[PATCH] rmap 35 mmap.c cleanups

From: Hugh Dickins
Date: Tue May 18 2004 - 17:10:19 EST

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Before some real vma_merge work in mmap.c in the next patch,
a patch of miscellaneous cleanups to cut down the noise:

- remove rb_parent arg from vma_merge: mm->mmap can do that case
- scatter pgoff_t around to ingratiate myself with the boss
- reorder is_mergeable_vma tests, vm_ops->close is least likely
- can_vma_merge_before take combined pgoff+pglen arg (from Andrea)
- rearrange do_mmap_pgoff's ever-confusing anonymous flags switch
- comment do_mmap_pgoff's mysterious (vm_flags & VM_SHARED) test
- fix ISO C90 warning on browse_rb if building with DEBUG_MM_RB
- stop that long MNT_NOEXEC line wrapping

Yes, buried in amidst these is indeed one pgoff replaced by
"next->vm_pgoff - pglen" (reverting a mod of mine which took pgoff
supplied by user too seriously in the anon case), and another pgoff
replaced by 0 (reverting anon_vma mod which crept in with NUMA API):
neither of them really matters, except perhaps in /proc/pid/maps.

include/linux/mm.h | 2 -
mm/mmap.c | 90 +++++++++++++++++++++++++++--------------------------
2 files changed, 47 insertions(+), 45 deletions(-)

--- rmap34/include/linux/mm.h 2004-05-16 11:39:23.000000000 +0100
+++ rmap35/include/linux/mm.h 2004-05-18 20:50:45.788661560 +0100
@@ -612,7 +612,7 @@ extern void insert_vm_struct(struct mm_s
extern void __vma_link_rb(struct mm_struct *, struct vm_area_struct *,
struct rb_node **, struct rb_node *);
extern struct vm_area_struct *copy_vma(struct vm_area_struct **,
- unsigned long addr, unsigned long len, unsigned long pgoff);
+ unsigned long addr, unsigned long len, pgoff_t pgoff);
extern void exit_mmap(struct mm_struct *);

extern unsigned long get_unmapped_area(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
--- rmap34/mm/mmap.c 2004-05-16 11:39:25.000000000 +0100
+++ rmap35/mm/mmap.c 2004-05-18 20:50:45.816657304 +0100
@@ -153,10 +153,10 @@ out:
}

#ifdef DEBUG_MM_RB
-static int browse_rb(struct rb_root *root) {
- int i, j;
+static int browse_rb(struct rb_root *root)
+{
+ int i = 0, j;
struct rb_node *nd, *pn = NULL;
- i = 0;
unsigned long prev = 0, pend = 0;

for (nd = rb_first(root); nd; nd = rb_next(nd)) {
@@ -180,10 +180,11 @@ static int browse_rb(struct rb_root *roo
return i;
}

-void validate_mm(struct mm_struct * mm) {
+void validate_mm(struct mm_struct *mm)
+{
int bug = 0;
int i = 0;
- struct vm_area_struct * tmp = mm->mmap;
+ struct vm_area_struct *tmp = mm->mmap;
while (tmp) {
tmp = tmp->vm_next;
i++;
@@ -406,17 +407,17 @@ void vma_adjust(struct vm_area_struct *v
static inline int is_mergeable_vma(struct vm_area_struct *vma,
struct file *file, unsigned long vm_flags)
{
- if (vma->vm_ops && vma->vm_ops->close)
+ if (vma->vm_flags != vm_flags)
return 0;
if (vma->vm_file != file)
return 0;
- if (vma->vm_flags != vm_flags)
+ if (vma->vm_ops && vma->vm_ops->close)
return 0;
return 1;
}

/*
- * Return true if we can merge this (vm_flags,file,vm_pgoff,size)
+ * Return true if we can merge this (vm_flags,file,vm_pgoff)
* in front of (at a lower virtual address and file offset than) the vma.
*
* We don't check here for the merged mmap wrapping around the end of pagecache
@@ -425,12 +426,12 @@ static inline int is_mergeable_vma(struc
*/
static int
can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
- struct file *file, unsigned long vm_pgoff, unsigned long size)
+ struct file *file, pgoff_t vm_pgoff)
{
if (is_mergeable_vma(vma, file, vm_flags)) {
if (!file)
return 1; /* anon mapping */
- if (vma->vm_pgoff == vm_pgoff + size)
+ if (vma->vm_pgoff == vm_pgoff)
return 1;
}
return 0;
@@ -442,16 +443,16 @@ can_vma_merge_before(struct vm_area_stru
*/
static int
can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
- struct file *file, unsigned long vm_pgoff)
+ struct file *file, pgoff_t vm_pgoff)
{
if (is_mergeable_vma(vma, file, vm_flags)) {
- unsigned long vma_size;
+ pgoff_t vm_pglen;

if (!file)
return 1; /* anon mapping */

- vma_size = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
- if (vma->vm_pgoff + vma_size == vm_pgoff)
+ vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
+ if (vma->vm_pgoff + vm_pglen == vm_pgoff)
return 1;
}
return 0;
@@ -463,12 +464,12 @@ can_vma_merge_after(struct vm_area_struc
* both (it neatly fills a hole).
*/
static struct vm_area_struct *vma_merge(struct mm_struct *mm,
- struct vm_area_struct *prev,
- struct rb_node *rb_parent, unsigned long addr,
+ struct vm_area_struct *prev, unsigned long addr,
unsigned long end, unsigned long vm_flags,
- struct file *file, unsigned long pgoff,
+ struct file *file, pgoff_t pgoff,
struct mempolicy *policy)
{
+ pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
struct vm_area_struct *next;

/*
@@ -479,7 +480,7 @@ static struct vm_area_struct *vma_merge(
return NULL;

if (!prev) {
- next = rb_entry(rb_parent, struct vm_area_struct, vm_rb);
+ next = mm->mmap;
goto merge_next;
}
next = prev->vm_next;
@@ -496,7 +497,7 @@ static struct vm_area_struct *vma_merge(
if (next && end == next->vm_start &&
mpol_equal(policy, vma_policy(next)) &&
can_vma_merge_before(next, vm_flags, file,
- pgoff, (end - addr) >> PAGE_SHIFT)) {
+ pgoff+pglen)) {
vma_adjust(prev, prev->vm_start,
next->vm_end, prev->vm_pgoff, next);
if (file)
@@ -510,17 +511,18 @@ static struct vm_area_struct *vma_merge(
return prev;
}

+merge_next:
+
/*
* Can this new request be merged in front of next?
*/
if (next) {
- merge_next:
if (end == next->vm_start &&
mpol_equal(policy, vma_policy(next)) &&
can_vma_merge_before(next, vm_flags, file,
- pgoff, (end - addr) >> PAGE_SHIFT)) {
- vma_adjust(next, addr,
- next->vm_end, pgoff, NULL);
+ pgoff+pglen)) {
+ vma_adjust(next, addr, next->vm_end,
+ next->vm_pgoff - pglen, NULL);
return next;
}
}
@@ -553,7 +555,8 @@ unsigned long do_mmap_pgoff(struct file
if (!file->f_op || !file->f_op->mmap)
return -ENODEV;

- if ((prot & PROT_EXEC) && (file->f_vfsmnt->mnt_flags & MNT_NOEXEC))
+ if ((prot & PROT_EXEC) &&
+ (file->f_vfsmnt->mnt_flags & MNT_NOEXEC))
return -EPERM;
}

@@ -635,15 +638,14 @@ unsigned long do_mmap_pgoff(struct file
return -EINVAL;
}
} else {
- vm_flags |= VM_SHARED | VM_MAYSHARE;
switch (flags & MAP_TYPE) {
- default:
- return -EINVAL;
- case MAP_PRIVATE:
- vm_flags &= ~(VM_SHARED | VM_MAYSHARE);
- /* fall through */
case MAP_SHARED:
+ vm_flags |= VM_SHARED | VM_MAYSHARE;
+ break;
+ case MAP_PRIVATE:
break;
+ default:
+ return -EINVAL;
}
}

@@ -682,11 +684,14 @@ munmap_back:
}
}

- /* Can we just expand an old anonymous mapping? */
- if (!file && !(vm_flags & VM_SHARED) && rb_parent)
- if (vma_merge(mm, prev, rb_parent, addr, addr + len,
- vm_flags, NULL, pgoff, NULL))
- goto out;
+ /*
+ * Can we just expand an old private anonymous mapping?
+ * The VM_SHARED test is necessary because shmem_zero_setup
+ * will create the file object for a shared anonymous map below.
+ */
+ if (!file && !(vm_flags & VM_SHARED) &&
+ vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, 0, NULL))
+ goto out;

/*
* Determine the object being mapped and call the appropriate
@@ -743,10 +748,8 @@ munmap_back:
*/
addr = vma->vm_start;

- if (!file || !rb_parent || !vma_merge(mm, prev, rb_parent, addr,
- vma->vm_end,
- vma->vm_flags, file, pgoff,
- vma_policy(vma))) {
+ if (!file || !vma_merge(mm, prev, addr, vma->vm_end,
+ vma->vm_flags, file, pgoff, vma_policy(vma))) {
vma_link(mm, vma, prev, rb_link, rb_parent);
if (correct_wcount)
atomic_inc(&inode->i_writecount);
@@ -1429,9 +1432,8 @@ unsigned long do_brk(unsigned long addr,

flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;

- /* Can we just expand an old anonymous mapping? */
- if (rb_parent && vma_merge(mm, prev, rb_parent, addr, addr + len,
- flags, NULL, 0, NULL))
+ /* Can we just expand an old private anonymous mapping? */
+ if (vma_merge(mm, prev, addr, addr + len, flags, NULL, 0, NULL))
goto out;

/*
@@ -1524,7 +1526,7 @@ void insert_vm_struct(struct mm_struct *
* prior to moving page table entries, to effect an mremap move.
*/
struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
- unsigned long addr, unsigned long len, unsigned long pgoff)
+ unsigned long addr, unsigned long len, pgoff_t pgoff)
{
struct vm_area_struct *vma = *vmap;
unsigned long vma_start = vma->vm_start;
@@ -1534,7 +1536,7 @@ struct vm_area_struct *copy_vma(struct v
struct mempolicy *pol;

find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
- new_vma = vma_merge(mm, prev, rb_parent, addr, addr + len,
+ new_vma = vma_merge(mm, prev, addr, addr + len,
vma->vm_flags, vma->vm_file, pgoff, vma_policy(vma));
if (new_vma) {
/*

-
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Next message: Hugh Dickins: "[PATCH] rmap 38 remove anonmm rmap"
Previous message: Hugh Dickins: "[PATCH] rmap 37 page_add_anon_rmap vma"
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Next in thread: Hugh Dickins: "[PATCH] rmap 38 remove anonmm rmap"
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