btrfs: remove dio iomap DSYNC workaround

This effectively reverts 09745ff88d93 ("btrfs: dio iomap DSYNC
workaround") now that the iomap API has been updated to allow
iomap_dio_complete() not to be called under i_rwsem anymore.
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NGoldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/ctree.h

@@ -3068,7 +3068,6 @@ void btrfs_writepage_endio_finish_ordered(struct page *page, u64 start,
 extern const struct dentry_operations btrfs_dentry_operations;
 extern const struct iomap_ops btrfs_dio_iomap_ops;
 extern const struct iomap_dio_ops btrfs_dio_ops;
-extern const struct iomap_dio_ops btrfs_sync_dops;
 
 /* Inode locking type flags, by default the exclusive lock is taken */
 #define BTRFS_ILOCK_SHARED	(1U << 0)

fs/btrfs/file.c

@@ -2018,44 +2018,10 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
 	if (sync)
 		atomic_inc(&BTRFS_I(inode)->sync_writers);
 
-	if (iocb->ki_flags & IOCB_DIRECT) {
-		/*
-		 * 1. We must always clear IOCB_DSYNC in order to not deadlock
-		 *    in iomap, as it calls generic_write_sync() in this case.
-		 * 2. If we are async, we can call iomap_dio_complete() either
-		 *    in
-		 *
-		 *    2.1. A worker thread from the last bio completed.  In this
-		 *	   case we need to mark the btrfs_dio_data that it is
-		 *	   async in order to call generic_write_sync() properly.
-		 *	   This is handled by setting BTRFS_DIO_SYNC_STUB in the
-		 *	   current->journal_info.
-		 *    2.2  The submitter context, because all IO completed
-		 *         before we exited iomap_dio_rw().  In this case we can
-		 *         just re-set the IOCB_DSYNC on the iocb and we'll do
-		 *         the sync below.  If our ->end_io() gets called and
-		 *         current->journal_info is set, then we know we're in
-		 *         our current context and we will clear
-		 *         current->journal_info to indicate that we need to
-		 *         sync below.
-		 */
-		if (sync) {
-			ASSERT(current->journal_info == NULL);
-			iocb->ki_flags &= ~IOCB_DSYNC;
-			current->journal_info = BTRFS_DIO_SYNC_STUB;
-		}
+	if (iocb->ki_flags & IOCB_DIRECT)
 		num_written = btrfs_direct_write(iocb, from);
-
-		/*
-		 * As stated above, we cleared journal_info, so we need to do
-		 * the sync ourselves.
-		 */
-		if (sync && current->journal_info == NULL)
-			iocb->ki_flags |= IOCB_DSYNC;
-		current->journal_info = NULL;
-	} else {
+	else
 		num_written = btrfs_buffered_write(iocb, from);
-	}
 
 	/*
 	 * We also have to set last_sub_trans to the current log transid,

fs/btrfs/inode.c

@@ -62,7 +62,6 @@ struct btrfs_dio_data {
 	loff_t length;
 	ssize_t submitted;
 	struct extent_changeset *data_reserved;
-	bool sync;
 };
 
 static const struct inode_operations btrfs_dir_inode_operations;
@@ -7431,17 +7430,6 @@ static int btrfs_dio_iomap_begin(struct inode *inode, loff_t start,
 	int ret = 0;
 	u64 len = length;
 	bool unlock_extents = false;
-	bool sync = (current->journal_info == BTRFS_DIO_SYNC_STUB);
-
-	/*
-	 * We used current->journal_info here to see if we were sync, but
-	 * there's a lot of tests in the enospc machinery to not do flushing if
-	 * we have a journal_info set, so we need to clear this out and re-set
-	 * it in iomap_end.
-	 */
-	ASSERT(current->journal_info == NULL ||
-	       current->journal_info == BTRFS_DIO_SYNC_STUB);
-	current->journal_info = NULL;
 
 	if (!write)
 		len = min_t(u64, len, fs_info->sectorsize);
@@ -7467,7 +7455,6 @@ static int btrfs_dio_iomap_begin(struct inode *inode, loff_t start,
 	if (!dio_data)
 		return -ENOMEM;
 
-	dio_data->sync = sync;
 	dio_data->length = length;
 	if (write) {
 		dio_data->reserve = round_up(length, fs_info->sectorsize);
@@ -7615,14 +7602,6 @@ static int btrfs_dio_iomap_end(struct inode *inode, loff_t pos, loff_t length,
 		extent_changeset_free(dio_data->data_reserved);
 	}
 out:
-	/*
-	 * We're all done, we can re-set the current->journal_info now safely
-	 * for our endio.
-	 */
-	if (dio_data->sync) {
-		ASSERT(current->journal_info == NULL);
-		current->journal_info = BTRFS_DIO_SYNC_STUB;
-	}
 	kfree(dio_data);
 	iomap->private = NULL;
 
@@ -7999,30 +7978,6 @@ static blk_qc_t btrfs_submit_direct(struct inode *inode, struct iomap *iomap,
 	return BLK_QC_T_NONE;
 }
 
-static inline int btrfs_maybe_fsync_end_io(struct kiocb *iocb, ssize_t size,
-					   int error, unsigned flags)
-{
-	/*
-	 * Now if we're still in the context of our submitter we know we can't
-	 * safely run generic_write_sync(), so clear our flag here so that the
-	 * caller knows to follow up with a sync.
-	 */
-	if (current->journal_info == BTRFS_DIO_SYNC_STUB) {
-		current->journal_info = NULL;
-		return error;
-	}
-
-	if (error)
-		return error;
-
-	if (size) {
-		iocb->ki_flags |= IOCB_DSYNC;
-		return generic_write_sync(iocb, size);
-	}
-
-	return 0;
-}
-
 const struct iomap_ops btrfs_dio_iomap_ops = {
 	.iomap_begin            = btrfs_dio_iomap_begin,
 	.iomap_end              = btrfs_dio_iomap_end,
@@ -8032,11 +7987,6 @@ const struct iomap_dio_ops btrfs_dio_ops = {
 	.submit_io		= btrfs_submit_direct,
 };
 
-const struct iomap_dio_ops btrfs_sync_dops = {
-	.submit_io		= btrfs_submit_direct,
-	.end_io			= btrfs_maybe_fsync_end_io,
-};
-
 static int btrfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 			u64 start, u64 len)
 {

fs/btrfs/transaction.h

@@ -112,7 +112,6 @@ struct btrfs_transaction {
 #define TRANS_EXTWRITERS	(__TRANS_START | __TRANS_ATTACH)
 
 #define BTRFS_SEND_TRANS_STUB	((void *)1)
-#define BTRFS_DIO_SYNC_STUB	((void *)2)
 
 struct btrfs_trans_handle {
 	u64 transid;