Messages in this thread | | | From | "Duane Griffin" <> | Date | Wed, 12 Mar 2008 02:42:46 +0000 | Subject | Re: [RFC, PATCH 6/6] ext3: do not write to the disk when mounting a dirty read-only filesystem |
| |
On Tue, Mar 11, 2008 at 04:11:23PM +0100, Jan Kara wrote: > Actually, this is nastier than it looks - currently fs, asks > ext3_sb_getblk() for block 'a' and it gets buffer head with b_blocknr == 'b' > instead.
Note that it will be a different device as well, in the case of an external journal.
> So when remounting you'd have to rewrite these buffers with > original block numbers which is not really possible. So I think > remapping will have to be solved differently, like providing buffer > head with correct b_blocknr but taking care when reading data to it and > reading them from elsewhere. Actually, this has to be done anyway > because JBD escapes data in the journal and you have to do unescaping > when reading data...
Hmm, I'll think about this and try to get something working. As a quick proof-of-concept hack, getting both buffers then overwriting the fs block's data with the unescaped journal data should do the trick, right?
Cheers, Duane.
-- "I never could learn to drink that blood and call it wine" - Bob Dylan
| |