ext4: add delalloc support for inline data

For delayed allocation mode, we write to inline data if the file
is small enough. And in case of we write to some offset larger
than the inline size, the 1st page is dirtied, so that
ext4_da_writepages can handle the conversion. When the 1st page
is initialized with blocks, the inline part is removed.

Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 177 insertions, 0 deletions

diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index 01274b1e7d40..65f7ffb5437f 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -771,6 +771,183 @@ ext4_journalled_write_inline_data(struct inode *inode,
         return iloc.bh;
 }
 
+/*
+ * Try to make the page cache and handle ready for the inline data case.
+ * We can call this function in 2 cases:
+ * 1. The inode is created and the first write exceeds inline size. We can
+ *    clear the inode state safely.
+ * 2. The inode has inline data, then we need to read the data, make it
+ *    update and dirty so that ext4_da_writepages can handle it. We don't
+ *    need to start the journal since the file's metatdata isn't changed now.
+ */
+static int ext4_da_convert_inline_data_to_extent(struct address_space *mapping,
+                                                 struct inode *inode,
+                                                 unsigned flags,
+                                                 void **fsdata)
+{
+        int ret = 0, inline_size;
+        struct page *page;
+
+        page = grab_cache_page_write_begin(mapping, 0, flags);
+        if (!page)
+                return -ENOMEM;
+
+        down_read(&EXT4_I(inode)->xattr_sem);
+        if (!ext4_has_inline_data(inode)) {
+                ext4_clear_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA);
+                goto out;
+        }
+
+        inline_size = ext4_get_inline_size(inode);
+
+        if (!PageUptodate(page)) {
+                ret = ext4_read_inline_page(inode, page);
+                if (ret < 0)
+                        goto out;
+        }
+
+        ret = __block_write_begin(page, 0, inline_size,
+                                  ext4_da_get_block_prep);
+        if (ret) {
+                ext4_truncate_failed_write(inode);
+                goto out;
+        }
+
+        SetPageDirty(page);
+        SetPageUptodate(page);
+        ext4_clear_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA);
+        *fsdata = (void *)CONVERT_INLINE_DATA;
+
+out:
+        up_read(&EXT4_I(inode)->xattr_sem);
+        if (page) {
+                unlock_page(page);
+                page_cache_release(page);
+        }
+        return ret;
+}
+
+/*
+ * Prepare the write for the inline data.
+ * If the the data can be written into the inode, we just read
+ * the page and make it uptodate, and start the journal.
+ * Otherwise read the page, makes it dirty so that it can be
+ * handle in writepages(the i_disksize update is left to the
+ * normal ext4_da_write_end).
+ */
+int ext4_da_write_inline_data_begin(struct address_space *mapping,
+                                    struct inode *inode,
+                                    loff_t pos, unsigned len,
+                                    unsigned flags,
+                                    struct page **pagep,
+                                    void **fsdata)
+{
+        int ret, inline_size;
+        handle_t *handle;
+        struct page *page;
+        struct ext4_iloc iloc;
+
+        ret = ext4_get_inode_loc(inode, &iloc);
+        if (ret)
+                return ret;
+
+        handle = ext4_journal_start(inode, 1);
+        if (IS_ERR(handle)) {
+                ret = PTR_ERR(handle);
+                handle = NULL;
+                goto out;
+        }
+
+        inline_size = ext4_get_max_inline_size(inode);
+
+        ret = -ENOSPC;
+        if (inline_size >= pos + len) {
+                ret = ext4_prepare_inline_data(handle, inode, pos + len);
+                if (ret && ret != -ENOSPC)
+                        goto out;
+        }
+
+        if (ret == -ENOSPC) {
+                ret = ext4_da_convert_inline_data_to_extent(mapping,
+                                                            inode,
+                                                            flags,
+                                                            fsdata);
+                goto out;
+        }
+
+        /*
+         * We cannot recurse into the filesystem as the transaction
+         * is already started.
+         */
+        flags |= AOP_FLAG_NOFS;
+
+        page = grab_cache_page_write_begin(mapping, 0, flags);
+        if (!page) {
+                ret = -ENOMEM;
+                goto out;
+        }
+
+        down_read(&EXT4_I(inode)->xattr_sem);
+        if (!ext4_has_inline_data(inode)) {
+                ret = 0;
+                goto out_release_page;
+        }
+
+        if (!PageUptodate(page)) {
+                ret = ext4_read_inline_page(inode, page);
+                if (ret < 0)
+                        goto out_release_page;
+        }
+
+        up_read(&EXT4_I(inode)->xattr_sem);
+        *pagep = page;
+        handle = NULL;
+        brelse(iloc.bh);
+        return 1;
+out_release_page:
+        up_read(&EXT4_I(inode)->xattr_sem);
+        unlock_page(page);
+        page_cache_release(page);
+out:
+        if (handle)
+                ext4_journal_stop(handle);
+        brelse(iloc.bh);
+        return ret;
+}
+
+int ext4_da_write_inline_data_end(struct inode *inode, loff_t pos,
+                                  unsigned len, unsigned copied,
+                                  struct page *page)
+{
+        int i_size_changed = 0;
+
+        copied = ext4_write_inline_data_end(inode, pos, len, copied, page);
+
+        /*
+         * No need to use i_size_read() here, the i_size
+         * cannot change under us because we hold i_mutex.
+         *
+         * But it's important to update i_size while still holding page lock:
+         * page writeout could otherwise come in and zero beyond i_size.
+         */
+        if (pos+copied > inode->i_size) {
+                i_size_write(inode, pos+copied);
+                i_size_changed = 1;
+        }
+        unlock_page(page);
+        page_cache_release(page);
+
+        /*
+         * Don't mark the inode dirty under page lock. First, it unnecessarily
+         * makes the holding time of page lock longer. Second, it forces lock
+         * ordering of page lock and transaction start for journaling
+         * filesystems.
+         */
+        if (i_size_changed)
+                mark_inode_dirty(inode);
+
+        return copied;
+}
 
 int ext4_destroy_inline_data(handle_t *handle, struct inode *inode)
 {