/* added: begin address space operations definitions */
static int wrapfs_writepage(struct page *page, struct writeback_control *wbc){
int err = -EIO;
struct inode *inode;
struct inode *lower_inode;
struct page *lower_page;
struct address_space *lower_mapping; /* lower inode mapping */
gfp_t mask;
BUG_ON(!PageUptodate(page));
inode = page->mapping->host;
if (!inode || !WRAPFS_I(inode)){
err = 0;
goto out;
}
lower_inode = wrapfs_lower_inode(inode);
lower_mapping = lower_inode->i_mapping;
mask = mapping_gfp_mask(lower_mapping) & ~(__GFP_FS);
lower_page = find_or_create_page(lower_mapping, page->index, mask);
if (!lower_page) {
err = 0;
set_page_dirty(page);
goto out;
}
copy_highpage(lower_page, page);
flush_dcache_page(lower_page);
SetPageUptodate(lower_page);
set_page_dirty(lower_page);
if (wbc->for_reclaim) {
unlock_page(lower_page);
goto out_release;
}
BUG_ON(!lower_mapping->a_ops->writepage);
wait_on_page_writeback(lower_page); /* prevent multiple writers */
clear_page_dirty_for_io(lower_page); /* emulate VFS behavior */
err = lower_mapping->a_ops->writepage(lower_page, wbc);
if (err < 0)
goto out_release;
if (err == AOP_WRITEPAGE_ACTIVATE) {
err = 0;
unlock_page(lower_page);
}
fsstack_copy_attr_times(inode, lower_inode);
out_release:
page_cache_release(lower_page);
out:
unlock_page(page);
return err;
}
static int wrapfs_open(struct inode *inode, struct file *file)
{
int err = 0;
struct dentry *dentry = file->f_path.dentry;
struct dentry *parent = NULL;
int size;
/* don't open unhashed/deleted files */
if (d_unhashed(dentry)) {
err = -ENOENT;
goto out_err;
}
file->private_data =
kzalloc(sizeof(struct wrapfs_file_info), GFP_KERNEL);
if (!WRAPFS_F(file)) {
err = -ENOMEM;
goto out_err;
}
atomic_set(&WRAPFS_F(file)->generation,
atomic_read(&WRAPFS_I(inode)->generation));
size = sizeof(struct file *) * 2;
WRAPFS_F(file)->lower_files = kzalloc(size, GFP_KERNEL);
if (unlikely(!WRAPFS_F(file)->lower_files)) {
err = -ENOMEM;
goto out_err;
}
parent = dget_parent(dentry);
if (S_ISDIR(inode->i_mode))
err = __open_dir(inode, file, parent);
else
err = __open_file(inode, file, parent);
/* if(!err)
fsstack_copy_attr_all(inode, wrapfs_lower_inode(inode));
*/
out_err:
dput(parent);
return err;
}
static int wrapfs_writepage(struct page *page, struct writeback_control *wbc)
{
int err = -EIO;
struct inode *inode;
struct inode *lower_inode;
struct page *lower_page;
struct address_space *lower_mapping; /* lower inode mapping */
gfp_t mask;
/*printk(KERN_ALERT "in writepage() \n");*/
BUG_ON(!PageUptodate(page));
inode = page->mapping->host;
/* if no lower inode, nothing to do */
if (!inode || !WRAPFS_I(inode) || WRAPFS_I(inode)->lower_inode) {
err = 0;
goto out;
}
lower_inode = wrapfs_lower_inode(inode);
lower_mapping = lower_inode->i_mapping;
/*
* find lower page (returns a locked page)
*
* We turn off __GFP_FS while we look for or create a new lower
* page. This prevents a recursion into the file system code, which
* under memory pressure conditions could lead to a deadlock. This
* is similar to how the loop driver behaves (see loop_set_fd in
* drivers/block/loop.c). If we can't find the lower page, we
* redirty our page and return "success" so that the VM will call us
* again in the (hopefully near) future.
*/
mask = mapping_gfp_mask(lower_mapping) & ~(__GFP_FS);
lower_page = find_or_create_page(lower_mapping, page->index, mask);
if (!lower_page) {
err = 0;
set_page_dirty(page);
goto out;
}
/* copy page data from our upper page to the lower page */
copy_highpage(lower_page, page);
flush_dcache_page(lower_page);
SetPageUptodate(lower_page);
set_page_dirty(lower_page);
/*
* Call lower writepage (expects locked page). However, if we are
* called with wbc->for_reclaim, then the VFS/VM just wants to
* reclaim our page. Therefore, we don't need to call the lower
* ->writepage: just copy our data to the lower page (already done
* above), then mark the lower page dirty and unlock it, and return
* success.
*/
if (wbc->for_reclaim) {
unlock_page(lower_page);
goto out_release;
}
BUG_ON(!lower_mapping->a_ops->writepage);
wait_on_page_writeback(lower_page); /* prevent multiple writers */
clear_page_dirty_for_io(lower_page); /* emulate VFS behavior */
err = lower_mapping->a_ops->writepage(lower_page, wbc);
if (err < 0)
goto out_release;
/*
* Lower file systems such as ramfs and tmpfs, may return
* AOP_WRITEPAGE_ACTIVATE so that the VM won't try to (pointlessly)
* write the page again for a while. But those lower file systems
* also set the page dirty bit back again. Since we successfully
* copied our page data to the lower page, then the VM will come
* back to the lower page (directly) and try to flush it. So we can
* save the VM the hassle of coming back to our page and trying to
* flush too. Therefore, we don't re-dirty our own page, and we
* never return AOP_WRITEPAGE_ACTIVATE back to the VM (we consider
* this a success).
*
* We also unlock the lower page if the lower ->writepage returned
* AOP_WRITEPAGE_ACTIVATE. (This "anomalous" behaviour may be
* addressed in future shmem/VM code.)
*/
if (err == AOP_WRITEPAGE_ACTIVATE) {
err = 0;
unlock_page(lower_page);
}
/* all is well */
/* lower mtimes have changed: update ours */
/* fsstack_copy_inode_size(dentry->d_inode,
lower_file->f_path.dentry->d_inode);
fsstack_copy_attr_times(dentry->d_inode,
lower_file->f_path.dentry->d_inode);
*/
out_release:
/* b/c find_or_create_page increased refcnt */
page_cache_release(lower_page);
out:
/*
* We unlock our page unconditionally, because we never return
* AOP_WRITEPAGE_ACTIVATE.
*/
unlock_page(page);
return err;
}
struct inode *wrapfs_iget(struct super_block *sb, struct inode *lower_inode)
{
struct wrapfs_inode_info *info;
struct inode *inode; /* the new inode to return */
int err;
inode = iget5_locked(sb, /* our superblock */
/*
* hashval: we use inode number, but we can
* also use "(unsigned long)lower_inode"
* instead.
*/
lower_inode->i_ino, /* hashval */
wrapfs_inode_test, /* inode comparison function */
wrapfs_inode_set, /* inode init function */
lower_inode); /* data passed to test+set fxns */
if (!inode) {
err = -EACCES;
iput(lower_inode);
return ERR_PTR(err);
}
/* if found a cached inode, then just return it */
if (!(inode->i_state & I_NEW))
return inode;
/* initialize new inode */
info = WRAPFS_I(inode);
inode->i_ino = lower_inode->i_ino;
if (!igrab(lower_inode)) {
err = -ESTALE;
return ERR_PTR(err);
}
wrapfs_set_lower_inode(inode, lower_inode);
inode->i_version++;
/* use different set of inode ops for symlinks & directories */
if (S_ISDIR(lower_inode->i_mode))
inode->i_op = &wrapfs_dir_iops;
else if (S_ISLNK(lower_inode->i_mode))
inode->i_op = &wrapfs_symlink_iops;
else
inode->i_op = &wrapfs_main_iops;
/* use different set of file ops for directories */
if (S_ISDIR(lower_inode->i_mode))
inode->i_fop = &wrapfs_dir_fops;
else
inode->i_fop = &wrapfs_main_fops;
inode->i_mapping->a_ops = &wrapfs_aops;
inode->i_atime.tv_sec = 0;
inode->i_atime.tv_nsec = 0;
inode->i_mtime.tv_sec = 0;
inode->i_mtime.tv_nsec = 0;
inode->i_ctime.tv_sec = 0;
inode->i_ctime.tv_nsec = 0;
/* properly initialize special inodes */
if (S_ISBLK(lower_inode->i_mode) || S_ISCHR(lower_inode->i_mode) ||
S_ISFIFO(lower_inode->i_mode) || S_ISSOCK(lower_inode->i_mode))
init_special_inode(inode, lower_inode->i_mode,
lower_inode->i_rdev);
/* all well, copy inode attributes */
fsstack_copy_attr_all(inode, lower_inode);
fsstack_copy_inode_size(inode, lower_inode);
unlock_new_inode(inode);
return inode;
}
static void wrapfs_destroy_inode(struct inode *inode)
{
kmem_cache_free(wrapfs_inode_cachep, WRAPFS_I(inode));
}
static int wrapfs_writepage(struct page *page, struct writeback_control *wbc)
{
int err = -EIO;
struct inode *inode;
struct inode *lower_inode;
struct page *lower_page;
struct address_space *lower_mapping; /* lower inode mapping */
gfp_t mask;
char *lower_page_data = NULL;
/*#ifdef WRAPFS_CRYPTO
char *enc_buf = NULL;
#endif*/
wrapfs_debug_aops(
WRAPFS_SB(page->mapping->host->i_sb)->wrapfs_debug_a_ops, "");
wrapfs_debug("");
BUG_ON(!PageUptodate(page));
wrapfs_debug("");
inode = page->mapping->host;
/* if no lower inode, nothing to do */
if (!inode || !WRAPFS_I(inode) || WRAPFS_I(inode)->lower_inode) {
err = 0;
goto out;
}
lower_inode = wrapfs_lower_inode(inode);
lower_mapping = lower_inode->i_mapping;
/*
* find lower page (returns a locked page)
*
* We turn off __GFP_FS while we look for or create a new lower
* page. This prevents a recursion into the file system code, which
* under memory pressure conditions could lead to a deadlock. This
* is similar to how the loop driver behaves (see loop_set_fd in
* drivers/block/loop.c). If we can't find the lower page, we
* redirty our page and return "success" so that the VM will call us
* again in the (hopefully near) future.
*/
mask = mapping_gfp_mask(lower_mapping) & ~(__GFP_FS);
lower_page = find_or_create_page(lower_mapping, page->index, mask);
if (!lower_page) {
err = 0;
set_page_dirty(page);
goto out;
}
lower_page_data = (char *)kmap(lower_page);
/* copy page data from our upper page to the lower page */
copy_highpage(lower_page, page);
flush_dcache_page(lower_page);
SetPageUptodate(lower_page);
set_page_dirty(lower_page);
/*#ifdef WRAPFS_CRYPTO
enc_buf = kmalloc(PAGE_CACHE_SIZE, GFP_KERNEL);
if (enc_buf == NULL) {
wrapfs_debug("No memory!!");
err = -ENOMEM;
goto out_release;
}
err = my_encrypt(lower_page_data, PAGE_CACHE_SIZE, enc_buf,
PAGE_CACHE_SIZE,
WRAPFS_SB(inode->i_sb)->key,
WRAPFS_CRYPTO_KEY_LEN);
if (err < 0) {
wrapfs_debug("encrypt error!!");
kfree(enc_buf);
err = -EINVAL;
goto out_release;
}
memcpy(lower_page_data, enc_buf, PAGE_CACHE_SIZE);
kfree(enc_buf);
#endif*/
/*
* Call lower writepage (expects locked page). However, if we are
* called with wbc->for_reclaim, then the VFS/VM just wants to
* reclaim our page. Therefore, we don't need to call the lower
* ->writepage: just copy our data to the lower page (already done
* above), then mark the lower page dirty and unlock it, and return
* success.
*/
/*if (wbc->for_reclaim) {
unlock_page(lower_page);
goto out_release;
}*/
BUG_ON(!lower_mapping->a_ops->writepage);
wait_on_page_writeback(lower_page); /* prevent multiple writers */
clear_page_dirty_for_io(lower_page); /* emulate VFS behavior */
err = lower_mapping->a_ops->writepage(lower_page, wbc);
if (err < 0)
goto out_release;
/*
* Lower file systems such as ramfs and tmpfs, may return
* AOP_WRITEPAGE_ACTIVATE so that the VM won't try to (pointlessly)
* write the page again for a while. But those lower file systems
* also set the page dirty bit back again. Since we successfully
* copied our page data to the lower page, then the VM will come
* back to the lower page (directly) and try to flush it. So we can
* save the VM the hassle of coming back to our page and trying to
* flush too. Therefore, we don't re-dirty our own page, and we
* never return AOP_WRITEPAGE_ACTIVATE back to the VM (we consider
* this a success).
*
* We also unlock the lower page if the lower ->writepage returned
* AOP_WRITEPAGE_ACTIVATE. (This "anomalous" behaviour may be
* addressed in future shmem/VM code.)
*/
if (err == AOP_WRITEPAGE_ACTIVATE) {
err = 0;
unlock_page(lower_page);
}
out_release:
kunmap(lower_page);
/* b/c find_or_create_page increased refcnt */
page_cache_release(lower_page);
out:
/*
* We unlock our page unconditionally, because we never return
* AOP_WRITEPAGE_ACTIVATE.
*/
unlock_page(page);
wrapfs_debug_aops(WRAPFS_SB(inode->i_sb)->wrapfs_debug_a_ops,
"err : %d", err);
return err;
}
