Re: [Libguestfs] [PATCH nbdkit v2 3/3] tmpdisk: Implement this plugin using fileops.

This plugin now implements efficient zeroing, pre-fetch and extents, which should give quite a performance boost. XXX On the flip side, it no longer ignores flush and FUA (which we can ignore because these are temporary disks), which very likely has a large negative impact on performance. Fixing this would involve generalising fileops a little.

static void * tmpdisk_open (int readonly) { - struct handle *h; + struct fileops *fops;

@@ -325,29 +273,14 @@ tmpdisk_open (int readonly) flags = O_RDONLY | O_CLOEXEC; else flags = O_RDWR | O_CLOEXEC; - h->fd = open (disk, flags); - if (h->fd == -1) { + fd = open (disk, flags); + if (fd == -1) { nbdkit_error ("open: %s: %m", disk); - goto error; + goto error2; }

+ if (init_fileops (fd, fops) == -1) + goto error3; /* We don't need the disk to appear in the filesystem since we hold * a file descriptor and access it through that, so unlink the disk. @@ -357,139 +290,26 @@ tmpdisk_open (int readonly) rmdir (dir); /* Return the handle. */ - return h; + return fops; - error: - if (h) { - if (h->fd >= 0) { - close (h->fd); - unlink (disk); - } - free (h); - } + error3: + close (fd);

@@ -505,19 +325,12 @@ static struct nbdkit_plugin plugin = { .config_help = tmpdisk_config_help, .magic_config_key = "size", - .can_multi_conn = tmpdisk_can_multi_conn, - .can_trim = tmpdisk_can_trim, - .can_fua = tmpdisk_can_fua, - .get_size = tmpdisk_get_size, - .open = tmpdisk_open, .close = tmpdisk_close, - .pread = tmpdisk_pread, - .pwrite = tmpdisk_pwrite, - .flush = tmpdisk_flush, - .trim = tmpdisk_trim, + .can_multi_conn = tmpdisk_can_multi_conn, - .errno_is_preserved = 1, + /* Data serving is implemented in common/fileops/fileops.c */ + FILEOPS_READ_WRITE_CALLBACKS }; NBDKIT_REGISTER_PLUGIN(plugin)