linux-ext4 - [PATCH -v2] ext4: fake direct I/O mode for data=journal

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Date:	Tue, 16 Aug 2011 15:32:25 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc:	Theodore Ts'o <tytso@....edu>
Subject: [PATCH -v2] ext4: fake direct I/O mode for data=journal

Currently attempts to open a file with O_DIRECT in data=journal mode
causes the open to fail with -EINVAL.  This makes it very hard to test
data=journal mode.  So we will let the open succeed, but then always
fall back to O_DSYNC buffered writes.

Signed-off-by: "Theodore Ts'o" <tytso@....edu>
---
 fs/ext4/file.c  |   28 +++++++++++++++++++++++++++-
 fs/ext4/inode.c |    1 +
 2 files changed, 28 insertions(+), 1 deletions(-)

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index e4095e9..566f33f 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -89,6 +89,24 @@ ext4_unaligned_aio(struct inode *inode, const struct iovec *iov,
 	return 0;
 }
 
+ssize_t
+ext4_file_read(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;
+
+	/*
+	 * If O_DIRECT is set and we are doing data journalling we
+	 * don't support O_DIRECT so force it off.
+	 */
+	if ((iocb->ki_filp->f_flags & O_DIRECT) &&
+	    ext4_should_journal_data(inode))
+		iocb->ki_filp->f_flags &= ~O_DIRECT;
+
+	return generic_file_aio_read(iocb, iov, nr_segs, pos);
+}
+
+
 static ssize_t
 ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
 		unsigned long nr_segs, loff_t pos)
@@ -98,6 +116,14 @@ ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
 	int ret;
 
 	/*
+	 * If O_DIRECT is set and we are doing data journalling we
+	 * don't support O_DIRECT so force it off.
+	 */
+	if ((iocb->ki_filp->f_flags & O_DIRECT) &&
+	    ext4_should_journal_data(inode))
+		iocb->ki_filp->f_flags &= ~O_DIRECT;
+
+	/*
 	 * If we have encountered a bitmap-format file, the size limit
 	 * is smaller than s_maxbytes, which is for extent-mapped files.
 	 */
@@ -277,7 +303,7 @@ const struct file_operations ext4_file_operations = {
 	.llseek		= ext4_llseek,
 	.read		= do_sync_read,
 	.write		= do_sync_write,
-	.aio_read	= generic_file_aio_read,
+	.aio_read	= ext4_file_read,
 	.aio_write	= ext4_file_write,
 	.unlocked_ioctl = ext4_ioctl,
 #ifdef CONFIG_COMPAT
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 762e803..b7088e2 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2921,6 +2921,7 @@ static const struct address_space_operations ext4_journalled_aops = {
 	.bmap			= ext4_bmap,
 	.invalidatepage		= ext4_invalidatepage,
 	.releasepage		= ext4_releasepage,
+	.direct_IO		= ext4_direct_IO,
 	.is_partially_uptodate  = block_is_partially_uptodate,
 	.error_remove_page	= generic_error_remove_page,
 };
-- 
1.7.4.1.22.gec8e1.dirty

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