On Thu, May 09, 2019 at 07:14:52PM -0500, Eric Blake wrote: > It may be useful to test whether the client's use of > NBD_CMD_FLAG_NO_HOLE makes a difference; do this by adding a mode to > --filter=nozero to force a non-trimming zero write. > > Signed-off-by: Eric Blake <[email protected]> > --- > filters/nozero/nbdkit-nozero-filter.pod | 19 +++++++---- > filters/nozero/nozero.c | 45 ++++++++++++++++++++----- > tests/test-nozero.sh | 27 +++++++++++++-- > 3 files changed, 74 insertions(+), 17 deletions(-) > > diff --git a/filters/nozero/nbdkit-nozero-filter.pod > b/filters/nozero/nbdkit-nozero-filter.pod > index 7e06570..8e694bb 100644 > --- a/filters/nozero/nbdkit-nozero-filter.pod > +++ b/filters/nozero/nbdkit-nozero-filter.pod > @@ -18,14 +18,19 @@ testing client or server fallbacks. > > =over 4 > > -=item B<zeromode=none|emulate> > +=item B<zeromode=none|emulate|notrim> > > Optional, controls which mode the filter will use. Mode B<none> > -(default) means that zero support is not advertised to the client; > -mode B<emulate> means that zero support is emulated by the filter > -using the plugin's C<pwrite> callback, regardless of whether the > -plugin itself implemented the C<zero> callback with a more efficient > -way to write zeroes. > +(default) means that zero support is not advertised to the > +client. Mode B<emulate> means that zero support is emulated by the > +filter using the plugin's C<pwrite> callback, regardless of whether > +the plugin itself implemented the C<zero> callback with a more > +efficient way to write zeros. Since nbdkit E<ge> 1.13.4, mode > +B<notrim> means that zero requests are forwarded on to the plugin, > +except that the plugin will never see the NBDKIT_MAY_TRIM flag, to > +determine if the client permitting trimming during zero operations > +makes a difference (it is an error to request this mode if the plugin > +does not support the C<zero> callback). > > =back > > @@ -55,4 +60,4 @@ Eric Blake > > =head1 COPYRIGHT > > -Copyright (C) 2018 Red Hat Inc. > +Copyright (C) 2018-2019 Red Hat Inc. > diff --git a/filters/nozero/nozero.c b/filters/nozero/nozero.c > index 3ec6346..6e0ffa9 100644 > --- a/filters/nozero/nozero.c > +++ b/filters/nozero/nozero.c > @@ -47,8 +47,12 @@ > > #define MAX_WRITE (64 * 1024 * 1024) > > -static char buffer[MAX_WRITE]; > -static bool emulate; > +static const char buffer[MAX_WRITE]; > +static enum ZeroMode { > + NONE, > + EMULATE, > + NOTRIM, > +} zeromode; > > static int > nozero_config (nbdkit_next_config *next, void *nxdata, > @@ -56,7 +60,9 @@ nozero_config (nbdkit_next_config *next, void *nxdata, > { > if (strcmp (key, "zeromode") == 0) { > if (strcmp (value, "emulate") == 0) > - emulate = true; > + zeromode = EMULATE; > + else if (strcmp (value, "notrim") == 0) > + zeromode = NOTRIM; > else if (strcmp (value, "none") != 0) { > nbdkit_error ("unknown zeromode '%s'", value); > return -1; > @@ -67,13 +73,31 @@ nozero_config (nbdkit_next_config *next, void *nxdata, > } > > #define nozero_config_help \ > - "zeromode=<MODE> Either 'none' (default) or 'emulate'.\n" \ > + "zeromode=<MODE> Either 'none' (default), 'emulate', or 'notrim'.\n" \ > + > +/* Check that desired mode is supported by plugin. */ > +static int > +nozero_prepare (struct nbdkit_next_ops *next_ops, void *nxdata, void *handle) > +{ > + int r; > + > + if (zeromode == NOTRIM) { > + r = next_ops->can_zero (nxdata); > + if (r == -1) > + return -1; > + if (!r) { > + nbdkit_error ("zeromode 'notrim' requires plugin zero support"); > + return -1; > + } > + } > + return 0; > +} > > /* Advertise desired WRITE_ZEROES mode. */ > static int > nozero_can_zero (struct nbdkit_next_ops *next_ops, void *nxdata, void > *handle) > { > - return emulate; > + return zeromode != NONE; > } > > static int > @@ -81,11 +105,15 @@ nozero_zero (struct nbdkit_next_ops *next_ops, void > *nxdata, > void *handle, uint32_t count, uint64_t offs, uint32_t flags, > int *err) > { > - assert (emulate); > + assert (zeromode != NONE); > + flags &= ~NBDKIT_FLAG_MAY_TRIM; > + > + if (zeromode == NOTRIM) > + return next_ops->zero (nxdata, count, offs, flags, err); > + > while (count) { > uint32_t size = MIN (count, MAX_WRITE); > - if (next_ops->pwrite (nxdata, buffer, size, offs, > - flags & ~NBDKIT_FLAG_MAY_TRIM, err) == -1) > + if (next_ops->pwrite (nxdata, buffer, size, offs, flags, err) == -1) > return -1; > offs += size; > count -= size; > @@ -99,6 +127,7 @@ static struct nbdkit_filter filter = { > .version = PACKAGE_VERSION, > .config = nozero_config, > .config_help = nozero_config_help, > + .prepare = nozero_prepare, > .can_zero = nozero_can_zero, > .zero = nozero_zero, > }; > diff --git a/tests/test-nozero.sh b/tests/test-nozero.sh > index 1282586..fc22420 100755 > --- a/tests/test-nozero.sh > +++ b/tests/test-nozero.sh > @@ -39,12 +39,14 @@ sock3=`mktemp -u` > sock4=`mktemp -u` > sock5a=`mktemp -u` > sock5b=`mktemp -u` > +sock6=`mktemp -u` > files="nozero1.img nozero1.log $sock1 nozero1.pid > nozero2.img nozero2.log $sock2 nozero2.pid > nozero3.img nozero3.log $sock3 nozero3.pid > nozero4.img nozero4.log $sock4 nozero4.pid > nozero5.img nozero5a.log nozero5b.log $sock5a $sock5b > - nozero5a.pid nozero5b.pid" > + nozero5a.pid nozero5b.pid > + nozero6.img nozero6.log $sock6 nozero6.pid" > rm -f $files > > # Prep images, and check that qemu-io understands the actions we plan on > @@ -54,6 +56,7 @@ cp nozero1.img nozero2.img > cp nozero1.img nozero3.img > cp nozero1.img nozero4.img > cp nozero1.img nozero5.img > +cp nozero1.img nozero6.img > if ! qemu-io -f raw -d unmap -c 'w -z -u 0 1M' nozero1.img; then > echo "$0: missing or broken qemu-io" > rm nozero?.img > @@ -82,17 +85,20 @@ cleanup () > cat nozero5a.log || : > echo "Log 5b file contents:" > cat nozero5b.log || : > + echo "Log 6 file contents:" > + cat nozero6.log || : > rm -f $files > } > cleanup_fn cleanup > > -# Run four parallel nbdkit; to compare the logs and see what changes. > +# Run several parallel nbdkit; to compare the logs and see what changes. > # 1: unfiltered, to check that qemu-io sends ZERO request and plugin trims > # 2: log before filter with zeromode=none (default), to ensure no ZERO > request > # 3: log before filter with zeromode=emulate, to ensure ZERO from client > # 4: log after filter with zeromode=emulate, to ensure no ZERO to plugin > # 5a/b: both sides of nbd plugin: even though server side does not advertise > # ZERO, the client side still exposes it, and just skips calling nbd's .zero > +# 6: log after filter with zeromode=notrim, to ensure plugin does not trim > start_nbdkit -P nozero1.pid -U $sock1 --filter=log \ > file logfile=nozero1.log nozero1.img > start_nbdkit -P nozero2.pid -U $sock2 --filter=log --filter=nozero \ > @@ -105,6 +111,8 @@ start_nbdkit -P nozero5a.pid -U $sock5a --filter=log > --filter=nozero \ > file logfile=nozero5a.log nozero5.img > start_nbdkit -P nozero5b.pid -U $sock5b --filter=log \ > nbd logfile=nozero5b.log socket=$sock5a > +start_nbdkit -P nozero6.pid -U $sock6 --filter=nozero --filter=log \ > + file logfile=nozero6.log nozero6.img zeromode=notrim > > # Perform the zero write. > qemu-io -f raw -c 'w -z -u 0 1M' "nbd+unix://?socket=$sock1" > @@ -112,6 +120,7 @@ qemu-io -f raw -c 'w -z -u 0 1M' > "nbd+unix://?socket=$sock2" > qemu-io -f raw -c 'w -z -u 0 1M' "nbd+unix://?socket=$sock3" > qemu-io -f raw -c 'w -z -u 0 1M' "nbd+unix://?socket=$sock4" > qemu-io -f raw -c 'w -z -u 0 1M' "nbd+unix://?socket=$sock5b" > +qemu-io -f raw -c 'w -z -u 0 1M' "nbd+unix://?socket=$sock6" > > # Check for expected ZERO vs. WRITE results > grep 'connection=1 Zero' nozero1.log > @@ -129,9 +138,23 @@ if grep 'connection=1 Zero' nozero5a.log; then > echo "nbdkit should have converted zero into write before nbd plugin" > exit 1 > fi > +grep 'connection=1 Zero' nozero6.log > > # Sanity check on contents - all 5 files should read identically > cmp nozero1.img nozero2.img > cmp nozero2.img nozero3.img > cmp nozero3.img nozero4.img > cmp nozero4.img nozero5.img > +cmp nozero5.img nozero6.img > + > +# Sanity check on sparseness; only image 1 should be sparse > +if test "$(stat -c %b nozero1.img)" = "$(stat -c %b nozero2.img)"; then > + echo "nozero1.img was not trimmed" > + exit 1 > +fi > +for i in 3 4 5 6; do > + if test "$(stat -c %b nozero2.img)" != "$(stat -c %b nozero$i.img)"; then > + echo "nozero$i.img was trimmed by mistake" > + exit 1 > + fi > +done > -- > 2.20.1
ACK Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com Fedora Windows cross-compiler. Compile Windows programs, test, and build Windows installers. Over 100 libraries supported. http://fedoraproject.org/wiki/MinGW _______________________________________________ Libguestfs mailing list [email protected] https://www.redhat.com/mailman/listinfo/libguestfs
