diff options
| -rw-r--r-- | qemu-img.c | 23 | ||||
| -rw-r--r-- | tests/qemu-iotests/122.out | 8 |
2 files changed, 21 insertions, 10 deletions
@@ -1171,19 +1171,34 @@ static int is_allocated_sectors(const uint8_t *buf, int n, int *pnum, } } + if (i == n) { + /* + * The whole buf is the same. + * No reason to split it into chunks, so return now. + */ + *pnum = i; + return !is_zero; + } + tail = (sector_num + i) & (alignment - 1); if (tail) { if (is_zero && i <= tail) { - /* treat unallocated areas which only consist - * of a small tail as allocated. */ + /* + * For sure next sector after i is data, and it will rewrite this + * tail anyway due to RMW. So, let's just write data now. + */ is_zero = false; } if (!is_zero) { - /* align up end offset of allocated areas. */ + /* If possible, align up end offset of allocated areas. */ i += alignment - tail; i = MIN(i, n); } else { - /* align down end offset of zero areas. */ + /* + * For sure next sector after i is data, and it will rewrite this + * tail anyway due to RMW. Better is avoid RMW and write zeroes up + * to aligned bound. + */ i -= tail; } } diff --git a/tests/qemu-iotests/122.out b/tests/qemu-iotests/122.out index 69b8e8b..e18766e 100644 --- a/tests/qemu-iotests/122.out +++ b/tests/qemu-iotests/122.out @@ -201,9 +201,7 @@ convert -S 4k { "start": 8192, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}, { "start": 12288, "length": 4096, "depth": 0, "present": false, "zero": true, "data": false}, { "start": 16384, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}, -{ "start": 20480, "length": 46080, "depth": 0, "present": false, "zero": true, "data": false}, -{ "start": 66560, "length": 1024, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}, -{ "start": 67584, "length": 67041280, "depth": 0, "present": false, "zero": true, "data": false}] +{ "start": 20480, "length": 67088384, "depth": 0, "present": false, "zero": true, "data": false}] convert -c -S 4k [{ "start": 0, "length": 1024, "depth": 0, "present": true, "zero": false, "data": true}, @@ -215,9 +213,7 @@ convert -c -S 4k convert -S 8k [{ "start": 0, "length": 24576, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}, -{ "start": 24576, "length": 41984, "depth": 0, "present": false, "zero": true, "data": false}, -{ "start": 66560, "length": 1024, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}, -{ "start": 67584, "length": 67041280, "depth": 0, "present": false, "zero": true, "data": false}] +{ "start": 24576, "length": 67084288, "depth": 0, "present": false, "zero": true, "data": false}] convert -c -S 8k [{ "start": 0, "length": 1024, "depth": 0, "present": true, "zero": false, "data": true}, |