[PATCH RFC v5 10/10] iomap: Rename ATOMIC flags again

From: John Garry
Date: Mon Mar 10 2025 - 14:42:56 EST

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Dave Chinner thought that names IOMAP_ATOMIC_HW and IOMAP_ATOMIC_SW were
not appropopiate. Specifically because IOMAP_ATOMIC_HW could actually be
realised with a SW-based method in the block or md/dm layers.

So rename to IOMAP_ATOMIC_BIO and IOMAP_ATOMIC_FS.

Also renumber the flags so that the atomic flags are adjacent.

Signed-off-by: John Garry <john.g.garry@xxxxxxxxxx>
---
Documentation/filesystems/iomap/operations.rst | 6 +++---
fs/ext4/inode.c | 2 +-
fs/iomap/direct-io.c | 18 +++++++++---------
fs/iomap/trace.h | 3 ++-
fs/xfs/xfs_file.c | 4 ++--
fs/xfs/xfs_iomap.c | 10 +++++-----
include/linux/iomap.h | 10 +++++-----
7 files changed, 27 insertions(+), 26 deletions(-)

diff --git a/Documentation/filesystems/iomap/operations.rst b/Documentation/filesystems/iomap/operations.rst
index b08a79d11d9f..f1d9aa767d30 100644
--- a/Documentation/filesystems/iomap/operations.rst
+++ b/Documentation/filesystems/iomap/operations.rst
@@ -514,7 +514,7 @@ IOMAP_WRITE`` with any combination of the following enhancements:
if the mapping is unwritten and the filesystem cannot handle zeroing
the unaligned regions without exposing stale contents.

- * ``IOMAP_ATOMIC_HW``: This write is being issued with torn-write
+ * ``IOMAP_BIO_ATOMIC``: This write is being issued with torn-write
protection based on HW-offload support.
Only a single bio can be created for the write, and the write must
not be split into multiple I/O requests, i.e. flag REQ_ATOMIC must be
@@ -530,10 +530,10 @@ IOMAP_WRITE`` with any combination of the following enhancements:
the mapping start disk block must have at least the same alignment as
the write offset.

- * ``IOMAP_ATOMIC_SW``: This write is being issued with torn-write
+ * ``IOMAP_FS_ATOMIC``: This write is being issued with torn-write
protection via a software mechanism provided by the filesystem.
All the disk block alignment and single bio restrictions which apply
- to IOMAP_ATOMIC_HW do not apply here.
+ to IOMAP_BIO_ATOMIC do not apply here.
SW-based untorn writes would typically be used as a fallback when
HW-based untorn writes may not be issued, e.g. the range of the write
covers multiple extents, meaning that it is not possible to issue
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index ba2f1e3db7c7..da385862c1b5 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3467,7 +3467,7 @@ static inline bool ext4_want_directio_fallback(unsigned flags, ssize_t written)
return false;

/* atomic writes are all-or-nothing */
- if (flags & IOMAP_ATOMIC_HW)
+ if (flags & IOMAP_BIO_ATOMIC)
return false;

/* can only try again if we wrote nothing */
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 5299f70428ef..d728d894bd90 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -317,7 +317,7 @@ static int iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio,
* clearing the WRITE_THROUGH flag in the dio request.
*/
static inline blk_opf_t iomap_dio_bio_opflags(struct iomap_dio *dio,
- const struct iomap *iomap, bool use_fua, bool atomic_hw)
+ const struct iomap *iomap, bool use_fua, bool bio_atomic)
{
blk_opf_t opflags = REQ_SYNC | REQ_IDLE;

@@ -329,7 +329,7 @@ static inline blk_opf_t iomap_dio_bio_opflags(struct iomap_dio *dio,
opflags |= REQ_FUA;
else
dio->flags &= ~IOMAP_DIO_WRITE_THROUGH;
- if (atomic_hw)
+ if (bio_atomic)
opflags |= REQ_ATOMIC;

return opflags;
@@ -340,7 +340,7 @@ static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio)
const struct iomap *iomap = &iter->iomap;
struct inode *inode = iter->inode;
unsigned int fs_block_size = i_blocksize(inode), pad;
- bool atomic_hw = iter->flags & IOMAP_ATOMIC_HW;
+ bool bio_atomic = iter->flags & IOMAP_BIO_ATOMIC;
const loff_t length = iomap_length(iter);
loff_t pos = iter->pos;
blk_opf_t bio_opf;
@@ -351,7 +351,7 @@ static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio)
u64 copied = 0;
size_t orig_count;

- if (atomic_hw && length != iter->len)
+ if (bio_atomic && length != iter->len)
return -EINVAL;

if ((pos | length) & (bdev_logical_block_size(iomap->bdev) - 1) ||
@@ -428,7 +428,7 @@ static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio)
goto out;
}

- bio_opf = iomap_dio_bio_opflags(dio, iomap, use_fua, atomic_hw);
+ bio_opf = iomap_dio_bio_opflags(dio, iomap, use_fua, bio_atomic);

nr_pages = bio_iov_vecs_to_alloc(dio->submit.iter, BIO_MAX_VECS);
do {
@@ -461,7 +461,7 @@ static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio)
}

n = bio->bi_iter.bi_size;
- if (WARN_ON_ONCE(atomic_hw && n != length)) {
+ if (WARN_ON_ONCE(bio_atomic && n != length)) {
/*
* This bio should have covered the complete length,
* which it doesn't, so error. We may need to zero out
@@ -686,10 +686,10 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
iomi.flags |= IOMAP_OVERWRITE_ONLY;
}

- if (dio_flags & IOMAP_DIO_ATOMIC_SW)
- iomi.flags |= IOMAP_ATOMIC_SW;
+ if (dio_flags & IOMAP_DIO_FS_ATOMIC)
+ iomi.flags |= IOMAP_FS_ATOMIC;
else if (iocb->ki_flags & IOCB_ATOMIC)
- iomi.flags |= IOMAP_ATOMIC_HW;
+ iomi.flags |= IOMAP_BIO_ATOMIC;

/* for data sync or sync, we need sync completion processing */
if (iocb_is_dsync(iocb)) {
diff --git a/fs/iomap/trace.h b/fs/iomap/trace.h
index 69af89044ebd..4b71f1711b69 100644
--- a/fs/iomap/trace.h
+++ b/fs/iomap/trace.h
@@ -99,7 +99,8 @@ DEFINE_RANGE_EVENT(iomap_dio_rw_queued);
{ IOMAP_FAULT, "FAULT" }, \
{ IOMAP_DIRECT, "DIRECT" }, \
{ IOMAP_NOWAIT, "NOWAIT" }, \
- { IOMAP_ATOMIC_HW, "ATOMIC_HW" }
+ { IOMAP_BIO_ATOMIC, "ATOMIC_BIO" }, \
+ { IOMAP_FS_ATOMIC, "ATOMIC_FS" }

#define IOMAP_F_FLAGS_STRINGS \
{ IOMAP_F_NEW, "NEW" }, \
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 16739c408af3..4ad80179173a 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -755,9 +755,9 @@ xfs_file_dio_write_atomic(
&xfs_dio_write_ops, dio_flags, NULL, 0);

if (ret == -EAGAIN && !(iocb->ki_flags & IOCB_NOWAIT) &&
- !(dio_flags & IOMAP_DIO_ATOMIC_SW)) {
+ !(dio_flags & IOMAP_DIO_FS_ATOMIC)) {
xfs_iunlock(ip, iolock);
- dio_flags = IOMAP_DIO_ATOMIC_SW | IOMAP_DIO_FORCE_WAIT;
+ dio_flags = IOMAP_DIO_FS_ATOMIC | IOMAP_DIO_FORCE_WAIT;
iolock = XFS_IOLOCK_EXCL;
goto retry;
}
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 6c963786530d..71ddd5979091 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -830,7 +830,7 @@ xfs_direct_write_iomap_begin(
xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
xfs_fileoff_t end_fsb = xfs_iomap_end_fsb(mp, offset, length);
xfs_fileoff_t orig_end_fsb = end_fsb;
- bool atomic_hw = flags & IOMAP_ATOMIC_HW;
+ bool atomic_bio = flags & IOMAP_BIO_ATOMIC;
int nimaps = 1, error = 0;
unsigned int reflink_flags = 0;
bool shared = false;
@@ -895,7 +895,7 @@ xfs_direct_write_iomap_begin(
if (error)
goto out_unlock;
if (shared) {
- if (atomic_hw &&
+ if (atomic_bio &&
!xfs_bmap_valid_for_atomic_write(&cmap,
offset_fsb, end_fsb)) {
error = -EAGAIN;
@@ -909,7 +909,7 @@ xfs_direct_write_iomap_begin(

needs_alloc = imap_needs_alloc(inode, flags, &imap, nimaps);

- if (atomic_hw) {
+ if (atomic_bio) {
error = -EAGAIN;
/*
* Use CoW method for when we need to alloc > 1 block,
@@ -1141,11 +1141,11 @@ xfs_atomic_write_iomap_begin(
ASSERT(flags & IOMAP_WRITE);
ASSERT(flags & IOMAP_DIRECT);

- if (flags & IOMAP_ATOMIC_SW)
+ if (flags & IOMAP_FS_ATOMIC)
return xfs_atomic_write_sw_iomap_begin(inode, offset, length,
flags, iomap, srcmap);

- ASSERT(flags & IOMAP_ATOMIC_HW);
+ ASSERT(flags & IOMAP_BIO_ATOMIC);
return xfs_direct_write_iomap_begin(inode, offset, length, flags,
iomap, srcmap);
}
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 9cd93530013c..5e44ca17a64a 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -189,9 +189,9 @@ struct iomap_folio_ops {
#else
#define IOMAP_DAX 0
#endif /* CONFIG_FS_DAX */
-#define IOMAP_ATOMIC_HW (1 << 9) /* HW-based torn-write protection */
-#define IOMAP_DONTCACHE (1 << 10)
-#define IOMAP_ATOMIC_SW (1 << 11)/* SW-based torn-write protection */
+#define IOMAP_DONTCACHE (1 << 9)
+#define IOMAP_BIO_ATOMIC (1 << 10) /* Use REQ_ATOMIC on single bio */
+#define IOMAP_FS_ATOMIC (1 << 11) /* FS-based torn-write protection */

struct iomap_ops {
/*
@@ -504,9 +504,9 @@ struct iomap_dio_ops {
#define IOMAP_DIO_PARTIAL (1 << 2)

/*
- * Use software-based torn-write protection.
+ * Use FS-based torn-write protection.
*/
-#define IOMAP_DIO_ATOMIC_SW (1 << 3)
+#define IOMAP_DIO_FS_ATOMIC (1 << 3)

ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
--
2.31.1

Next message: kth: "[PATCH] fs: Fix typo from smpfs to smbfs in filesystem documentation"
Previous message: John Garry: "[PATCH v5 09/10] xfs: Allow block allocator to take an alignment hint"
In reply to: John Garry: "Re: [PATCH v5 09/10] xfs: Allow block allocator to take an alignment hint"
Next in thread: Christoph Hellwig: "Re: [PATCH RFC v5 10/10] iomap: Rename ATOMIC flags again"
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