From ecdc254dbaa7995a94f67e7dfafb17137d15759e Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Thu, 17 Apr 2025 11:05:28 -0400 Subject: [PATCH 2/3] block/io: skip head/tail requests on EINVAL RH-Author: Stefan Hajnoczi RH-MergeRequest: 450: file-posix: probe discard alignment on Linux block devices RH-Jira: RHEL-87734 RH-Acked-by: Kevin Wolf RH-Acked-by: Eric Blake RH-Commit: [2/3] 30b17fc1828c45cf958b8254999ce1ef1f100868 When guests send misaligned discard requests, the block layer breaks them up into a misaligned head, an aligned main body, and a misaligned tail. The file-posix block driver on Linux returns -EINVAL on misaligned discard requests. This causes bdrv_co_pdiscard() to fail and guests configured with werror=stop will pause. Add a special case for misaligned head/tail requests. Simply continue when EINVAL is encountered so that the aligned main body of the request can be completed and the guest is not paused. This is the best we can do when guest discard limits do not match the host discard limits. Fixes: https://issues.redhat.com/browse/RHEL-86032 Signed-off-by: Stefan Hajnoczi Reviewed-by: Hanna Czenczek Message-ID: <20250417150528.76470-3-stefanha@redhat.com> Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf (cherry picked from commit 4733cb0833c4b223f92ec0136980eeb5239ecb87) Signed-off-by: Stefan Hajnoczi --- block/io.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/block/io.c b/block/io.c index 301514c880..3e189837a1 100644 --- a/block/io.c +++ b/block/io.c @@ -3105,11 +3105,12 @@ int coroutine_fn bdrv_co_pdiscard(BdrvChild *child, int64_t offset, /* Invalidate the cached block-status data range if this discard overlaps */ bdrv_bsc_invalidate_range(bs, offset, bytes); - /* Discard is advisory, but some devices track and coalesce + /* + * Discard is advisory, but some devices track and coalesce * unaligned requests, so we must pass everything down rather than - * round here. Still, most devices will just silently ignore - * unaligned requests (by returning -ENOTSUP), so we must fragment - * the request accordingly. */ + * round here. Still, most devices reject unaligned requests with + * -EINVAL or -ENOTSUP, so we must fragment the request accordingly. + */ align = MAX(bs->bl.pdiscard_alignment, bs->bl.request_alignment); assert(align % bs->bl.request_alignment == 0); head = offset % align; @@ -3176,7 +3177,11 @@ int coroutine_fn bdrv_co_pdiscard(BdrvChild *child, int64_t offset, } } if (ret && ret != -ENOTSUP) { - goto out; + if (ret == -EINVAL && (offset % align != 0 || num % align != 0)) { + /* Silently skip rejected unaligned head/tail requests */ + } else { + goto out; /* bail out */ + } } offset += num; -- 2.48.1