MFC r323918: MFV r323917: 8648 Fix range locking in ZIL commit codepath

This fixes a problem introduced in r315441, MFC of r308782.

2 files changed, 13 insertions, 4 deletions

diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
index 1d9e691..dae85d9 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
@@ -1342,7 +1342,7 @@ zfs_get_data(void *arg, lr_write_t *lr, char *buf, zio_t *zio)
 	} else { /* indirect write */
 		/*
 		 * Have to lock the whole block to ensure when it's
-		 * written out and it's checksum is being calculated
+		 * written out and its checksum is being calculated
 		 * that no one can change the data. We need to re-check
 		 * blocksize after we get the lock in case it's changed!
 		 */
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c
index 95908a6..10d647b 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c
@@ -1349,7 +1349,6 @@ zvol_get_data(void *arg, lr_write_t *lr, char *buf, zio_t *zio)
 
 	zgd = kmem_zalloc(sizeof (zgd_t), KM_SLEEP);
 	zgd->zgd_zilog = zv->zv_zilog;
-	zgd->zgd_rl = zfs_range_lock(&zv->zv_znode, offset, size, RL_READER);
 
 	/*
 	 * Write records come in two flavors: immediate and indirect.
@@ -1358,12 +1357,22 @@ zvol_get_data(void *arg, lr_write_t *lr, char *buf, zio_t *zio)
 	 * sync the data and get a pointer to it (indirect) so that
 	 * we don't have to write the data twice.
 	 */
-	if (buf != NULL) {	/* immediate write */
+	if (buf != NULL) { /* immediate write */
+		zgd->zgd_rl = zfs_range_lock(&zv->zv_znode, offset, size,
+		    RL_READER);
 		error = dmu_read(os, object, offset, size, buf,
 		    DMU_READ_NO_PREFETCH);
-	} else {
+	} else { /* indirect write */
+		/*
+		 * Have to lock the whole block to ensure when it's written out
+		 * and its checksum is being calculated that no one can change
+		 * the data. Contrarily to zfs_get_data we need not re-check
+		 * blocksize after we get the lock because it cannot be changed.
+		 */
 		size = zv->zv_volblocksize;
 		offset = P2ALIGN(offset, size);
+		zgd->zgd_rl = zfs_range_lock(&zv->zv_znode, offset, size,
+		    RL_READER);
 		error = dmu_buf_hold(os, object, offset, zgd, &db,
 		    DMU_READ_NO_PREFETCH);
 		if (error == 0) {