search for: file_can_fua

...file/file.c +++ b/plugins/file/file.c @@ -52,6 +52,8 @@ #include <linux/fs.h> /* For BLKZEROOUT */ #endif +#define NBDKIT_API_VERSION 2 + #include <nbdkit-plugin.h> #include "isaligned.h" @@ -263,9 +265,30 @@ file_can_trim (void *handle) #endif } +static int +file_can_fua (void *handle) +{ + return NBDKIT_FUA_NATIVE; +} + +/* Flush the file to disk. */ +static int +file_flush (void *handle, uint32_t flags) +{ + struct handle *h = handle; + + if (fdatasync (h->fd) == -1) { + nbdkit_error ("fdatasync: %m"); + return -1; + } + + return 0; +} +...

...trim (void *handle) { @@ -507,6 +514,7 @@ static struct nbdkit_plugin plugin = { .open = file_open, .close = file_close, .get_size = file_get_size, + .can_multi_conn = file_can_multi_conn, .can_trim = file_can_trim, .can_fua = file_can_fua, .pread = file_pread, -- 2.19.2

First thing to say is that I need to do a *lot* more testing on this, so this is just an early peek. In particular, although it passed ‘make check && make check-valgrind’ I have *not* tested it against a multi-conn-aware client such as the Linux kernel >= 4.9. This implements NBD_FLAG_CAN_MULTI_CONN, described in the protocol doc as: "NBD_FLAG_CAN_MULTI_CONN: Indicates that

For existing commits, this is almost identical to v1, except that I updated some commit messages and reordered the commits in a somewhat more logical sequence. The main changes are the extra commits: [06/11] plugins: Return NBD_FLAG_CAN_MULTI_CONN from some readonly plugins. - Readonly plugins that can set the flag unconditionally. [09/11] partitioning: Return NBD_FLAG_CAN_MULTI_CONN. [10/11]

...nce not all filesystems - * support all fallocate modes, it would be nice if we had a way - * from fpathconf() to definitively learn what will work on a given - * fd for a more precise answer; oh well. */ -#ifdef FALLOC_FL_PUNCH_HOLE - return 1; -#else - return 0; -#endif -} - -static int -file_can_fua (void *handle) -{ - return NBDKIT_FUA_NATIVE; -} - -static int -file_can_cache (void *handle) -{ - /* Prefer posix_fadvise(), but letting nbdkit call .pread on our - * behalf also tends to work well for the local file system - * cache. - */ -#if HAVE_POSIX_FADVISE - return NBDKIT_FUA_NATIV...

There's a lot of code in nbdkit-file-plugin which it would be nice to reuse elsewhere. One possible approach (as outlined here) is simply to move the file callbacks (like file.pread, file.pwrite, file.zero etc) to a new mini-library. They can then be consumed by other plugins fairly easily by doing: static void * foo_open (int readonly) { struct fileops *fops; int fd, flags; /*

Needs some work still, see in particular the commit message for patch 3. Rich.

Since v1: - rework .can_cache to be tri-state, with default of no advertisement (ripple effect through other patches) - add a lot more patches in order to round out filter support And in the meantime, Rich pushed NBD_CMD_CACHE support into libnbd, so in theory we now have a way to test cache commands through the entire stack. Eric Blake (24): server: Internal hooks for implementing