[PATCH] shmem: misc changes and cleanups

If PAGE_CACHE_SIZE were to differ from PAGE_SIZE, the VM_ACCT macro,
and shmem_nopage's vm_pgoff manipulation, were still not quite right.

Slip a cond_resched_lock into shmem_truncate's long loop; but not into
shmem_unuse_inode's, since other locks held, and swapoff awful anyway.

Move SetPageUptodate to where it's not already set.  Replace
copy_from_user by __copy_from_user since access already verified.

Replace BUG()s by BUG_ON()s.  Remove an uninteresting PAGE_BUG().

diff --git a/mm/shmem.c b/mm/shmem.c
index 329cb873c74132fa1b5799917d461147359ed0c6..908c03044c9f04bff86a1ab77324838b94fe518f 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -43,7 +43,7 @@
 #define SHMEM_MAX_INDEX  (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
 #define SHMEM_MAX_BYTES  ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT)
 
-#define VM_ACCT(size)    (((size) + PAGE_CACHE_SIZE - 1) >> PAGE_SHIFT)
+#define VM_ACCT(size)    (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
 
 /* Pretend that each entry is of this size in directory's i_size */
 #define BOGO_DIRENT_SIZE 20
@@ -428,6 +428,7 @@ static void shmem_truncate(struct inode *inode)
                                info->alloced++;
                        }
                        empty = subdir;
+                       cond_resched_lock(&info->lock);
                        dir = shmem_dir_map(subdir);
                }
                subdir = *dir;
@@ -657,10 +658,8 @@ static int shmem_writepage(struct page * page)
        unsigned long index;
        struct inode *inode;
 
-       if (!PageLocked(page))
-               BUG();
-       if (page_mapped(page))
-               BUG();
+       BUG_ON(!PageLocked(page));
+       BUG_ON(page_mapped(page));
 
        mapping = page->mapping;
        index = page->index;
@@ -675,10 +674,8 @@ static int shmem_writepage(struct page * page)
        spin_lock(&info->lock);
        shmem_recalc_inode(inode);
        entry = shmem_swp_entry(info, index, NULL);
-       if (!entry)
-               BUG();
-       if (entry->val)
-               BUG();
+       BUG_ON(!entry);
+       BUG_ON(entry->val);
 
        if (move_to_swap_cache(page, swap) == 0) {
                shmem_swp_set(info, entry, swap.val);
@@ -852,10 +849,10 @@ repeat:
                info->alloced++;
                spin_unlock(&info->lock);
                clear_highpage(page);
+               SetPageUptodate(page);
        }
 
        /* We have the page */
-       SetPageUptodate(page);
        *pagep = page;
        return 0;
 }
@@ -896,8 +893,9 @@ struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int
        unsigned long idx;
        int error;
 
-       idx = (address - vma->vm_start) >> PAGE_CACHE_SHIFT;
+       idx = (address - vma->vm_start) >> PAGE_SHIFT;
        idx += vma->vm_pgoff;
+       idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT;
 
        if (((loff_t) idx << PAGE_CACHE_SHIFT) >= inode->i_size)
                return NOPAGE_SIGBUS;
@@ -1118,13 +1116,8 @@ shmem_file_write(struct file *file,const char *buf,size_t count,loff_t *ppos)
                if (status)
                        break;
 
-               /* We have exclusive IO access to the page.. */
-               if (!PageLocked(page)) {
-                       PAGE_BUG(page);
-               }
-
                kaddr = kmap(page);
-               status = copy_from_user(kaddr+offset, buf, bytes);
+               status = __copy_from_user(kaddr+offset, buf, bytes);
                kunmap(page);
                if (status)
                        goto fail_write;