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From: David Howells <dhowells@redhat.com>
To: Christian Brauner <christian@brauner.io>,
	Jeff Layton <jlayton@kernel.org>,
	Gao Xiang <hsiangkao@linux.alibaba.com>,
	Dominique Martinet <asmadeus@codewreck.org>
Cc: David Howells <dhowells@redhat.com>,
	Matthew Wilcox <willy@infradead.org>,
	Steve French <smfrench@gmail.com>,
	Marc Dionne <marc.dionne@auristor.com>,
	Paulo Alcantara <pc@manguebit.com>,
	Shyam Prasad N <sprasad@microsoft.com>,
	Tom Talpey <tom@talpey.com>,
	Eric Van Hensbergen <ericvh@kernel.org>,
	Ilya Dryomov <idryomov@gmail.com>,
	netfs@lists.linux.dev,
	linux-cachefs@redhat.com,
	linux-afs@lists.infradead.org,
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	ceph-devel@vger.kernel.org,
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	Steve French <sfrench@samba.org>,
	Shyam Prasad N <nspmangalore@gmail.com>,
	Rohith Surabattula <rohiths.msft@gmail.com>
Subject: [PATCH v2 01/22] netfs: Update i_blocks when write committed to pagecache
Date: Tue, 30 Apr 2024 15:00:32 +0100
Message-ID: <20240430140056.261997-2-dhowells@redhat.com>
In-Reply-To: <20240430140056.261997-1-dhowells@redhat.com>
References: <20240430140056.261997-1-dhowells@redhat.com>
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Update i_blocks when i_size is updated when we finish making a write to the
pagecache to reflect the amount of space we think will be consumed.

This maintains cifs commit dbfdff402d89854126658376cbcb08363194d3cd ("smb3:
update allocation size more accurately on write completion") which would
otherwise be removed by the cifs part of the netfs writeback rewrite.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: Steve French <sfrench@samba.org>
cc: Shyam Prasad N <nspmangalore@gmail.com>
cc: Rohith Surabattula <rohiths.msft@gmail.com>
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
---
 fs/netfs/buffered_write.c | 45 +++++++++++++++++++++++++++++----------
 1 file changed, 34 insertions(+), 11 deletions(-)

diff --git a/fs/netfs/buffered_write.c b/fs/netfs/buffered_write.c
index 267b622d923b..f7455a579f21 100644
--- a/fs/netfs/buffered_write.c
+++ b/fs/netfs/buffered_write.c
@@ -130,6 +130,37 @@ static struct folio *netfs_grab_folio_for_write(struct address_space *mapping,
 				   mapping_gfp_mask(mapping));
 }
 
+/*
+ * Update i_size and estimate the update to i_blocks to reflect the additional
+ * data written into the pagecache until we can find out from the server what
+ * the values actually are.
+ */
+static void netfs_update_i_size(struct netfs_inode *ctx, struct inode *inode,
+				loff_t i_size, loff_t pos, size_t copied)
+{
+	blkcnt_t add;
+	size_t gap;
+
+	if (ctx->ops->update_i_size) {
+		ctx->ops->update_i_size(inode, pos);
+		return;
+	}
+
+	i_size_write(inode, pos);
+#if IS_ENABLED(CONFIG_FSCACHE)
+	fscache_update_cookie(ctx->cache, NULL, &pos);
+#endif
+
+	gap = SECTOR_SIZE - (i_size & (SECTOR_SIZE - 1));
+	if (copied > gap) {
+		add = DIV_ROUND_UP(copied - gap, SECTOR_SIZE);
+
+		inode->i_blocks = min_t(blkcnt_t,
+					DIV_ROUND_UP(pos, SECTOR_SIZE),
+					inode->i_blocks + add);
+	}
+}
+
 /**
  * netfs_perform_write - Copy data into the pagecache.
  * @iocb: The operation parameters
@@ -351,18 +382,10 @@ ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
 		trace_netfs_folio(folio, trace);
 
 		/* Update the inode size if we moved the EOF marker */
-		i_size = i_size_read(inode);
 		pos += copied;
-		if (pos > i_size) {
-			if (ctx->ops->update_i_size) {
-				ctx->ops->update_i_size(inode, pos);
-			} else {
-				i_size_write(inode, pos);
-#if IS_ENABLED(CONFIG_FSCACHE)
-				fscache_update_cookie(ctx->cache, NULL, &pos);
-#endif
-			}
-		}
+		i_size = i_size_read(inode);
+		if (pos > i_size)
+			netfs_update_i_size(ctx, inode, i_size, pos, copied);
 		written += copied;
 
 		if (likely(!wreq)) {