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    Subject[RFC PATCH 11/35] ovl: readd read_iter
    Date
    Implement stacked reading.

    Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
    ---
    fs/overlayfs/file.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++++
    1 file changed, 56 insertions(+)

    diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
    index 409b542ff30c..a19429c5965d 100644
    --- a/fs/overlayfs/file.c
    +++ b/fs/overlayfs/file.c
    @@ -9,6 +9,7 @@
    #include <linux/cred.h>
    #include <linux/file.h>
    #include <linux/xattr.h>
    +#include <linux/uio.h>
    #include "overlayfs.h"

    static struct file *ovl_open_realfile(const struct file *file)
    @@ -129,8 +130,63 @@ static loff_t ovl_llseek(struct file *file, loff_t offset, int whence)
    i_size_read(realinode));
    }

    +static void ovl_file_accessed(struct file *file)
    +{
    + struct inode *inode = file_inode(file);
    +
    + if ((file->f_flags & O_NOATIME) || !ovl_inode_upper(inode))
    + return;
    +
    + ovl_copytimes(inode);
    + touch_atime(&file->f_path);
    +}
    +
    +static rwf_t ovl_iocb_to_rwf(struct kiocb *iocb)
    +{
    + int ifl = iocb->ki_flags;
    + rwf_t flags = 0;
    +
    + if (ifl & IOCB_NOWAIT)
    + flags |= RWF_NOWAIT;
    + if (ifl & IOCB_HIPRI)
    + flags |= RWF_HIPRI;
    + if (ifl & IOCB_DSYNC)
    + flags |= RWF_DSYNC;
    + if (ifl & IOCB_SYNC)
    + flags |= RWF_SYNC;
    +
    + return flags;
    +}
    +
    +static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter)
    +{
    + struct file *file = iocb->ki_filp;
    + struct fd real;
    + const struct cred *old_cred;
    + ssize_t ret;
    +
    + if (!iov_iter_count(iter))
    + return 0;
    +
    + ret = ovl_real_file(file, &real);
    + if (ret)
    + return ret;
    +
    + old_cred = ovl_override_creds(file_inode(file)->i_sb);
    + ret = vfs_iter_read(real.file, iter, &iocb->ki_pos,
    + ovl_iocb_to_rwf(iocb));
    + revert_creds(old_cred);
    +
    + ovl_file_accessed(file);
    +
    + fdput(real);
    +
    + return ret;
    +}
    +
    const struct file_operations ovl_file_operations = {
    .open = ovl_open,
    .release = ovl_release,
    .llseek = ovl_llseek,
    + .read_iter = ovl_read_iter,
    };
    --
    2.14.3
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