fs: add IOCB_SYNC and IOCB_DSYNC

This will allow us to do per-I/O sync file writes, as required by a lot
of fileservers or storage targets.

XXX: Will need a few additional audits for O_DSYNC
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/block_dev.c

@@ -1662,7 +1662,7 @@ ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	ret = __generic_file_write_iter(iocb, from);
 	if (ret > 0) {
 		ssize_t err;
-		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
+		err = generic_write_sync(iocb, iocb->ki_pos - ret, ret);
 		if (err < 0)
 			ret = err;
 	}

fs/btrfs/file.c

@@ -1852,7 +1852,7 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
 	BTRFS_I(inode)->last_sub_trans = root->log_transid;
 	spin_unlock(&BTRFS_I(inode)->lock);
 	if (num_written > 0) {
-		err = generic_write_sync(file, pos, num_written);
+		err = generic_write_sync(iocb, pos, num_written);
 		if (err < 0)
 			num_written = err;
 	}

fs/cifs/file.c

@@ -2688,7 +2688,7 @@ cifs_writev(struct kiocb *iocb, struct iov_iter *from)
 	inode_unlock(inode);
 
 	if (rc > 0) {
-		ssize_t err = generic_write_sync(file, iocb->ki_pos - rc, rc);
+		ssize_t err = generic_write_sync(iocb, iocb->ki_pos - rc, rc);
 		if (err < 0)
 			rc = err;
 	}

fs/direct-io.c

@@ -268,7 +268,7 @@ static ssize_t dio_complete(struct dio *dio, ssize_t ret, bool is_async)
 		if (dio->rw & WRITE) {
 			int err;
 
-			err = generic_write_sync(dio->iocb->ki_filp, offset,
+			err = generic_write_sync(dio->iocb, offset,
 						 transferred);
 			if (err < 0 && ret > 0)
 				ret = err;

fs/ext4/file.c

@@ -172,7 +172,7 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	if (ret > 0) {
 		ssize_t err;
 
-		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
+		err = generic_write_sync(iocb, iocb->ki_pos - ret, ret);
 		if (err < 0)
 			ret = err;
 	}

fs/f2fs/file.c

@@ -1885,7 +1885,7 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	if (ret > 0) {
 		ssize_t err;
 
-		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
+		err = generic_write_sync(iocb, iocb->ki_pos - ret, ret);
 		if (err < 0)
 			ret = err;
 	}

fs/gfs2/file.c

@@ -895,7 +895,10 @@ static long __gfs2_fallocate(struct file *file, int mode, loff_t offset, loff_t
 		mark_inode_dirty(inode);
 	}
 
-	return generic_write_sync(file, pos, count);
+	if ((file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host))
+		return vfs_fsync_range(file, pos, pos + count - 1,
+			       (file->f_flags & __O_SYNC) ? 0 : 1);
+	return 0;
 
 out_trans_fail:
 	gfs2_inplace_release(ip);

fs/nfs/direct.c

@@ -1054,7 +1054,7 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter)
 			if (i_size_read(inode) < iocb->ki_pos)
 				i_size_write(inode, iocb->ki_pos);
 			spin_unlock(&inode->i_lock);
-			generic_write_sync(file, pos, result);
+			generic_write_sync(iocb, pos, result);
 		}
 	}
 	nfs_direct_req_release(dreq);

fs/ntfs/file.c

@@ -1953,7 +1953,7 @@ static ssize_t ntfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	current->backing_dev_info = NULL;
 	inode_unlock(vi);
 	if (likely(written > 0)) {
-		err = generic_write_sync(file, iocb->ki_pos, written);
+		err = generic_write_sync(iocb, iocb->ki_pos, written);
 		if (err < 0)
 			written = 0;
 	}

fs/udf/file.c

@@ -152,7 +152,7 @@ static ssize_t udf_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 
 	if (retval > 0) {
 		mark_inode_dirty(inode);
-		err = generic_write_sync(file, iocb->ki_pos - retval, retval);
+		err = generic_write_sync(iocb, iocb->ki_pos - retval, retval);
 		if (err < 0)
 			retval = err;
 	}

fs/xfs/xfs_file.c

@@ -908,7 +908,7 @@ xfs_file_write_iter(
 		XFS_STATS_ADD(ip->i_mount, xs_write_bytes, ret);
 
 		/* Handle various SYNC-type writes */
-		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
+		err = generic_write_sync(iocb, iocb->ki_pos - ret, ret);
 		if (err < 0)
 			ret = err;
 	}

include/linux/fs.h

@@ -323,6 +323,8 @@ struct writeback_control;
 #define IOCB_APPEND		(1 << 1)
 #define IOCB_DIRECT		(1 << 2)
 #define IOCB_HIPRI		(1 << 3)
+#define IOCB_DSYNC		(1 << 4)
+#define IOCB_SYNC		(1 << 5)
 
 struct kiocb {
 	struct file		*ki_filp;
@@ -2485,12 +2487,12 @@ extern int filemap_fdatawrite_range(struct address_space *mapping,
 extern int vfs_fsync_range(struct file *file, loff_t start, loff_t end,
 			   int datasync);
 extern int vfs_fsync(struct file *file, int datasync);
-static inline int generic_write_sync(struct file *file, loff_t pos, loff_t count)
+static inline int generic_write_sync(struct kiocb *iocb, loff_t pos, loff_t count)
 {
-	if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host))
+	if (!(iocb->ki_flags & IOCB_DSYNC))
 		return 0;
-	return vfs_fsync_range(file, pos, pos + count - 1,
-			       (file->f_flags & __O_SYNC) ? 0 : 1);
+	return vfs_fsync_range(iocb->ki_filp, pos, pos + count - 1,
+			       (iocb->ki_flags & IOCB_SYNC) ? 0 : 1);
 }
 extern void emergency_sync(void);
 extern void emergency_remount(void);
@@ -2942,6 +2944,10 @@ static inline int iocb_flags(struct file *file)
 		res |= IOCB_APPEND;
 	if (io_is_direct(file))
 		res |= IOCB_DIRECT;
+	if ((file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host))
+		res |= IOCB_DSYNC;
+	if (file->f_flags & __O_SYNC)
+		res |= IOCB_SYNC;
 	return res;
 }
 

mm/filemap.c

@@ -2794,7 +2794,7 @@ ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	if (ret > 0) {
 		ssize_t err;
 
-		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
+		err = generic_write_sync(iocb, iocb->ki_pos - ret, ret);
 		if (err < 0)
 			ret = err;
 	}