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Subject[PATCH 2/19] do_mremap() untangling, part 2
From

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

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
mm/mremap.c | 120 +++++++++++++++++++++++++++++++++++-----------------------
1 files changed, 72 insertions(+), 48 deletions(-)

diff --git a/mm/mremap.c b/mm/mremap.c
index 6776136..5f34617 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -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;
-
- 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;
+ 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;
ret = move_vma(vma, addr, old_len, new_len, new_addr);
}
out:
--
1.5.6.5



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