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Message-ID: <1267739098.4204.12.camel@michlmayr> Date: Thu, 04 Mar 2010 22:44:58 +0100 From: Leonard Michlmayr <leonard.michlmayr@...il.com> To: Akira Fujita <a-fujita@...jp.nec.com>, tytso@....edu Cc: Ext4 Developers List <linux-ext4@...r.kernel.org> Subject: Re: [PATCH 11/28] ext4: correctly calculate number of blocks for fiemap Akira Fujita: > <kernel-space> > fs/ioctl.c ioctl_fimap(): > > filemap_check_ranges(): > len(~0ULL) > new_len(4398046511103 = s_maxbytes) <--- Because 'len > s_maxbytes' > > fs/ext4/extents.c ext4_fiemap(): > last_blk = start(0) + len(4398046511103) - 1 >> s_blocksize_bits(11) > = 4294967295 (0xFFFFFFFF) > len_blks = 4294967295 + 1 (0xFFFFFFFF + 0x00000001) > = 4294967296 (0x100000000) <--- _OVERFLOW!!_ > > ext4_ext_walk_space(): > num = 0 > > This overflow leads to incorrect output like the below, > even though 2 extents exist. > Thank you for pointing this out. I had not checked s_maxbytes. Appearently s_maxbytes can be 1<<(32 + s_blocksize_bits) - 1. Therefore the number of blocks in a file cannot be stored in a 32bit integer. I have a patch that should fix it for fiemap. I have just compiled it and I will do some testing and double checking tomorrow. I will send a separate email with the patch. regards Leonard -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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