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do_mremap() untangling, part 2

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Take the MREMAP_FIXED into a separate helper, simplify the living
hell out of conditions in both cases.

Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2009-11-24 07:28:07 -05:00
parent 54f5de7099
commit ecc1a89937
1 changed files with 71 additions and 47 deletions
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118
mm/mremap.c
View file

@ -313,6 +313,59 @@ Eagain:
return ERR_PTR(-EAGAIN);
}
static unsigned long mremap_to(unsigned long addr,
unsigned long old_len, unsigned long new_addr,
unsigned long new_len)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
unsigned long ret = -EINVAL;
unsigned long charged = 0;
if (new_addr & ~PAGE_MASK)
goto out;
if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
goto out;
/* Check if the location we're moving into overlaps the
* old location at all, and fail if it does.
*/
if ((new_addr <= addr) && (new_addr+new_len) > addr)
goto out;
if ((addr <= new_addr) && (addr+old_len) > new_addr)
goto out;
ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
if (ret)
goto out;
ret = do_munmap(mm, new_addr, new_len);
if (ret)
goto out;
if (old_len >= new_len) {
ret = do_munmap(mm, addr+new_len, old_len - new_len);
if (ret && old_len != new_len)
goto out;
old_len = new_len;
}
vma = vma_to_resize(addr, old_len, new_len, &charged);
if (IS_ERR(vma)) {
ret = PTR_ERR(vma);
goto out;
}
ret = move_vma(vma, addr, old_len, new_len, new_addr);
if (ret & ~PAGE_MASK)
vm_unacct_memory(charged);
out:
return ret;
}
/*
* Expand (or shrink) an existing mapping, potentially moving it at the
* same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
@ -346,32 +399,10 @@ unsigned long do_mremap(unsigned long addr,
if (!new_len)
goto out;
/* new_addr is only valid if MREMAP_FIXED is specified */
if (flags & MREMAP_FIXED) {
if (new_addr & ~PAGE_MASK)
goto out;
if (!(flags & MREMAP_MAYMOVE))
goto out;
if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
goto out;
/* Check if the location we're moving into overlaps the
* old location at all, and fail if it does.
*/
if ((new_addr <= addr) && (new_addr+new_len) > addr)
goto out;
if ((addr <= new_addr) && (addr+old_len) > new_addr)
goto out;
ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
if (ret)
goto out;
ret = do_munmap(mm, new_addr, new_len);
if (ret)
goto out;
if (flags & MREMAP_MAYMOVE)
ret = mremap_to(addr, old_len, new_addr, new_len);
goto out;
}
/*
@ -384,13 +415,11 @@ unsigned long do_mremap(unsigned long addr,
if (ret && old_len != new_len)
goto out;
ret = addr;
if (!(flags & MREMAP_FIXED) || (new_addr == addr))
goto out;
old_len = new_len;
goto out;
}
/*
* Ok, we need to grow.. or relocate.
* Ok, we need to grow..
*/
vma = vma_to_resize(addr, old_len, new_len, &charged);
if (IS_ERR(vma)) {
@ -399,11 +428,8 @@ unsigned long do_mremap(unsigned long addr,
}
/* old_len exactly to the end of the area..
* And we're not relocating the area.
*/
if (old_len == vma->vm_end - addr &&
!((flags & MREMAP_FIXED) && (addr != new_addr)) &&
(old_len != new_len || !(flags & MREMAP_MAYMOVE))) {
if (old_len == vma->vm_end - addr) {
unsigned long max_addr = TASK_SIZE;
if (vma->vm_next)
max_addr = vma->vm_next->vm_start;
@ -432,22 +458,20 @@ unsigned long do_mremap(unsigned long addr,
*/
ret = -ENOMEM;
if (flags & MREMAP_MAYMOVE) {
if (!(flags & MREMAP_FIXED)) {
unsigned long map_flags = 0;
if (vma->vm_flags & VM_MAYSHARE)
map_flags |= MAP_SHARED;
unsigned long map_flags = 0;
if (vma->vm_flags & VM_MAYSHARE)
map_flags |= MAP_SHARED;
new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
vma->vm_pgoff, map_flags);
if (new_addr & ~PAGE_MASK) {
ret = new_addr;
goto out;
}
ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
if (ret)
goto out;
new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
vma->vm_pgoff, map_flags);
if (new_addr & ~PAGE_MASK) {
ret = new_addr;
goto out;
}
ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
if (ret)
goto out;
ret = move_vma(vma, addr, old_len, new_len, new_addr);
}
out: