From 884e6dfecc8b0f155015f0a25888300d8e1707f8 Mon Sep 17 00:00:00 2001 From: Hanna Czenczek Date: Tue, 11 Apr 2023 19:34:15 +0200 Subject: [PATCH 1/5] util/iov: Make qiov_slice() public RH-Author: Hanna Czenczek RH-MergeRequest: 291: block: Split padded I/O vectors exceeding IOV_MAX RH-Bugzilla: 2141964 RH-Acked-by: Emanuele Giuseppe Esposito RH-Acked-by: Stefan Hajnoczi RH-Commit: [1/5] 7f082982e49bacbcc21ca24e471b4399e64321a9 We want to inline qemu_iovec_init_extended() in block/io.c for padding requests, and having access to qiov_slice() is useful for this. As a public function, it is renamed to qemu_iovec_slice(). (We will need to count the number of I/O vector elements of a slice there, and then later process this slice. Without qiov_slice(), we would need to call qemu_iovec_subvec_niov(), and all further IOV-processing functions may need to skip prefixing elements to accomodate for a qiov_offset. Because qemu_iovec_subvec_niov() internally calls qiov_slice(), we can just have the block/io.c code call qiov_slice() itself, thus get the number of elements, and also create an iovec array with the superfluous prefixing elements stripped, so the following processing functions no longer need to skip them.) Reviewed-by: Eric Blake Reviewed-by: Vladimir Sementsov-Ogievskiy Signed-off-by: Hanna Czenczek Message-Id: <20230411173418.19549-2-hreitz@redhat.com> (cherry picked from commit 3d06cea8256d54a6b0238934c31012f7f17100f5) Signed-off-by: Hanna Czenczek --- include/qemu/iov.h | 3 +++ util/iov.c | 14 +++++++------- 2 files changed, 10 insertions(+), 7 deletions(-) diff --git a/include/qemu/iov.h b/include/qemu/iov.h index 9330746680..46fadfb27a 100644 --- a/include/qemu/iov.h +++ b/include/qemu/iov.h @@ -229,6 +229,9 @@ int qemu_iovec_init_extended( void *tail_buf, size_t tail_len); void qemu_iovec_init_slice(QEMUIOVector *qiov, QEMUIOVector *source, size_t offset, size_t len); +struct iovec *qemu_iovec_slice(QEMUIOVector *qiov, + size_t offset, size_t len, + size_t *head, size_t *tail, int *niov); int qemu_iovec_subvec_niov(QEMUIOVector *qiov, size_t offset, size_t len); void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len); void qemu_iovec_concat(QEMUIOVector *dst, diff --git a/util/iov.c b/util/iov.c index 58c7b3eeee..3ccb530b16 100644 --- a/util/iov.c +++ b/util/iov.c @@ -373,15 +373,15 @@ static struct iovec *iov_skip_offset(struct iovec *iov, size_t offset, } /* - * qiov_slice + * qemu_iovec_slice * * Find subarray of iovec's, containing requested range. @head would * be offset in first iov (returned by the function), @tail would be * count of extra bytes in last iovec (returned iov + @niov - 1). */ -static struct iovec *qiov_slice(QEMUIOVector *qiov, - size_t offset, size_t len, - size_t *head, size_t *tail, int *niov) +struct iovec *qemu_iovec_slice(QEMUIOVector *qiov, + size_t offset, size_t len, + size_t *head, size_t *tail, int *niov) { struct iovec *iov, *end_iov; @@ -406,7 +406,7 @@ int qemu_iovec_subvec_niov(QEMUIOVector *qiov, size_t offset, size_t len) size_t head, tail; int niov; - qiov_slice(qiov, offset, len, &head, &tail, &niov); + qemu_iovec_slice(qiov, offset, len, &head, &tail, &niov); return niov; } @@ -434,8 +434,8 @@ int qemu_iovec_init_extended( } if (mid_len) { - mid_iov = qiov_slice(mid_qiov, mid_offset, mid_len, - &mid_head, &mid_tail, &mid_niov); + mid_iov = qemu_iovec_slice(mid_qiov, mid_offset, mid_len, + &mid_head, &mid_tail, &mid_niov); } total_niov = !!head_len + mid_niov + !!tail_len; -- 2.39.3