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Commit 109f5565 authored by Mingming's avatar Mingming Committed by Theodore Ts'o
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ext4: fix ext4_ext_direct_IO()'s return value after converting uninit extents 



After a direct I/O request covering an uninitalized extent (i.e.,
created using the fallocate system call) or a hole in a file, ext4
will convert the uninitialized extent so it is marked as initialized
by calling ext4_convert_unwritten_extents().  This function returns
zero on success.

This return value was getting returned by ext4_direct_IO(); however
the file system's direct_IO function is supposed to return the number
of bytes read or written on a success.  By returning zero, it confused
the direct I/O code into falling back to buffered I/O unnecessarily.

Signed-off-by: default avatarMingming Cao <cmm@us.ibm.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent fa5d1113

fs/ext4/extents.c

+1 −0
Original line number Diff line number Diff line
@@ -3519,6 +3519,7 @@ long ext4_fallocate(struct inode *inode, int mode, loff_t offset, loff_t len) 
 *

 * This function is called from the direct IO end io call back

 * function, to convert the fallocated extents after IO is completed.

 * Returns 0 on success.

 */

int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset,

				    loff_t len)

fs/ext4/inode.c

+7 −3
Original line number Diff line number Diff line
@@ -3772,13 +3772,17 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb, 
		if (ret != -EIOCBQUEUED && ret <= 0 && iocb->private) {

			ext4_free_io_end(iocb->private);

			iocb->private = NULL;

		} else if (ret > 0)

		} else if (ret > 0) {

			int err;

			/*

			 * for non AIO case, since the IO is already

			 * completed, we could do the convertion right here

			 */

			ret = ext4_convert_unwritten_extents(inode,

			err = ext4_convert_unwritten_extents(inode,

							     offset, ret);

			if (err < 0)

				ret = err;

		}

		return ret;

	}