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file-posix: Switch to .bdrv_co_block_status()

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We are gradually moving away from sector-based interfaces, towards
byte-based.  Update the file protocol driver accordingly.

In want_zero mode, we continue to report fine-grained hole
information (the caller wants as much mapping detail as possible);
but when not in that mode, the caller prefers larger *pnum and
merely cares about what offsets are allocated at this layer, rather
than where the holes live.  Since holes still read as zeroes at
this layer (rather than deferring to a backing layer), we can take
the shortcut of skipping lseek(), and merely state that all bytes
are allocated.

We can also drop redundant bounds checks that are already
guaranteed by the block layer.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Eric Blake 2018-02-13 14:26:44 -06:00 committed by Kevin Wolf
parent 3e4d0e72b7
commit a290f08590
1 changed files with 29 additions and 33 deletions
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62
block/file-posix.c
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@ -2131,25 +2131,24 @@ static int find_allocation(BlockDriverState *bs, off_t start,
} }
/* /*
* Returns the allocation status of the specified sectors. * Returns the allocation status of the specified offset.
* *
* If 'sector_num' is beyond the end of the disk image the return value is 0 * The block layer guarantees 'offset' and 'bytes' are within bounds.
* and 'pnum' is set to 0.
* *
* 'pnum' is set to the number of sectors (including and immediately following * 'pnum' is set to the number of bytes (including and immediately following
* the specified sector) that are known to be in the same * the specified offset) that are known to be in the same
* allocated/unallocated state. * allocated/unallocated state.
* *
* 'nb_sectors' is the max value 'pnum' should be set to. If nb_sectors goes * 'bytes' is the max value 'pnum' should be set to.
* beyond the end of the disk image it will be clamped.
*/ */
static int64_t coroutine_fn raw_co_get_block_status(BlockDriverState *bs, static int coroutine_fn raw_co_block_status(BlockDriverState *bs,
int64_t sector_num, bool want_zero,
int nb_sectors, int *pnum, int64_t offset,
BlockDriverState **file) int64_t bytes, int64_t *pnum,
int64_t *map,
BlockDriverState **file)
{ {
off_t start, data = 0, hole = 0; off_t data = 0, hole = 0;
int64_t total_size;
int ret; int ret;
ret = fd_open(bs); ret = fd_open(bs);
@ -2157,39 +2156,36 @@ static int64_t coroutine_fn raw_co_get_block_status(BlockDriverState *bs,
return ret; return ret;
} }
start = sector_num * BDRV_SECTOR_SIZE; if (!want_zero) {
total_size = bdrv_getlength(bs); *pnum = bytes;
if (total_size < 0) { *map = offset;
return total_size; *file = bs;
} else if (start >= total_size) { return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID;
*pnum = 0;
return 0;
} else if (start + nb_sectors * BDRV_SECTOR_SIZE > total_size) {
nb_sectors = DIV_ROUND_UP(total_size - start, BDRV_SECTOR_SIZE);
} }
ret = find_allocation(bs, start, &data, &hole); ret = find_allocation(bs, offset, &data, &hole);
if (ret == -ENXIO) { if (ret == -ENXIO) {
/* Trailing hole */ /* Trailing hole */
*pnum = nb_sectors; *pnum = bytes;
ret = BDRV_BLOCK_ZERO; ret = BDRV_BLOCK_ZERO;
} else if (ret < 0) { } else if (ret < 0) {
/* No info available, so pretend there are no holes */ /* No info available, so pretend there are no holes */
*pnum = nb_sectors; *pnum = bytes;
ret = BDRV_BLOCK_DATA; ret = BDRV_BLOCK_DATA;
} else if (data == start) { } else if (data == offset) {
/* On a data extent, compute sectors to the end of the extent, /* On a data extent, compute bytes to the end of the extent,
* possibly including a partial sector at EOF. */ * possibly including a partial sector at EOF. */
*pnum = MIN(nb_sectors, DIV_ROUND_UP(hole - start, BDRV_SECTOR_SIZE)); *pnum = MIN(bytes, hole - offset);
ret = BDRV_BLOCK_DATA; ret = BDRV_BLOCK_DATA;
} else { } else {
/* On a hole, compute sectors to the beginning of the next extent. */ /* On a hole, compute bytes to the beginning of the next extent. */
assert(hole == start); assert(hole == offset);
*pnum = MIN(nb_sectors, (data - start) / BDRV_SECTOR_SIZE); *pnum = MIN(bytes, data - offset);
ret = BDRV_BLOCK_ZERO; ret = BDRV_BLOCK_ZERO;
} }
*map = offset;
*file = bs; *file = bs;
return ret | BDRV_BLOCK_OFFSET_VALID | start; return ret | BDRV_BLOCK_OFFSET_VALID;
} }
static coroutine_fn BlockAIOCB *raw_aio_pdiscard(BlockDriverState *bs, static coroutine_fn BlockAIOCB *raw_aio_pdiscard(BlockDriverState *bs,
@ -2282,7 +2278,7 @@ BlockDriver bdrv_file = {
.bdrv_close = raw_close, .bdrv_close = raw_close,
.bdrv_create = raw_create, .bdrv_create = raw_create,
.bdrv_has_zero_init = bdrv_has_zero_init_1, .bdrv_has_zero_init = bdrv_has_zero_init_1,
.bdrv_co_get_block_status = raw_co_get_block_status, .bdrv_co_block_status = raw_co_block_status,
.bdrv_co_pwrite_zeroes = raw_co_pwrite_zeroes, .bdrv_co_pwrite_zeroes = raw_co_pwrite_zeroes,
.bdrv_co_preadv = raw_co_preadv, .bdrv_co_preadv = raw_co_preadv,