Under high memory pressure and very high KVP R/W test pressure, the netlink
recvfrom() may transiently return ENOBUFS to the daemon -- we found this
during a 2-week stress test.

We'd better not terminate the daemon on the failure, because a typical KVP
user will re-try the R/W and hopefully it will succeed next time.

We can also ignore the errors on sending.

Cc: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Instead of making a list of exceptions for readonly filesystems
in addition to iso9660 we already have it is better to skip freeze
operation for all readonly-mounted filesystems.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Acked-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

When ioctl(fd, FIFREEZE, 0) results in an error we cannot report it
to syslog instantly since that can cause write to a frozen disk.
However, the name of the filesystem which caused the error and errno
are valuable and we would like to get a nice human-readable message
in the log. Save errno before calling vss_operate(VSS_OP_THAW) and
report the error right after.

Unfortunately, FITHAW errors cannot be reported the same way as we
need to finish thawing all filesystems before calling syslog().

We should also avoid calling endmntent() for the second time in
case we encountered an error during freezing of '/' as it usually
results in SEGSEGV.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Acked-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

All tools/hv daemons do mandatory daemon() on startup. However, no pidfile
is created, this make it difficult for an init system to track such daemons.
Modern linux distros use systemd as their init system. It can handle the
daemonizing by itself, however, it requires a daemon to stay in foreground
for that. Some distros already carry distro-specific patch for hv tools
which switches off daemon().

Introduce -n/--no-daemon option for all 3 daemons in hv/tools. Parse options
with getopt() to make this part easily expandable.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

If a partition appears mounted more than once in /proc/mounts, vss_do_freeze()
succeeds only for the first time and gets EBUSY (on freeze) or EINVAL (on
thaw) for the second time. The patch ignores these to make the backup feature
work.

Also improved the error handling in case a freeze operation fails.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

hv_fcopy_daemon fails to overwrite a file if the target file already
exits.

Add O_TRUNC flag on opening.

Signed-off-by: Yue Zhang <yuezha@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Return the appropriate error code and handle the case when the target
file exists correctly. This fixes a bug.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Cc: <stable@vger.kernel.org> [3.14]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Implement the file copy service for Linux guests on Hyper-V. This permits the
host to copy a file (over VMBUS) into the guest. This facility is part of
"guest integration services" supported on the Windows platform.
Here is a link that provides additional details on this functionality:

http://technet.microsoft.com/en-us/library/dn464282.aspx

In V1 version of the patch I have addressed comments from
Olaf Hering <olaf@aepfle.de> and Dan Carpenter <dan.carpenter@oracle.com>

In V2 version of this patch I did some minor cleanup (making some globals
static). In V4 version of the patch I have addressed all of Olaf's
most recent set of comments/concerns.

In V5 version of the patch I had addressed Greg's most recent comments.
I would like to thank Greg for suggesting that I use misc device; it has
significantly simplified the code.

In V6 version of the patch I have cleaned up error message based on Olaf's
comments. I have also rebased the patch based on the current tip.

In this version of the patch, I have addressed the latest comments from Greg.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

If the guest has a FAT file system mounted, skip it during the FREEZE
operation. With this change we can support host initiated backup of
the guest even when the guest may have FAT file systems mounted.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Currently, there is no makefile for the Hyper-V tools.
This patch adds the missing makefile, and adds it to the main tools makefile.

Signed-off-by: Bjarke Istrup Pedersen <gurligebis@gentoo.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>