From eeeb0ba9a562fb3647751409bb2aebe91815f64d Mon Sep 17 00:00:00 2001
From: Alex John <alex@stty.io>
Date: Sun, 12 Apr 2020 00:16:49 +0800
Subject: [PATCH] zfs_create: round up volume size to multiple of bs

Round up the volume size requested in `zfs create -V size` to the next
higher multiple of the volblocksize. Updates the man page and adds a
test to verify the new behavior.

Reported-by: puffi <puffi@users.noreply.github.com>
Signed-off-by: Alex John <alex@stty.io>
---
 cmd/zfs/zfs_main.c                            | 23 +++++++++++++++++++
 man/man8/zfs-create.8                         |  3 +--
 .../cli_root/zfs_create/zfs_create.cfg        |  8 ++++++-
 .../zfs_create/zfs_create_002_pos.ksh         | 14 +++++++++++
 4 files changed, 45 insertions(+), 3 deletions(-)

diff --git a/cmd/zfs/zfs_main.c b/cmd/zfs/zfs_main.c
index ae71cdc881fe..a9c4ca0bc21b 100644
--- a/cmd/zfs/zfs_main.c
+++ b/cmd/zfs/zfs_main.c
@@ -1038,6 +1038,29 @@ zfs_do_create(int argc, char **argv)
 		}
 	}
 
+	/*
+	 * if volsize is not a multiple of volblocksize, round it up to the
+	 * nearest multiple of the volblocksize
+	 */
+	if (type == ZFS_TYPE_VOLUME) {
+		uint64_t volblocksize;
+
+		if (nvlist_lookup_uint64(props,
+		    zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE),
+		    &volblocksize) != 0)
+			volblocksize = ZVOL_DEFAULT_BLOCKSIZE;
+
+		if (volsize % volblocksize) {
+			volsize = P2ROUNDUP_TYPED(volsize, volblocksize,
+			    uint64_t);
+
+			if (nvlist_add_uint64(props,
+			    zfs_prop_to_name(ZFS_PROP_VOLSIZE), volsize) != 0)
+				nomem();
+		}
+	}
+
+
 	if (type == ZFS_TYPE_VOLUME && !noreserve) {
 		uint64_t spa_version;
 		zfs_prop_t resv_prop;
diff --git a/man/man8/zfs-create.8 b/man/man8/zfs-create.8
index 6aef2bb572d7..24ad77d021b6 100644
--- a/man/man8/zfs-create.8
+++ b/man/man8/zfs-create.8
@@ -143,8 +143,7 @@ The size represents the logical size as exported by the device.
 By default, a reservation of equal size is created.
 .Pp
 .Ar size
-is automatically rounded up to the nearest 128 Kbytes to ensure that the volume
-has an integral number of blocks regardless of
+is automatically rounded up to the nearest multiple of the
 .Sy blocksize .
 .Bl -tag -width "-b"
 .It Fl b Ar blocksize
diff --git a/tests/zfs-tests/tests/functional/cli_root/zfs_create/zfs_create.cfg b/tests/zfs-tests/tests/functional/cli_root/zfs_create/zfs_create.cfg
index b96908ce12c7..9bf25327ef8d 100644
--- a/tests/zfs-tests/tests/functional/cli_root/zfs_create/zfs_create.cfg
+++ b/tests/zfs-tests/tests/functional/cli_root/zfs_create/zfs_create.cfg
@@ -54,6 +54,12 @@ export VOL_LIMIT_KEYWORD1="1TB on 32-bit"
 export VOL_LIMIT_KEYWORD2="value is too large"
 export VOL_LIMIT_KEYWORD3="volume size exceeds limit"
 
-set -A size "8k" "8K" "1m" "1M" "1mb" "1mB" "1Mb" "1MB" "1g" "1G" \
+set -A size "8k" "8K" "35K" "1m" "1M" "1mb" "1mB" "1Mb" "1MB" "1g" "1G" \
 	"1p" "1P" "1z" "1Z" "1gb" "1gB" "1Gb" "1GB" "1pb" "1pB" "1Pb" \
 	"1PB" "1zb" "1zB" "1Zb" "1ZB"
+
+# If a datasize has a volume size that is not a multiple of the blocksize,
+# explicitly check that its size has been rounded up to the nearest multiple
+# The volume with the exact size must exist in the "size" array above
+set -A explicit_size_check "35K"
+set -A expected_rounded_size "40960"
diff --git a/tests/zfs-tests/tests/functional/cli_root/zfs_create/zfs_create_002_pos.ksh b/tests/zfs-tests/tests/functional/cli_root/zfs_create/zfs_create_002_pos.ksh
index 6f36b40bfd59..cabe984ca2d3 100755
--- a/tests/zfs-tests/tests/functional/cli_root/zfs_create/zfs_create_002_pos.ksh
+++ b/tests/zfs-tests/tests/functional/cli_root/zfs_create/zfs_create_002_pos.ksh
@@ -31,6 +31,7 @@
 
 . $STF_SUITE/include/libtest.shlib
 . $STF_SUITE/tests/functional/cli_root/zfs_create/zfs_create.cfg
+. $STF_SUITE/tests/functional/cli_root/zfs_create/zfs_create_common.kshlib
 
 #
 # DESCRIPTION:
@@ -39,6 +40,8 @@
 # STRATEGY:
 # 1. Create a volume in the storage pool.
 # 2. Verify the volume is created correctly.
+# 3. Verify that the volume created has its volsize rounded to the nearest
+#    multiple of the blocksize (in this case, the default blocksize)
 #
 
 verify_runnable "global"
@@ -78,4 +81,15 @@ while (( $j < ${#size[*]} )); do
 	((j = j + 1))
 
 done
+
+typeset -i j=0
+while (( $j < ${#explicit_size_check[*]} )); do
+  propertycheck ${TESTPOOL}/${TESTVOL}${explicit_size_check[j]} \
+    volsize=${expected_rounded_size[j]} || \
+    log_fail "volsize ${size[j]} was not rounded up"
+
+	((j = j + 1))
+
+done
+
 log_pass "'zfs create -s -V <size> <volume>' works as expected."