diff options
Diffstat (limited to 'hurd/translator/ext2fs.mdwn')
| -rw-r--r-- | hurd/translator/ext2fs.mdwn | 68 |
1 files changed, 60 insertions, 8 deletions
diff --git a/hurd/translator/ext2fs.mdwn b/hurd/translator/ext2fs.mdwn index 81e54dff..9be6c885 100644 --- a/hurd/translator/ext2fs.mdwn +++ b/hurd/translator/ext2fs.mdwn @@ -22,16 +22,68 @@ License|/fdl]]."]]"""]] * [[internal_allocator]] +## Current Limitations -## Large Stores - -The `ext2fs` translator from the upstream Hurd code base can only handle file -systems with sizes of less than roughly 2 GiB. +### Use 64 bit time by default -[[!tag open_issue_hurd]] +Extend ext2fs to support 64bit time. +## Large Stores -### Ognyan's Work +[[!inline pagenames=faq/2_gib_partition_limit raw=yes feeds=no]] + +## Create your own custom ext2fs + + $ dd if=/dev/zero of=silly.fs bs=1024k count=8 + $ /sbin/mkfs.ext2 -E root_owner=$UID:0 silly.fs + $ settrans -c silly /hurd/ext2fs `pwd`/silly.fs + $ ps -e | grep silly # ext2fs has not started + $ ls silly + $ ps -e | grep silly | awk '{ print $6 " " $7 }' + /hurd/ext2fs /home/joshua/silly.fs + $ cd silly + $ echo 'hello' > hello.txt + $ mkdir silly-dir + $ cd .. + $ fsysopts silly + /hurd/ext2fs --writable --relatime --no-inherit-dir-group /home/joshua/silly.fs + $ fsysopts silly --readonly # stop writes to the filesystem + $ fsysopts silly --writable # let writes again + +Try to make the filesystem read-only with fsysopts. Note how further +write attempts fail now. Try to kill the active translator with +settrans -g. + +You could go crazy even! Why not make something like this: + + ~/silly <--> silly.fs + | \ + | \ + | \ + | \ + | \ + \|/ \/ + silly1 <-> silly1.fs + ... + + /hurd/joshua/silly/silly1/silly2/silly3/silly4 + +Each sillyN is another ext2fs filesystem! Make sure that as N gets +bigger sillyN.fs gets smaller. Let us know in the `#hurd` [irc +channel](https://web.libera.chat/) how "silly" you are. :) + +The current record is 2! + + $ ps -e | grep silly | awk '{print $6 " " $7}' + /hurd/ext2fs /home/joshua/silly.fs + /hurd/ext2fs /home/joshua/silly/silly1.fs + +What is the limit? How many nested ext2fs translators can you have? +You could have 32 ["silly" +directories](https://logs.guix.gnu.org/hurd/2024-05-31.log#005021). +That's very silly! + +### Ognyan's Work to allow ext2 to surpass the 2 GiB limit * Ognyan Kulev, [[*Supporting Large ext2 File Systems in the Hurd*|ogi-fosdem2005.mgp]], 2005, at FOSDEM @@ -40,8 +92,8 @@ systems with sizes of less than roughly 2 GiB. * <http://kerneltrap.org/node/4429> -Ognyan's patch lifts this limitation (and is being used in the -[[Debian_GNU/Hurd_distribution|running/debian]]), but it introduces another +Ognyan's patch lifted this limitation (and is being used in the +[[Debian_GNU/Hurd_distribution|running/debian]]), but it introduced another incompatibility: `ext2fs` then only supports block sizes of 4096 bytes. Smaller block sizes are commonly automatically selected by `mke2fs` when using small backend stores, like floppy devices. |