> -----Original Message----- > From: devel [mailto:driverdev-devel-boun...@linuxdriverproject.org] On > Behalf Of Dexuan Cui > Sent: Tuesday, October 21, 2014 17:56 PM > To: gre...@linuxfoundation.org; linux-kernel@vger.kernel.org; driverdev- > de...@linuxdriverproject.org; o...@aepfle.de; a...@canonical.com; > jasow...@redhat.com > Cc: Haiyang Zhang > Subject: [PATCH v3 RESEND] Tools: hv: vssdaemon: ignore the EBUSY on > multiple freezing the same partition > > 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 <de...@microsoft.com> > Reviewed-by: K. Y. Srinivasan <k...@microsoft.com> > --- > > v2: Add "errno = 0;" before the ioctl() > (Unnecessary and removed now since we remove syslog() in vss_do_freeze() > in v3) > > v3: Remove the unsafe syslog() in vss_do_freeze(): that could write the disk. > Thaw the filesystems in case the freezing operation fails. > In main(), add syslog() when we check the return value of vss_operate(). > > [Oct 21, 2014] This is just a RESEND since the previous one I sent about a > month > ago seems neglected. :-( > > tools/hv/hv_vss_daemon.c | 48 > ++++++++++++++++++++++++++++++++++++++++-------- > 1 file changed, 40 insertions(+), 8 deletions(-) > > diff --git a/tools/hv/hv_vss_daemon.c b/tools/hv/hv_vss_daemon.c > index 6a213b8..1db9430 100644 > --- a/tools/hv/hv_vss_daemon.c > +++ b/tools/hv/hv_vss_daemon.c > @@ -44,21 +44,39 @@ static struct sockaddr_nl addr; > #endif > > > -static int vss_do_freeze(char *dir, unsigned int cmd, char *fs_op) > +/* Don't use syslog() in the function since that can cause write to disk */ > +static int vss_do_freeze(char *dir, unsigned int cmd) > { > int ret, fd = open(dir, O_RDONLY); > > if (fd < 0) > return 1; > + > ret = ioctl(fd, cmd, 0); > - syslog(LOG_INFO, "VSS: %s of %s: %s\n", fs_op, dir, strerror(errno)); > + > + /* > + * If a partition is mounted more than once, only the first > + * FREEZE/THAW can succeed and the later ones will get > + * EBUSY/EINVAL respectively: there could be 2 cases: > + * 1) a user may mount the same partition to differnt directories > + * by mistake or on purpose; > + * 2) The subvolume of btrfs appears to have the same partition > + * mounted more than once. > + */ > + if (ret) { > + if ((cmd == FIFREEZE && errno == EBUSY) || > + (cmd == FITHAW && errno == EINVAL)) { > + close(fd); > + return 0; > + } > + } > + > close(fd); > return !!ret; > } > > static int vss_operate(int operation) > { > - char *fs_op; > char match[] = "/dev/"; > FILE *mounts; > struct mntent *ent; > @@ -68,11 +86,9 @@ static int vss_operate(int operation) > switch (operation) { > case VSS_OP_FREEZE: > cmd = FIFREEZE; > - fs_op = "freeze"; > break; > case VSS_OP_THAW: > cmd = FITHAW; > - fs_op = "thaw"; > break; > default: > return -1; > @@ -93,15 +109,23 @@ static int vss_operate(int operation) > root_seen = 1; > continue; > } > - error |= vss_do_freeze(ent->mnt_dir, cmd, fs_op); > + error |= vss_do_freeze(ent->mnt_dir, cmd); > + if (error && operation == VSS_OP_FREEZE) > + goto err; > } > endmntent(mounts); > > if (root_seen) { > - error |= vss_do_freeze("/", cmd, fs_op); > + error |= vss_do_freeze("/", cmd); > + if (error && operation == VSS_OP_FREEZE) > + goto err; > } > > return error; > +err: > + endmntent(mounts); > + vss_operate(VSS_OP_THAW); > + return error; > } > > static int netlink_send(int fd, struct cn_msg *msg) > @@ -249,8 +273,16 @@ int main(void) > case VSS_OP_FREEZE: > case VSS_OP_THAW: > error = vss_operate(op); > - if (error) > + syslog(LOG_INFO, "VSS: op=%s: %s\n", > + op == VSS_OP_FREEZE ? "FREEZE" : "THAW", > + error ? "failed" : "succeeded"); > + > + if (error) { > error = HV_E_FAIL; > + syslog(LOG_ERR, "op=%d failed!", op); > + syslog(LOG_ERR, "report it with these files:"); > + syslog(LOG_ERR, "/etc/fstab and > /proc/mounts"); > + } > break; > default: > syslog(LOG_ERR, "Illegal op:%d\n", op); > -- > 1.9.1
Hi Greg, ping. (I saw you replying in the lists 3 minutes ago. :-) Thanks, -- Dexuan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
