From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay2.corp.sgi.com [137.38.102.29]) by oss.sgi.com (Postfix) with ESMTP id B911D29DFA for ; Fri, 12 Apr 2013 05:26:55 -0500 (CDT) Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by relay2.corp.sgi.com (Postfix) with ESMTP id 8DE91304043 for ; Fri, 12 Apr 2013 03:26:55 -0700 (PDT) Received: from userp1040.oracle.com (userp1040.oracle.com [156.151.31.81]) by cuda.sgi.com with ESMTP id Qkkq3OT9G6UbRRJA (version=TLSv1 cipher=AES256-SHA bits=256 verify=NO) for ; Fri, 12 Apr 2013 03:26:51 -0700 (PDT) Message-ID: <5167E160.3020800@oracle.com> Date: Fri, 12 Apr 2013 18:26:40 +0800 From: Jeff Liu MIME-Version: 1.0 Subject: [PATCH] xfs: fix s_max_bytes to MAX_LFS_FILESIZE if needed List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: "xfs@oss.sgi.com" Cc: "Michael L. Semon" From: Jie Liu On 32-bit machine, the s_maxbytes is larger than the MAX_LFS_FILESIZE limits if CONFIG_LBDAF is not enabled. Hence it's possible to create a huge file via buffered-IO write with a given offset beyond this limitation. e.g. # block_size=4096 # offset=$(((2**32 - 1) * $block_size)) # xfs_io -f -c "pwrite $offset $block_size" /storage/test_file In this case, xfs_io will hang at the page writeback stage soon since the given offset would cause an overflow at xfs_vm_writepage(): end_index = offset >> PAGE_CACHE_SHIFT; last_index = (offset - 1) >> PAGE_CACHE_SHIFT; if (page->index >= end_index) { unsigned offset_into_page = offset & (PAGE_CACHE_SIZE - 1); /* * Just skip the page if it is fully outside i_size, e.g. due * to a truncate operation that is in progress. */ if (page->index >= end_index + 1 || offset_into_page == 0) { ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unlock_page(page); return 0; } end_index is unsigned long so that the max value is '2^32-1 = 4294967295', and it would be evaluated to the max value with the given offset(when writing the page offset up to s_max_bytes) for above test case. As a result, (page->index >= end_index + 1) is ok as (end_index + 1) is overflowed to ZERO. Actually, create a file as above on 32-bit machine should be failed with EFBIG error returned because there has strict check up at generic_write_checks() against the given offset with a *correct* s_max_bytes. This patch fix the s_max_bytes to MAX_LFS_FILESIZE if the pre-calculated value is greater than it. Reported-by: Michael L. Semon Signed-off-by: Jie Liu --- fs/xfs/xfs_super.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c index ea341ce..0644d61 100644 --- a/fs/xfs/xfs_super.c +++ b/fs/xfs/xfs_super.c @@ -585,6 +585,7 @@ xfs_max_file_offset( { unsigned int pagefactor = 1; unsigned int bitshift = BITS_PER_LONG - 1; + __uint64_t offset; /* Figure out maximum filesize, on Linux this can depend on * the filesystem blocksize (on 32 bit platforms). @@ -610,7 +611,10 @@ xfs_max_file_offset( # endif #endif - return (((__uint64_t)pagefactor) << bitshift) - 1; + offset = (((__uint64_t)pagefactor) << bitshift) - 1; + + /* Check against VM & VFS exposed limits */ + return (offset > MAX_LFS_FILESIZE) ? MAX_LFS_FILESIZE : offset; } xfs_agnumber_t -- 1.7.9.5 _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs