From 5a6523ecf45c88704cea61b3de127d5fc0e2bb9b Mon Sep 17 00:00:00 2001
From: Auke Kok <auke.kok@versity.com>
Date: Wed, 25 Mar 2026 13:53:29 -0700
Subject: [PATCH] Ramping up data preallocation

Ramps up data preallocation based on the number of online
blocks. This results in a simple 2<<n block allocation pattern
until n=11 (2048) - the default value of data_prealloc_blocks.

Signed-off-by: Auke Kok <auke.kok@versity.com>
---
 kmod/src/data.c            | 10 +++++++++-
 tests/golden/data-prealloc | 12 ++++++------
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/kmod/src/data.c b/kmod/src/data.c
index 0abb48c0..b6ca5eb1 100644
--- a/kmod/src/data.c
+++ b/kmod/src/data.c
@@ -422,6 +422,8 @@ static int alloc_block(struct super_block *sb, struct inode *inode,
 
 	mutex_lock(&datinf->mutex);
 
+	scoutfs_inode_get_onoff(inode, &online, &offline);
+
 	/* default to single allocation at the written block */
 	start = iblock;
 	count = 1;
@@ -444,7 +446,6 @@ static int alloc_block(struct super_block *sb, struct inode *inode,
 		 * the preallocation size to the number of online
 		 * blocks.
 		 */
-		scoutfs_inode_get_onoff(inode, &online, &offline);
 		if (iblock > 1 && iblock == online) {
 			ret = scoutfs_ext_next(sb, &data_ext_ops, &args,
 					       iblock, 1, &found);
@@ -486,6 +487,13 @@ static int alloc_block(struct super_block *sb, struct inode *inode,
 		/* trim count by next extent after iblock */
 		if (found.len && found.start > start && found.start < start + count)
 			count = (found.start - start);
+
+		/*
+		 * Ramp the aligned region size up proportionally with
+		 * the file's online block count rather than jumping to
+		 * the full prealloc size.
+		 */
+		count = max_t(u64, 1, min(count, online));
 	}
 
 	/* overall prealloc limit */
diff --git a/tests/golden/data-prealloc b/tests/golden/data-prealloc
index 19efd20a..69fb3a23 100644
--- a/tests/golden/data-prealloc
+++ b/tests/golden/data-prealloc
@@ -8,10 +8,10 @@
 /mnt/test/test/data-prealloc/file-1: extents: 32
 /mnt/test/test/data-prealloc/file-2: extents: 32
 == any writes to region prealloc get full extents
-/mnt/test/test/data-prealloc/file-1: extents: 4
-/mnt/test/test/data-prealloc/file-2: extents: 4
-/mnt/test/test/data-prealloc/file-1: extents: 4
-/mnt/test/test/data-prealloc/file-2: extents: 4
+/mnt/test/test/data-prealloc/file-1: extents: 8
+/mnt/test/test/data-prealloc/file-2: extents: 8
+/mnt/test/test/data-prealloc/file-1: extents: 8
+/mnt/test/test/data-prealloc/file-2: extents: 8
 == streaming offline writes get full extents either way
 /mnt/test/test/data-prealloc/file-1: extents: 4
 /mnt/test/test/data-prealloc/file-2: extents: 4
@@ -20,8 +20,8 @@
 == goofy preallocation amounts work
 /mnt/test/test/data-prealloc/file-1: extents: 6
 /mnt/test/test/data-prealloc/file-2: extents: 6
-/mnt/test/test/data-prealloc/file-1: extents: 6
-/mnt/test/test/data-prealloc/file-2: extents: 6
+/mnt/test/test/data-prealloc/file-1: extents: 10
+/mnt/test/test/data-prealloc/file-2: extents: 10
 /mnt/test/test/data-prealloc/file-1: extents: 3
 /mnt/test/test/data-prealloc/file-2: extents: 3
 == block writes into region allocs hole