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 (2^32 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@xxxxxxxxxx>
---
Index: linux-2.6.29.noarch/fs/ext4/super.c
===================================================================
--- linux-2.6.29.noarch.orig/fs/ext4/super.c
+++ linux-2.6.29.noarch/fs/ext4/super.c
@@ -2274,13 +2274,20 @@ static int ext4_fill_super(struct super_
goto failed_mount;
}
+ /*
+ * 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)) {
+ (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9) ||
+ ext4_blocks_count(es) >
+ (pgoff_t)(~0ULL) >> (PAGE_CACHE_SHIFT - sb->s_blocksize_bits)) {
printk(KERN_ERR "EXT4-fs: filesystem on %s:"
- " too large to mount safely\n", sb->s_id);
+ " too large to mount safely on this system\n", sb->s_id);
if (sizeof(sector_t) < 8)
- printk(KERN_WARNING "EXT4-fs: CONFIG_LBD not "
+ printk(KERN_WARNING "EXT4-fs: CONFIG_LBDAF not "
"enabled\n");
+ ret = EFBIG;
goto failed_mount;
}
--
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