[PATCH v2 11/11] xfs: Allow block allocator to take an alignment hint

John Garry
2025-02-13T13:57:30Z

When issuing an atomic write by the CoW method, give the block allocator a
hint to naturally align the data blocks.

This means that we have a better chance to issuing the atomic write via
HW offload next time.

Signed-off-by: John Garry <john.g.garry@oracle.com>
---
fs/xfs/libxfs/xfs_bmap.c | 7 ++++++-
fs/xfs/libxfs/xfs_bmap.h | 6 +++++-
fs/xfs/xfs_reflink.c | 8 ++++++--
3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 0ef19f1469ec..9bfdfb7cdcae 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -3454,6 +3454,12 @@ xfs_bmap_compute_alignments(
align = xfs_get_cowextsz_hint(ap->ip);
else if (ap->datatype & XFS_ALLOC_USERDATA)
align = xfs_get_extsz_hint(ap->ip);
+
+ if (align > 1 && ap->flags & XFS_BMAPI_EXTSZALIGN)
+ args->alignment = align;
+ else
+ args->alignment = 1;
+
if (align) {
if (xfs_bmap_extsize_align(mp, &ap->got, &ap->prev, align, 0,
ap->eof, 0, ap->conv, &ap->offset,
@@ -3782,7 +3788,6 @@ xfs_bmap_btalloc(
.wasdel = ap->wasdel,
.resv = XFS_AG_RESV_NONE,
.datatype = ap->datatype,
- .alignment = 1,
.minalignslop = 0,
};
xfs_fileoff_t orig_offset;
diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h
index 4b721d935994..7a31697331dc 100644
--- a/fs/xfs/libxfs/xfs_bmap.h
+++ b/fs/xfs/libxfs/xfs_bmap.h
@@ -87,6 +87,9 @@ struct xfs_bmalloca {
/* Do not update the rmap btree. Used for reconstructing bmbt from rmapbt. */
#define XFS_BMAPI_NORMAP (1u << 10)

+/* Try to naturally align allocations to extsz hint */
+#define XFS_BMAPI_EXTSZALIGN (1u << 11)
+
#define XFS_BMAPI_FLAGS \
{ XFS_BMAPI_ENTIRE, "ENTIRE" }, \
{ XFS_BMAPI_METADATA, "METADATA" }, \
@@ -98,7 +101,8 @@ struct xfs_bmalloca {
{ XFS_BMAPI_REMAP, "REMAP" }, \
{ XFS_BMAPI_COWFORK, "COWFORK" }, \
{ XFS_BMAPI_NODISCARD, "NODISCARD" }, \
- { XFS_BMAPI_NORMAP, "NORMAP" }
+ { XFS_BMAPI_NORMAP, "NORMAP" },\
+ { XFS_BMAPI_EXTSZALIGN, "EXTSZALIGN" }

static inline int xfs_bmapi_aflag(int w)
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index d097d33dc000..033dff86ecf0 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -445,6 +445,11 @@ xfs_reflink_fill_cow_hole(
int nimaps;
int error;
bool found;
+ uint32_t bmapi_flags = XFS_BMAPI_COWFORK |
+ XFS_BMAPI_PREALLOC;
+
+ if (atomic)
+ bmapi_flags |= XFS_BMAPI_EXTSZALIGN;

resaligned = xfs_aligned_fsb_count(imap->br_startoff,
imap->br_blockcount, xfs_get_cowextsz_hint(ip));
@@ -478,8 +483,7 @@ xfs_reflink_fill_cow_hole(
/* Allocate the entire reservation as unwritten blocks. */
nimaps = 1;
error = xfs_bmapi_write(tp, ip, imap->br_startoff, imap->br_blockcount,
- XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC, 0, cmap,
- &nimaps);
+ bmapi_flags, 0, cmap, &nimaps);
if (error)
goto out_trans_cancel;

--
2.31.1