netfs: Merge i_size update functions

Netfslib has two functions for updating the i_size after a write: one for
buffered writes into the pagecache and one for direct/unbuffered writes.
However, what needs to be done is much the same in both cases, so merge
them together.

This does raise one question, though: should updating the i_size after a
direct write do the same estimated update of i_blocks as is done for
buffered writes.

Also get rid of the cleanup function pointer from netfs_io_request as it's
only used for direct write to update i_size; instead do the i_size setting
directly from write collection.

Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/20250701163852.2171681-12-dhowells@redhat.com
cc: Steve French <sfrench@samba.org>
cc: Paulo Alcantara <pc@manguebit.org>
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

1 files changed, 21 insertions, 15 deletions

diff --git a/fs/netfs/buffered_write.c b/fs/netfs/buffered_write.c
index b87ef3fe4ea4..f27ea5099a68 100644
--- a/fs/netfs/buffered_write.c
+++ b/fs/netfs/buffered_write.c
@@ -53,30 +53,38 @@ static struct folio *netfs_grab_folio_for_write(struct address_space *mapping,
  * 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)
+void netfs_update_i_size(struct netfs_inode *ctx, struct inode *inode,
+			 loff_t pos, size_t copied)
 {
+	loff_t i_size, end = pos + copied;
 	blkcnt_t add;
 	size_t gap;
 
+	if (end <= i_size_read(inode))
+		return;
+
 	if (ctx->ops->update_i_size) {
-		ctx->ops->update_i_size(inode, pos);
+		ctx->ops->update_i_size(inode, end);
 		return;
 	}
 
 	spin_lock(&inode->i_lock);
-	i_size_write(inode, pos);
+
+	i_size = i_size_read(inode);
+	if (end > i_size) {
+		i_size_write(inode, end);
 #if IS_ENABLED(CONFIG_FSCACHE)
-	fscache_update_cookie(ctx->cache, NULL, &pos);
+		fscache_update_cookie(ctx->cache, NULL, &end);
 #endif
 
-	gap = SECTOR_SIZE - (i_size & (SECTOR_SIZE - 1));
-	if (copied > gap) {
-		add = DIV_ROUND_UP(copied - gap, SECTOR_SIZE);
+		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);
+			inode->i_blocks = min_t(blkcnt_t,
+						DIV_ROUND_UP(end, SECTOR_SIZE),
+						inode->i_blocks + add);
+		}
 	}
 	spin_unlock(&inode->i_lock);
 }
@@ -113,7 +121,7 @@ ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
 	struct folio *folio = NULL, *writethrough = NULL;
 	unsigned int bdp_flags = (iocb->ki_flags & IOCB_NOWAIT) ? BDP_ASYNC : 0;
 	ssize_t written = 0, ret, ret2;
-	loff_t i_size, pos = iocb->ki_pos;
+	loff_t pos = iocb->ki_pos;
 	size_t max_chunk = mapping_max_folio_size(mapping);
 	bool maybe_trouble = false;
 
@@ -346,10 +354,8 @@ ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
 		flush_dcache_folio(folio);
 
 		/* Update the inode size if we moved the EOF marker */
+		netfs_update_i_size(ctx, inode, pos, copied);
 		pos += copied;
-		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)) {