xfs: split xfs_file_read_iter into buffered and direct I/O helpers

Similar to what we did on the write side a while ago.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

1 files changed, 57 insertions, 26 deletions

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 7ec8225b7fd2..fdb123ffd616 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -282,35 +282,33 @@ xfs_file_fsync(
 }
 
 STATIC ssize_t
-xfs_file_read_iter(
+xfs_file_dio_aio_read(
         struct kiocb            *iocb,
         struct iov_iter         *to)
 {
-        struct file             *file = iocb->ki_filp;
-        struct inode            *inode = file->f_mapping->host;
+        struct address_space    *mapping = iocb->ki_filp->f_mapping;
+        struct inode            *inode = mapping->host;
         struct xfs_inode        *ip = XFS_I(inode);
-        struct xfs_mount        *mp = ip->i_mount;
-        size_t                  size = iov_iter_count(to);
+        size_t                  count = iov_iter_count(to);
+        struct xfs_buftarg      *target;
         ssize_t                 ret = 0;
-        loff_t                  pos = iocb->ki_pos;
 
-        XFS_STATS_INC(mp, xs_read_calls);
+        trace_xfs_file_direct_read(ip, count, iocb->ki_pos);
 
-        if ((iocb->ki_flags & IOCB_DIRECT) && !IS_DAX(inode)) {
-                xfs_buftarg_t   *target =
-                        XFS_IS_REALTIME_INODE(ip) ?
-                                mp->m_rtdev_targp : mp->m_ddev_targp;
+        if (XFS_IS_REALTIME_INODE(ip))
+                target = ip->i_mount->m_rtdev_targp;
+        else
+                target = ip->i_mount->m_ddev_targp;
+
+        if (!IS_DAX(inode)) {
                 /* DIO must be aligned to device logical sector size */
-                if ((pos | size) & target->bt_logical_sectormask) {
-                        if (pos == i_size_read(inode))
+                if ((iocb->ki_pos | count) & target->bt_logical_sectormask) {
+                        if (iocb->ki_pos == i_size_read(inode))
                                 return 0;
                         return -EINVAL;
                 }
         }
 
-        if (XFS_FORCED_SHUTDOWN(mp))
-                return -EIO;
-
         /*
          * Locking is a bit tricky here. If we take an exclusive lock for direct
          * IO, we effectively serialise all new concurrent read IO to this file
@@ -322,7 +320,7 @@ xfs_file_read_iter(
          * serialisation.
          */
         xfs_rw_ilock(ip, XFS_IOLOCK_SHARED);
-        if ((iocb->ki_flags & IOCB_DIRECT) && inode->i_mapping->nrpages) {
+        if (mapping->nrpages) {
                 xfs_rw_iunlock(ip, XFS_IOLOCK_SHARED);
                 xfs_rw_ilock(ip, XFS_IOLOCK_EXCL);
 
@@ -337,8 +335,8 @@ xfs_file_read_iter(
                  * flush and reduce the chances of repeated iolock cycles going
                  * forward.
                  */
-                if (inode->i_mapping->nrpages) {
-                        ret = filemap_write_and_wait(VFS_I(ip)->i_mapping);
+                if (mapping->nrpages) {
+                        ret = filemap_write_and_wait(mapping);
                         if (ret) {
                                 xfs_rw_iunlock(ip, XFS_IOLOCK_EXCL);
                                 return ret;
@@ -349,23 +347,56 @@ xfs_file_read_iter(
                          * we fail to invalidate a page, but this should never
                          * happen on XFS. Warn if it does fail.
                          */
-                        ret = invalidate_inode_pages2(VFS_I(ip)->i_mapping);
+                        ret = invalidate_inode_pages2(mapping);
                         WARN_ON_ONCE(ret);
                         ret = 0;
                 }
                 xfs_rw_ilock_demote(ip, XFS_IOLOCK_EXCL);
         }
 
+        ret = generic_file_read_iter(iocb, to);
+        xfs_rw_iunlock(ip, XFS_IOLOCK_SHARED);
+
+        return ret;
+}
+
+STATIC ssize_t
+xfs_file_buffered_aio_read(
+        struct kiocb            *iocb,
+        struct iov_iter         *to)
+{
+        struct xfs_inode        *ip = XFS_I(file_inode(iocb->ki_filp));
+        ssize_t                 ret;
+
+        trace_xfs_file_buffered_read(ip, iov_iter_count(to), iocb->ki_pos);
+
+        xfs_rw_ilock(ip, XFS_IOLOCK_SHARED);
+        ret = generic_file_read_iter(iocb, to);
+        xfs_rw_iunlock(ip, XFS_IOLOCK_SHARED);
+
+        return ret;
+}
+
+STATIC ssize_t
+xfs_file_read_iter(
+        struct kiocb            *iocb,
+        struct iov_iter         *to)
+{
+        struct xfs_mount        *mp = XFS_I(file_inode(iocb->ki_filp))->i_mount;
+        ssize_t                 ret = 0;
+
+        XFS_STATS_INC(mp, xs_read_calls);
+
+        if (XFS_FORCED_SHUTDOWN(mp))
+                return -EIO;
+
         if (iocb->ki_flags & IOCB_DIRECT)
-                trace_xfs_file_direct_read(ip, size, pos);
+                ret = xfs_file_dio_aio_read(iocb, to);
         else
-                trace_xfs_file_buffered_read(ip, size, pos);
+                ret = xfs_file_buffered_aio_read(iocb, to);
 
-        ret = generic_file_read_iter(iocb, to);
         if (ret > 0)
                 XFS_STATS_ADD(mp, xs_read_bytes, ret);
-
-        xfs_rw_iunlock(ip, XFS_IOLOCK_SHARED);
         return ret;
 }
 
@@ -747,7 +778,7 @@ xfs_file_dio_aio_write(
         end = iocb->ki_pos + count - 1;
 
         /*
-         * See xfs_file_read_iter() for why we do a full-file flush here.
+         * See xfs_file_dio_aio_read() for why we do a full-file flush here.
          */
         if (mapping->nrpages) {
                 ret = filemap_write_and_wait(VFS_I(ip)->i_mapping);