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block: Allow BDRV_REQ_FUA through blk_pwrite()

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We have several block drivers that understand BDRV_REQ_FUA,
and emulate it in the block layer for the rest by a full flush.
But without a way to actually request BDRV_REQ_FUA during a
pass-through blk_pwrite(), FUA-aware block drivers like NBD are
forced to repeat the emulation logic of a full flush regardless
of whether the backend they are writing to could do it more
efficiently.

This patch just wires up a flags argument; followup patches
will actually make use of it in the NBD driver and in qemu-io.

Signed-off-by: Eric Blake <eblake@redhat.com>
Acked-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Eric Blake 2016-05-06 10:26:27 -06:00 • committed by Kevin Wolf
parent 0e01b76e7c
commit 8341f00dc2
15 changed files with 37 additions and 33 deletions
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8
block/qcow.c
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@ -853,14 +853,14 @@ static int qcow_create(const char *filename, QemuOpts *opts, Error **errp)
}
/* write all the data */
ret = blk_pwrite(qcow_blk, 0, &header, sizeof(header));
ret = blk_pwrite(qcow_blk, 0, &header, sizeof(header), 0);
if (ret != sizeof(header)) {
goto exit;
}
if (backing_file) {
ret = blk_pwrite(qcow_blk, sizeof(header),
backing_file, backing_filename_len);
backing_file, backing_filename_len, 0);
if (ret != backing_filename_len) {
goto exit;
}
@ -869,8 +869,8 @@ static int qcow_create(const char *filename, QemuOpts *opts, Error **errp)
tmp = g_malloc0(BDRV_SECTOR_SIZE);
for (i = 0; i < ((sizeof(uint64_t)*l1_size + BDRV_SECTOR_SIZE - 1)/
BDRV_SECTOR_SIZE); i++) {
ret = blk_pwrite(qcow_blk, header_size +
BDRV_SECTOR_SIZE*i, tmp, BDRV_SECTOR_SIZE);
ret = blk_pwrite(qcow_blk, header_size + BDRV_SECTOR_SIZE * i,
tmp, BDRV_SECTOR_SIZE, 0);
if (ret != BDRV_SECTOR_SIZE) {
g_free(tmp);
goto exit;