Al Boldi wrote: > Eric Van Hensbergen wrote: > > On 7/8/06, Al Boldi <a1426z@xxxxxxxxx> wrote: > > > Copy on Write is a neat way to quickly achieve a semi-clustered > > > system, by mounting any shared FS read-only and redirecting writes to > > > some perClient FS. > > > > > > Would this redirection be easy to implement into the VFS? > > > > There are a variety of solutions that have been proposed or are > > available to do this sort of thing. You may want to start by looking > > at unionfs and mapfs. There are also folks looking at doing this from > > the block layer (look at the dm-userspace + cowd as well as evms and > > lvm snapshots). > > The idea here, is to do things completely transparent while being as > unintrusive as possible, by relying on the current FS infrastructure, w/o > introducing another VFS. > > Consider something simple like this: > > VFS - anyFS1 (r/w) used normally, unless ENotFound, then redirect read to > \ anyFS2, or CoW from anyFS2 to anyFS1. > anyFS2 (r/o) used normally. > > i.e: Does the VFS provide hooks for perMount Handlers? Silence is probably an indication that the VFS does not provide hooks. The question then: 1. Would it be difficult to introduce perMount Handler hooks into the VFS? 2. Would it be easier to replace the current VFS with one that offers a more flexible/open configuration? 3. Would these changes be welcome, or is the VFS considered to be a forbidden zone? Thanks! -- Al - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
