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    Subject[PATCH V1 03/17] ext4: Add read support for inline data.
    Date
    From: Tao Ma <boyu.mt@taobao.com>

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

    Signed-off-by: Tao Ma <boyu.mt@taobao.comc.
    ---
    fs/ext4/inode.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
    1 files changed, 68 insertions(+), 0 deletions(-)

    diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
    index 017e119..2fa8cf4 100644
    --- a/fs/ext4/inode.c
    +++ b/fs/ext4/inode.c
    @@ -540,6 +540,9 @@ 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;

    @@ -2483,6 +2486,12 @@ static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
    journal_t *journal;
    int err;

    + /*
    + * XXX: Can we arrive here for a inline file? Maybe not.
    + */
    + if (ext4_has_inline_data(inode))
    + return 0;
    +
    if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
    test_opt(inode->i_sb, DELALLOC)) {
    /*
    @@ -2526,9 +2535,58 @@ static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
    return generic_block_bmap(mapping, block, ext4_get_block);
    }

    +static int ext4_read_inline_page(struct inode *inode, struct page *page)
    +{
    + void *kaddr;
    + loff_t size;
    + int ret;
    + struct ext4_iloc iloc;
    +
    + BUG_ON(!PageLocked(page));
    + BUG_ON(!ext4_has_inline_data(inode));
    +
    + ret = ext4_get_inode_loc(inode, &iloc);
    + if (ret)
    + return ret;
    +
    + size = i_size_read(inode);
    +
    + if (size > PAGE_CACHE_SIZE ||
    + size > ext4_get_max_inline_size(inode)) {
    + ext4_error_inode(inode, __func__, __LINE__, 0,
    + "bad size %ld for a inline file", (long)size);
    + return -EROFS;
    + }
    +
    + kaddr = kmap_atomic(page, KM_USER0);
    + ext4_read_inline_data(inode, &iloc, kaddr, size);
    + flush_dcache_page(page);
    + kunmap_atomic(kaddr, KM_USER0);
    + SetPageUptodate(page);
    +
    + brelse(iloc.bh);
    + return 0;
    +}
    +
    +static int ext4_readpage_inline(struct inode *inode, struct page *page)
    +{
    + int ret;
    +
    + ret = ext4_read_inline_page(inode, page);
    +
    + unlock_page(page);
    + return ret;
    +}
    +
    static int ext4_readpage(struct file *file, struct page *page)
    {
    + struct inode *inode = file->f_mapping->host;
    +
    trace_ext4_readpage(page);
    +
    + if (ext4_has_inline_data(inode))
    + return ext4_readpage_inline(inode, page);
    +
    return mpage_readpage(page, ext4_get_block);
    }

    @@ -2536,6 +2594,12 @@ 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);
    }

    @@ -2854,6 +2918,10 @@ static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
    struct inode *inode = file->f_mapping->host;
    ssize_t ret;

    + /* 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);
    --
    1.7.0.4


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