linux-kernel - [PATCH 2/4] fs/netfs: reorderd struct fields to eliminate holes

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Message-ID: <20250428154859.3228933-2-max.kellermann@ionos.com>
Date: Mon, 28 Apr 2025 17:48:57 +0200
From: Max Kellermann <max.kellermann@...os.com>
To: dhowells@...hat.com,
	netfs@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Cc: Max Kellermann <max.kellermann@...os.com>
Subject: [PATCH 2/4] fs/netfs: reorderd struct fields to eliminate holes

This shrinks `struct netfs_io_stream` from 104 to 96 bytes and `struct
netfs_io_request` from 600 to 576 bytes.

Signed-off-by: Max Kellermann <max.kellermann@...os.com>
---
 include/linux/netfs.h | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index da0d36615bef..f0436bac5b59 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -146,8 +146,8 @@ struct netfs_io_stream {
 	struct netfs_io_subrequest *front;	/* Op being collected */
 	unsigned long long	collected_to;	/* Position we've collected results to */
 	size_t			transferred;	/* The amount transferred from this stream */
-	enum netfs_io_source	source;		/* Where to read from/write to */
 	unsigned short		error;		/* Aggregate error for the stream */
+	enum netfs_io_source	source;		/* Where to read from/write to */
 	unsigned char		stream_nr;	/* Index of stream in parent table */
 	bool			avail;		/* T if stream is available */
 	bool			active;		/* T if stream is active */
@@ -243,19 +243,9 @@ struct netfs_io_request {
 	void			*netfs_priv;	/* Private data for the netfs */
 	void			*netfs_priv2;	/* Private data for the netfs */
 	struct bio_vec		*direct_bv;	/* DIO buffer list (when handling iovec-iter) */
-	unsigned int		direct_bv_count; /* Number of elements in direct_bv[] */
-	unsigned int		debug_id;
-	unsigned int		rsize;		/* Maximum read size (0 for none) */
-	unsigned int		wsize;		/* Maximum write size (0 for none) */
-	atomic_t		subreq_counter;	/* Next subreq->debug_index */
-	unsigned int		nr_group_rel;	/* Number of refs to release on ->group */
-	spinlock_t		lock;		/* Lock for queuing subreqs */
 	unsigned long long	submitted;	/* Amount submitted for I/O so far */
 	unsigned long long	len;		/* Length of the request */
 	size_t			transferred;	/* Amount to be indicated as transferred */
-	short			error;		/* 0 or error that occurred */
-	enum netfs_io_origin	origin;		/* Origin of the request */
-	bool			direct_bv_unpin; /* T if direct_bv[] must be unpinned */
 	unsigned long long	i_size;		/* Size of the file */
 	unsigned long long	start;		/* Start position */
 	atomic64_t		issued_to;	/* Write issuer folio cursor */
@@ -263,7 +253,17 @@ struct netfs_io_request {
 	unsigned long long	cleaned_to;	/* Position we've cleaned folios to */
 	unsigned long long	abandon_to;	/* Position to abandon folios to */
 	pgoff_t			no_unlock_folio; /* Don't unlock this folio after read */
+	unsigned int		direct_bv_count; /* Number of elements in direct_bv[] */
+	unsigned int		debug_id;
+	unsigned int		rsize;		/* Maximum read size (0 for none) */
+	unsigned int		wsize;		/* Maximum write size (0 for none) */
+	atomic_t		subreq_counter;	/* Next subreq->debug_index */
+	unsigned int		nr_group_rel;	/* Number of refs to release on ->group */
+	spinlock_t		lock;		/* Lock for queuing subreqs */
+	short			error;		/* 0 or error that occurred */
 	unsigned char		front_folio_order; /* Order (size) of front folio */
+	enum netfs_io_origin	origin;		/* Origin of the request */
+	bool			direct_bv_unpin; /* T if direct_bv[] must be unpinned */
 	refcount_t		ref;
 	unsigned long		flags;
 #define NETFS_RREQ_OFFLOAD_COLLECTION	0	/* Offload collection to workqueue */
-- 
2.47.2