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Commit bf43d84b authored by Eric Sandeen's avatar Eric Sandeen Committed by Theodore Ts'o
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ext4: reject too-large filesystems on 32-bit kernels 



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: default avatarEric Sandeen <sandeen@redhat.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 0ccff1a4

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;

	}