ext4: split ext4_file_write into buffered IO and direct IO

ext4_file_dio_write is defined in order to split buffered IO and
direct IO in ext4.  This patch just refactor some stuff in write path.

CC: Tao Ma <tm@tao.ma>
CC: Eric Sandeen <sandeen@redhat.com>
CC: Robin Dong <hao.bigrat@gmail.com>
Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 38 insertions, 22 deletions

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 8c7642a00054..a10dc7742aec 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -90,34 +90,16 @@ ext4_unaligned_aio(struct inode *inode, const struct iovec *iov,
 }
 
 static ssize_t
-ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
-                unsigned long nr_segs, loff_t pos)
+ext4_file_dio_write(struct kiocb *iocb, const struct iovec *iov,
+                    unsigned long nr_segs, loff_t pos)
 {
         struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
         int unaligned_aio = 0;
         ssize_t ret;
 
-        /*
-         * If we have encountered a bitmap-format file, the size limit
-         * is smaller than s_maxbytes, which is for extent-mapped files.
-         */
-
-        if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
-                struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
-                size_t length = iov_length(iov, nr_segs);
-
-                if ((pos > sbi->s_bitmap_maxbytes ||
-                    (pos == sbi->s_bitmap_maxbytes && length > 0)))
-                        return -EFBIG;
-
-                if (pos + length > sbi->s_bitmap_maxbytes) {
-                        nr_segs = iov_shorten((struct iovec *)iov, nr_segs,
-                                              sbi->s_bitmap_maxbytes - pos);
-                }
-        } else if (unlikely((iocb->ki_filp->f_flags & O_DIRECT) &&
-                   !is_sync_kiocb(iocb))) {
+        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
+            !is_sync_kiocb(iocb))
                 unaligned_aio = ext4_unaligned_aio(inode, iov, nr_segs, pos);
-        }
 
         /* Unaligned direct AIO must be serialized; see comment above */
         if (unaligned_aio) {
@@ -141,6 +123,40 @@ ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
         return ret;
 }
 
+static ssize_t
+ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
+                unsigned long nr_segs, loff_t pos)
+{
+        struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
+        ssize_t ret;
+
+        /*
+         * If we have encountered a bitmap-format file, the size limit
+         * is smaller than s_maxbytes, which is for extent-mapped files.
+         */
+
+        if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
+                struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+                size_t length = iov_length(iov, nr_segs);
+
+                if ((pos > sbi->s_bitmap_maxbytes ||
+                    (pos == sbi->s_bitmap_maxbytes && length > 0)))
+                        return -EFBIG;
+
+                if (pos + length > sbi->s_bitmap_maxbytes) {
+                        nr_segs = iov_shorten((struct iovec *)iov, nr_segs,
+                                              sbi->s_bitmap_maxbytes - pos);
+                }
+        }
+
+        if (unlikely(iocb->ki_filp->f_flags & O_DIRECT))
+                ret = ext4_file_dio_write(iocb, iov, nr_segs, pos);
+        else
+                ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
+
+        return ret;
+}
+
 static const struct vm_operations_struct ext4_file_vm_ops = {
         .fault          = filemap_fault,
         .page_mkwrite   = ext4_page_mkwrite,