linux-ext4 - Re: [PATCH] ext4: Optimize ext4 DIO overwrites

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Date:   Thu, 26 Dec 2019 12:17:31 -0500
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Jan Kara <jack@...e.cz>
Cc:     Ritesh Harjani <riteshh@...ux.ibm.com>, linux-ext4@...r.kernel.org,
        Dan Williams <dan.j.williams@...el.com>,
        "Berrocal, Eduardo" <eduardo.berrocal@...el.com>
Subject: Re: [PATCH] ext4: Optimize ext4 DIO overwrites

On Thu, Dec 19, 2019 at 08:28:23PM +0100, Jan Kara wrote:
> > However depending on which patch lands first one may need a
> > re-basing. Will conflict with this-
> > https://marc.info/?l=linux-ext4&m=157613016931238&w=2
> 
> Yes, but the conflict is minor and trivial to resolve.
> 

Is this the correct resolution?

--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -447,6 +447,7 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	struct inode *inode = file_inode(iocb->ki_filp);
 	loff_t offset = iocb->ki_pos;
 	size_t count = iov_iter_count(from);
+	const struct iomap_ops *iomap_ops = &ext4_iomap_ops;
 	bool extend = false, unaligned_io = false;
 	bool ilock_shared = true;
 
@@ -526,7 +527,9 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
 		ext4_journal_stop(handle);
 	}
 
-	ret = iomap_dio_rw(iocb, from, &ext4_iomap_ops, &ext4_dio_write_ops,
+	if (ilock_shared)
+		iomap_ops = &ext4_iomap_overwrite_ops;
+	ret = iomap_dio_rw(iocb, from, iomap_ops, &ext4_dio_write_ops,
 			   is_sync_kiocb(iocb) || unaligned_io || extend);
 
 	if (extend)

     	   	    	      	  - Ted