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mdadm/SOURCES/0103-mdadm-Add-write-zeros-option-for-Create.patch

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From 577fd10486d8d1472a6b559066f344ac30a3a391 Mon Sep 17 00:00:00 2001
From: Logan Gunthorpe <logang@deltatee.com>
Date: Wed, 1 Mar 2023 13:41:33 -0700
Subject: [PATCH 103/125] mdadm: Add --write-zeros option for Create
Add the --write-zeros option for Create which will send a write zeros
request to all the disks before assembling the array. After zeroing
the array, the disks will be in a known clean state and the initial
sync may be skipped.
Writing zeroes is best used when there is a hardware offload method
to zero the data. But even still, zeroing can take several minutes on
a large device. Because of this, all disks are zeroed in parallel using
their own forked process and a message is printed to the user. The main
process will proceed only after all the zeroing processes have completed
successfully.
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Acked-by: Kinga Tanska <kinga.tanska@linux.intel.com>
Reviewed-by: Xiao Ni <xni@redhat.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Acked-by: Coly Li <colyli@suse.de>
Signed-off-by: Jes Sorensen <jes@trained-monkey.org>
---
Create.c | 176 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
ReadMe.c | 2 +
mdadm.c | 9 +++
mdadm.h | 5 ++
4 files changed, 190 insertions(+), 2 deletions(-)
diff --git a/Create.c b/Create.c
index 4acda30c..bbe9e13d 100644
--- a/Create.c
+++ b/Create.c
@@ -26,6 +26,10 @@
#include "md_u.h"
#include "md_p.h"
#include <ctype.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <sys/signalfd.h>
+#include <sys/wait.h>
static int round_size_and_verify(unsigned long long *size, int chunk)
{
@@ -91,9 +95,149 @@ int default_layout(struct supertype *st, int level, int verbose)
return layout;
}
+static pid_t write_zeroes_fork(int fd, struct shape *s, struct supertype *st,
+ struct mddev_dev *dv)
+
+{
+ const unsigned long long req_size = 1 << 30;
+ unsigned long long offset_bytes, size_bytes, sz;
+ sigset_t sigset;
+ int ret = 0;
+ pid_t pid;
+
+ size_bytes = KIB_TO_BYTES(s->size);
+
+ /*
+ * If size_bytes is zero, this is a zoned raid array where
+ * each disk is of a different size and uses its full
+ * disk. Thus zero the entire disk.
+ */
+ if (!size_bytes && !get_dev_size(fd, dv->devname, &size_bytes))
+ return -1;
+
+ if (dv->data_offset != INVALID_SECTORS)
+ offset_bytes = SEC_TO_BYTES(dv->data_offset);
+ else
+ offset_bytes = SEC_TO_BYTES(st->data_offset);
+
+ pr_info("zeroing data from %lld to %lld on: %s\n",
+ offset_bytes, size_bytes, dv->devname);
+
+ pid = fork();
+ if (pid < 0) {
+ pr_err("Could not fork to zero disks: %s\n", strerror(errno));
+ return pid;
+ } else if (pid != 0) {
+ return pid;
+ }
+
+ sigemptyset(&sigset);
+ sigaddset(&sigset, SIGINT);
+ sigprocmask(SIG_UNBLOCK, &sigset, NULL);
+
+ while (size_bytes) {
+ /*
+ * Split requests to the kernel into 1GB chunks seeing the
+ * fallocate() call is not interruptible and blocking a
+ * ctrl-c for several minutes is not desirable.
+ *
+ * 1GB is chosen as a compromise: the user may still have
+ * to wait several seconds if they ctrl-c on devices that
+ * zero slowly, but will reduce the number of requests
+ * required and thus the overhead on devices that perform
+ * better.
+ */
+ sz = size_bytes;
+ if (sz >= req_size)
+ sz = req_size;
+
+ if (fallocate(fd, FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE,
+ offset_bytes, sz)) {
+ pr_err("zeroing %s failed: %s\n", dv->devname,
+ strerror(errno));
+ ret = 1;
+ break;
+ }
+
+ offset_bytes += sz;
+ size_bytes -= sz;
+ }
+
+ exit(ret);
+}
+
+static int wait_for_zero_forks(int *zero_pids, int count)
+{
+ int wstatus, ret = 0, i, sfd, wait_count = 0;
+ struct signalfd_siginfo fdsi;
+ bool interrupted = false;
+ sigset_t sigset;
+ ssize_t s;
+
+ for (i = 0; i < count; i++)
+ if (zero_pids[i])
+ wait_count++;
+ if (!wait_count)
+ return 0;
+
+ sigemptyset(&sigset);
+ sigaddset(&sigset, SIGINT);
+ sigaddset(&sigset, SIGCHLD);
+ sigprocmask(SIG_BLOCK, &sigset, NULL);
+
+ sfd = signalfd(-1, &sigset, 0);
+ if (sfd < 0) {
+ pr_err("Unable to create signalfd: %s\n", strerror(errno));
+ return 1;
+ }
+
+ while (1) {
+ s = read(sfd, &fdsi, sizeof(fdsi));
+ if (s != sizeof(fdsi)) {
+ pr_err("Invalid signalfd read: %s\n", strerror(errno));
+ close(sfd);
+ return 1;
+ }
+
+ if (fdsi.ssi_signo == SIGINT) {
+ printf("\n");
+ pr_info("Interrupting zeroing processes, please wait...\n");
+ interrupted = true;
+ } else if (fdsi.ssi_signo == SIGCHLD) {
+ if (!--wait_count)
+ break;
+ }
+ }
+
+ close(sfd);
+
+ for (i = 0; i < count; i++) {
+ if (!zero_pids[i])
+ continue;
+
+ waitpid(zero_pids[i], &wstatus, 0);
+ zero_pids[i] = 0;
+ if (!WIFEXITED(wstatus) || WEXITSTATUS(wstatus))
+ ret = 1;
+ }
+
+ if (interrupted) {
+ pr_err("zeroing interrupted!\n");
+ return 1;
+ }
+
+ if (ret)
+ pr_err("zeroing failed!\n");
+ else
+ pr_info("zeroing finished\n");
+
+ return ret;
+}
+
static int add_disk_to_super(int mdfd, struct shape *s, struct context *c,
struct supertype *st, struct mddev_dev *dv,
- struct mdinfo *info, int have_container, int major_num)
+ struct mdinfo *info, int have_container, int major_num,
+ int *zero_pid)
{
dev_t rdev;
int fd;
@@ -148,6 +292,14 @@ static int add_disk_to_super(int mdfd, struct shape *s, struct context *c,
}
st->ss->getinfo_super(st, info, NULL);
+ if (fd >= 0 && s->write_zeroes) {
+ *zero_pid = write_zeroes_fork(fd, s, st, dv);
+ if (*zero_pid <= 0) {
+ ioctl(mdfd, STOP_ARRAY, NULL);
+ return 1;
+ }
+ }
+
if (have_container && c->verbose > 0)
pr_err("Using %s for device %d\n",
map_dev(info->disk.major, info->disk.minor, 0),
@@ -224,10 +376,23 @@ static int add_disks(int mdfd, struct mdinfo *info, struct shape *s,
{
struct mddev_dev *moved_disk = NULL;
int pass, raid_disk_num, dnum;
+ int zero_pids[total_slots];
struct mddev_dev *dv;
struct mdinfo *infos;
+ sigset_t sigset, orig_sigset;
int ret = 0;
+ /*
+ * Block SIGINT so the main thread will always wait for the
+ * zeroing processes when being interrupted. Otherwise the
+ * zeroing processes will finish their work in the background
+ * keeping the disk busy.
+ */
+ sigemptyset(&sigset);
+ sigaddset(&sigset, SIGINT);
+ sigprocmask(SIG_BLOCK, &sigset, &orig_sigset);
+ memset(zero_pids, 0, sizeof(zero_pids));
+
infos = xmalloc(sizeof(*infos) * total_slots);
enable_fds(total_slots);
for (pass = 1; pass <= 2; pass++) {
@@ -261,7 +426,7 @@ static int add_disks(int mdfd, struct mdinfo *info, struct shape *s,
ret = add_disk_to_super(mdfd, s, c, st, dv,
&infos[dnum], have_container,
- major_num);
+ major_num, &zero_pids[dnum]);
if (ret)
goto out;
@@ -287,6 +452,10 @@ static int add_disks(int mdfd, struct mdinfo *info, struct shape *s,
}
if (pass == 1) {
+ ret = wait_for_zero_forks(zero_pids, total_slots);
+ if (ret)
+ goto out;
+
ret = update_metadata(mdfd, s, st, map, info,
chosen_name);
if (ret)
@@ -295,7 +464,10 @@ static int add_disks(int mdfd, struct mdinfo *info, struct shape *s,
}
out:
+ if (ret)
+ wait_for_zero_forks(zero_pids, total_slots);
free(infos);
+ sigprocmask(SIG_SETMASK, &orig_sigset, NULL);
return ret;
}
diff --git a/ReadMe.c b/ReadMe.c
index bd8d50d2..db251ed2 100644
--- a/ReadMe.c
+++ b/ReadMe.c
@@ -138,6 +138,7 @@ struct option long_options[] = {
{"size", 1, 0, 'z'},
{"auto", 1, 0, Auto}, /* also for --assemble */
{"assume-clean",0,0, AssumeClean },
+ {"write-zeroes",0,0, WriteZeroes },
{"metadata", 1, 0, 'e'}, /* superblock format */
{"bitmap", 1, 0, Bitmap},
{"bitmap-chunk", 1, 0, BitmapChunk},
@@ -390,6 +391,7 @@ char Help_create[] =
" --write-journal= : Specify journal device for RAID-4/5/6 array\n"
" --consistency-policy= : Specify the policy that determines how the array\n"
" -k : maintains consistency in case of unexpected shutdown.\n"
+" --write-zeroes : Write zeroes to the disks before creating. This will bypass initial sync.\n"
"\n"
;
diff --git a/mdadm.c b/mdadm.c
index 57e8e6fa..4685ad6b 100644
--- a/mdadm.c
+++ b/mdadm.c
@@ -590,6 +590,10 @@ int main(int argc, char *argv[])
s.assume_clean = 1;
continue;
+ case O(CREATE, WriteZeroes):
+ s.write_zeroes = 1;
+ continue;
+
case O(GROW,'n'):
case O(CREATE,'n'):
case O(BUILD,'n'): /* number of raid disks */
@@ -1251,6 +1255,11 @@ int main(int argc, char *argv[])
}
}
+ if (s.write_zeroes && !s.assume_clean) {
+ pr_info("Disk zeroing requested, setting --assume-clean to skip resync\n");
+ s.assume_clean = 1;
+ }
+
if (!mode && devs_found) {
mode = MISC;
devmode = 'Q';
diff --git a/mdadm.h b/mdadm.h
index 4336be4d..b9127f9a 100644
--- a/mdadm.h
+++ b/mdadm.h
@@ -275,6 +275,9 @@ static inline void __put_unaligned32(__u32 val, void *p)
#define ARRAY_SIZE(x) (sizeof(x)/sizeof(x[0]))
+#define KIB_TO_BYTES(x) ((x) << 10)
+#define SEC_TO_BYTES(x) ((x) << 9)
+
extern const char Name[];
struct md_bb_entry {
@@ -435,6 +438,7 @@ extern char Version[], Usage[], Help[], OptionHelp[],
*/
enum special_options {
AssumeClean = 300,
+ WriteZeroes,
BitmapChunk,
WriteBehind,
ReAdd,
@@ -640,6 +644,7 @@ struct shape {
int bitmap_chunk;
char *bitmap_file;
int assume_clean;
+ bool write_zeroes;
int write_behind;
unsigned long long size;
unsigned long long data_offset;
--
2.38.1
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