[Libguestfs] [PATCH v3 03/10] New API: blkdiscardzeroes - do discarded blocks read back as zeroes?

--- daemon/blkdiscard.c | 23 +++++++++++++++++++++++ generator/actions.ml | 13 +++++++++++++ src/MAX_PROC_NR | 2 +- 3 files changed, 37 insertions(+), 1 deletion(-) diff --git a/daemon/blkdiscard.c b/daemon/blkdiscard.c index 26d5f7d..0651788 100644 --- a/daemon/blkdiscard.c +++ b/daemon/blkdiscard.c @@ -75,3 +75,26 @@ do_blkdiscard (const char *device) close (fd); return 0; } + +int +do_blkdiscardzeroes (const char *device) +{ + int fd; + unsigned int arg; + + fd = open (device, O_RDONLY|O_CLOEXEC); + if (fd == -1) { + reply_with_perror ("open: %s", device); + return -1; + } + + if (ioctl (fd, BLKDISCARDZEROES, &arg) == -1) { + reply_with_perror ("ioctl: %s: BLKDISCARDZEROES", device); + close (fd); + return -1; + } + + close (fd); + + return arg != 0; +} diff --git a/generator/actions.ml b/generator/actions.ml index beb1182..4e2c9e0 100644 --- a/generator/actions.ml +++ b/generator/actions.ml @@ -11833,6 +11833,19 @@ an error or even appear to run but do nothing. You must also set the C<discard> attribute on the block device (see C<guestfs_add_drive_opts>)." }; + { defaults with + name = "blkdiscardzeroes"; + style = RBool "zeroes", [Device "device"], []; + proc_nr = Some 418; + shortdesc = "return true if discarded blocks are read as zeroes"; + longdesc = "\ +This call returns true if blocks on C<device> that have been +discarded by a call to C<guestfs_blkdiscard> are returned as +blocks of zero bytes when read the next time. + +If it returns false, then it may be that discarded blocks are +read as stale or random data." }; + ] (* Non-API meta-commands available only in guestfish. diff --git a/src/MAX_PROC_NR b/src/MAX_PROC_NR index 53c86ff..29aae8e 100644 --- a/src/MAX_PROC_NR +++ b/src/MAX_PROC_NR @@ -1 +1 @@ -417 +418 -- 1.8.5.3