[v5,1/3] block/file-posix: Optimize for macOS

Commit Message

Akihiko Odaki July 5, 2021, 1:04 p.m. UTC

This commit introduces "punch hole" operation and optimizes transfer
block size for macOS.

Thanks to Konstantin Nazarov for detailed analysis of a flaw in an
old version of this change:
https://gist.github.com/akihikodaki/87df4149e7ca87f18dc56807ec5a1bc5#gistcomment-3654667

Signed-off-by: Akihiko Odaki <[e-mail]>
---
 block/file-posix.c | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

Comments

Stefan Hajnoczi July 6, 2021, 1:17 p.m. UTC | #1

On Mon, Jul 05, 2021 at 10:04:56PM +0900, Akihiko Odaki wrote:
> This commit introduces "punch hole" operation and optimizes transfer
> block size for macOS.
> 
> Thanks to Konstantin Nazarov for detailed analysis of a flaw in an
> old version of this change:
> https://gist.github.com/akihikodaki/87df4149e7ca87f18dc56807ec5a1bc5#gistcomment-3654667
> 
> Signed-off-by: Akihiko Odaki <[e-mail]>
> ---
>  block/file-posix.c | 27 +++++++++++++++++++++++++--
>  1 file changed, 25 insertions(+), 2 deletions(-)

Thanks, applied to my block tree:
https://gitlab.com/stefanha/qemu/commits/block

Stefan

Patch

diff --git a/block/file-posix.c b/block/file-posix.c
index b3fbb9bd63a..80da1f59a60 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -44,6 +44,7 @@ 
 #if defined(__APPLE__) && (__MACH__)
 #include <paths.h>
 #include <sys/param.h>
+#include <sys/mount.h>
 #include <IOKit/IOKitLib.h>
 #include <IOKit/IOBSD.h>
 #include <IOKit/storage/IOMediaBSDClient.h>
@@ -1217,6 +1218,15 @@  static void raw_refresh_limits(BlockDriverState *bs, Error **errp)
 {
     BDRVRawState *s = bs->opaque;
 
+#if defined(__APPLE__) && (__MACH__)
+    struct statfs buf;
+
+    if (!fstatfs(s->fd, &buf)) {
+        bs->bl.opt_transfer = buf.f_iosize;
+        bs->bl.pdiscard_alignment = buf.f_bsize;
+    }
+#endif
+
     if (bs->sg) {
         int ret = sg_get_max_transfer_length(s->fd);
 
@@ -1557,6 +1567,7 @@  out:
     }
 }
 
+#if defined(CONFIG_FALLOCATE) || defined(BLKZEROOUT) || defined(BLKDISCARD)
 static int translate_err(int err)
 {
     if (err == -ENODEV || err == -ENOSYS || err == -EOPNOTSUPP ||
@@ -1565,6 +1576,7 @@  static int translate_err(int err)
     }
     return err;
 }
+#endif
 
 #ifdef CONFIG_FALLOCATE
 static int do_fallocate(int fd, int mode, off_t offset, off_t len)
@@ -1777,16 +1789,27 @@  static int handle_aiocb_discard(void *opaque)
             }
         } while (errno == EINTR);
 
-        ret = -errno;
+        ret = translate_err(-errno);
 #endif
     } else {
 #ifdef CONFIG_FALLOCATE_PUNCH_HOLE
         ret = do_fallocate(s->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
                            aiocb->aio_offset, aiocb->aio_nbytes);
+        ret = translate_err(-errno);
+#elif defined(__APPLE__) && (__MACH__)
+        fpunchhole_t fpunchhole;
+        fpunchhole.fp_flags = 0;
+        fpunchhole.reserved = 0;
+        fpunchhole.fp_offset = aiocb->aio_offset;
+        fpunchhole.fp_length = aiocb->aio_nbytes;
+        if (fcntl(s->fd, F_PUNCHHOLE, &fpunchhole) == -1) {
+            ret = errno == ENODEV ? -ENOTSUP : -errno;
+        } else {
+            ret = 0;
+        }
 #endif
     }
 
-    ret = translate_err(ret);
     if (ret == -ENOTSUP) {
         s->has_discard = false;
     }