search for: io_manag

...ps to be > have a life equal to the connection itself, rather than > stack-allocated. I'm hoping to post a patch for that shortly, as > part of my experimentation with implementing ext2 as a filter > instead of a plugin, where ext2 has the limitation that when writing > a custom io_manager, you only get ONE spot where you can pass in an > opaque pointer: our .prepare will have to pass a long-lived nxdata > to ext2fs_open(). Yes I can see this could be tricky, especially in the presence of multiple threads serving a single connection. The only alternative way I can think to...

https://github.com/libguestfs/nbdkit/blob/ecef5b16359fb5af7e7abf4fd2fb3ad5438b16be/TODO#L76 Already existing filters (readahead, cache) could be improved if filters could open a background work thread or threads which connect independently to the plugin. A proposed new filter (scan) cannot really be written at all without this capability. First of all the reason this can't be done today is

...this: we want next_ops to be have a life equal to the connection itself, rather than stack-allocated. I'm hoping to post a patch for that shortly, as part of my experimentation with implementing ext2 as a filter instead of a plugin, where ext2 has the limitation that when writing a custom io_manager, you only get ONE spot where you can pass in an opaque pointer: our .prepare will have to pass a long-lived nxdata to ext2fs_open(). But that's only a partial solution towards the rest of your goal of having threading available. > > The seemingly obvious implementation - which is...

..._FLAG_64BITS; #endif + r = next_ops->get_size (nxdata); + if (r == -1) + return -1; + r = next_ops->can_write (nxdata); + if (r == -1) + return -1; + if (r == 0) + readonly = 1; + if (!readonly) fs_flags |= EXT2_FLAG_RW; - err = ext2fs_open (disk, fs_flags, 0, 0, unix_io_manager, &h->fs); + h->next.next_ops = next_ops; + h->next.nxdata = nxdata; + name = nbdkit_io_encode (&h->next); + if (!name) { + nbdkit_error ("nbdkit_io_encode: %m"); + return -1; + } + + err = ext2fs_open (name, fs_flags, 0, 0, nbdkit_io_manager, &h->f...