> -----Original Message-----
> From: Vitaly Kuznetsov [mailto:vkuzn...@redhat.com]
> Sent: Monday, November 10, 2014 8:37 AM
> To: KY Srinivasan; Haiyang Zhang; Greg Kroah-Hartman
> Cc: de...@linuxdriverproject.org; linux-ker...@vger.kernel.org; Dexuan Cui
> Subject: [PATCH v2 1/2] Tools: hv: vssdaemon: report freeze errors
>
> 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 <vkuzn...@redhat.com>
Signed-off-by: K. Y. Srinivasan <k...@microsoft.com>
> ---
> tools/hv/hv_vss_daemon.c | 16 ++++++++++++----
> 1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/tools/hv/hv_vss_daemon.c b/tools/hv/hv_vss_daemon.c index
> b720d8f..ee44f0d 100644
> --- a/tools/hv/hv_vss_daemon.c
> +++ b/tools/hv/hv_vss_daemon.c
> @@ -82,7 +82,7 @@ static int vss_operate(int operation)
> FILE *mounts;
> struct mntent *ent;
> unsigned int cmd;
> - int error = 0, root_seen = 0;
> + int error = 0, root_seen = 0, save_errno = 0;
>
> switch (operation) {
> case VSS_OP_FREEZE:
> @@ -114,7 +114,6 @@ static int vss_operate(int operation)
> if (error && operation == VSS_OP_FREEZE)
> goto err;
> }
> - endmntent(mounts);
>
> if (root_seen) {
> error |= vss_do_freeze("/", cmd);
> @@ -122,10 +121,19 @@ static int vss_operate(int operation)
> goto err;
> }
>
> - return error;
> + goto out;
> err:
> - endmntent(mounts);
> + save_errno = errno;
> vss_operate(VSS_OP_THAW);
> + /* Call syslog after we thaw all filesystems */
> + if (ent)
> + syslog(LOG_ERR, "FREEZE of %s failed; error:%d %s",
> + ent->mnt_dir, save_errno, strerror(save_errno));
> + else
> + syslog(LOG_ERR, "FREEZE of / failed; error:%d %s",
> save_errno,
> + strerror(save_errno));
> +out:
> + endmntent(mounts);
> return error;
> }
>
> --
> 1.9.3
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