[PATCH] NOMMU: Make SYSV IPC SHM use ramfs facilities on NOMMU

[safe/jmp/linux-2.6] / mm / shmem.c

diff --git a/mm/shmem.c b/mm/shmem.c
index 6796311..a1f2f02 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -71,9 +71,6 @@
 /* Pretend that each entry is of this size in directory's i_size */
 #define BOGO_DIRENT_SIZE 20
 
-/* Keep swapped page count in private field of indirect struct page */
-#define nr_swapped             private
-
 /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
 enum sgp_type {
        SGP_QUICK,      /* don't try more than file page cache lookup */
@@ -324,8 +321,10 @@ static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, uns
 
        entry->val = value;
        info->swapped += incdec;
-       if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT)
-               kmap_atomic_to_page(entry)->nr_swapped += incdec;
+       if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
+               struct page *page = kmap_atomic_to_page(entry);
+               set_page_private(page, page_private(page) + incdec);
+       }
 }
 
 /*
@@ -368,9 +367,8 @@ static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long
 
                spin_unlock(&info->lock);
                page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO);
-               if (page) {
-                       page->nr_swapped = 0;
-               }
+               if (page)
+                       set_page_private(page, 0);
                spin_lock(&info->lock);
 
                if (!page) {
@@ -459,7 +457,7 @@ static void shmem_free_pages(struct list_head *next)
        } while (next);
 }
 
-static void shmem_truncate(struct inode *inode)
+static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
 {
        struct shmem_inode_info *info = SHMEM_I(inode);
        unsigned long idx;
@@ -477,18 +475,27 @@ static void shmem_truncate(struct inode *inode)
        long nr_swaps_freed = 0;
        int offset;
        int freed;
+       int punch_hole = 0;
 
        inode->i_ctime = inode->i_mtime = CURRENT_TIME;
-       idx = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+       idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
        if (idx >= info->next_index)
                return;
 
        spin_lock(&info->lock);
        info->flags |= SHMEM_TRUNCATE;
-       limit = info->next_index;
-       info->next_index = idx;
+       if (likely(end == (loff_t) -1)) {
+               limit = info->next_index;
+               info->next_index = idx;
+       } else {
+               limit = (end + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+               if (limit > info->next_index)
+                       limit = info->next_index;
+               punch_hole = 1;
+       }
+
        topdir = info->i_indirect;
-       if (topdir && idx <= SHMEM_NR_DIRECT) {
+       if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
                info->i_indirect = NULL;
                nr_pages_to_free++;
                list_add(&topdir->lru, &pages_to_free);
@@ -561,7 +568,7 @@ static void shmem_truncate(struct inode *inode)
                        diroff = 0;
                }
                subdir = dir[diroff];
-               if (subdir && subdir->nr_swapped) {
+               if (subdir && page_private(subdir)) {
                        size = limit - idx;
                        if (size > ENTRIES_PER_PAGE)
                                size = ENTRIES_PER_PAGE;
@@ -572,14 +579,15 @@ static void shmem_truncate(struct inode *inode)
                        nr_swaps_freed += freed;
                        if (offset)
                                spin_lock(&info->lock);
-                       subdir->nr_swapped -= freed;
+                       set_page_private(subdir, page_private(subdir) - freed);
                        if (offset)
                                spin_unlock(&info->lock);
-                       BUG_ON(subdir->nr_swapped > offset);
+                       if (!punch_hole)
+                               BUG_ON(page_private(subdir) > offset);
                }
                if (offset)
                        offset = 0;
-               else if (subdir) {
+               else if (subdir && !page_private(subdir)) {
                        dir[diroff] = NULL;
                        nr_pages_to_free++;
                        list_add(&subdir->lru, &pages_to_free);
@@ -596,7 +604,7 @@ done2:
                 * Also, though shmem_getpage checks i_size before adding to
                 * cache, no recheck after: so fix the narrow window there too.
                 */
-               truncate_inode_pages(inode->i_mapping, inode->i_size);
+               truncate_inode_pages_range(inode->i_mapping, start, end);
        }
 
        spin_lock(&info->lock);
@@ -616,6 +624,11 @@ done2:
        }
 }
 
+static void shmem_truncate(struct inode *inode)
+{
+       shmem_truncate_range(inode, inode->i_size, (loff_t)-1);
+}
+
 static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
 {
        struct inode *inode = dentry->d_inode;
@@ -743,7 +756,7 @@ static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, s
                        dir = shmem_dir_map(subdir);
                }
                subdir = *dir;
-               if (subdir && subdir->nr_swapped) {
+               if (subdir && page_private(subdir)) {
                        ptr = shmem_swp_map(subdir);
                        size = limit - idx;
                        if (size > ENTRIES_PER_PAGE)
@@ -857,7 +870,7 @@ unlock:
        swap_free(swap);
 redirty:
        set_page_dirty(page);
-       return WRITEPAGE_ACTIVATE;      /* Return with the page locked */
+       return AOP_WRITEPAGE_ACTIVATE;  /* Return with the page locked */
 }
 
 #ifdef CONFIG_NUMA
@@ -1257,7 +1270,7 @@ out_nomem:
        return retval;
 }
 
-static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
+int shmem_mmap(struct file *file, struct vm_area_struct *vma)
 {
        file_accessed(file);
        vma->vm_ops = &shmem_vm_ops;
@@ -1506,8 +1519,10 @@ static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_
                         */
                        if (!offset)
                                mark_page_accessed(page);
-               } else
+               } else {
                        page = ZERO_PAGE(0);
+                       page_cache_get(page);
+               }
 
                /*
                 * Ok, we have the page, and it's up-to-date, so
@@ -2083,6 +2098,7 @@ static struct file_operations shmem_file_operations = {
 static struct inode_operations shmem_inode_operations = {
        .truncate       = shmem_truncate,
        .setattr        = shmem_notify_change,
+       .truncate_range = shmem_truncate_range,
 };
 
 static struct inode_operations shmem_dir_inode_operations = {