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authorOleg Nesterov <oleg@redhat.com>2013-09-11 14:20:20 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-09-11 15:57:07 -0700
commite86867720e617774b560dfbc169b7f3d0d490950 (patch)
treeb28f617ed448da3906131b9a67def196e0ce76c4 /mm/mmap.c
parent077bf22b5cf233863826afbfa4af9b18650a832d (diff)
downloadlinux-e86867720e617774b560dfbc169b7f3d0d490950.tar.gz
mm: mmap_region: kill correct_wcount/inode, use allow_write_access()
correct_wcount and inode in mmap_region() just complicate the code. This boolean was needed previously, when deny_write_access() was called before vma_merge(), now we can simply check VM_DENYWRITE and do allow_write_access() if it is set. allow_write_access() checks file != NULL, so this is safe even if it was possible to use VM_DENYWRITE && !file. Just we need to ensure we use the same file which was deny_write_access()'ed, so the patch also moves "file = vma->vm_file" down after allow_write_access(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Colin Cross <ccross@android.com> Cc: David Rientjes <rientjes@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/mmap.c')
-rw-r--r--mm/mmap.c14
1 files changed, 5 insertions, 9 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index 1e7a3ea23f1..13926a5a690 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1479,11 +1479,9 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma, *prev;
- int correct_wcount = 0;
int error;
struct rb_node **rb_link, *rb_parent;
unsigned long charged = 0;
- struct inode *inode = file ? file_inode(file) : NULL;
/* Check against address space limit. */
if (!may_expand_vm(mm, len >> PAGE_SHIFT)) {
@@ -1552,7 +1550,6 @@ munmap_back:
error = deny_write_access(file);
if (error)
goto free_vma;
- correct_wcount = 1;
}
vma->vm_file = get_file(file);
error = file->f_op->mmap(file, vma);
@@ -1593,11 +1590,10 @@ munmap_back:
}
vma_link(mm, vma, prev, rb_link, rb_parent);
- file = vma->vm_file;
-
/* Once vma denies write, undo our temporary denial count */
- if (correct_wcount)
- atomic_inc(&inode->i_writecount);
+ if (vm_flags & VM_DENYWRITE)
+ allow_write_access(file);
+ file = vma->vm_file;
out:
perf_event_mmap(vma);
@@ -1616,8 +1612,8 @@ out:
return addr;
unmap_and_free_vma:
- if (correct_wcount)
- atomic_inc(&inode->i_writecount);
+ if (vm_flags & VM_DENYWRITE)
+ allow_write_access(file);
vma->vm_file = NULL;
fput(file);