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[device/bcache] add bcache_prefetch_bytes() and bcache_read_bytes()

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Not tested yet.
This commit is contained in:
Joe Thornber 2018-02-05 16:56:56 +00:00 committed by David Teigland
parent 467adfa082
commit 6a57ed17a2
2 changed files with 69 additions and 0 deletions
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59
lib/device/bcache.c
View File

@ -966,5 +966,64 @@ void bcache_invalidate_fd(struct bcache *cache, int fd)
_recycle_block(cache, b);
}
static void byte_range_to_block_range(struct bcache *cache, off_t start, size_t len,
block_address *bb, block_address *be)
{
block_address block_size = cache->block_sectors << SECTOR_SHIFT;
*bb = start / block_size;
*be = (start + len + block_size - 1) / block_size;
}
void bcache_prefetch_bytes(struct bcache *cache, int fd, off_t start, size_t len)
{
block_address bb, be;
byte_range_to_block_range(cache, start, len, &bb, &be);
while (bb < be) {
bcache_prefetch(cache, fd, bb);
bb++;
}
}
static off_t _min(off_t lhs, off_t rhs)
{
if (rhs > lhs)
return rhs;
return lhs;
}
bool bcache_read_bytes(struct bcache *cache, int fd, off_t start, size_t len, void *data)
{
struct block *b;
block_address bb, be, i;
unsigned char *udata = data;
off_t block_size = cache->block_sectors << SECTOR_SHIFT;
byte_range_to_block_range(cache, start, len, &bb, &be);
for (i = bb; i < be; i++)
bcache_prefetch(cache, fd, i);
for (i = bb; i < be; i++) {
if (!bcache_get(cache, fd, i, 0, &b))
return false;
if (i == bb) {
off_t block_offset = start % block_size;
size_t blen = _min(block_size - block_offset, len);
memcpy(udata, ((unsigned char *) b->data) + block_offset, blen);
len -= blen;
udata += blen;
} else {
size_t blen = _min(block_size, len);
memcpy(udata, b->data, blen);
len -= blen;
udata += blen;
}
}
return true;
}
//----------------------------------------------------------------

10
lib/device/bcache.h
View File

@ -137,6 +137,16 @@ void bcache_invalidate(struct bcache *cache, int fd, block_address index);
*/
void bcache_invalidate_fd(struct bcache *cache, int fd);
/*
* Prefetches the blocks neccessary to satisfy a byte range.
*/
void bcache_prefetch_bytes(struct bcache *cache, int fd, off_t start, size_t len);
/*
* Reads the bytes.
*/
bool bcache_read_bytes(struct bcache *cache, int fd, off_t start, size_t len, void *data);
/*----------------------------------------------------------------*/
#endif