From: Darrick J. Wong <djwong@xxxxxxxxxx> Source kernel commit: 26de64629d8b439a03bce243f14a46f7440729f3 When constructing a new btree, xfs_btree_bload_node needs to read the btree blocks for level N to compute the keyptrs for the blocks that will be loaded into level N+1. The level N blocks must be formatted at that point. A subsequent patch will change the btree bulkloader to write new btree blocks in 256K chunks to moderate memory consumption if the new btree is very large. As a consequence of that, it's possible that the buffers for lower level blocks might have been reclaimed by the time the node builder comes back to the block. Therefore, change xfs_btree_bload_node to read the lower level blocks to handle the reclaimed buffer case. As a side effect, the read will increase the LRU refs, which will bias towards keeping new btree buffers in memory after the new btree commits. Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> Reviewed-by: Bill O'Donnell <bodonnel@xxxxxxxxxx> --- libxfs/xfs_btree.c | 2 +- libxfs/xfs_btree.h | 3 +++ libxfs/xfs_btree_staging.c | 7 ++++++- 3 files changed, 10 insertions(+), 2 deletions(-) diff --git a/libxfs/xfs_btree.c b/libxfs/xfs_btree.c index 85f8bef06..97962fc16 100644 --- a/libxfs/xfs_btree.c +++ b/libxfs/xfs_btree.c @@ -1327,7 +1327,7 @@ xfs_btree_get_buf_block( * Read in the buffer at the given ptr and return the buffer and * the block pointer within the buffer. */ -STATIC int +int xfs_btree_read_buf_block( struct xfs_btree_cur *cur, const union xfs_btree_ptr *ptr, diff --git a/libxfs/xfs_btree.h b/libxfs/xfs_btree.h index 4d68a58be..e0875cec4 100644 --- a/libxfs/xfs_btree.h +++ b/libxfs/xfs_btree.h @@ -700,6 +700,9 @@ void xfs_btree_set_ptr_null(struct xfs_btree_cur *cur, int xfs_btree_get_buf_block(struct xfs_btree_cur *cur, const union xfs_btree_ptr *ptr, struct xfs_btree_block **block, struct xfs_buf **bpp); +int xfs_btree_read_buf_block(struct xfs_btree_cur *cur, + const union xfs_btree_ptr *ptr, int flags, + struct xfs_btree_block **block, struct xfs_buf **bpp); void xfs_btree_set_sibling(struct xfs_btree_cur *cur, struct xfs_btree_block *block, const union xfs_btree_ptr *ptr, int lr); diff --git a/libxfs/xfs_btree_staging.c b/libxfs/xfs_btree_staging.c index ae2d9c63f..be0b43e45 100644 --- a/libxfs/xfs_btree_staging.c +++ b/libxfs/xfs_btree_staging.c @@ -489,7 +489,12 @@ xfs_btree_bload_node( ASSERT(!xfs_btree_ptr_is_null(cur, child_ptr)); - ret = xfs_btree_get_buf_block(cur, child_ptr, &child_block, + /* + * Read the lower-level block in case the buffer for it has + * been reclaimed. LRU refs will be set on the block, which is + * desirable if the new btree commits. + */ + ret = xfs_btree_read_buf_block(cur, child_ptr, 0, &child_block, &child_bp); if (ret) return ret;
