search for: file_pread

...VE; +} + +/* 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; +} + /* Read data from the file. */ static int -file_pread (void *handle, void *buf, uint32_t count, uint64_t offset) +file_pread (void *handle, void *buf, uint32_t count, uint64_t offset, + uint32_t flags) { struct handle *h = handle; @@ -289,7 +312,8 @@ file_pread (void *handle, void *buf, uint32_t count, uint64_t offset) /* Write dat...

...atbuf.st_size; } +static int +file_can_trim (void *handle) +{ + /* Trim is advisory, but we prefer to advertise it only when we can + * actually (attempt to) punch holes. */ +#ifdef FALLOC_FL_PUNCH_HOLE + return 1; +#else + return 0; +#endif +} + /* Read data from the file. */ static int file_pread (void *handle, void *buf, uint32_t count, uint64_t offset) @@ -219,7 +231,7 @@ file_pwrite (void *handle, const void *buf, uint32_t count, uint64_t offset) return 0; } -/* Write data to the file. */ +/* Write zeroes to the file. */ static int file_zero (void *handle, uint32_t count, uint64_t...

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]

...f (strcmp (value, "writeback") == 0) + cache_mode = cache_writeback; + else if (strcmp (value, "writethrough") == 0) + cache_mode = cache_writethrough; else { nbdkit_error ("unknown cache mode: %s", value); return -1; @@ -423,7 +423,7 @@ file_pread (void *handle, void *buf, uint32_t count, uint64_t offset, #ifdef HAVE_POSIX_FADVISE /* On Linux this will evict the pages we just read from the page cache. */ - if (cache_mode == cache_none) + if (cache_mode == cache_writethrough) posix_fadvise (h->fd, orig_offset, orig_count, POSI...

...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

...uot;) == 0) > + cache_mode = cache_writeback; > + else if (strcmp (value, "writethrough") == 0) > + cache_mode = cache_writethrough; > else { > nbdkit_error ("unknown cache mode: %s", value); > return -1; > @@ -423,7 +423,7 @@ file_pread (void *handle, void *buf, uint32_t count, uint64_t offset, > > #ifdef HAVE_POSIX_FADVISE > /* On Linux this will evict the pages we just read from the page cache. */ > - if (cache_mode == cache_none) > + if (cache_mode == cache_writethrough) > posix_fadvise (h->fd,...

...== -1) + nbdkit_debug ("posix_fadvise: %s: %m (ignored)", filename); +#else + nbdkit_debug ("fadvise is not supported"); +#endif + } + h->is_block_device = S_ISBLK (statbuf.st_mode); h->sector_size = 4096; /* Start with safe guess */ @@ -329,6 +392,10 @@ file_pread (void *handle, void *buf, uint32_t count, uint64_t offset, uint32_t flags) { struct handle *h = handle; +#if defined (HAVE_POSIX_FADVISE) && defined (POSIX_FADV_DONTNEED) + uint32_t orig_count = count; + uint64_t orig_offset = offset; +#endif while (count > 0) {...

...mode = cache_writeback; > > + else if (strcmp (value, "writethrough") == 0) > > + cache_mode = cache_writethrough; > > else { > > nbdkit_error ("unknown cache mode: %s", value); > > return -1; > > @@ -423,7 +423,7 @@ file_pread (void *handle, void *buf, uint32_t count, uint64_t offset, > > > > #ifdef HAVE_POSIX_FADVISE > > /* On Linux this will evict the pages we just read from the page cache. */ > > - if (cache_mode == cache_none) > > + if (cache_mode == cache_writethrough) > >...

...dif -} - -/* 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; -} - -/* Read data from the file. */ -static int -file_pread (void *handle, void *buf, uint32_t count, uint64_t offset, - uint32_t flags) -{ - struct handle *h = handle; - - while (count > 0) { - ssize_t r = pread (h->fd, buf, count, offset); - if (r == -1) { - nbdkit_error ("pread: %m"); - return -1; - } -...

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.

The upstream protocol recently promoted NBD_CMD_WRITE_ZEROES from experimental to a documented extension. Exposing support for this allows plugin writers to create sparse files when driven by a client that knows how to use the extension; meanwhile, even if a plugin does not support this extension, the server benefits from less network traffic from the client. Eric Blake (5): protocol: Support

...Read delay in seconds/milliseconds.\n" \ - "wdelay=<NN>[ms] Write delay in seconds/milliseconds." \ + "file=<FILENAME> (required) The filename to serve." \ /* The per-connection handle. */ struct handle { @@ -241,8 +181,6 @@ file_pread (void *handle, void *buf, uint32_t count, uint64_t offset) { struct handle *h = handle; - read_delay (); - while (count > 0) { ssize_t r = pread (h->fd, buf, count, offset); if (r == -1) { @@ -267,8 +205,6 @@ file_pwrite (void *handle, const void *buf, uint32_t count, uint...

This patch isn't complete (patch 6/6 isn't finished) so it's just for discussion, although it does compile and run. This introduces to nbdkit a concept of "filters" which can be placed in front of plugins to modify their behaviour. Some examples where you might use filters: * Serve a subset of the data, such as (offset, range) or a single partition from a disk image.

This is still tentative and needs a lot of work, but: - partition filter works, supporting MBR & GPT - prepare and finalize methods fixed - open method can now be changed (allowing readonly flag to be modified) - thread_model can be limited I believe I made most of the changes which were previously suggested in email. I think the only one I didn't was preventing inclusion of both

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

Rebased filters patch. Requires current git master + the locks / thread model fix (https://www.redhat.com/archives/libguestfs/2018-January/msg00128.html) So a few changes here since last time: The "introduce filters" and "implement filters" patches are squashed together. I introduced a concept of .prepare and .finalize. These run before and after the data serving phase

The first three patches are identical to: https://www.redhat.com/archives/libguestfs/2018-January/msg00079.html "[PATCH nbdkit v2 0/3] Refactor plugin_* functions into a backend" The rest of the patches add filters using the new filter API previously described here: https://www.redhat.com/archives/libguestfs/2018-January/msg00073.html This needs a lot more testing -- and tests --

A combination of the work that both Rich and I have been doing lately, where filters use only the new API with flags on every command that the client can send over the wire (we can then add support for more flags in nbdkit without having to add new callbacks, as NBD adds more flags upstream). Eric Blake (4): protocol: Split flags from cmd field in requests backend: Pass flags argument through