From 1644cccea5c71b02b9cf8f78b780e7069a29b189 Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Wed, 17 Nov 2021 11:02:29 -0600 Subject: [PATCH 1/2] nbd/server: Don't complain on certain client disconnects When a client disconnects abruptly, but did not have any pending requests (for example, when using nbdsh without calling h.shutdown), we used to output the following message: $ qemu-nbd -f raw file $ nbdsh -u 'nbd://localhost:10809' -c 'h.trim(1,0)' qemu-nbd: Disconnect client, due to: Failed to read request: Unexpected end-of-file before all bytes were read Then in commit f148ae7, we refactored nbd_receive_request() to use nbd_read_eof(); when this returns 0, we regressed into tracing uninitialized memory (if tracing is enabled) and reporting a less-specific: qemu-nbd: Disconnect client, due to: Request handling failed in intermediate state Note that with Unix sockets, we have yet another error message, unchanged by the 6.0 regression: $ qemu-nbd -k /tmp/sock -f raw file $ nbdsh -u 'nbd+unix:///?socket=/tmp/sock' -c 'h.trim(1,0)' qemu-nbd: Disconnect client, due to: Failed to send reply: Unable to write to socket: Broken pipe But in all cases, the error message goes away if the client performs a soft shutdown by using NBD_CMD_DISC, rather than a hard shutdown by abrupt disconnect: $ nbdsh -u 'nbd://localhost:10809' -c 'h.trim(1,0)' -c 'h.shutdown()' This patch fixes things to avoid uninitialized memory, and in general avoids warning about a client that does a hard shutdown when not in the middle of a packet. A client that aborts mid-request, or which does not read the full server's reply, can still result in warnings, but those are indeed much more unusual situations. CC: qemu-stable@nongnu.org Fixes: f148ae7d36 ("nbd/server: Quiesce coroutines on context switch", v6.0.0) Signed-off-by: Eric Blake Reviewed-by: Vladimir Sementsov-Ogievskiy [eblake: defer unrelated typo fixes to later patch] Message-Id: <20211117170230.1128262-2-eblake@redhat.com> Signed-off-by: Eric Blake --- nbd/server.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/nbd/server.c b/nbd/server.c index d9164ee6d0..74ba487094 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -1418,6 +1418,9 @@ static int nbd_receive_request(NBDClient *client, NBDRequest *request, if (ret < 0) { return ret; } + if (ret == 0) { + return -EIO; + } /* Request [ 0 .. 3] magic (NBD_REQUEST_MAGIC) From e35574226a63f29e32eda8da5cc14832f19850e2 Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Wed, 17 Nov 2021 11:02:30 -0600 Subject: [PATCH 2/2] nbd/server: Simplify zero and trim Now that the block layer supports 64-bit operations (see commit 2800637a and friends, new to v6.2), we no longer have to self-fragment requests larger than 2G, reverting the workaround added in 890cbccb08 ("nbd: Fix large trim/zero requests", v5.1.0). Signed-off-by: Eric Blake Message-Id: <20211117170230.1128262-3-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy --- nbd/server.c | 23 +++-------------------- 1 file changed, 3 insertions(+), 20 deletions(-) diff --git a/nbd/server.c b/nbd/server.c index 74ba487094..4630dd7322 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -2509,16 +2509,8 @@ static coroutine_fn int nbd_handle_request(NBDClient *client, if (request->flags & NBD_CMD_FLAG_FAST_ZERO) { flags |= BDRV_REQ_NO_FALLBACK; } - ret = 0; - /* FIXME simplify this when blk_pwrite_zeroes switches to 64-bit */ - while (ret >= 0 && request->len) { - int align = client->check_align ?: 1; - int len = MIN(request->len, QEMU_ALIGN_DOWN(BDRV_REQUEST_MAX_BYTES, - align)); - ret = blk_pwrite_zeroes(exp->common.blk, request->from, len, flags); - request->len -= len; - request->from += len; - } + ret = blk_pwrite_zeroes(exp->common.blk, request->from, request->len, + flags); return nbd_send_generic_reply(client, request->handle, ret, "writing to file failed", errp); @@ -2532,16 +2524,7 @@ static coroutine_fn int nbd_handle_request(NBDClient *client, "flush failed", errp); case NBD_CMD_TRIM: - ret = 0; - /* FIXME simplify this when blk_co_pdiscard switches to 64-bit */ - while (ret >= 0 && request->len) { - int align = client->check_align ?: 1; - int len = MIN(request->len, QEMU_ALIGN_DOWN(BDRV_REQUEST_MAX_BYTES, - align)); - ret = blk_co_pdiscard(exp->common.blk, request->from, len); - request->len -= len; - request->from += len; - } + ret = blk_co_pdiscard(exp->common.blk, request->from, request->len); if (ret >= 0 && request->flags & NBD_CMD_FLAG_FUA) { ret = blk_co_flush(exp->common.blk); }