Messages in this thread | | | Date | Wed, 5 Feb 2003 00:16:53 +0100 | From | Pavel Machek <> | Subject | Re: 2.0, 2.2, 2.4, 2.5: fsync buffer race |
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Hi!
> > there's a race condition in filesystem > > > > let's have a two inodes that are placed in the same buffer. > > > > call fsync on inode 1 > > it goes down to ext2_update_inode [update == 1] > > it calls ll_rw_block at the end > > ll_rw_block starts to write buffer > > ext2_update_inode waits on buffer > > > > while the buffer is writing, another process calls fsync on inode 2 > > it goes again to ext2_update_inode > > it calls ll_rw_block > > ll_rw_block sees buffer locked and exits immediatelly > > ext2_update_inode waits for buffer > > the first write finished, ext2_update_inode exits and changes made by > > second proces to inode 2 ARE NOT WRITTEN TO DISK. > > > > hmm, yes. This is a general weakness in the ll_rw_block() interface. It is > not suitable for data-integrity writeouts, as you've pointed out. > > A suitable fix would be do create a new > > void wait_and_rw_block(...) > { > wait_on_buffer(bh); > ll_rw_block(...); > } > > and go use that in all the appropriate places. > > I shall make that change for 2.5, thanks.
Should this be fixed at least in 2.4, too? It seems pretty serious for mail servers (etc)... Pavel -- Worst form of spam? Adding advertisment signatures ala sourceforge.net. What goes next? Inserting advertisment *into* email? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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