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| author | Ilya Dryomov <idryomov@gmail.com> | 2021-12-30 15:13:32 +0100 |
|---|---|---|
| committer | Ilya Dryomov <idryomov@gmail.com> | 2022-02-02 18:50:36 +0100 |
| commit | 038b8d1d1ab1cce11a158d30bf080ff41a2cfd15 (patch) | |
| tree | 83f509c79a7d909bd440882f0f39492b08dbc31c /include | |
| parent | 2ea88716369ac9a7486a8cb309d6bf1239ea156c (diff) | |
| download | linux-038b8d1d1ab1cce11a158d30bf080ff41a2cfd15.tar.bz2 | |
libceph: optionally use bounce buffer on recv path in crc mode
Both msgr1 and msgr2 in crc mode are zero copy in the sense that
message data is read from the socket directly into the destination
buffer. We assume that the destination buffer is stable (i.e. remains
unchanged while it is being read to) though. Otherwise, CRC errors
ensue:
libceph: read_partial_message 0000000048edf8ad data crc 1063286393 != exp. 228122706
libceph: osd1 (1)192.168.122.1:6843 bad crc/signature
libceph: bad data crc, calculated 57958023, expected 1805382778
libceph: osd2 (2)192.168.122.1:6876 integrity error, bad crc
Introduce rxbounce option to enable use of a bounce buffer when
receiving message data. In particular this is needed if a mapped
image is a Windows VM disk, passed to QEMU. Windows has a system-wide
"dummy" page that may be mapped into the destination buffer (potentially
more than once into the same buffer) by the Windows Memory Manager in
an effort to generate a single large I/O [1][2]. QEMU makes a point of
preserving overlap relationships when cloning I/O vectors, so krbd gets
exposed to this behaviour.
[1] "What Is Really in That MDL?"
https://docs.microsoft.com/en-us/previous-versions/windows/hardware/design/dn614012(v=vs.85)
[2] https://blogs.msmvps.com/kernelmustard/2005/05/04/dummy-pages/
URL: https://bugzilla.redhat.com/show_bug.cgi?id=1973317
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/ceph/libceph.h | 1 | ||||
| -rw-r--r-- | include/linux/ceph/messenger.h | 1 |
2 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/ceph/libceph.h b/include/linux/ceph/libceph.h index 6a89ea410e43..edf62eaa6285 100644 --- a/include/linux/ceph/libceph.h +++ b/include/linux/ceph/libceph.h @@ -35,6 +35,7 @@ #define CEPH_OPT_TCP_NODELAY (1<<4) /* TCP_NODELAY on TCP sockets */ #define CEPH_OPT_NOMSGSIGN (1<<5) /* don't sign msgs (msgr1) */ #define CEPH_OPT_ABORT_ON_FULL (1<<6) /* abort w/ ENOSPC when full */ +#define CEPH_OPT_RXBOUNCE (1<<7) /* double-buffer read data */ #define CEPH_OPT_DEFAULT (CEPH_OPT_TCP_NODELAY) diff --git a/include/linux/ceph/messenger.h b/include/linux/ceph/messenger.h index 6c6b6ea52bb8..e7f2fb2fc207 100644 --- a/include/linux/ceph/messenger.h +++ b/include/linux/ceph/messenger.h @@ -461,6 +461,7 @@ struct ceph_connection { struct ceph_msg *out_msg; /* sending message (== tail of out_sent) */ + struct page *bounce_page; u32 in_front_crc, in_middle_crc, in_data_crc; /* calculated crc */ struct timespec64 last_keepalive_ack; /* keepalive2 ack stamp */ |