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Message-ID: <20250430051822.GY25675@frogsfrogsfrogs>
Date: Tue, 29 Apr 2025 22:18:22 -0700
From: "Darrick J. Wong" <djwong@...nel.org>
To: John Garry <john.g.garry@...cle.com>
Cc: brauner@...nel.org, hch@....de, viro@...iv.linux.org.uk, jack@...e.cz,
cem@...nel.org, linux-fsdevel@...r.kernel.org, dchinner@...hat.com,
linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org,
ojaswin@...ux.ibm.com, ritesh.list@...il.com,
martin.petersen@...cle.com, linux-ext4@...r.kernel.org,
linux-block@...r.kernel.org, catherine.hoang@...cle.com,
linux-api@...r.kernel.org
Subject: [PATCH v9.1 05/15] xfs: ignore HW which cannot atomic write a single
block
From: Darrick J. Wong <djwong@...nel.org>
Currently only HW which can write at least 1x block is supported.
For supporting atomic writes > 1x block, a CoW-based method will also be
used and this will not be resticted to using HW which can write >= 1x
block.
However for deciding if HW-based atomic writes can be used, we need to
start adding checks for write length < HW min, which complicates the
code. Indeed, a statx field similar to unit_max_opt should also be
added for this minimum, which is undesirable.
HW which can only write > 1x blocks would be uncommon and quite weird,
so let's just not support it.
Signed-off-by: "Darrick J. Wong" <djwong@...nel.org>
---
v9.1: move the atomic hw geometry calls to xfs_setup_devices
---
fs/xfs/xfs_buf.h | 3 ++-
fs/xfs/xfs_inode.h | 14 ++------------
fs/xfs/xfs_buf.c | 41 ++++++++++++++++++++++++++++++++++-------
fs/xfs/xfs_super.c | 6 +++++-
4 files changed, 43 insertions(+), 21 deletions(-)
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index d0b065a9a9f0d2..6f691779887f77 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -112,7 +112,7 @@ struct xfs_buftarg {
struct percpu_counter bt_readahead_count;
struct ratelimit_state bt_ioerror_rl;
- /* Atomic write unit values */
+ /* Atomic write unit values, bytes */
unsigned int bt_bdev_awu_min;
unsigned int bt_bdev_awu_max;
@@ -375,6 +375,7 @@ extern void xfs_free_buftarg(struct xfs_buftarg *);
extern void xfs_buftarg_wait(struct xfs_buftarg *);
extern void xfs_buftarg_drain(struct xfs_buftarg *);
extern int xfs_setsize_buftarg(struct xfs_buftarg *, unsigned int);
+void xfs_buftarg_config_atomic_writes(struct xfs_buftarg *btp);
#define xfs_getsize_buftarg(buftarg) block_size((buftarg)->bt_bdev)
#define xfs_readonly_buftarg(buftarg) bdev_read_only((buftarg)->bt_bdev)
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index bdbbff0d8d9920..d7e2b902ef5c97 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -356,19 +356,9 @@ static inline bool xfs_inode_has_bigrtalloc(const struct xfs_inode *ip)
(XFS_IS_REALTIME_INODE(ip) ? \
(ip)->i_mount->m_rtdev_targp : (ip)->i_mount->m_ddev_targp)
-static inline bool
-xfs_inode_can_hw_atomic_write(
- struct xfs_inode *ip)
+static inline bool xfs_inode_can_hw_atomic_write(const struct xfs_inode *ip)
{
- struct xfs_mount *mp = ip->i_mount;
- struct xfs_buftarg *target = xfs_inode_buftarg(ip);
-
- if (mp->m_sb.sb_blocksize < target->bt_bdev_awu_min)
- return false;
- if (mp->m_sb.sb_blocksize > target->bt_bdev_awu_max)
- return false;
-
- return true;
+ return xfs_inode_buftarg(ip)->bt_bdev_awu_max > 0;
}
/*
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 5ae77ffdc947b1..c1bd5654c3afa8 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1779,6 +1779,40 @@ xfs_init_buftarg(
return -ENOMEM;
}
+/*
+ * Configure this buffer target for hardware-assisted atomic writes if the
+ * underlying block device supports is congruent with the filesystem geometry.
+ */
+void
+xfs_buftarg_config_atomic_writes(
+ struct xfs_buftarg *btp)
+{
+ struct xfs_mount *mp = btp->bt_mount;
+ unsigned int min_bytes, max_bytes;
+
+ ASSERT(btp->bt_bdev != NULL);
+
+ if (!bdev_can_atomic_write(btp->bt_bdev))
+ return;
+
+ min_bytes = bdev_atomic_write_unit_min_bytes(btp->bt_bdev);
+ max_bytes = bdev_atomic_write_unit_max_bytes(btp->bt_bdev);
+
+ /*
+ * Ignore atomic write geometry that is nonsense or doesn't even cover
+ * a single fsblock.
+ */
+ if (min_bytes > max_bytes ||
+ min_bytes > mp->m_sb.sb_blocksize ||
+ max_bytes < mp->m_sb.sb_blocksize) {
+ min_bytes = 0;
+ max_bytes = 0;
+ }
+
+ btp->bt_bdev_awu_min = min_bytes;
+ btp->bt_bdev_awu_max = max_bytes;
+}
+
struct xfs_buftarg *
xfs_alloc_buftarg(
struct xfs_mount *mp,
@@ -1799,13 +1833,6 @@ 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)) {
- btp->bt_bdev_awu_min = bdev_atomic_write_unit_min_bytes(
- btp->bt_bdev);
- btp->bt_bdev_awu_max = bdev_atomic_write_unit_max_bytes(
- btp->bt_bdev);
- }
-
/*
* When allocating the buftargs we have not yet read the super block and
* thus don't know the file system sector size yet.
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index b2dd0c0bf50979..af4c541251d859 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -520,7 +520,8 @@ xfs_open_devices(
}
/*
- * Setup xfs_mount buffer target pointers based on superblock
+ * Setup xfs_mount buffer target pointers based on superblock, and configure
+ * the atomic write capabilities now that we've validated the blocksize.
*/
STATIC int
xfs_setup_devices(
@@ -531,6 +532,7 @@ xfs_setup_devices(
error = xfs_setsize_buftarg(mp->m_ddev_targp, mp->m_sb.sb_sectsize);
if (error)
return error;
+ xfs_buftarg_config_atomic_writes(mp->m_ddev_targp);
if (mp->m_logdev_targp && mp->m_logdev_targp != mp->m_ddev_targp) {
unsigned int log_sector_size = BBSIZE;
@@ -541,6 +543,7 @@ xfs_setup_devices(
log_sector_size);
if (error)
return error;
+ xfs_buftarg_config_atomic_writes(mp->m_logdev_targp);
}
if (mp->m_sb.sb_rtstart) {
@@ -555,6 +558,7 @@ xfs_setup_devices(
mp->m_sb.sb_sectsize);
if (error)
return error;
+ xfs_buftarg_config_atomic_writes(mp->m_rtdev_targp);
}
return 0;
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