Hi,
I have encountered a problem/issue relating to using ext2 filesystems with
(very) large sparse files, where the file length is much larger than the
filesystem size.
I'm using an x86 PC, the same issue appears in kernel 2.6.14 & 2.6.20. Use
dd 5.97 to replicate the problem.
On a ~500MB ext2 volume with about 60MB free (a 512MB flash card in a USB
reader), testing using dd like this:
dd if=/dev/zero of=test.bin bs=1 count=1 seek=17247252479
works fine, but
dd if=/dev/zero of=test.bin bs=1 count=1 seek=17247252480
gives a "File size limit exceeded" message and this warning appears in dmesg
output:
"EXT2-fs warning (device sdd): ext2_block_to_path: block > big"
[For whatever reason, it seems the maximum file size for that
partition is 17,247,252,480 bytes. In itself that behaviour isn't
necessarily a bug; but if you have any clue how the ext2 maximum file size
is related (or not) to the amount of free space or the volume size, please
let me know!]
After doing
dd if=/dev/zero of=test.bin bs=1 count=1 seek=17247252480
ls -l shows test.bin to be 17247252480 bytes long.
I unmounted the partition and used e2fsck -f to check it:
# e2fsck -f /dev/sdd
e2fsck 1.38 (30-Jun-2005)
Pass 1: Checking inodes, blocks, and sizes
Inode 123466, i_size is 17247252480, should be 0. Fix<y>? yes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
VolName: ***** FILE SYSTEM WAS MODIFIED *****
VolName: 107/125488 files (2.8% non-contiguous), 428147/501760 blocks
Regards,
-- Mark
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