Should we add a random wait to avoid all the machines retrying au the same
time?
Le mer. 26 juin 2024, 13:57, Mukesh Kumar Chaurasiya <mchau...@linux.ibm.com>
a écrit :
> Sometimes, when booting from a very busy SAN, the access to the
> disk can fail and then GRUB will eventually drop to GRUB prompt.
> This scenario is more frequent when deploying many machines at
> the same time using the same SAN.
> This patch aims to force the ofdisk module to retry the open or
> read function for network disks after it fails. We use
> DEFAULT_RETRY_TIMEOUT, which is 15 seconds to specify the time it'll
> retry to access the disk before it definitely fails. The timeout can be
> changed by setting the environment variable ofdisk_retry_timeout.
> If the environment variable fails to read, GRUB will consider the
> default value of 15 seconds.
>
> Signed-off-by: Diego Domingos <dieg...@linux.vnet.ibm.com>
> Signed-off-by: Mukesh Kumar Chaurasiya <mchau...@linux.ibm.com>
> ---
> docs/grub.texi | 8 ++++
> grub-core/disk/ieee1275/ofdisk.c | 82 ++++++++++++++++++++++++++++++--
> 2 files changed, 87 insertions(+), 3 deletions(-)
>
> diff --git a/docs/grub.texi b/docs/grub.texi
> index f3bdc2564..9514271fc 100644
> --- a/docs/grub.texi
> +++ b/docs/grub.texi
> @@ -3308,6 +3308,7 @@ These variables have special meaning to GRUB.
> * net_default_ip::
> * net_default_mac::
> * net_default_server::
> +* ofdisk_retry_timeout::
> * pager::
> * prefix::
> * pxe_blksize::
> @@ -3738,6 +3739,13 @@ The default is the value of @samp{color_normal}
> (@pxref{color_normal}).
> @xref{Network}.
>
>
> +@node ofdisk_retry_timeout
> +@subsection ofdisk_retry_timeout
> +
> +The time in seconds till which the GRUB will retry to open or read a disk
> in
> +case of failure to do so. This value defaults to 15 seconds.
> +
> +
> @node pager
> @subsection pager
>
> diff --git a/grub-core/disk/ieee1275/ofdisk.c
> b/grub-core/disk/ieee1275/ofdisk.c
> index c6cba0c8a..675e039c5 100644
> --- a/grub-core/disk/ieee1275/ofdisk.c
> +++ b/grub-core/disk/ieee1275/ofdisk.c
> @@ -24,6 +24,9 @@
> #include <grub/ieee1275/ofdisk.h>
> #include <grub/i18n.h>
> #include <grub/time.h>
> +#include <grub/env.h>
> +
> +#define RETRY_DEFAULT_TIMEOUT 15
>
> static char *last_devpath;
> static grub_ieee1275_ihandle_t last_ihandle;
> @@ -452,7 +455,7 @@ compute_dev_path (const char *name)
> }
>
> static grub_err_t
> -grub_ofdisk_open (const char *name, grub_disk_t disk)
> +grub_ofdisk_open_real (const char *name, grub_disk_t disk)
> {
> grub_ieee1275_phandle_t dev;
> char *devpath;
> @@ -525,6 +528,54 @@ grub_ofdisk_open (const char *name, grub_disk_t disk)
> return 0;
> }
>
> +static grub_uint64_t
> +grub_ofdisk_disk_timeout (grub_disk_t disk)
> +{
> + grub_uint64_t retry = RETRY_DEFAULT_TIMEOUT;
> + const char *timeout = grub_env_get ("ofdisk_retry_timeout");
> + const char *timeout_end;
> +
> + if (grub_strstr (disk->name, "fibre-channel") != NULL ||
> + grub_strstr (disk->name, "vfc-client") != NULL)
> + {
> + if (timeout == NULL)
> + return retry;
> + retry = grub_strtoul (timeout, &timeout_end, 10);
> + /* Ignore all errors and return default timeout */
> + if (*timeout == '\0' ||
> + *timeout_end != '\0')
> + return RETRY_DEFAULT_TIMEOUT;
> + }
> + else
> + return 0;
> +
> + return retry;
> +}
> +
> +static grub_err_t
> +grub_ofdisk_open (const char *name, grub_disk_t disk)
> +{
> + grub_err_t err;
> + grub_uint64_t timeout = grub_get_time_ms () + (grub_ofdisk_disk_timeout
> (disk) * 1000);
> + grub_uint16_t inc = 0;
> +
> + do
> + {
> + err = grub_ofdisk_open_real (name, disk);
> + if (err == GRUB_ERR_UNKNOWN_DEVICE)
> + grub_dprintf ("ofdisk", "Failed to open disk %s.\n", name);
> + if (grub_get_time_ms () >= timeout)
> + break;
> + grub_dprintf ("ofdisk", "Retry to open disk %s.\n", name);
> + /*
> + * Increase wait time for subsequent requests
> + * Cur time is used as a source of randomness
> + */
> + grub_millisleep ((32 << ++inc) * (grub_get_time_ms () % 32));
> + } while (1);
> + return err;
> +}
> +
> static void
> grub_ofdisk_close (grub_disk_t disk)
> {
> @@ -568,8 +619,8 @@ grub_ofdisk_prepare (grub_disk_t disk,
> grub_disk_addr_t sector)
> }
>
> static grub_err_t
> -grub_ofdisk_read (grub_disk_t disk, grub_disk_addr_t sector,
> - grub_size_t size, char *buf)
> +grub_ofdisk_read_real (grub_disk_t disk, grub_disk_addr_t sector,
> + grub_size_t size, char *buf)
> {
> grub_err_t err;
> grub_ssize_t actual;
> @@ -587,6 +638,31 @@ grub_ofdisk_read (grub_disk_t disk, grub_disk_addr_t
> sector,
> return 0;
> }
>
> +static grub_err_t
> +grub_ofdisk_read (grub_disk_t disk, grub_disk_addr_t sector,
> + grub_size_t size, char *buf)
> +{
> + grub_err_t err;
> + grub_uint64_t timeout = grub_get_time_ms () + (grub_ofdisk_disk_timeout
> (disk) * 1000);
> + grub_uint16_t inc = 0;
> +
> + do
> + {
> + err = grub_ofdisk_read_real (disk, sector, size, buf);
> + if (err == GRUB_ERR_UNKNOWN_DEVICE)
> + grub_dprintf ("ofdisk", "Failed to read disk %s.\n",
> (char*)disk->data);
> + if (grub_get_time_ms () >= timeout)
> + break;
> + grub_dprintf ("ofdisk", "Retry to read disk %s.\n",
> (char*)disk->data);
> + /*
> + * Increase wait time for subsequent requests
> + * Cur time is used as a source of randomness
> + */
> + grub_millisleep ((32 << ++inc) * (grub_get_time_ms () % 32));
> + } while (1);
> + return err;
> +}
> +
> static grub_err_t
> grub_ofdisk_write (grub_disk_t disk, grub_disk_addr_t sector,
> grub_size_t size, const char *buf)
> --
> 2.45.2
>
>
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>
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