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ext4: reject too-large filesystems on 32-bit kernels

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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>
This commit is contained in:
Eric Sandeen 2009-08-17 23:48:51 -04:00 committed by Theodore Ts'o
parent 0ccff1a49d
commit bf43d84b18
1 changed files with 10 additions and 3 deletions
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13
fs/ext4/super.c
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@ -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;
}