[f2fs-dev] [PATCH v2] libf2fs: don't allow mkfs / fsck on non power-of-2 zoned devices

[Pankaj Raghav <p.raghav@samsung.com>]

From: Luis Chamberlain <mcgrof@kernel.org>

f2fs currently only work with zoned storage devices with a zone
size which is a power of 2 (PO2). So check if a non-power of 2
zoned device is found, and if so disallow its use. This prevents
users from incorrectly using these devices.

This is a non-issue today given today's kernel does not allow NPO2
zoned devices to exist as a block device. But NPO2 zoned devices do exist
so proactively put a stop-gap measure in place to prevent it from being
incorrectly used.

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
---
Changes since v1:
- Squash the commits for clarity (Damien)
- f2fs_get_zone_chunk_sectors can return uint32_t (Damien)
- Include the units for zone size in msg info (Damien)
- Sections can be npo2 but it should only be a multiple of 2MB (Jaegeuk)

 include/f2fs_fs.h   |  1 +
 lib/libf2fs.c       | 17 +++++++++++++++--
 lib/libf2fs_zoned.c | 34 ++++++++++++++++++++++------------
 3 files changed, 38 insertions(+), 14 deletions(-)

diff --git a/include/f2fs_fs.h b/include/f2fs_fs.h
index d236437..83c5b33 100644
--- a/include/f2fs_fs.h
+++ b/include/f2fs_fs.h
@@ -386,6 +386,7 @@ struct device_info {
 	u_int32_t nr_zones;
 	u_int32_t nr_rnd_zones;
 	size_t zone_blocks;
+	uint64_t zone_size;
 	size_t *zone_cap_blocks;
 };
 
diff --git a/lib/libf2fs.c b/lib/libf2fs.c
index 420dfda..8104667 100644
--- a/lib/libf2fs.c
+++ b/lib/libf2fs.c
@@ -882,6 +882,11 @@ static int open_check_fs(char *path, int flag)
 	return open(path, O_RDONLY | flag);
 }
 
+static int is_power_of_2(unsigned long n)
+{
+	return (n != 0 && ((n & (n - 1)) == 0));
+}
+
 int get_device_info(int i)
 {
 	int32_t fd = 0;
@@ -1043,6 +1048,13 @@ int get_device_info(int i)
 			return -1;
 		}
 
+		if (!is_power_of_2(dev->zone_size)) {
+			MSG(0, "\tError: zoned: illegal zone size %lu (not a power of 2)\n",
+					dev->zone_size);
+			free(stat_buf);
+			return -1;
+		}
+
 		/*
 		 * Check zone configuration: for the first disk of a
 		 * multi-device volume, conventional zones are needed.
@@ -1055,8 +1067,9 @@ int get_device_info(int i)
 		MSG(0, "Info: Host-%s zoned block device:\n",
 				(dev->zoned_model == F2FS_ZONED_HA) ?
 					"aware" : "managed");
-		MSG(0, "      %u zones, %u randomly writeable zones\n",
-				dev->nr_zones, dev->nr_rnd_zones);
+		MSG(0, "      %u zones, %lu zone size(bytes), %u randomly writeable zones\n",
+				dev->nr_zones, dev->zone_size,
+				dev->nr_rnd_zones);
 		MSG(0, "      %lu blocks per zone\n",
 				dev->zone_blocks);
 	}
diff --git a/lib/libf2fs_zoned.c b/lib/libf2fs_zoned.c
index ce73b9a..48a23c0 100644
--- a/lib/libf2fs_zoned.c
+++ b/lib/libf2fs_zoned.c
@@ -146,40 +146,50 @@ int f2fs_get_zoned_model(int i)
 	return 0;
 }
 
-int f2fs_get_zone_blocks(int i)
+uint32_t f2fs_get_zone_chunk_sectors(struct device_info *dev)
 {
-	struct device_info *dev = c.devices + i;
-	uint64_t sectors;
+	uint32_t sectors;
 	char str[PATH_MAX];
 	FILE *file;
 	int res;
 
-	/* Get zone size */
-	dev->zone_blocks = 0;
-
 	res = get_sysfs_path(dev, "queue/chunk_sectors", str, sizeof(str));
 	if (res != 0) {
 		MSG(0, "\tError: Failed to get device sysfs attribute path\n");
-		return -1;
+		return 0;
 	}
 
 	file = fopen(str, "r");
 	if (!file)
-		return -1;
+		return 0;
 
 	memset(str, 0, sizeof(str));
 	res = fscanf(file, "%s", str);
 	fclose(file);
 
 	if (res != 1)
-		return -1;
+		return 0;
 
-	sectors = atol(str);
+	sectors = atoi(str);
+
+	return sectors;
+}
+
+int f2fs_get_zone_blocks(int i)
+{
+	struct device_info *dev = c.devices + i;
+	uint64_t sectors;
+
+	/* Get zone size */
+	dev->zone_blocks = 0;
+
+	sectors = f2fs_get_zone_chunk_sectors(dev);
 	if (!sectors)
 		return -1;
 
-	dev->zone_blocks = sectors >> (F2FS_BLKSIZE_BITS - 9);
-	sectors = (sectors << 9) / c.sector_size;
+	dev->zone_size = sectors << SECTOR_SHIFT;
+	dev->zone_blocks = sectors >> (F2FS_BLKSIZE_BITS - SECTOR_SHIFT);
+	sectors = dev->zone_size / c.sector_size;
 
 	/*
 	 * Total number of zones: there may
-- 
2.25.1



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