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kernel/file_cache: Properly size I/O request vectors when writing zeros.

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Should fix #16039.

Change-Id: Ifc5c79354979aaa7b27b09acc6d6450e21146e76
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2727
Reviewed-by: waddlesplash <waddlesplash@gmail.com>
This commit is contained in:
Augustin Cavalier 2020-05-17 13:22:29 -04:00 committed by waddlesplash
parent a742970be5
commit 8ba0b5eb9b
1 changed files with 21 additions and 7 deletions
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28
src/system/kernel/cache/file_cache.cpp vendored
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@ -109,7 +109,7 @@ static struct cache_module_info* sCacheModule;
static const uint32 kZeroVecCount = 32;
static const size_t kZeroVecSize = kZeroVecCount * B_PAGE_SIZE;
static phys_addr_t sZeroPage; // physical address
static phys_addr_t sZeroPage;
static generic_io_vec sZeroVecs[kZeroVecCount];
@ -1327,17 +1327,31 @@ file_cache_write(void* _cacheRef, void* cookie, off_t offset,
// NULL buffer -- use a dummy buffer to write zeroes
size_t size = *_size;
while (size > 0) {
size_t toWrite = min_c(size, kZeroVecSize);
generic_size_t written = toWrite;
generic_size_t length = min_c(size, kZeroVecSize);
generic_io_vec* vecs = sZeroVecs;
generic_io_vec vec;
size_t count = kZeroVecCount;
if ((length % B_PAGE_SIZE) != 0) {
if (length > B_PAGE_SIZE) {
length = ROUNDDOWN(length, B_PAGE_SIZE);
count = length / B_PAGE_SIZE;
} else {
vec.base = sZeroPage;
vec.length = length;
vecs = &vec;
count = 1;
}
}
status_t error = vfs_write_pages(ref->vnode, cookie, offset,
sZeroVecs, kZeroVecCount, B_PHYSICAL_IO_REQUEST, &written);
vecs, count, B_PHYSICAL_IO_REQUEST, &length);
if (error != B_OK)
return error;
if (written == 0)
if (length == 0)
break;
offset += written;
size -= written;
offset += length;
size -= length;
}
*_size -= size;