[dm-devel] [PATCH v2 08/14] libmultipath: sysfs_attr_set_value(): don't return 0 on partial write
Benjamin Marzinski
bmarzins at redhat.com
Fri Jul 15 15:17:27 UTC 2022
On Wed, Jul 13, 2022 at 10:20:43AM +0200, mwilck at suse.com wrote:
> From: Martin Wilck <mwilck at suse.com>
>
> sysfs_attr_set_value() returned 0 if not all requested bytes were written.
> Change this to return the number of bytes written. Error checking is now
> somewhat more involved; provide a helper macro for it.
>
Reviewed-by: Benjamin Marzinski <bmarzins at redhat.com>
> Signed-off-by: Martin Wilck <mwilck at suse.com>
> ---
> libmultipath/configure.c | 10 ++++--
> libmultipath/discovery.c | 74 +++++++++++++++++++++++++---------------
> libmultipath/sysfs.c | 6 ++--
> libmultipath/sysfs.h | 10 ++++++
> 4 files changed, 66 insertions(+), 34 deletions(-)
>
> diff --git a/libmultipath/configure.c b/libmultipath/configure.c
> index 467bbaa..0607dba 100644
> --- a/libmultipath/configure.c
> +++ b/libmultipath/configure.c
> @@ -568,6 +568,7 @@ sysfs_set_max_sectors_kb(struct multipath *mpp, int is_reload)
> struct pathgroup * pgp;
> struct path *pp;
> char buff[11];
> + ssize_t len;
> int i, j, ret, err = 0;
> struct udev_device *udd;
> int max_sectors_kb;
> @@ -600,14 +601,17 @@ sysfs_set_max_sectors_kb(struct multipath *mpp, int is_reload)
> }
> }
> snprintf(buff, 11, "%d", max_sectors_kb);
> + len = strlen(buff);
>
> vector_foreach_slot (mpp->pg, pgp, i) {
> vector_foreach_slot(pgp->paths, pp, j) {
> ret = sysfs_attr_set_value(pp->udev,
> "queue/max_sectors_kb",
> - buff, strlen(buff));
> - if (ret < 0) {
> - condlog(1, "failed setting max_sectors_kb on %s : %s", pp->dev, strerror(-ret));
> + buff, len);
> + if (ret != len) {
> + log_sysfs_attr_set_value(1, ret,
> + "failed setting max_sectors_kb on %s",
> + pp->dev);
> err = 1;
> }
> }
> diff --git a/libmultipath/discovery.c b/libmultipath/discovery.c
> index 54b1caf..ee29009 100644
> --- a/libmultipath/discovery.c
> +++ b/libmultipath/discovery.c
> @@ -598,13 +598,15 @@ sysfs_set_eh_deadline(struct path *pp)
> len = sprintf(value, "%d", pp->eh_deadline);
>
> ret = sysfs_attr_set_value(hostdev, "eh_deadline",
> - value, len + 1);
> + value, len);
> /*
> * not all scsi drivers support setting eh_deadline, so failing
> * is totally reasonable
> */
> - if (ret <= 0)
> - condlog(3, "%s: failed to set eh_deadline to %s, error %d", udev_device_get_sysname(hostdev), value, -ret);
> + if (ret != len)
> + log_sysfs_attr_set_value(3, ret,
> + "%s: failed to set eh_deadline to %s",
> + udev_device_get_sysname(hostdev), value);
>
> udev_device_unref(hostdev);
> return (ret <= 0);
> @@ -667,19 +669,22 @@ sysfs_set_rport_tmo(struct multipath *mpp, struct path *pp)
> pp->fast_io_fail != MP_FAST_IO_FAIL_OFF) {
> /* Check if we need to temporarily increase dev_loss_tmo */
> if ((unsigned int)pp->fast_io_fail >= tmo) {
> + ssize_t len;
> +
> /* Increase dev_loss_tmo temporarily */
> snprintf(value, sizeof(value), "%u",
> (unsigned int)pp->fast_io_fail + 1);
> + len = strlen(value);
> ret = sysfs_attr_set_value(rport_dev, "dev_loss_tmo",
> - value, strlen(value));
> - if (ret <= 0) {
> + value, len);
> + if (ret != len) {
> if (ret == -EBUSY)
> condlog(3, "%s: rport blocked",
> rport_id);
> else
> - condlog(0, "%s: failed to set "
> - "dev_loss_tmo to %s, error %d",
> - rport_id, value, -ret);
> + log_sysfs_attr_set_value(0, ret,
> + "%s: failed to set dev_loss_tmo to %s",
> + rport_id, value);
> goto out;
> }
> }
> @@ -691,32 +696,39 @@ sysfs_set_rport_tmo(struct multipath *mpp, struct path *pp)
> pp->dev_loss = DEFAULT_DEV_LOSS_TMO;
> }
> if (pp->fast_io_fail != MP_FAST_IO_FAIL_UNSET) {
> + ssize_t len;
> +
> if (pp->fast_io_fail == MP_FAST_IO_FAIL_OFF)
> sprintf(value, "off");
> else if (pp->fast_io_fail == MP_FAST_IO_FAIL_ZERO)
> sprintf(value, "0");
> else
> snprintf(value, 16, "%u", pp->fast_io_fail);
> + len = strlen(value);
> ret = sysfs_attr_set_value(rport_dev, "fast_io_fail_tmo",
> - value, strlen(value));
> - if (ret <= 0) {
> + value, len);
> + if (ret != len) {
> if (ret == -EBUSY)
> condlog(3, "%s: rport blocked", rport_id);
> else
> - condlog(0, "%s: failed to set fast_io_fail_tmo to %s, error %d",
> - rport_id, value, -ret);
> + log_sysfs_attr_set_value(0, ret,
> + "%s: failed to set fast_io_fail_tmo to %s",
> + rport_id, value);
> }
> }
> if (pp->dev_loss != DEV_LOSS_TMO_UNSET) {
> + ssize_t len;
> +
> snprintf(value, 16, "%u", pp->dev_loss);
> - ret = sysfs_attr_set_value(rport_dev, "dev_loss_tmo",
> - value, strlen(value));
> - if (ret <= 0) {
> + len = strlen(value);
> + ret = sysfs_attr_set_value(rport_dev, "dev_loss_tmo", value, len);
> + if (ret != len) {
> if (ret == -EBUSY)
> condlog(3, "%s: rport blocked", rport_id);
> else
> - condlog(0, "%s: failed to set dev_loss_tmo to %s, error %d",
> - rport_id, value, -ret);
> + log_sysfs_attr_set_value(0, ret,
> + "%s: failed to set dev_loss_tmo to %s",
> + rport_id, value);
> }
> }
> out:
> @@ -754,12 +766,16 @@ sysfs_set_session_tmo(struct path *pp)
> condlog(3, "%s: can't set fast_io_fail_tmo to '0'"
> "on iSCSI", pp->dev);
> } else {
> + ssize_t len, ret;
> +
> snprintf(value, 11, "%u", pp->fast_io_fail);
> - if (sysfs_attr_set_value(session_dev, "recovery_tmo",
> - value, strlen(value)) <= 0) {
> - condlog(3, "%s: Failed to set recovery_tmo, "
> - " error %d", pp->dev, errno);
> - }
> + len = strlen(value);
> + ret = sysfs_attr_set_value(session_dev, "recovery_tmo",
> + value, len);
> + if (ret != len)
> + log_sysfs_attr_set_value(3, ret,
> + "%s: Failed to set recovery_tmo to %s",
> + pp->dev, value);
> }
> }
> udev_device_unref(session_dev);
> @@ -802,12 +818,16 @@ sysfs_set_nexus_loss_tmo(struct path *pp)
> pp->sg_id.channel, pp->sg_id.scsi_id, end_dev_id);
>
> if (pp->dev_loss != DEV_LOSS_TMO_UNSET) {
> + ssize_t len, ret;
> +
> snprintf(value, 11, "%u", pp->dev_loss);
> - if (sysfs_attr_set_value(sas_dev, "I_T_nexus_loss_timeout",
> - value, strlen(value)) <= 0)
> - condlog(3, "%s: failed to update "
> - "I_T Nexus loss timeout, error %d",
> - pp->dev, errno);
> + len = strlen(value);
> + ret = sysfs_attr_set_value(sas_dev, "I_T_nexus_loss_timeout",
> + value, len);
> + if (ret != len)
> + log_sysfs_attr_set_value(3, ret,
> + "%s: failed to update I_T Nexus loss timeout",
> + pp->dev);
> }
> udev_device_unref(sas_dev);
> return;
> diff --git a/libmultipath/sysfs.c b/libmultipath/sysfs.c
> index 125f1c2..9c84af7 100644
> --- a/libmultipath/sysfs.c
> +++ b/libmultipath/sysfs.c
> @@ -134,7 +134,7 @@ ssize_t sysfs_attr_set_value(struct udev_device *dev, const char *attr_name,
> /* write attribute value */
> fd = open(devpath, O_WRONLY);
> if (fd < 0) {
> - condlog(2, "%s: attribute '%s' can not be opened: %s",
> + condlog(3, "%s: attribute '%s' can not be opened: %s",
> __func__, devpath, strerror(errno));
> return -errno;
> }
> @@ -144,11 +144,9 @@ ssize_t sysfs_attr_set_value(struct udev_device *dev, const char *attr_name,
> size = -errno;
> condlog(3, "%s: write to %s failed: %s", __func__,
> devpath, strerror(errno));
> - } else if (size < (ssize_t)value_len) {
> + } else if (size < (ssize_t)value_len)
> condlog(3, "%s: underflow writing %zu bytes to %s. Wrote %zd bytes",
> __func__, value_len, devpath, size);
> - size = 0;
> - }
>
> close(fd);
> return size;
> diff --git a/libmultipath/sysfs.h b/libmultipath/sysfs.h
> index cdc84e4..799f68e 100644
> --- a/libmultipath/sysfs.h
> +++ b/libmultipath/sysfs.h
> @@ -5,6 +5,7 @@
> #ifndef _LIBMULTIPATH_SYSFS_H
> #define _LIBMULTIPATH_SYSFS_H
> #include <stdbool.h>
> +#include "strbuf.h"
>
> ssize_t sysfs_attr_set_value(struct udev_device *dev, const char *attr_name,
> const char * value, size_t value_len);
> @@ -25,6 +26,15 @@ ssize_t sysfs_bin_attr_get_value(struct udev_device *dev, const char *attr_name,
> sysfs_attr_value_ok(__rc, __l); \
> })
>
> +#define log_sysfs_attr_set_value(prio, rc, fmt, __args...) \
> +do { \
> + STRBUF_ON_STACK(__buf); \
> + if (print_strbuf(&__buf, fmt, ##__args) >= 0 && \
> + print_strbuf(&__buf, ": %s", rc < 0 ? strerror(-rc) : \
> + "write underflow") >= 0) \
> + condlog(prio, "%s", get_strbuf_str(&__buf)); \
> +} while(0)
> +
> int sysfs_get_size (struct path *pp, unsigned long long * size);
> int sysfs_check_holders(char * check_devt, char * new_devt);
> bool sysfs_is_multipathed(struct path *pp, bool set_wwid);
> --
> 2.36.1
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