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List:       linux-raid
Subject:    [PATCH 05/12] Zeroout whole ppl space during creation/force assemble
From:       Pawel Baldysiak <pawel.baldysiak () intel ! com>
Date:       2017-09-28 12:41:11
Message-ID: 20170928124118.23361-6-pawel.baldysiak () intel ! com
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PPL area should be cleared before creation/force assemble.
If the drive was used in other RAID array, it might contains PPL from it.
There is a risk that mdadm recognizes those PPLs and
refuses to assemble the RAID due to PPL conflict with created
array.

Signed-off-by: Pawel Baldysiak <pawel.baldysiak@intel.com>
---
 mdadm.h       |  1 +
 super-intel.c |  7 ++++++-
 super1.c      |  5 +++++
 util.c        | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 61 insertions(+), 1 deletion(-)

diff --git a/mdadm.h b/mdadm.h
index 191ae8f7..8f802e50 100644
--- a/mdadm.h
+++ b/mdadm.h
@@ -687,6 +687,7 @@ extern int sysfs_unique_holder(char *devnm, long rdev);
 extern int sysfs_freeze_array(struct mdinfo *sra);
 extern int sysfs_wait(int fd, int *msec);
 extern int load_sys(char *path, char *buf, int len);
+extern int zero_disk_range(int fd, unsigned long long sector, size_t count);
 extern int reshape_prepare_fdlist(char *devname,
 				  struct mdinfo *sra,
 				  int raid_disks,
diff --git a/super-intel.c b/super-intel.c
index d11ddae4..e1862d4a 100644
--- a/super-intel.c
+++ b/super-intel.c
@@ -6065,7 +6065,12 @@ static int write_init_ppl_imsm(struct supertype *st, struct mdinfo *info, int fd
 	struct ppl_header *ppl_hdr;
 	int ret;
 
-	ret = posix_memalign(&buf, 4096, PPL_HEADER_SIZE);
+	/* first clear entire ppl space */
+	ret = zero_disk_range(fd, info->ppl_sector, info->ppl_size);
+	if (ret)
+		return ret;
+
+	ret = posix_memalign(&buf, MAX_SECTOR_SIZE, PPL_HEADER_SIZE);
 	if (ret) {
 		pr_err("Failed to allocate PPL header buffer\n");
 		return ret;
diff --git a/super1.c b/super1.c
index b31f8450..6b821525 100644
--- a/super1.c
+++ b/super1.c
@@ -1823,6 +1823,11 @@ static int write_init_ppl1(struct supertype *st, struct mdinfo *info, int fd)
 	struct ppl_header *ppl_hdr;
 	int ret;
 
+	/* first clear entire ppl space */
+	ret = zero_disk_range(fd, info->ppl_sector, info->ppl_size);
+	if (ret)
+		return ret;
+
 	ret = posix_memalign(&buf, 4096, PPL_HEADER_SIZE);
 	if (ret) {
 		pr_err("Failed to allocate PPL header buffer\n");
diff --git a/util.c b/util.c
index c1c85095..bab7d6c1 100644
--- a/util.c
+++ b/util.c
@@ -30,6 +30,7 @@
 #include	<sys/un.h>
 #include	<sys/resource.h>
 #include	<sys/vfs.h>
+#include	<sys/mman.h>
 #include	<linux/magic.h>
 #include	<poll.h>
 #include	<ctype.h>
@@ -2325,3 +2326,51 @@ void set_hooks(void)
 	set_dlm_hooks();
 	set_cmap_hooks();
 }
+
+int zero_disk_range(int fd, unsigned long long sector, size_t count)
+{
+	int ret = 0;
+	int fd_zero;
+	void *addr = NULL;
+	size_t written = 0;
+	size_t len = count * 512;
+	ssize_t n;
+
+	fd_zero = open("/dev/zero", O_RDONLY);
+	if (fd_zero < 0) {
+		pr_err("Cannot open /dev/zero\n");
+		return -1;
+	}
+
+	if (lseek64(fd, sector * 512, SEEK_SET) < 0) {
+		ret = -errno;
+		pr_err("Failed to seek offset for zeroing\n");
+		goto out;
+	}
+
+	addr = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd_zero, 0);
+
+	if (addr == MAP_FAILED) {
+		ret = -errno;
+		pr_err("Mapping /dev/zero failed\n");
+		goto out;
+	}
+
+	do {
+		n = write(fd, addr + written, len - written);
+		if (n < 0) {
+			if (errno == EINTR)
+				continue;
+			ret = -errno;
+			pr_err("Zeroing disk range failed\n");
+			break;
+		}
+		written += n;
+	} while (written != len);
+
+	munmap(addr, len);
+
+out:
+	close(fd_zero);
+	return ret;
+}
-- 
2.13.5

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