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[PULL,24/30] nfs: Support BDRV_REQ_ZERO_WRITE for truncate

Message ID 20200508124135.252565-25-kwolf@redhat.com
State New
Headers show
Series Block layer patches | expand

Commit Message

Kevin Wolf May 8, 2020, 12:41 p.m. UTC 
From: Eric Blake <eblake@redhat.com>

Our .bdrv_has_zero_init_truncate returns 1 if we detect that the OS
always 0-fills; we can use that same knowledge to implement
BDRV_REQ_ZERO_WRITE by ignoring it when the OS gives it to us for
free.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200428202905.770727-4-eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/nfs.c | 3 +++
 1 file changed, 3 insertions(+)
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Patch

diff --git a/block/nfs.c b/block/nfs.c
index 385d756e1d..76daa7c9f6 100644
--- a/block/nfs.c
+++ b/block/nfs.c
@@ -620,6 +620,9 @@  static int nfs_file_open(BlockDriverState *bs, QDict *options, int flags,
     }
 
     bs->total_sectors = ret;
+    if (client->has_zero_init) {
+        bs->supported_truncate_flags = BDRV_REQ_ZERO_WRITE;
+    }
     return 0;
 }