ext4: reject too-large filesystems on 32-bit kernels (bf43d84b) · Commits · 戴 / test

ext4 will happily mount a > 16T filesystem on a 32-bit box, but this is not safe; writes to the block device will wrap past 16T and the page cache can't index past 16T (232 index * 4k pages). Adding another test to the existing "too many sectors" test should do the trick. Add a comment, a relevant return value, and fix the reference to the CONFIG_LBD(AF) option as well. Signed-off-by:

Eric Sandeen <sandeen@redhat.com> Signed-off-by:

"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/super.c

+10 −3

Original line number	Diff line number	Diff line
		@@ -2550,12 +2550,19 @@ static int ext4_fill_super(struct super_block sb, void data, int silent)
		goto failed_mount;
		}

		if (ext4_blocks_count(es) >
		(sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
		/*
		* Test whether we have more sectors than will fit in sector_t,
		* and whether the max offset is addressable by the page cache.
		*/
		if ((ext4_blocks_count(es) >
		(sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) \|\|
		(ext4_blocks_count(es) >
		(pgoff_t)(~0ULL) >> (PAGE_CACHE_SHIFT - sb->s_blocksize_bits))) {
		ext4_msg(sb, KERN_ERR, "filesystem"
		" too large to mount safely");
		" too large to mount safely on this system");
		if (sizeof(sector_t) < 8)
		ext4_msg(sb, KERN_WARNING, "CONFIG_LBDAF not enabled");
		ret = -EFBIG;
		goto failed_mount;
		}

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