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Align file accesses with cache=off (Kevin Wolf, Laurent Vivier) 

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4367 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
blueswir1 2008-05-06 17:26:59 +00:00
parent dd53ded3f7
commit adcbebaa40
1 changed files with 113 additions and 6 deletions
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119
block-raw-posix.c
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@ -77,10 +77,10 @@
typedef struct BDRVRawState {
int fd;
int type;
int open_flags;
unsigned int lseek_err_cnt;
#if defined(__linux__)
/* linux floppy specific */
int fd_open_flags;
int64_t fd_open_time;
int64_t fd_error_time;
int fd_got_error;
@ -111,6 +111,7 @@ static int raw_open(BlockDriverState *bs, const char *filename, int flags)
open_flags |= O_DIRECT;
#endif
s->open_flags = open_flags;
s->type = FTYPE_FILE;
fd = open(filename, open_flags, 0644);
@ -141,7 +142,14 @@ static int raw_open(BlockDriverState *bs, const char *filename, int flags)
#endif
*/
static int raw_pread(BlockDriverState *bs, int64_t offset,
/*
* offset and count are in bytes, but must be multiples of 512 for files
* opened with O_DIRECT. buf must be aligned to 512 bytes then.
*
* This function may be called without alignment if the caller ensures
* that O_DIRECT is not in effect.
*/
static int raw_pread_aligned(BlockDriverState *bs, int64_t offset,
uint8_t *buf, int count)
{
BDRVRawState *s = bs->opaque;
@ -194,7 +202,14 @@ label__raw_read__success:
return ret;
}
static int raw_pwrite(BlockDriverState *bs, int64_t offset,
/*
* offset and count are in bytes, but must be multiples of 512 for files
* opened with O_DIRECT. buf must be aligned to 512 bytes then.
*
* This function may be called without alignment if the caller ensures
* that O_DIRECT is not in effect.
*/
static int raw_pwrite_aligned(BlockDriverState *bs, int64_t offset,
const uint8_t *buf, int count)
{
BDRVRawState *s = bs->opaque;
@ -230,6 +245,67 @@ label__raw_write__success:
return ret;
}
#ifdef O_DIRECT
/*
* offset and count are in bytes and possibly not aligned. For files opened
* with O_DIRECT, necessary alignments are ensured before calling
* raw_pread_aligned to do the actual read.
*/
static int raw_pread(BlockDriverState *bs, int64_t offset,
uint8_t *buf, int count)
{
BDRVRawState *s = bs->opaque;
if (unlikely((s->open_flags & O_DIRECT) &&
(offset % 512 || count % 512 || (uintptr_t) buf % 512))) {
int ret;
// Temporarily disable O_DIRECT for unaligned access
fcntl(s->fd, F_SETFL, s->open_flags & ~O_DIRECT);
ret = raw_pread_aligned(bs, offset, buf, count);
fcntl(s->fd, F_SETFL, s->open_flags);
return ret;
} else {
return raw_pread_aligned(bs, offset, buf, count);
}
}
/*
* offset and count are in bytes and possibly not aligned. For files opened
* with O_DIRECT, necessary alignments are ensured before calling
* raw_pwrite_aligned to do the actual write.
*/
static int raw_pwrite(BlockDriverState *bs, int64_t offset,
const uint8_t *buf, int count)
{
BDRVRawState *s = bs->opaque;
if (unlikely((s->open_flags & O_DIRECT) &&
(offset % 512 || count % 512 || (uintptr_t) buf % 512))) {
int ret;
// Temporarily disable O_DIRECT for unaligned access
fcntl(s->fd, F_SETFL, s->open_flags & ~O_DIRECT);
ret = raw_pwrite_aligned(bs, offset, buf, count);
fcntl(s->fd, F_SETFL, s->open_flags);
return ret;
} else {
return raw_pwrite_aligned(bs, offset, buf, count);
}
}
#else
#define raw_pread raw_pread_aligned
#define raw_pwrite raw_pwrite_aligned
#endif
/***********************************************************/
/* Unix AIO using POSIX AIO */
@ -402,10 +478,26 @@ static BlockDriverAIOCB *raw_aio_read(BlockDriverState *bs,
BlockDriverCompletionFunc *cb, void *opaque)
{
RawAIOCB *acb;
BDRVRawState *s = bs->opaque;
/*
* If O_DIRECT is used and the buffer is not aligned fall back
* to synchronous IO.
*/
if (unlikely((s->open_flags & O_DIRECT) && ((uintptr_t) buf % 512))) {
int ret;
acb = qemu_aio_get(bs, cb, opaque);
ret = raw_pread(bs, 512 * sector_num, buf, 512 * nb_sectors);
acb->common.cb(acb->common.opaque, ret);
qemu_aio_release(acb);
return &acb->common;
}
acb = raw_aio_setup(bs, sector_num, buf, nb_sectors, cb, opaque);
if (!acb)
return NULL;
if (aio_read(&acb->aiocb) < 0) {
qemu_aio_release(acb);
return NULL;
@ -418,6 +510,21 @@ static BlockDriverAIOCB *raw_aio_write(BlockDriverState *bs,
BlockDriverCompletionFunc *cb, void *opaque)
{
RawAIOCB *acb;
BDRVRawState *s = bs->opaque;
/*
* If O_DIRECT is used and the buffer is not aligned fall back
* to synchronous IO.
*/
if (unlikely((s->open_flags & O_DIRECT) && ((uintptr_t) buf % 512))) {
int ret;
acb = qemu_aio_get(bs, cb, opaque);
ret = raw_pwrite(bs, 512 * sector_num, buf, 512 * nb_sectors);
acb->common.cb(acb->common.opaque, ret);
qemu_aio_release(acb);
return &acb->common;
}
acb = raw_aio_setup(bs, sector_num, (uint8_t*)buf, nb_sectors, cb, opaque);
if (!acb)
@ -679,7 +786,7 @@ static int hdev_open(BlockDriverState *bs, const char *filename, int flags)
s->type = FTYPE_CD;
} else if (strstart(filename, "/dev/fd", NULL)) {
s->type = FTYPE_FD;
s->fd_open_flags = open_flags;
s->open_flags = open_flags;
/* open will not fail even if no floppy is inserted */
open_flags |= O_NONBLOCK;
} else if (strstart(filename, "/dev/sg", NULL)) {
@ -734,7 +841,7 @@ static int fd_open(BlockDriverState *bs)
#endif
return -EIO;
}
s->fd = open(bs->filename, s->fd_open_flags);
s->fd = open(bs->filename, s->open_flags);
if (s->fd < 0) {
s->fd_error_time = qemu_get_clock(rt_clock);
s->fd_got_error = 1;
@ -831,7 +938,7 @@ static int raw_eject(BlockDriverState *bs, int eject_flag)
close(s->fd);
s->fd = -1;
}
fd = open(bs->filename, s->fd_open_flags | O_NONBLOCK);
fd = open(bs->filename, s->open_flags | O_NONBLOCK);
if (fd >= 0) {
if (ioctl(fd, FDEJECT, 0) < 0)
perror("FDEJECT");