[PATCH 33/67] xfs: constrain dirty buffers while formatting a staged btree

Darrick J. Wong
2024-03-26T03:11:27Z

From: Darrick J. Wong <djwong@kernel.org>

Source kernel commit: e069d549705e49841247acf9b3176744e27d5425

Constrain the number of dirty buffers that are locked by the btree
staging code at any given time by establishing a threshold at which we
put them all on the delwri queue and push them to disk. This limits
memory consumption while writing out new btrees.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bill O'Donnell <bodonnel@redhat.com>
---
libxfs/xfs_btree_staging.c | 50 ++++++++++++++++++++++++++++++++++----------
libxfs/xfs_btree_staging.h | 10 +++++++++
repair/agbtree.c | 1 +
3 files changed, 50 insertions(+), 11 deletions(-)

diff --git a/libxfs/xfs_btree_staging.c b/libxfs/xfs_btree_staging.c
index a6f0d7d3b286..d4164e37bd38 100644
--- a/libxfs/xfs_btree_staging.c
+++ b/libxfs/xfs_btree_staging.c
@@ -333,24 +333,41 @@ xfs_btree_commit_ifakeroot(
/*
* Put a btree block that we're loading onto the ordered list and release it.
* The btree blocks will be written to disk when bulk loading is finished.
+ * If we reach the dirty buffer threshold, flush them to disk before
+ * continuing.
*/
-static void
+static int
xfs_btree_bload_drop_buf(
- struct list_head *buffers_list,
- struct xfs_buf **bpp)
+ struct xfs_btree_bload *bbl,
+ struct list_head *buffers_list,
+ struct xfs_buf **bpp)
{
- if (*bpp == NULL)
- return;
+ struct xfs_buf *bp = *bpp;
+ int error;
+
+ if (!bp)
+ return 0;

/*
* Mark this buffer XBF_DONE (i.e. uptodate) so that a subsequent
* xfs_buf_read will not pointlessly reread the contents from the disk.
*/
- (*bpp)->b_flags |= XBF_DONE;
+ bp->b_flags |= XBF_DONE;

- xfs_buf_delwri_queue_here(*bpp, buffers_list);
- xfs_buf_relse(*bpp);
+ xfs_buf_delwri_queue_here(bp, buffers_list);
+ xfs_buf_relse(bp);
*bpp = NULL;
+ bbl->nr_dirty++;
+
+ if (!bbl->max_dirty || bbl->nr_dirty < bbl->max_dirty)
+ return 0;
+
+ error = xfs_buf_delwri_submit(buffers_list);
+ if (error)
+ return error;
+
+ bbl->nr_dirty = 0;
+ return 0;
}

/*
@@ -422,7 +439,10 @@ xfs_btree_bload_prep_block(
*/
if (*blockp)
xfs_btree_set_sibling(cur, *blockp, &new_ptr, XFS_BB_RIGHTSIB);
- xfs_btree_bload_drop_buf(buffers_list, bpp);
+
+ ret = xfs_btree_bload_drop_buf(bbl, buffers_list, bpp);
+ if (ret)
+ return ret;

/* Initialize the new btree block. */
xfs_btree_init_block_cur(cur, new_bp, level, nr_this_block);
@@ -770,6 +790,7 @@ xfs_btree_bload(
cur->bc_nlevels = bbl->btree_height;
xfs_btree_set_ptr_null(cur, &child_ptr);
xfs_btree_set_ptr_null(cur, &ptr);
+ bbl->nr_dirty = 0;

xfs_btree_bload_level_geometry(cur, bbl, level, nr_this_level,
&avg_per_block, &blocks, &blocks_with_extra);
@@ -808,7 +829,10 @@ xfs_btree_bload(
xfs_btree_copy_ptrs(cur, &child_ptr, &ptr, 1);
}
total_blocks += blocks;
- xfs_btree_bload_drop_buf(&buffers_list, &bp);
+
+ ret = xfs_btree_bload_drop_buf(bbl, &buffers_list, &bp);
+ if (ret)
+ goto out;

/* Populate the internal btree nodes. */
for (level = 1; level < cur->bc_nlevels; level++) {
@@ -850,7 +874,11 @@ xfs_btree_bload(
xfs_btree_copy_ptrs(cur, &first_ptr, &ptr, 1);
}
total_blocks += blocks;
- xfs_btree_bload_drop_buf(&buffers_list, &bp);
+
+ ret = xfs_btree_bload_drop_buf(bbl, &buffers_list, &bp);
+ if (ret)
+ goto out;
+
xfs_btree_copy_ptrs(cur, &child_ptr, &first_ptr, 1);
}

diff --git a/libxfs/xfs_btree_staging.h b/libxfs/xfs_btree_staging.h
index bd5b3f004823..f0a5007284ef 100644
--- a/libxfs/xfs_btree_staging.h
+++ b/libxfs/xfs_btree_staging.h
@@ -112,6 +112,16 @@ struct xfs_btree_bload {
* height of the new btree.
*/
unsigned int btree_height;
+
+ /*
+ * Flush the new btree block buffer list to disk after this many blocks
+ * have been formatted. Zero prohibits writing any buffers until all
+ * blocks have been formatted.
+ */
+ uint16_t max_dirty;
+
+ /* Number of dirty buffers. */
+ uint16_t nr_dirty;
};

int xfs_btree_bload_compute_geometry(struct xfs_btree_cur *cur,
diff --git a/repair/agbtree.c b/repair/agbtree.c
index 10a0c7e48c9a..981d8e340bf2 100644
--- a/repair/agbtree.c
+++ b/repair/agbtree.c
@@ -23,6 +23,7 @@ init_rebuild(
memset(btr, 0, sizeof(struct bt_rebuild));

bulkload_init_ag(&btr->newbt, sc, oinfo);
+ btr->bload.max_dirty = XFS_B_TO_FSBT(sc->mp, 256U << 10); /* 256K */
bulkload_estimate_ag_slack(sc, &btr->bload, est_agfreeblocks);
}