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From: John Garry <john.g.garry@oracle.com>
To: david@fromorbit.com, djwong@kernel.org, hch@lst.de,
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Cc: axboe@kernel.dk, martin.petersen@oracle.com, linux-kernel@vger.kernel.org,
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        p.raghav@samsung.com, linux-xfs@vger.kernel.org,
        catherine.hoang@oracle.com, John Garry <john.g.garry@oracle.com>
Subject: [PATCH v3 18/21] xfs: Support FS_XFLAG_ATOMICWRITES for forcealign
Date: Mon, 29 Apr 2024 17:47:43 +0000
Message-Id: <20240429174746.2132161-19-john.g.garry@oracle.com>
In-Reply-To: <20240429174746.2132161-1-john.g.garry@oracle.com>
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Add initial support for FS_XFLAG_ATOMICWRITES for forcealign enabled.

Current kernel support for atomic writes is based on HW support (for atomic
writes). As such, it is required to ensure extent alignment with
atomic_write_unit_max so that an atomic write can result in a single
HW-compliant IO operation.

rtvol also guarantees extent alignment, but we are basing support initially
on forcealign, which is not supported for rtvol yet.

Signed-off-by: John Garry <john.g.garry@oracle.com>
---
 fs/xfs/libxfs/xfs_format.h    | 11 +++++++++--
 fs/xfs/libxfs/xfs_inode_buf.c | 36 +++++++++++++++++++++++++++++++++++
 fs/xfs/libxfs/xfs_sb.c        |  2 ++
 fs/xfs/xfs_buf.c              | 15 ++++++++++++++-
 fs/xfs/xfs_buf.h              |  4 +++-
 fs/xfs/xfs_inode.c            |  2 ++
 fs/xfs/xfs_inode.h            |  5 +++++
 fs/xfs/xfs_ioctl.c            | 21 ++++++++++++++++++--
 fs/xfs/xfs_mount.h            |  2 ++
 fs/xfs/xfs_super.c            |  4 ++++
 10 files changed, 96 insertions(+), 6 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index 0c73b96dbefc..8e32fb068430 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -354,12 +354,16 @@ xfs_sb_has_compat_feature(
 #define XFS_SB_FEAT_RO_COMPAT_REFLINK  (1 << 2)		/* reflinked files */
 #define XFS_SB_FEAT_RO_COMPAT_INOBTCNT (1 << 3)		/* inobt block counts */
 #define XFS_SB_FEAT_RO_COMPAT_FORCEALIGN (1 << 30)	/* aligned file data extents */
+#define XFS_SB_FEAT_RO_COMPAT_ATOMICWRITES (1 << 31)	/* atomicwrites enabled */
+
 #define XFS_SB_FEAT_RO_COMPAT_ALL \
 		(XFS_SB_FEAT_RO_COMPAT_FINOBT | \
 		 XFS_SB_FEAT_RO_COMPAT_RMAPBT | \
 		 XFS_SB_FEAT_RO_COMPAT_REFLINK| \
 		 XFS_SB_FEAT_RO_COMPAT_INOBTCNT | \
-		 XFS_SB_FEAT_RO_COMPAT_FORCEALIGN)
+		 XFS_SB_FEAT_RO_COMPAT_FORCEALIGN | \
+		 XFS_SB_FEAT_RO_COMPAT_ATOMICWRITES)
+
 #define XFS_SB_FEAT_RO_COMPAT_UNKNOWN	~XFS_SB_FEAT_RO_COMPAT_ALL
 static inline bool
 xfs_sb_has_ro_compat_feature(
@@ -1088,6 +1092,7 @@ static inline void xfs_dinode_put_rdev(struct xfs_dinode *dip, xfs_dev_t rdev)
 #define XFS_DIFLAG2_NREXT64_BIT 4	/* large extent counters */
 /* data extent mappings for regular files must be aligned to extent size hint */
 #define XFS_DIFLAG2_FORCEALIGN_BIT 5
+#define XFS_DIFLAG2_ATOMICWRITES_BIT 6
 
 #define XFS_DIFLAG2_DAX		(1 << XFS_DIFLAG2_DAX_BIT)
 #define XFS_DIFLAG2_REFLINK     (1 << XFS_DIFLAG2_REFLINK_BIT)
@@ -1095,10 +1100,12 @@ static inline void xfs_dinode_put_rdev(struct xfs_dinode *dip, xfs_dev_t rdev)
 #define XFS_DIFLAG2_BIGTIME	(1 << XFS_DIFLAG2_BIGTIME_BIT)
 #define XFS_DIFLAG2_NREXT64	(1 << XFS_DIFLAG2_NREXT64_BIT)
 #define XFS_DIFLAG2_FORCEALIGN	(1 << XFS_DIFLAG2_FORCEALIGN_BIT)
+#define XFS_DIFLAG2_ATOMICWRITES	(1 << XFS_DIFLAG2_ATOMICWRITES_BIT)
 
 #define XFS_DIFLAG2_ANY \
 	(XFS_DIFLAG2_DAX | XFS_DIFLAG2_REFLINK | XFS_DIFLAG2_COWEXTSIZE | \
-	 XFS_DIFLAG2_BIGTIME | XFS_DIFLAG2_NREXT64 | XFS_DIFLAG2_FORCEALIGN)
+	 XFS_DIFLAG2_BIGTIME | XFS_DIFLAG2_NREXT64 | XFS_DIFLAG2_FORCEALIGN | \
+	 XFS_DIFLAG2_ATOMICWRITES)
 
 static inline bool xfs_dinode_has_bigtime(const struct xfs_dinode *dip)
 {
diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c
index 12f128f12824..5e42ec1dadb6 100644
--- a/fs/xfs/libxfs/xfs_inode_buf.c
+++ b/fs/xfs/libxfs/xfs_inode_buf.c
@@ -178,7 +178,10 @@ xfs_inode_from_disk(
 	struct xfs_inode	*ip,
 	struct xfs_dinode	*from)
 {
+	struct xfs_buftarg	*target = xfs_inode_buftarg(ip);
 	struct inode		*inode = VFS_I(ip);
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_sb		*sbp = &mp->m_sb;
 	int			error;
 	xfs_failaddr_t		fa;
 
@@ -261,6 +264,13 @@ xfs_inode_from_disk(
 	}
 	if (xfs_is_reflink_inode(ip))
 		xfs_ifork_init_cow(ip);
+
+	if (xfs_inode_has_atomicwrites(ip)) {
+		if (sbp->sb_blocksize < target->bt_bdev_awu_min ||
+		    sbp->sb_blocksize * ip->i_extsize > target->bt_bdev_awu_max)
+			ip->i_diflags2 &= ~XFS_DIFLAG2_ATOMICWRITES;
+	}
+
 	return 0;
 
 out_destroy_data_fork:
@@ -460,6 +470,25 @@ xfs_dinode_verify_nrext64(
 	return NULL;
 }
 
+static xfs_failaddr_t
+xfs_inode_validate_atomicwrites(
+	struct xfs_mount	*mp,
+	bool			forcealign)
+{
+	/* superblock rocompat feature flag */
+	if (!xfs_has_atomicwrites(mp))
+		return __this_address;
+
+	/*
+	 * forcealign is required, so rely on sanity checks in
+	 * xfs_inode_validate_forcealign()
+	 */
+	if (!forcealign)
+		return __this_address;
+
+	return NULL;
+}
+
 xfs_failaddr_t
 xfs_dinode_verify(
 	struct xfs_mount	*mp,
@@ -624,6 +653,13 @@ xfs_dinode_verify(
 			return fa;
 	}
 
+	if (flags2 & XFS_DIFLAG2_ATOMICWRITES) {
+		fa = xfs_inode_validate_atomicwrites(mp,
+			flags2 & XFS_DIFLAG2_FORCEALIGN);
+		if (fa)
+			return fa;
+	}
+
 	return NULL;
 }
 
diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
index e746c57c4cc4..a9ae8ab7d610 100644
--- a/fs/xfs/libxfs/xfs_sb.c
+++ b/fs/xfs/libxfs/xfs_sb.c
@@ -165,6 +165,8 @@ xfs_sb_version_to_features(
 		features |= XFS_FEAT_INOBTCNT;
 	if (sbp->sb_features_ro_compat & XFS_SB_FEAT_RO_COMPAT_FORCEALIGN)
 		features |= XFS_FEAT_FORCEALIGN;
+	if (sbp->sb_features_ro_compat & XFS_SB_FEAT_RO_COMPAT_ATOMICWRITES)
+		features |= XFS_FEAT_ATOMICWRITES;
 	if (sbp->sb_features_incompat & XFS_SB_FEAT_INCOMPAT_FTYPE)
 		features |= XFS_FEAT_FTYPE;
 	if (sbp->sb_features_incompat & XFS_SB_FEAT_INCOMPAT_SPINODES)
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 1a18c381127e..6e7ac6c90ec1 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -2057,6 +2057,8 @@ int
 xfs_init_buftarg(
 	struct xfs_buftarg		*btp,
 	size_t				logical_sectorsize,
+	unsigned int			awu_min,
+	unsigned int			awu_max,
 	const char			*descr)
 {
 	/* Set up device logical sector size mask */
@@ -2083,6 +2085,9 @@ xfs_init_buftarg(
 	btp->bt_shrinker->scan_objects = xfs_buftarg_shrink_scan;
 	btp->bt_shrinker->private_data = btp;
 	shrinker_register(btp->bt_shrinker);
+
+	btp->bt_bdev_awu_min = awu_min;
+	btp->bt_bdev_awu_max = awu_max;
 	return 0;
 
 out_destroy_io_count:
@@ -2099,6 +2104,7 @@ xfs_alloc_buftarg(
 {
 	struct xfs_buftarg	*btp;
 	const struct dax_holder_operations *ops = NULL;
+	unsigned int awu_min = 0, awu_max = 0;
 
 #if defined(CONFIG_FS_DAX) && defined(CONFIG_MEMORY_FAILURE)
 	ops = &xfs_dax_holder_operations;
@@ -2112,6 +2118,13 @@ xfs_alloc_buftarg(
 	btp->bt_daxdev = fs_dax_get_by_bdev(btp->bt_bdev, &btp->bt_dax_part_off,
 					    mp, ops);
 
+	if (bdev_can_atomic_write(btp->bt_bdev)) {
+		struct request_queue *q = bdev_get_queue(btp->bt_bdev);
+
+		awu_min = queue_atomic_write_unit_min_bytes(q);
+		awu_max = queue_atomic_write_unit_max_bytes(q);
+	}
+
 	/*
 	 * When allocating the buftargs we have not yet read the super block and
 	 * thus don't know the file system sector size yet.
@@ -2119,7 +2132,7 @@ xfs_alloc_buftarg(
 	if (xfs_setsize_buftarg(btp, bdev_logical_block_size(btp->bt_bdev)))
 		goto error_free;
 	if (xfs_init_buftarg(btp, bdev_logical_block_size(btp->bt_bdev),
-			mp->m_super->s_id))
+			awu_min, awu_max, mp->m_super->s_id))
 		goto error_free;
 
 	return btp;
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index b1580644501f..3bcd8137d739 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -124,6 +124,8 @@ struct xfs_buftarg {
 	struct percpu_counter	bt_io_count;
 	struct ratelimit_state	bt_ioerror_rl;
 
+	unsigned int		bt_bdev_awu_min, bt_bdev_awu_max;
+
 	/* built-in cache, if we're not using the perag one */
 	struct xfs_buf_cache	bt_cache[];
 };
@@ -393,7 +395,7 @@ bool xfs_verify_magic16(struct xfs_buf *bp, __be16 dmagic);
 
 /* for xfs_buf_mem.c only: */
 int xfs_init_buftarg(struct xfs_buftarg *btp, size_t logical_sectorsize,
-		const char *descr);
+		unsigned int awu_min, unsigned int awu_max, const char *descr);
 void xfs_destroy_buftarg(struct xfs_buftarg *btp);
 
 #endif	/* __XFS_BUF_H__ */
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index db5a0f66a121..d674fca22de9 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -609,6 +609,8 @@ xfs_ip2xflags(
 			flags |= FS_XFLAG_COWEXTSIZE;
 		if (ip->i_diflags2 & XFS_DIFLAG2_FORCEALIGN)
 			flags |= FS_XFLAG_FORCEALIGN;
+		if (ip->i_diflags2 & XFS_DIFLAG2_ATOMICWRITES)
+			flags |= FS_XFLAG_ATOMICWRITES;
 	}
 
 	if (xfs_inode_has_attr_fork(ip))
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 3f13943ab3a3..d796456215e2 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -321,6 +321,11 @@ static inline bool xfs_inode_has_extsize(struct xfs_inode *ip)
 	return ip->i_diflags & XFS_DIFLAG_EXTSIZE;
 }
 
+static inline bool xfs_inode_has_atomicwrites(struct xfs_inode *ip)
+{
+	return ip->i_diflags2 & XFS_DIFLAG2_ATOMICWRITES;
+}
+
 /*
  * Return the buftarg used for data allocations on a given inode.
  */
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index d1126509ceb9..94a6d9f6d0d8 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -1112,6 +1112,8 @@ xfs_flags2diflags2(
 		di_flags2 |= XFS_DIFLAG2_COWEXTSIZE;
 	if (xflags & FS_XFLAG_FORCEALIGN)
 		di_flags2 |= XFS_DIFLAG2_FORCEALIGN;
+	if (xflags & FS_XFLAG_ATOMICWRITES)
+		di_flags2 |= XFS_DIFLAG2_ATOMICWRITES;
 
 	return di_flags2;
 }
@@ -1122,12 +1124,16 @@ xfs_ioctl_setattr_xflags(
 	struct xfs_inode	*ip,
 	struct fileattr		*fa)
 {
+	struct xfs_buftarg	*target = xfs_inode_buftarg(ip);
 	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_sb		*sbp = &mp->m_sb;
 	bool			rtflag = (fa->fsx_xflags & FS_XFLAG_REALTIME);
+	bool			atomic_writes = fa->fsx_xflags & FS_XFLAG_ATOMICWRITES;
 	uint64_t		i_flags2;
 
-	if (rtflag != XFS_IS_REALTIME_INODE(ip)) {
-		/* Can't change realtime flag if any extents are allocated. */
+	/* Can't change RT or atomic flags if any extents are allocated. */
+	if (rtflag != XFS_IS_REALTIME_INODE(ip) ||
+	    atomic_writes != xfs_inode_has_atomicwrites(ip)) {
 		if (ip->i_df.if_nextents || ip->i_delayed_blks)
 			return -EINVAL;
 	}
@@ -1164,6 +1170,17 @@ xfs_ioctl_setattr_xflags(
 			return -EINVAL;
 	}
 
+	if (atomic_writes) {
+		if (!xfs_has_atomicwrites(mp))
+			return -EINVAL;
+		if (target->bt_bdev_awu_min > sbp->sb_blocksize)
+			return -EINVAL;
+		if (target->bt_bdev_awu_max < fa->fsx_extsize)
+			return -EINVAL;
+		if (!(fa->fsx_xflags & FS_XFLAG_FORCEALIGN))
+			return -EINVAL;
+	}
+
 	ip->i_diflags = xfs_flags2diflags(ip, fa->fsx_xflags);
 	ip->i_diflags2 = i_flags2;
 
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index a8266cf654c4..5856a72d431e 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -293,6 +293,7 @@ typedef struct xfs_mount {
 #define XFS_FEAT_NEEDSREPAIR	(1ULL << 25)	/* needs xfs_repair */
 #define XFS_FEAT_NREXT64	(1ULL << 26)	/* large extent counters */
 #define XFS_FEAT_FORCEALIGN	(1ULL << 27)	/* aligned file data extents */
+#define XFS_FEAT_ATOMICWRITES	(1ULL << 28)	/* atomic writes support */
 
 /* Mount features */
 #define XFS_FEAT_NOATTR2	(1ULL << 48)	/* disable attr2 creation */
@@ -357,6 +358,7 @@ __XFS_HAS_FEAT(bigtime, BIGTIME)
 __XFS_HAS_FEAT(needsrepair, NEEDSREPAIR)
 __XFS_HAS_FEAT(large_extent_counts, NREXT64)
 __XFS_HAS_FEAT(forcealign, FORCEALIGN)
+__XFS_HAS_FEAT(atomicwrites, ATOMICWRITES)
 
 /*
  * Mount features
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 63d4312785ef..757c90b3d71b 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1710,6 +1710,10 @@ xfs_fs_fill_super(
 		xfs_warn(mp,
 "EXPERIMENTAL forced data extent alignment feature in use. Use at your own risk!");
 
+	if (xfs_has_atomicwrites(mp))
+		xfs_warn(mp,
+"EXPERIMENTAL atomicwrites feature in use. Use at your own risk!");
+
 	if (xfs_has_reflink(mp)) {
 		if (mp->m_sb.sb_rblocks) {
 			xfs_alert(mp,
-- 
2.31.1