ext4: add read support for inline data

Let readpage and readpages handle the case when we want to read an
inlined file.

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

3 files changed, 98 insertions, 1 deletions

diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index bec68b364832..e4a41d5d06db 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -454,6 +454,67 @@ out:
         return error;
 }
 
+static int ext4_read_inline_page(struct inode *inode, struct page *page)
+{
+        void *kaddr;
+        int ret = 0;
+        size_t len;
+        struct ext4_iloc iloc;
+
+        BUG_ON(!PageLocked(page));
+        BUG_ON(!ext4_has_inline_data(inode));
+        BUG_ON(page->index);
+
+        if (!EXT4_I(inode)->i_inline_off) {
+                ext4_warning(inode->i_sb, "inode %lu doesn't have inline data.",
+                             inode->i_ino);
+                goto out;
+        }
+
+        ret = ext4_get_inode_loc(inode, &iloc);
+        if (ret)
+                goto out;
+
+        len = min_t(size_t, ext4_get_inline_size(inode), i_size_read(inode));
+        kaddr = kmap_atomic(page);
+        ret = ext4_read_inline_data(inode, kaddr, len, &iloc);
+        flush_dcache_page(page);
+        kunmap_atomic(kaddr);
+        zero_user_segment(page, len, PAGE_CACHE_SIZE);
+        SetPageUptodate(page);
+        brelse(iloc.bh);
+
+out:
+        return ret;
+}
+
+int ext4_readpage_inline(struct inode *inode, struct page *page)
+{
+        int ret = 0;
+
+        down_read(&EXT4_I(inode)->xattr_sem);
+        if (!ext4_has_inline_data(inode)) {
+                up_read(&EXT4_I(inode)->xattr_sem);
+                return -EAGAIN;
+        }
+
+        /*
+         * Current inline data can only exist in the 1st page,
+         * So for all the other pages, just set them uptodate.
+         */
+        if (!page->index)
+                ret = ext4_read_inline_page(inode, page);
+        else if (!PageUptodate(page)) {
+                zero_user_segment(page, 0, PAGE_CACHE_SIZE);
+                SetPageUptodate(page);
+        }
+
+        up_read(&EXT4_I(inode)->xattr_sem);
+
+        unlock_page(page);
+        return ret >= 0 ? 0 : ret;
+}
+
 int ext4_destroy_inline_data(handle_t *handle, struct inode *inode)
 {
         int ret;
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index e23f114e2cfe..1668abf80549 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -649,6 +649,9 @@ static int _ext4_get_block(struct inode *inode, sector_t iblock,
         int ret = 0, started = 0;
         int dio_credits;
 
+        if (ext4_has_inline_data(inode))
+                return -ERANGE;
+
         map.m_lblk = iblock;
         map.m_len = bh->b_size >> inode->i_blkbits;
 
@@ -2687,6 +2690,12 @@ static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
         journal_t *journal;
         int err;
 
+        /*
+         * We can get here for an inline file via the FIBMAP ioctl
+         */
+        if (ext4_has_inline_data(inode))
+                return 0;
+
         if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
                         test_opt(inode->i_sb, DELALLOC)) {
                 /*
@@ -2732,14 +2741,30 @@ static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
 
 static int ext4_readpage(struct file *file, struct page *page)
 {
+        int ret = -EAGAIN;
+        struct inode *inode = page->mapping->host;
+
         trace_ext4_readpage(page);
-        return mpage_readpage(page, ext4_get_block);
+
+        if (ext4_has_inline_data(inode))
+                ret = ext4_readpage_inline(inode, page);
+
+        if (ret == -EAGAIN)
+                return mpage_readpage(page, ext4_get_block);
+
+        return ret;
 }
 
 static int
 ext4_readpages(struct file *file, struct address_space *mapping,
                 struct list_head *pages, unsigned nr_pages)
 {
+        struct inode *inode = mapping->host;
+
+        /* If the file has inline data, no need to do readpages. */
+        if (ext4_has_inline_data(inode))
+                return 0;
+
         return mpage_readpages(mapping, pages, nr_pages, ext4_get_block);
 }
 
@@ -3078,6 +3103,10 @@ static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
         if (ext4_should_journal_data(inode))
                 return 0;
 
+        /* Let buffer I/O handle the inline data case. */
+        if (ext4_has_inline_data(inode))
+                return 0;
+
         trace_ext4_direct_IO_enter(inode, offset, iov_length(iov, nr_segs), rw);
         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
                 ret = ext4_ext_direct_IO(rw, iocb, iov, offset, nr_segs);
diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h
index 7ae0d05156e3..646c9b9be8ed 100644
--- a/fs/ext4/xattr.h
+++ b/fs/ext4/xattr.h
@@ -139,6 +139,8 @@ extern int ext4_prepare_inline_data(handle_t *handle, struct inode *inode,
 extern int ext4_init_inline_data(handle_t *handle, struct inode *inode,
                                  unsigned int len);
 extern int ext4_destroy_inline_data(handle_t *handle, struct inode *inode);
+
+extern int ext4_readpage_inline(struct inode *inode, struct page *page);
 # else  /* CONFIG_EXT4_FS_XATTR */
 
 static inline int
@@ -255,6 +257,11 @@ static inline int ext4_destroy_inline_data(handle_t *handle,
 {
         return 0;
 }
+
+static inline int ext4_readpage_inline(struct inode *inode, struct page *page)
+{
+        return 0;
+}
 # endif  /* CONFIG_EXT4_FS_XATTR */
 
 #ifdef CONFIG_EXT4_FS_SECURITY