Fix range locking in ZIL commit codepath

Since OpenZFS 7578 (1b7c1e5) if we have a ZVOL with logbias=throughput
we will force WR_INDIRECT itxs in zvol_log_write() setting itx->itx_lr
offset and length to the offset and length of the BIO from
zvol_write()->zvol_log_write(): these offset and length are later used
to take a range lock in zillog->zl_get_data function: zvol_get_data().

Now suppose we have a ZVOL with blocksize=8K and push 4K writes to
offset 0: we will only be range-locking 0-4096. This means the
ASSERTion we make in dbuf_unoverride() is no longer valid because now
dmu_sync() is called from zilog's get_data functions holding a partial
lock on the dbuf.

Fix this by taking a range lock on the whole block in zvol_get_data().

Reviewed-by: Chunwei Chen <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: loli10K <[email protected]>
Closes #6238 
Closes #6315 
Closes #6356 
Closes #6477 

1 files changed, 2 insertions, 0 deletions

diff --git a/cmd/ztest/ztest.c b/cmd/ztest/ztest.c
index 788e6aa6a..8613d3d63 100644
--- a/cmd/ztest/ztest.c
+++ b/cmd/ztest/ztest.c
@@ -2145,6 +2145,7 @@ ztest_get_data(void *arg, lr_write_t *lr, char *buf, zio_t *zio)
 	if (buf != NULL) {	/* immediate write */
 		zgd_private->z_rl = ztest_range_lock(zd, object, offset, size,
 		    RL_READER);
+		zgd->zgd_rl = zgd_private->z_rl->z_rl;
 
 		error = dmu_read(os, object, offset, size, buf,
 		    DMU_READ_NO_PREFETCH);
@@ -2160,6 +2161,7 @@ ztest_get_data(void *arg, lr_write_t *lr, char *buf, zio_t *zio)
 
 		zgd_private->z_rl = ztest_range_lock(zd, object, offset, size,
 		    RL_READER);
+		zgd->zgd_rl = zgd_private->z_rl->z_rl;
 
 		error = dmu_buf_hold(os, object, offset, zgd, &db,
 		    DMU_READ_NO_PREFETCH);