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fs/mmap: Suppor the partial unmap for anonymous mapping

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Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
This commit is contained in:
Xiang Xiao 2023-01-11 01:09:04 +08:00 committed by Petro Karashchenko
parent fcd4a421e3
commit fd0195b0d8
1 changed files with 48 additions and 11 deletions
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59
fs/mmap/fs_anonmap.c
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@ -39,32 +39,69 @@ static int unmap_anonymous(FAR struct task_group_s *group,
FAR void *start,
size_t length)
{
int ret;
FAR void *newaddr;
off_t offset;
bool kernel = entry->priv.i;
int ret = OK;
/* De-allocate memory.
* NB: This is incomplete anounymous mapping implementation
* see file_mmap_ below
/* Get the offset from the beginning of the region and the actual number
* of bytes to "unmap". All mappings must extend to the end of the region.
* There is no support for freeing a block of memory but leaving a block of
* memory at the end. This is a consequence of using kumm_realloc() to
* simulate the unmapping.
*/
if (start == entry->vaddr && length == entry->length)
offset = start - entry->vaddr;
if (offset + length < entry->length)
{
/* entry->priv marks allocation from kernel heap */
ferr("ERROR: Cannot umap without unmapping to the end\n");
return -ENOSYS;
}
if (entry->priv.i)
/* Okay.. the region is being unmapped to the end. Make sure the length
* indicates that.
*/
length = entry->length - offset;
/* Are we unmapping the entire region (offset == 0)? */
if (length >= entry->length)
{
/* Free the region */
if (kernel)
{
kmm_free(start);
kmm_free(entry->vaddr);
}
else
{
kumm_free(start);
kumm_free(entry->vaddr);
}
/* Then remove the mapping from the list */
ret = mm_map_remove(get_group_mm(group), entry);
}
/* No.. We have been asked to "unmap' only a portion of the memory
* (offset > 0).
*/
else
{
ret = -EINVAL;
ferr("ERROR: Unknown map type\n");
if (kernel)
{
newaddr = kmm_realloc(entry->vaddr, length);
}
else
{
newaddr = kumm_realloc(entry->vaddr, length);
}
DEBUGASSERT(newaddr == entry->vaddr);
entry->vaddr = newaddr;
entry->length = length;
}
return ret;