141 lines
4.2 KiB
Diff
141 lines
4.2 KiB
Diff
From 9c8493d3a6d2e4d879d1ef67ff1abebd532c87a0 Mon Sep 17 00:00:00 2001
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From: Paolo Bonzini <pbonzini@redhat.com>
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Date: Fri, 16 Jul 2021 16:51:34 -0400
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Subject: [PATCH 18/43] file-posix: try BLKSECTGET on block devices too, do not
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round to power of 2
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RH-Author: Miroslav Rezanina <mrezanin@redhat.com>
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RH-Bugzilla: 1957194
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bs->sg is only true for character devices, but block devices can also
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be used with scsi-block and scsi-generic. Unfortunately BLKSECTGET
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returns bytes in an int for /dev/sgN devices, and sectors in a short
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for block devices, so account for that in the code.
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The maximum transfer also need not be a power of 2 (for example I have
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seen disks with 1280 KiB maximum transfer) so there's no need to pass
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the result through pow2floor.
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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(cherry picked from commit 18473467d55a20d643b6c9b3a52de42f705b4d35)
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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block/file-posix.c | 57 +++++++++++++++++++++++++++-------------------
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1 file changed, 33 insertions(+), 24 deletions(-)
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diff --git a/block/file-posix.c b/block/file-posix.c
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index 44325a635d..7b4ebf65d5 100644
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--- a/block/file-posix.c
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+++ b/block/file-posix.c
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@@ -1173,22 +1173,27 @@ static void raw_reopen_abort(BDRVReopenState *state)
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s->reopen_state = NULL;
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}
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-static int sg_get_max_transfer_length(int fd)
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+static int hdev_get_max_hw_transfer(int fd, struct stat *st)
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{
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#ifdef BLKSECTGET
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- int max_bytes = 0;
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-
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- if (ioctl(fd, BLKSECTGET, &max_bytes) == 0) {
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- return max_bytes;
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+ if (S_ISBLK(st->st_mode)) {
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+ unsigned short max_sectors = 0;
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+ if (ioctl(fd, BLKSECTGET, &max_sectors) == 0) {
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+ return max_sectors * 512;
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+ }
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} else {
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- return -errno;
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+ int max_bytes = 0;
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+ if (ioctl(fd, BLKSECTGET, &max_bytes) == 0) {
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+ return max_bytes;
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+ }
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}
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+ return -errno;
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#else
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return -ENOSYS;
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#endif
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}
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-static int sg_get_max_segments(int fd)
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+static int hdev_get_max_segments(int fd, struct stat *st)
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{
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#ifdef CONFIG_LINUX
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char buf[32];
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@@ -1197,26 +1202,20 @@ static int sg_get_max_segments(int fd)
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int ret;
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int sysfd = -1;
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long max_segments;
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- struct stat st;
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-
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- if (fstat(fd, &st)) {
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- ret = -errno;
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- goto out;
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- }
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- if (S_ISCHR(st.st_mode)) {
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+ if (S_ISCHR(st->st_mode)) {
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if (ioctl(fd, SG_GET_SG_TABLESIZE, &ret) == 0) {
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return ret;
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}
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return -ENOTSUP;
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}
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- if (!S_ISBLK(st.st_mode)) {
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+ if (!S_ISBLK(st->st_mode)) {
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return -ENOTSUP;
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}
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sysfspath = g_strdup_printf("/sys/dev/block/%u:%u/queue/max_segments",
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- major(st.st_rdev), minor(st.st_rdev));
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+ major(st->st_rdev), minor(st->st_rdev));
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sysfd = open(sysfspath, O_RDONLY);
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if (sysfd == -1) {
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ret = -errno;
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@@ -1253,23 +1252,33 @@ out:
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static void raw_refresh_limits(BlockDriverState *bs, Error **errp)
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{
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BDRVRawState *s = bs->opaque;
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+ struct stat st;
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- if (bs->sg) {
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- int ret = sg_get_max_transfer_length(s->fd);
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+ raw_probe_alignment(bs, s->fd, errp);
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+ bs->bl.min_mem_alignment = s->buf_align;
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+ bs->bl.opt_mem_alignment = MAX(s->buf_align, qemu_real_host_page_size);
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+
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+ /*
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+ * Maximum transfers are best effort, so it is okay to ignore any
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+ * errors. That said, based on the man page errors in fstat would be
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+ * very much unexpected; the only possible case seems to be ENOMEM.
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+ */
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+ if (fstat(s->fd, &st)) {
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+ return;
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+ }
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+
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+ if (bs->sg || S_ISBLK(st.st_mode)) {
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+ int ret = hdev_get_max_hw_transfer(s->fd, &st);
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if (ret > 0 && ret <= BDRV_REQUEST_MAX_BYTES) {
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- bs->bl.max_hw_transfer = pow2floor(ret);
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+ bs->bl.max_hw_transfer = ret;
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}
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- ret = sg_get_max_segments(s->fd);
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+ ret = hdev_get_max_segments(s->fd, &st);
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if (ret > 0) {
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bs->bl.max_iov = ret;
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}
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}
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-
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- raw_probe_alignment(bs, s->fd, errp);
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- bs->bl.min_mem_alignment = s->buf_align;
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- bs->bl.opt_mem_alignment = MAX(s->buf_align, qemu_real_host_page_size);
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}
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static int check_for_dasd(int fd)
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--
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2.27.0
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