begin(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, unsigned flags, struct page **pagep, void **fsdata) @@ -2681,7 +2695,8 @@ retry_grab: * of file which has an already mapped buffer. */ retry_journal: - handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE, 1); + handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE, + ext4_da_write_credits(inode, pos, len)); if (IS_ERR(handle)) { page_cache_release(page); return PTR_ERR(handle); -- 2.1.0 -- 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/