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>

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 8c7642a..a10dc77 100644 (file)
--- 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,